Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

"Online First" included
Without submitted and only approved publications
Only approved publications

35175 Publications

P1802 - Universal Building Blocks for Radiolabeling

Pietzsch, H.-J.; Walther, M.

The present invention describes novel chelators (multidentate ligands) and precompounds for complexation of radiometals and non-radioactive counterparts, for use in radiopharmacy. The invention includes a process and a kit involving such chelators.
Active moieties directing to a pharmaceutical target (such as peptides or proteins) can be attached to the chelator very easily via the so called “click-chemistry” forming a triazole-ring moiety. The aromatic triazole-nitrogen itself acts as a new and “soft” nucleophilic site enabling for complexation of various radiometals or non-radioactive counterparts. The chelators are capable of fast complexation at low temperature.

  • Patent
    PCT/EP2019/054954 - Offenlegung 06.09.2019; Nachanmeldungen: EP

Permalink: https://www.hzdr.de/publications/Publ-31180
Publ.-Id: 31180


P1801 - Method for the preparation of nanoscale DNA-encircled lipid bilayers

Fahmy, K.; TU Dresden

The present invention relates to a method for the preparation of nanoscale nucleic acid-encircled lipid bilayers, the nanoscale nucleic acid-encircled lipid bilayers and their use.

  • Patent
    PCT/EP2019/054271 - Offenlegung 29.08.2019; Nachanmeldungen: EP

Permalink: https://www.hzdr.de/publications/Publ-31179
Publ.-Id: 31179


P1714 - Verfahren zur Trennung von Mineralien

Babel, B. M.; Kupka, N.; Rudolph, M.

Die Erfindung betrifft ein Verfahren zur Trennung von Mineralien aus Mineralgemengen mittels Flotation unter Verwendung eines Drückers. Dabei ist vorgesehen, dass kolloidales Siliciumdioxid einem wässerigen, das Mineralgemenge enthaltenden Gemisch als Drücker zugesetzt wird.

  • Patent
    DE102017129673 - Erteilung 13.12.2018

Permalink: https://www.hzdr.de/publications/Publ-31178
Publ.-Id: 31178


P1713 - Verfahren zum Herstellen eines Probenpräparats, Probenpräparat und Verfahren zum Untersuchen eines Probenmaterials

Bartzsch, A.; Gilbricht, S.; Bachmann, K.; Heinig, T.

Die Erfindung betrifft ein Verfahren zum Herstellen eines Probenpräparats, ein Probenpräparat und ein Verfahren zum Untersuchen eines Probenmaterials, wobei das Probenpräparat zur Untersuchung eines granularen Probenmaterials dient und herstellbar ist, indem das granulare Probenmaterial mit einem flüssigen ersten Einbettmaterial vermengt wird, das Einbettmaterial unter Ausbildung eines Vorpräparats verfestigt wird und unter Ausbildung von Trennflächen in mehrere Teilstücke zertrennt wird, die Teilstücke mit mehreren Trennflächen in einer gemeinsamen Ebene liegend in einem flüssigen zweiten Einbettmaterial eingebettet werden, und das zweite Einbettmaterial verfestigt wird.

  • Patent
    DE102017128355 - Erteilung 17.01.2019

Permalink: https://www.hzdr.de/publications/Publ-31177
Publ.-Id: 31177


P1712 - Method for determining the level of molten magnesium in a titanium reduction cell

Stefani, F.; Krauter, N.; Wondrak, T.; Gundrum, T.; Eckert, S.

FIELD: metallurgy. SUBSTANCE: invention relates to the metallurgy industry. Magnesium level and the skull characteristics in the titanium reduction reactor determining method, based on the EMF measurements in the receiving coil, induced by the electromagnetic field from located around the retort the exciting windings set, contains the steps, on which for the determination currents of different frequencies are used, at that, first, by the electrodynamics equations numerical solving, developing the reference base of the EMF calculated values in the located above the reactor receiving coil, with the molten magnesium different specified levels, different titanium skull given positions and sizes for the supply current given set of frequencies in the range of 1–50 Hz, and then, in the process of titanium reduction, with the same set of current parameters in the excitation coils, measuring the EMF values in the receiving coil, which are compared with the reference ones, and the least standard deviation is determined by the smallest standard deviation method, and the molten magnesium level, the titanium skull position and size are judged by it. EFFECT: increase in the molten metal level determining accuracy and the expansion in the method possibilities. 5 cl, 13 dwg

  • Patent
    RU2676845 - Erteilung 11.01.2019

Permalink: https://www.hzdr.de/publications/Publ-31176
Publ.-Id: 31176


P1711 - Peptid-Trägermaterialien als biofunktionalisierte Sammler

Lederer, F.; Pollmann, K.; Rudolph, M.

Die Erfindung betrifft ein Verfahren zur selektiven Abtrennung von Submikro- oder Mikropartikeln mittels eines biofunktionalisierten Sammlers, ein biofunktionalisierter Sammler umfassend mindestens ein selektiv bindendes Peptid, ein selektiv bindendes Peptid und die Verwendung eines Verfahrens oder eines biofunktionalisierten Sammlers zur Gewinnung oder Rückgewinnung von Submikro- oder Mikropartikeln.

  • Patent
    DE102017219800 - Offenlegung 09.05.2019

Permalink: https://www.hzdr.de/publications/Publ-31175
Publ.-Id: 31175


P1710 - 4-(Furan-2-yl)-1H-pyrazolo[3,4-d]pyrimidin-6-amin-Derivate und deren Verwendung

Moldovan, R.-P.; Lai, T. H.; Schröder, S.; Dukic-Stefanovic, S.; Deuther-Conrad, W.; Brust, P.; Fischer, S.; Ludwig, F.-A.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel I worin eine Phenylgruppe oder eine Pyridylgruppe ist, R1 aus der Gruppe ausgewählt ist, die aus Wasserstoff, Halogen und -CN besteht; R2 aus der Gruppe ausgewählt ist, die aus Fluor, einer fluorierten Alkylgruppe mit 1 bis 12 Kohlenstoffatomen, einer fluorierten Alkoxygruppe mit 1 bis 12 Kohlenstoffatomen und einer fluorierten Ethergruppe besteht; Z -(CH2)n- oder -(CH2)m-C(O)-(CH2)p- ist, wobei n eine Ganzzahl von 1 bis 12 ist und wobei m und p gleich oder verschieden sein können und jeweils 0 oder eine Ganzzahl von 1 bis 12 sind.

  • Patent
    DE102017125533 - Offenlegung 02.05.2019; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-31174
Publ.-Id: 31174


P1709 - Vorrichtung und Verfahren zum Erzeugen von Ionenpulsen

Wilhelm, R. A.; Klingner, N.; Facsko, S.

Die Erfindung betrifft eine Vorrichtung und ein Verfahren zum Erzeugen von Ionenpulsen, insbesondere von ultrakurzen Ionenpulsen, wobei die Vorrichtung eine Vakuumkammer, eine in der Vakuumkammer angeordnete Kathode, einen Laser zum Erzeugen von Laserpulsen, die auf die Kathode auftreffen und aus dieser Elektronen herauslösen, eine erste Beschleunigungseinrichtung zum Beschleunigen der Elektronen unter Erzeugung von Ionenpulsen in ein Ionisationsvolumen, eine Zuführeinrichtung zum Zuführen einer zu ionisierenden Substanzen das Ionisationsvolumen und eine zweite Beschleunigungseinrichtung zum Beschleunigen der Ionen unter Ausbildung von Ionenpulsen aus dem Ionisationsvolumen heraus aufweist.

  • Patent
    DE102017218456 - Erteilung 22.11.2018

Permalink: https://www.hzdr.de/publications/Publ-31173
Publ.-Id: 31173


P1708 - Justiereinrichtung

Bartheld, U.

Die Erfindung betrifft eine Justiereinrichtung zur räumlichen Lageeinstellung eines Objekts (4), umfassend eine 10 Mehrzahl übereinander angeordneter Plattenelemente (11,12,13,14), die an einander zugewandten Seiten ineinandergreifende Radialführungsstrukturen (21,22) aufweisen, wobei auf einer Grundplatte (11) zumindest ein Paar von Verschiebungsplatten (12) und ein Paar von 15 Neigungsplatten (13) angeordnet sind, wobei Verschiebungsplatten (12) eine konstante Dicke aufweisen und ihre jeweilige obere Radialführungsstruktur (21) und untere Radialführungsstruktur (22) exzentrisch versetzt zueinander angeordnet sind und Neigungsplatten (13) eine variable Dicke 20 aufweisen und ihre jeweilige obere Radialführungsstruktur (21) und untere Radialführungsstruktur (22) konzentrisch zueinander angeordnet sind.

  • Patent
    DE102017123920 - Erteilung 20.12.2018; Nachanmeldungen: WO, US

Permalink: https://www.hzdr.de/publications/Publ-31172
Publ.-Id: 31172


P1707 - 3-Methylbenzo[e]imidazo[5,1-c][1,2,4]triazin-Derivate zur Verwendung als Inhibitoren von Phosphodiesterase 2A

Scheunemann, M.; Ritawidya, R.; Brust, P.; Schröder, S.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel I oder ein pharmazeutisch akzeptables Salz davon, wobei A1, A2 und A3 unabhängig voneinander jeweils CH oder N sind; R1 -OR2 oder eine (3-Methyloxetan-3-yl)methyloxy-Gruppe ist, wobei R2 eine substituierte oder unsubstituierte Alkylgruppe mit 1 bis 12 Kohlenstoffatomen ist; X1 aus der Gruppe ausgewählt ist, die aus Wasserstoff, Halogen, Methyl -NO2 und einer kationischen Trialkylammoniumgruppe besteht; X2 aus der Gruppe ausgewählt ist, die aus Halogen, -NO2, einer Boronsäureester-Gruppe, einer Aryliodonium-Gruppe und einer spirocyclischen Iodoniumylid-Gruppe besteht, wobei die Boronsäureester-Gruppe eine Boronsäurepinakolester-Gruppe ist.

  • Patent
    DE102017119516 - Offenlegung 28.02.2019

Permalink: https://www.hzdr.de/publications/Publ-31171
Publ.-Id: 31171


P1705 - Wärmeübertrager

TU Dresden; Hampel, U.

Die Erfindung betrifft einen Wärmeübertrager mit wenigstens einer Trennwand und von wenigstens einer Seite der Trennwand abstehenden und die Oberfläche der Trennwand vergrößernden Oberflächenelementen, die von einem Fluid umströmbar sind. Es ist die Aufgabe der vorliegenden Erfindung, massearme Wärmeübertrager mit großer thermischer Übertragungsleistung vorzuschlagen. Diese Aufgabe wird durch einen Wärmeübertrager gelöst, bei dem die Oberflächenelemente flossenartig von der Trennwand abstehend ausgebildet sind und die Oberflächenelemente Verstärkungswülste aufweisen, wobei sich die Verstärkungswülste bis zu der Trennwand hin erstrecken.

  • Patent
    DE102017214261 - Offenlegung: 21.02.2019; Nachanmeldungen: WO, EP, JP, US

Permalink: https://www.hzdr.de/publications/Publ-31170
Publ.-Id: 31170


P1704 - Vorrichtung, Anordnung und Verfahren zum Charakterisieren der Torsion, der Rotation und/oder der Positionierung einer Welle

Buchenau, D.

Die Erfindung betrifft eine Vorrichtung, eine Anordnung und ein Verfahren zum Charakterisieren der Torsion, Rotation und/oder Positionierung einer Welle, wobei von einem zwischen mindestens zwei Magnetfelddetektoren angeordneten Magnetfelderzeuger mittels eines periodischen Erregersignals ein periodisches Magnetfeld erzeugt wird, das von der Welle modifiziert wird und an jedem der Magnetfelddetektoren ein Ausgangssignal hervorruft, wobei die amplitudenmäßige oder phasenmäßige Differenz zwischen dem Erregersignal und dem ersten Ausgangssignal als erste Messgröße und zwischen dem Erregersignal und dem zweiten Ausgangssignal als zweite Messgröße erfasst wird, die Summe und/oder die Differenz der ersten und der zweiten Messgröße gebildet wird, und basierend darauf die Torsion, Rotation und/oder Positionierung der Welle charakterisiert wird.

  • Patent
    DE102017111055 - Erteilung 06.09.2018; Nachanmeldungen: WO, CN, EP, US

Permalink: https://www.hzdr.de/publications/Publ-31169
Publ.-Id: 31169


Moisture repelling perovskite nanowires for higher stability in energy applications

Rajbhar, M. K.; Das, P.; Satpati, B.; Möller, W.; Ramgir, N.; Chatterjee, S.

Perovskite nanowires are known to be strongly interacting with the moisture. In this work, we demonstrate that strontium manganate (SrMnO3) nanowire, an oxide perovskite, which is initially superhydrophilic, becomes a water repellent upon suitable modification by the ion beam. Highly crystalline SrMnO3 nanowires have been synthesized hydrothermally with an average diameter of about 60 nm and possess 4H crystal structure. The nanowires have been systematically irradiated with nitrogen ions at different energies and in a specific range of ion fluence. For low energy (5 keV), and at a relatively high threshold ion fluence, the nanowire surface starts to become hydrophobic, and the hydrophobicity increases with the ion fluence. However, at higher energies (50–100 keV), the sample surface becomes superhydrophobic at relatively low fluence, and beyond this point, the contact angle is almost independent of the ion fluence. Using state-of-the-art TRI3DYN computer-based simulation, and by employing density functional theory based calculations, we have shown that at low ion energy, the defects turn out to be a dominating factor for the samples to become hydrophobic. At higher ion energies, nanowelding and porous structure lead the way to become superhydrophobic.

Permalink: https://www.hzdr.de/publications/Publ-31168
Publ.-Id: 31168


P1703 - Schichtanordnung, elektronisches Bauteil mit einer Schichtanordnung und Verwendung einer Schichtanordnung

TU Bergakademie Freiberg; Rebohle, L.

Gemäß verschiedenen Ausführungsformen wird eine Schichtanordnung (100) bereitgestellt, welche Folgendes aufweist: eine erste Barriereschicht (102a) und eine zweite Barriereschicht (102b), wobei die beiden Barriereschichten (102a, 102b) elektrisch isolierend sind, und eine Schichtstruktur (110), welche zwischen den beiden Barriereschichten (102a, 102b) angeordnet ist und derart eingerichtet ist, dass diese mittels eines elektrischen Feldes einer ersten Polarität (311a) und mittels eines elektrischen Feldes einer der ersten Polarität entgegengesetzten zweiten Polarität (311b) remanent polarisierbar ist, wobei die Schichtstruktur (110) mindestens eine erste Ladungsspeicherschicht (104a), eine zweite Ladungsspeicherschicht (104b) und eine zwischen der ersten Ladungsspeicherschicht (104a) und der zweiten Ladungsspeicherschicht (104b) angeordnete elektrisch isolierende Tunnelbarriereschicht (106) aufweist.

  • Patent
    DE102017109082 - Offenlegung 31.10.2018

Permalink: https://www.hzdr.de/publications/Publ-31167
Publ.-Id: 31167


P1702 - Vorrichtung zum Charakterisieren des elektrischen Widerstandes eines Messobjekts

Kosub, T.; Makarov, D.

Die Erfindung betrifft eine Messvorrichtung zum Charakterisieren des elektrischen Widerstandes eines Messobjekts, aufweisend eine elektrische Energiequelle mit zwei Polen, eine Spannungsmesseinrichtung mit zwei Messeingängen, vier Anschlusskontakte zum Anschließen von vier Kontaktelektroden, und eine Schalteinrichtung zum variablen paarweisen elektrischen Verbinden je eines der Pole und Messeingänge mit je einem der Anschlusskontakte unter Ausbildung unterschiedlicher Beschaltungskonfigurationen, wobei die Messvorrichtung zum Durchführen von mindestens vier Messsequenzen mit unterschiedlichen Beschaltungskonfigurationen und zum Ermitteln des Längswiderstandes des Messobjekts unter Einbeziehung von in diesen Beschaltungskonfigurationen erfassten Strom- und Spannungssignalen ausgebildet ist.

  • Patent
    DE102017105317 - Erteilung 09.05.2018, Nachanmeldungen: WO, CN, EP, US

Permalink: https://www.hzdr.de/publications/Publ-31166
Publ.-Id: 31166


PIConGPU setup: Gas-foil target for ion acceleration

Pausch, R.; Levy, D.; Andriyash, I.; Schultze-Makuch, A.; Bernert, C.; Zeil, K.; Bussmann, M.; Kluge, T.; Garten, M.; Steiniger, K.; Debus, A.

This data set contains the PIConGPU source code used for the simulations presented in "Gas-foil target for ion acceleration" and the setup files.

Keywords: PIConGPU

Related publications

  • Software in the HZDR data repository RODARE
    Publication date: 2020-06-18
    DOI: 10.14278/rodare.374
    License: GPL-3.0-only

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-31165
Publ.-Id: 31165


P1701 - In vivo stable Hg-197(m) compounds, method for the production thereof and use thereof in nuclear medical diagnostics and endoradionuclide therapy (theranostics)

Pietzsch, H.-J.; Walther, M.; Wünsche, T.

The present invention relates to in vivo stable 197(m)Hg compounds according to formula (I) for use in nuclear medical diagnostics and endoradionuclide therapy (theranostics), particularly the treatment of cancer, a method for the production of the 197(m)Hg compounds comprising the step of radiolabeling of organic precursor compounds with NCA 197(m)Hg by electrophilic substitution; and the use of the 197(m)Hg compounds for nuclear medical diagnostics and endoradionuclide therapy (theranostics), particularly the treatment of cancer.

  • Patent
    PCT/EP2018/052996 - Offenlegung 16.08.2018, Nachanmeldungen: CA, EP, US

Permalink: https://www.hzdr.de/publications/Publ-31164
Publ.-Id: 31164


P1611 - Method and system for calibration-free determination of a flow velocity of an electrically conductive fluid

Krauter, N.; Stefani, F.; Eckert, S.; Gerbeth, G.

The present invention refers to a method and a system for calibration-free determination of a flow velocity of an electrically conductive fluid (7). Each of two field coils (1a, 1b), which are designed to be positioned at a distance from each other in the respective fluid (7) and electrically insulated from the respective fluid (7), is provided simultaneously with a pulsed electrical current, wherein the two pulsed electrical currents are oppositely directed, so that a primary magnetic field is created leading to oppositely directed eddy currents induced by the primary magnetic field in the surrounding fluid (7), thereby creating a secondary magnetic field in the respective fluid (7). The secondary magnetic field is measured after the pulsed electrical currents by two magnetic field sensors (3a, 3b), which are designed to be positioned at a distance from each other in the respective fluid (7) and electrically insulated from the respective fluid (7), wherein the flow velocity is calculated from a measured time-dependent strength of the secondary magnetic field and/or its time derivative.

  • Patent
    PCT/EP2016/076967 - Offenlegung 17.05.2018; Nachanmeldungen: EP

Permalink: https://www.hzdr.de/publications/Publ-31163
Publ.-Id: 31163


P1607 - Anordnung zum Charakterisieren des Füllstandes eines elektrisch leitfähigen Materials in einem Behälter

Zürner, T.; Ratajczak, M.; Wondrak, T.; Eckert, S.

Die Erfindung betrifft eine Anordnung zum Charakterisieren des Füllstandes eines elektrisch leitfähigen Materials in einem Behälter, aufweisend ein seitlich des Behälter-Innenraumes angeordnetes Sensorelement mit einer Erregerspule und zwei gradiometrisch verschalteten Empfängerspulen, wobei die Anordnung zum Beaufschlagen der Erregerspule mit einem Wechselstrom, zum Erfassen der an den gradiometrisch verschalteten Empfängerspulen resultierenden Ausgangsspannung, zum Ermitteln des Anteils der Ausgangsspannung ohne Phasenverschiebung zu dem Wechselstrom und/oder des Anteils der Ausgangsspannung mit einer Phasenverschiebung von 90° zu dem Wechselstrom, und zum Charakterisieren des Füllstandes basierend darauf ausgebildet ist.

  • Patent
    DE102016112266 - Offenlegung 11.01.2018

Permalink: https://www.hzdr.de/publications/Publ-31162
Publ.-Id: 31162


P1606 - Verfahren und Vorrichtung zu Ga-Rückgewinnung

FCM GmbH; TU Bergakademie Freiberg; Zeidler, O.

Die vorliegende Erfindung umfasst ein Verfahren zur selektiven Abtrennung von Ga aus Ätzabwässern mit Hilfe eines Dialyseverfahrens. Hierbei wird das besondere Komplexbildungsverhaltens des Ga ausgenutzt, welches einen instabilen Tetrahalogenokomplex bildet. Dieser bildet sich nur bei ausreichend hoher Halogenidkonzentration. Da die Halogenidkonzentration über die Membran niedriger wird, zerfällt der Ga-Tetrahalogenidokomplex in der Membran, wodurch das Ga zurückgehalten wird. Andere Metalle wie In und Fe zeigen dieses Verhalten nicht, weswegen die Tetrahalogenokomplexe dieser Metalle die Membran passieren können und somit selektiv abgetrennt werden können.

  • Patent
    DE102016210451 - Offenlegung 14.12.2017; Nachanmeldungen: TW, WO

Permalink: https://www.hzdr.de/publications/Publ-31161
Publ.-Id: 31161


P1605 - Verfahren und Trägermaterial zur Bereitstellung von metallionenbindenden Molekülen zur Gewinnung und Rückgewinnung von Wertmetallen

Matys, S.; Pollmann, K.; Raff, J.; Lehmann, F.

Die Erfindung betrifft ein Verfahren zur Bereitstellung von metallionenbindenden Molekülen basierend auf der Phagen-Display-Methode mittels eines planaren Trägermaterials mit immobilisierten Metallionen. Die Erfindung betrifft weiterhin ein planares Trägermaterial mit immobilisierten Metallionen, metallionenbindende Peptide erhältlich durch das erfindungsgemäße Verfahren sowie die Verwendung der metallionenbindenden Moleküle zur Gewinnung oder Rückgewinnung von Wertmetallen.

  • Patent
    DE102016208110 - Offenlegung 16.11.2017

Permalink: https://www.hzdr.de/publications/Publ-31160
Publ.-Id: 31160


P1604 - Verfahren und Mittel zum Betrieb eines komplementären analogen rekonfigurierbaren memristiven Widerstandsschalters sowie dessen Verwendung als künstliche Synapse

Du, N.; Li, K.; Schmidt, H.; Skorupa, I.

Die Erfindung betrifft ein Verfahren zum Betrieb eines elektronischen memristiven Bauelementes, welches aus einem komplementären analogen rekonfigurierbaren memristiven bidirektionalen Widerstandsschalter besteht, welcher eine Dreilagenschicht und zwei Elektroden aufweist. Das erfindungsgemäße Verfahren schlägt angepasste Schreibprozesse vor, die mittels der Überlagerung von Schreibpulssequenzen die Festlegung eines Zustandspaares komplementärer Widerstandszustände realisieren. In Verbindung mit Lesepulsen angepasster Polarität kann das elektronische memristive Bauelement Fuzzy-Logik umsetzen und als künstliche Synapse mit der Realisierung aller vier Lernkurven für komplementäres Lernen betrieben werden. Eine Mehrzahl von Verwendungsmöglichkeiten des erfindungsgemäß betriebenen Bauelementes wird vorgeschlagen.

  • Patent
    DE102016205860 - Offenlegung: 12.10.2017; Nachanmeldungen: WO, CN, US

Permalink: https://www.hzdr.de/publications/Publ-31159
Publ.-Id: 31159


Towards 3D-Motion Tracking of Instrumented Flow Followers in Large Vessels

Buntkiel, L.; Reinecke, S.; Hampel, U.

A concept for 3D-motion tracking of instrumented flow-following sensor particles, equipped with a gyroscope, accelerometer, magnetometer and pressure sensor, has been developed. Consisting of an error state Kalman filter (ESKF) the algorithm can track the attitude of the sensor particle in relation to a reference coordinate system permanently, even under high acceleration, which interferes the attitude estimation because it is based on measuring the gravitational acceleration. Experimental results show, that using the ESKF for attitude estimation is giving accurate results even under high body acceleration.

Keywords: error state kalman filter; motion tracking; fluid dynamics; sensor particle; soft sensor

  • Open Access Logo Contribution to proceedings
    Sensor and Measurement Science International, 22.-25.06.2020, Nürnberg, Deutschland
    SMSI 2020 - Measurement Science, Hannover: AMA Service GmbH, 978-3-9819376-2-6, 309-310
    DOI: 10.5162/SMSI2020/E6.1

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-31158
Publ.-Id: 31158


P1603 - Verfahren zur Herstellung von auf Silizium basierenden Anoden für Sekundärbatterien

TU Bergakademie Freiberg; Prucnal, S.; Skorupa, W.

Die Erfindung betrifft ein Verfahren zur Herstellung von auf Silizium basierenden Anoden für Sekundärbatterien, wobei die Sekundärbatterien zumindest aus der Anode, aus mindestens einem Elektrolyten und einer Gegenelektrode bestehen. Dabei werden folgende Schritte zur Herstellung einer Anode (20) durchgeführt:
– Abscheiden einer Silizium-Schicht (3) auf einem Korngrenzen (2) aufweisenden Metallsubstrat (1), wobei die Silizium-Schicht (3) zum Metallsubstrat (1) gerichtet eine erste Grenzfläche (14) aufweist,
– Beheizen des Metallsubstrats (1) mittels einer Heizeinheit (22) auf eine Temperatur zwischen 200°C und 1000°C,
– Tempern des Bereiches der dem Metallsubstrat (1) abgewandten zweiten Grenzfläche (15) der Silizium-Schicht (3) mittels einer energieintensiven Bestrahlung während der Beheizung,
– Erzeugen von Mehrphasen im Bereich der Silizium-Schicht (3) und des Metallsubstrats (1), bestehend aus amorphem Silizium und/oder kristallinem Silizium des Siliziums der Silizium-Schicht (3) und aus kristallinem Metall des Metallsubstrats (1) und aus Silizid und
– Erzeugen von kristallinem Metall des Metallsubstrats (1).

  • Patent
    DE102016001949 - Offenlegung 17.08.2017; Nachanmeldungen: WO, CN, EP, US

Permalink: https://www.hzdr.de/publications/Publ-31157
Publ.-Id: 31157


P1509 - Verfahren zum Aufarbeiten von Bleiglas und Elektronikschrott

TU Bergakademie Freiberg; Wolf, R.

Beschrieben wird ein Verfahren zum Aufarbeiten von Bleiglas und Elektronikschrott. Erfindungsgemäß umfasst dies die Schritte Zerkleinern und Vermischen des Bleiglases und des Elektronikschrottes zu einer Charge Aufschmelzen der Charge unter Zusatz einer oder mehrerer Verbindungen aus der Gruppe der Carbonate, Oxide und Hydroxide der Alkalimetalle und Reduktion des im Bleiglas enthaltenden Bleioxids durch ein Reduktionsmittel zu metallischem Blei unter Ausbildung einer Phase enthaltend eine Metallschmelze und einer Phase enthaltend eine Glasschmelze, wobei in der Glasschmelze die Konzentration von Alkalimetalloxiden im Bereich von 20 mol.-% bis 45 mol.-%
Erdalkalimetalloxiden im Bereich von 10 mol.-% bis 25 mol.-% Siliziumdioxid im Bereich von 40 mol.-% bis 50 mol.-% liegt, bezogen auf die Gesamtmenge an Alkalimetalloxiden, Erdalkalimetalloxiden und Siliziumdioxid in der Glasschmelze.

  • Patent
    DE102016220045 - Offenlegung: 19.04.2018

Permalink: https://www.hzdr.de/publications/Publ-31156
Publ.-Id: 31156


P1510 - Self-cleaning high temperature resistant solar selective coating

Abengoa Research S.L.; Lungwitz, F.; Neubert, M.

Estructura selectiva solar con autolimpieza resistente a altas temperaturas. La presente invención se dirige a una estructura formada por una sección superior que comprende una capa superior que comprende TiO2 dopado que presenta una alta transmitancia en el espectro visible y una alta reflectancia en la región IR y propiedades de autolimpieza, una sección intermedia absorbente y un sustrato. Debido a las propiedades mencionadas y a la resistencia a altas temperaturas, la estructura es útil como estructura selectiva solar para receptores de torre en sistemas de energía solar por concentración (CSP).

  • Patent
    ES2575746 - Offenlegung 30.06.2016; Nachanmeldungen: WO, EP

Permalink: https://www.hzdr.de/publications/Publ-31155
Publ.-Id: 31155


P1506 - Complementary resistance switch,contact-connected polycrystalline piezo-or ferroelectric thin-film layer,method for encrypting a bit sequence

You, T.; Schmidt, H.; Du, N.; Bürger, D.; Skorupa, I.

Disclosed is a complementary resistor switch (3) comprising two outer contacts, between which two piezo- or ferroelectric layers (11a and 11b) having an inner common contact are situated. At least one region (11', 11'') of the layers is modified, either the outer contacts are rectifying (S) and the inner contact is non-rectifying (0), or vice versa, the modified regions are formed at the rectifying contacts, the layers have different strain-dependent structural phases with different band gaps and/or different polarization charges, and the electrical conductivity of the layers is different. Also disclosed are a connectable resistor structure having at least one Schottky contact at two adjoining piezo- or ferroelectric layers, a polycrystalline piezo- or ferroelectric layer comprising modified crystallites, and a method and circuits for encrypting and decrypting a bit sequence.

  • Patent
    US20150364682 - Offenlegung 17.12.2015

Permalink: https://www.hzdr.de/publications/Publ-31154
Publ.-Id: 31154


New algorithm to discriminate phase distribution of gas-oil-water pipe flow with dual-modality wire-mesh sensor - Data set

de Assis Dias, F.; Nunes Dos Santos, E.; Da Silva, M. J.; Schleicher, E.; Morales, R. E. M.; Hewakandamby, B.; Hampel, U.

Data set used on the work "New Algorithm to Discriminate Phase Distribution of Gas-Oil-Water Pipe Flow with Dual-Modality Wire-Mesh Sensor".

Data were acquired using a dual-modality wire-mesh sensor designed by the Brazilian partner UTFPR. The experiments were performed at the University of Nottingham in a water-oil liquid-liquid flow loop.

However, the gas phase was introduced into the system to perform stratified three-phase flow measurements as a proof of concept. In this set of data, you find the calibrated amplitude and phase signals of nine points as well as permittivity and conductivity estimations (post-processing).

Keywords: complex impedance; flow visualization; gas-oil-water horizontal flow; three-phase; wire-mesh sensor

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-06-16
    DOI: 10.14278/rodare.372

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-31152
Publ.-Id: 31152


A review on numerical modelling of flashing flow with application to nuclear safety analysis

Liao, Y.; Lucas, D.

The flashing flow is an relevant multiphase phenomenon in many technical applications including nuclear safety analysis, which has been the subject of intense research. Numerical studies have evolved from one-dimensional to multi-dimensional. A variety of methods have been proposed, while a broad consensus was not exiting. The present work aims to present an overview of available models as well their assumptions and limitations by conducting a literature survey. The final focus was put on recent computational fluid dynamics simulations. Some consensus on modelling interfacial slip, phase change mechanism and bubble size is identified. Since flashing scenarios often accompanying with high void fraction and broad bubble size range, a poly-disperse two-fluid model is recommended. Thermal phase change model is superior to pressure phase change, relaxation and equilibrium models for practical flashing problems. Major challenges include improving closure models for interphase transfer, bubble dynamics processes, interfacial area as well two-phase turbulence. For this purpose, high-resolution high quality experimental data are important, which are lacking in many cases. Considering that heterogeneous gas structures often exist in flashing flows, multi-field approaches able to handle different shapes of gas-liquid interface are recommended.

Keywords: computational fluid dynamics; flashing flow; nuclear safety analysis; numerical modelling; literature review

Downloads:

  • Secondary publication expected from 17.09.2021

Permalink: https://www.hzdr.de/publications/Publ-31151
Publ.-Id: 31151


Modelling and Simulation of Flow Boiling with an Eulerian-Eulerian Approach and Integrated Models for Bubble Dynamics and Temperature-dependent Heat Partitioning

Setoodeh, H.; Ding, W.; Lucas, D.; Hampel, U.

A time-averaged Eulerian-Eulerian (E-E) multiphase approach for the simulation of boiling flows is presented. A previously developed bubble dynamics model is implemented in the E-E framework as a sub-model to improve the accuracy of the simulations and reduce the case dependency. This mechanistic model, which is based on the balance of forces applied on a single bubble, considers the evaporation of the microlayer underneath the bubble, thermal diffusion and condensation around the bubble cap as well as geometry changes and dynamic inclination and contact angles. The advantage of this model is that it does not require a recalibration of parameters to predict the bubble departure size. However, its implementation in the E-E framework needs an extension of the current nucleation site activation and heat partitioning model. Further on, we use a population balance model in our approach.
With the new modelling approach, we are able to analyse the impact of bubble sliding on the heat transfer, which has been rarely considered in other modelling approaches. Validation was made with experimental data from flow in a vertical pipe and an annulus. The experimental test cases cover a wide range of operating parameters such as wall heat flux, fluid velocity, subcooling temperature and pressure.

Keywords: bubble dynamics; heat partitioning; subcooled flow boiling; Computational Fluid Dynamics (CFD)

Permalink: https://www.hzdr.de/publications/Publ-31148
Publ.-Id: 31148


Stone-Wales defects cause high proton permeability and isotope selectivity of single-layer graphene

An, Y.; Faria Oliveira, A.; Brumme, T.; Kuc, A. B.; Heine, T.

While the isotope-dependent hydrogen permeability of graphene membranes at ambient condition has been demonstrated, the underlying mechanism has been controversially discussed during the past five years. The reported room temperature H+-over-D+ selectivity is 10, much higher than in any competing method. Yet, it has not been understood how protons can penetrate through graphene membranes – proposed hypotheses include atomic defects and local hydrogenation. However, neither could explain both the high permeability and high selectivity of the atomically thin membranes. Here, we confirm that ideal graphene is quasi-impermeable to protons, yet the most common defect in sp2 carbons, the topological Stone-Wales defect, has a calculated penetration barrier below 1 eV and H+-over-D+ selectivity of 7 at room temperature and, thus, explains all experimental results on graphene membrane that are available to date. We challenge the competing explanation, local hydrogenation, which also reduces the penetration barrier, but shows significantly lower isotope selectivity

Keywords: proton isotopes separation; quantum tunneling; graphene; Stone-Wales defect; selectivity

Permalink: https://www.hzdr.de/publications/Publ-31147
Publ.-Id: 31147


In situ X-ray diffraction of silicate liquids and glasses under dynamic and static compression to megabar pressures

Morard, G.; Hernandez, J.-A.; Guarguaglini, M.; Bolis, R.; Benuzzi-Mounaix, A.; Vinci, T.; Fiquet, G.; Baron, M. A.; Heon Shim, S.; Ko, B.; Gleason, A. E.; Mao, W. L.; Alonso-Mori, R.; Ja Lee, H.; Nagler, B.; Galtier, E.; Sokaras, D.; Glenzer, S. H.; Andrault, D.; Garbarino, G.; Mezouar, M.; Schuster, A.; Ravasio, A.

Properties of liquid silicates under high-pressure and high- temperature conditions are critical for modeling the dynamics and solidification mechanisms of the magma ocean in the early Earth, as well as for constraining entrainment of melts in the mantle and in the present-day core–mantle boundary. Here we present in situ structural measurements by X-ray diffraction of selected amorphous silicates compressed statically in diamond anvil cells (up to 157 GPa at room temperature) or dynamically by laser-generated shock com- pression (up to 130 GPa and 6,000 K along the MgSiO3 glass Hugo- niot). The X-ray diffraction patterns of silicate glasses and liquids reveal similar characteristics over a wide pressure and temperature range. Beyond the increase in Si coordination observed at 20 GPa, we find no evidence for major structural changes occurring in the silicate melts studied up to pressures and temperatures exceeding Earth’s core mantle boundary conditions. This result is supported by molecular dynamics calculations. Our findings reinforce the widely used assumption that the silicate glasses studies are appropriate structural analogs for understanding the atomic arrangement of silicate liquids at these high pressures.

  • Proceedings of the National Academy of Sciences of the United States of America 117(2020)22, 11981-11986
    DOI: 10.1073/pnas.1920470117

Permalink: https://www.hzdr.de/publications/Publ-31146
Publ.-Id: 31146


New algorithm to discriminate phase distribution of gas-oil-water pipe flow with dual-modality wire-mesh sensor

de Assis Dias, F.; Nunes Dos Santos, E.; Da Silva, M. J.; Schleicher, E.; Morales, R. E. M.; Hewakandamby, B.; Hampel, U.

Three-phase gas-oil-water flow is an important type of flow present in petroleum extraction and processing. This paper reports a novel threshold-based method to visualize and estimate the cross-sectional phase fraction of gas-oil-water mixtures. A 16x16 dual-modality wire-mesh sensor (WMS) was employed to simultaneously determine the conductive and capacitive components of the impedance of fluid. Then, both electrical parameters are used to classify readings of WMS into either pure substance (gas, oil or water) or two-phase oil-water mixtures (foam is neglected in this work). Since the wire-mesh sensor interrogates small regions of the flow domain, we assume that the three-phase mixture can be segmented according to the spatial sensor resolution (typically 2-3 mm). Hence, the proposed method simplifies a complex three-phase system in several segments of single or two-phase mixtures. In addition to flow visualization, the novel approach can also be applied to estimate quantitative volume fractions of flowing gas-oil-water mixtures. The proposed method was tested in a horizontal air-oil-water flow loop in different flow conditions. Experimental results suggest that the threshold-based method is able to capture transient three-phase flows with high temporal and spatial resolution even in the presence of water-oil dispersion regardless of the continuous phase.

Keywords: complex impedance; flow visualization; gas-oil-water horizontal flow; three-phase; wire-mesh sensor

Related publications

Permalink: https://www.hzdr.de/publications/Publ-31145
Publ.-Id: 31145


The anomalous magnetic moment of the muon in the Standard Model

Aoyama, T.; Asmussen, N.; Benayoun, M.; Bijnens, J.; Blum, T.; Bruno, M.; Caprini, I.; Carloni Calame, C. M.; Cè, M.; Colangelo, G.; Curciarello, F.; Czyż, H.; Danilkin, I.; Davier, M.; Davies, C. T. H.; Della Morte, M.; Eidelman, S. I.; El-Khadra, A. X.; Gérardin, A.; Giusti, D.; Golterman, M.; Steven, G.; Gülpers, V.; Hagelstein, F.; Hayakawa, M.; Herdoíza, G.; Hertzog, D. W.; Hoecker, A.; Hoferichter, M.; Hoid, B.-L.; Hudspith, R. J.; Ignatov, F.; Izubuchi, T.; Jegerlehner, F.; Jin, L.; Keshavarzi, A.; Kinoshita, T.; Kubis, B.; Kupich, A.; Kupść, A.; Laub, L.; Lehner, C.; Lellouch, L.; Logashenko, I.; Malaescu, B.; Maltman, K.; Marinković, M. K.; Masjuan, P.; Meyer, A. S.; Meyer, H. B.; Mibe, T.; Miura, K.; Müller, S.; Nio, M.; Nomura, D.; Nyffeler, A.; Pascalutsa, V.; Passera, M.; Perez Del Rio, E.; Peris, S.; Portelli, A.; Procura, M.; Redmer, C. F.; Roberts, B. L.; Sánchez-Puertas, P.; Serednyakov, S.; Shwartz, B.; Simula, S.; Stöckinger, D.; Stöckinger-Kim, H.; Stoffer, P.; Teubner, T.; van de Water, R.; Vanderhaeghen, M.; Venanzoni, G.; von Hippel, G.; Wittig, H.; Zhang, Z.; Achasov, M. N.; Bashir, A.; Cardoso, N.; Chakraborty, B.; Chao, E.-H.; Charles, J.; Crivellin, A.; Deineka, O.; Denig, A.; Detar, C.; Dominguez, C. A.; Dorokhov, A. E.; Druzhinin, V. P.; Eichmann, G.; Fael, M.; Fischer, C. S.; Gámiz, E.; Gelzer, Z.; Green, J. R.; Guellati-Khelifa, S.; Hatton, D.; Hermansson-Truedsson, N.; Holz, S.; Hörz, B.; Knecht, M.; Koponen, J.; Kronfeld, A. S.; Laiho, J.; Leupold, S.; Mackenzie, P. B.; Marciano, W. J.; Mcneile, C.; Mohler, D.; Monnard, J.; Neil, E. T.; Nesterenko, A. V.; Ottnad, K.; Pauk, V.; Radzhabov, A. E.; de Rafael, E.; Raya, K.; Risch, A.; Rodríguez-Sánchez, A.; Roig, P.; San José, T.; Solodov, E. P.; Sugar, R.; Todyshev, K. Y.; Vainshtein, A.; Vaquero Avilés-Casco, A.; Weil, E.; Wilhelm, J.; Williams, R.; Zhevlakov, A. S.

We review the present status of the Standard Model calculation of the anomalous magnetic moment of the muon. This is performed in a perturbative expansion in the fine-structure constant α and is broken down into pure QED, electroweak, and hadronic contributions. The pure QED contribution is by far the largest and has been evaluated up to and including O(α5) with negligible numerical uncertainty. The electroweak contribution is suppressed by (m_μ/M_W)^2 and only shows up at the level of the seventh significant digit. It has been evaluated up to two loops and is known to better than one percent. Hadronic contributions are the most difficult to calculate and are responsible for almost all of the theoretical uncertainty. The leading hadronic contribution appears at O(α2) and is due to hadronic vacuum polarization, whereas at O(α3) the hadronic light-by-light scattering contribution appears. Given the low characteristic scale of this observable, these contributions have to be calculated with nonperturbative methods, in particular, dispersion relations and the lattice approach to QCD. The largest part of this review is dedicated to a detailed account of recent efforts to improve the calculation of these two contributions with either a data-driven, dispersive approach, or a first-principle, lattice-QCD approach. The final result reads a^{SM}_μ=116591810(43)×10^{−11} and is smaller than the Brookhaven measurement by 3.7σ. The experimental uncertainty will soon be reduced by up to a factor four by the new experiment currently running at Fermilab, and also by the future J-PARC experiment. This and the prospects to further reduce the theoretical uncertainty in the near future-which are also discussed here-make this quantity one of the most promising places to look for evidence of new physics.

Keywords: muon; g-2; anomalous magnetic moment

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Permalink: https://www.hzdr.de/publications/Publ-31144
Publ.-Id: 31144


Towards Geostatistical Learning for the Geosciences: A Case Study in Improving the Spatial Awareness of Spectral Clustering

Talebi, H.; Peeters, L. J. M.; Mueller, U.; Tolosana Delgado, R.; van den Boogaart, K. G.

The particularities of geosystems and geoscience data must be understood before any development or implementation of statistical learning algorithms. Without such knowledge, the predictions and inferences may not be accurate and physically consistent. Accuracy, transparency and interpretability, credibility, and physical realism are minimum criteria for statistical learning algorithms when applied to the geosciences. This study briefly reviews several characteristics of geoscience data and challenges for novel statistical learning algorithms. A novel spatial spectral clustering approach is introduced to illustrate how statistical learners can be adapted for modelling geoscience data. The spatial awareness and physical realism of the spectral clustering are improved by utilising a dissimilarity matrix based on nonparametric higher-order spatial statistics. The proposed model-free technique can identify meaningful spatial clusters (i.e. meaningful geographical subregions) from multivariate spatial data at different scales without the need to define a model of co-dependence. Several mixed (e.g. continuous and categorical) variables can be used as inputs to the proposed clustering technique. The proposed technique is illustrated using synthetic and real mining datasets. The results of the case studies confirm the usefulness of the proposed method for modelling spatial data.

Keywords: Statistical learning; Spatial data; Spatial clustering; Higher-order spatial statistics; Geoscience data

Permalink: https://www.hzdr.de/publications/Publ-31143
Publ.-Id: 31143


Combined tumor plus nontumor interim FDG‐PET parameters are prognostic for response to chemoradiation in squamous cell esophageal cancer

Zschaeck, S.; Li, Y.; Bütof, R.; Lili, C.; Hua, W.; Troost, E.; Beck, M.; Amthauer, H.; Kaul, D.; Kotzerke, J.; Baur, A.; Ghadjar, P.; Baumann, M.; Krause, M.; Hofheinz, F.

We have investigated the prognostic value of two novel interim 18F‐fluorodeoxyglucose positron emission tomography (FDG‐PET) parameters in patients undergoing chemoradiation (CRT) for esophageal squamous cell carcinoma (ESCC): one tumor parameter (maximal standardized uptake ratio rSUR) and one normal tissue parameter (change of FDG uptake within irradiated nontumor‐affected esophagus ∆ SUVNTO). PET data of 134 European and Chinese patients were analyzed. Parameter establishment was based on 36 patients undergoing preoperative CRT plus surgery, validation was performed in 98 patients receiving definitive CRT. Patients received PET imaging prior and during fourth week of CRT. Clinical parameters, baseline PET parameters, and interim PET parameters (rSUR and ∆ SUVNTO) were analyzed and compared to event‐free survival (EFS), overall survival (OS), loco‐regional control (LRC) and freedom from distant metastases (FFDM). Combining rSUR and ∆ SUVNTO revealed a strong prognostic impact on EFS, OS, LRC and FFDM in patients undergoing preoperative CRT. In the definitive CRT cohort, univariate analysis with respect to EFS revealed several staging plus both previously established interim PET parameters as significant prognostic factors. Multivariate analyses revealed only rSUR and ∆ SUVNTO as independent prognostic factors (p = 0.003, p = 0.008). Combination of these parameters with the cutoff established in preoperative CRT revealed excellent discrimination of patients with a long or short EFS (73% vs . 17% at 2 years, respectively) and significantly discriminated all other endpoints (OS, p < 0.001; LRC, p < 0.001; FFDM, p = 0.02), even in subgroups. Combined use of interim FDG‐PET derived parameters ∆ SUVNTO and rSUR seems to have predictive potential, allowing to select responders for definitive CRT and omission of surgery.

Keywords: esophageal cancer; interim PET; standardized uptake ratio; normal tissue FDG uptake; chemoradiation; personalized treatment

Permalink: https://www.hzdr.de/publications/Publ-31142
Publ.-Id: 31142


Reconstructed spatial resolution and contrast recovery with Bayesian penalized likelihood reconstruction (Q.Clear) for FDG-PET compared to time-of-flight (TOF) with point spread function (PSF)

Rogasch, J.; Suleiman, S.; Hofheinz, F.; Bluemel, S.; Lukas, M.; Amthauer, H.; Furth, C.

Background

Bayesian penalized likelihood reconstruction for PET (e.g., GE Q.Clear) aims at improving convergence of lesion activity while ensuring sufficient signal-to-noise ratio (SNR). This study evaluated reconstructed spatial resolution, maximum/peak contrast recovery (CRmax/CRpeak) and SNR of Q.Clear compared to time-of-flight (TOF) OSEM with and without point spread function (PSF) modeling.

Methods

The NEMA IEC Body phantom was scanned five times (3 min scan duration, 30 min between scans, background, 1.5–3.9 kBq/ml F18) with a GE Discovery MI PET/CT (3-ring detector) with spheres filled with 8-, 4-, or 2-fold the background activity concentration (SBR 8:1, 4:1, 2:1). Reconstruction included Q.Clear (beta, 150/300/450), “PSF+TOF4/16” (iterations, 4; subsets, 16; in-plane filter, 2.0 mm), “OSEM+TOF4/16” (identical parameters), “PSF+TOF2/17” (2 it, 17 ss, 2.0 mm filter), “OSEM+TOF2/17” (identical), “PSF+TOF4/8” (4 it, 8 ss, 6.4 mm), and “OSEM+TOF2/8” (2 it, 8 ss, 6.4 mm). Spatial resolution was derived from 3D sphere activity profiles. RC as (sphere activity concentration [AC]/true AC). SNR as (background mean AC/background AC standard deviation).

Results

Spatial resolution of Q.Clear150 was significantly better than all conventional algorithms at SBR 8:1 and 4:1 (Wilcoxon, each p < 0.05). At SBR 4:1 and 2:1, the spatial resolution of Q.Clear300/450 was similar or inferior to PSF+TOF4/16 and OSEM+TOF4/16. Small sphere CRpeak generally underestimated true AC, and it was similar for Q.Clear150/300/450 as with PSF+TOF4/16 or PSF+TOF2/17 (i.e., relative differences < 10%). Q.Clear provided similar or higher CRpeak as OSEM+TOF4/16 and OSEM+TOF2/17 resulting in a consistently better tradeoff between CRpeak and SNR with Q.Clear. Compared to PSF+TOF4/8/OSEM+TOF2/8, Q.Clear150/300/450 showed lower SNR but higher CRpeak.

Conclusions

Q.Clear consistently improved reconstructed spatial resolution at high and medium SBR compared to PSF+TOF and OSEM+TOF, but only with beta = 150. However, this is at the cost of inferior SNR with Q.Clear150 compared to Q.Clear300/450 and PSF+TOF4/16/PSF+TOF2/17 while CRpeak for the small spheres did not improve considerably. This suggests that Q.Clear300/450 may be advantageous for the 3-ring detector configuration because the tradeoff between CR and SNR with Q.Clear300/450 was superior to PSF+TOF4/16, OSEM+TOF4/16, and OSEM+TOF2/17. However, it requires validation by systematic evaluation in patients at different activity and acquisition protocols.

Keywords: PET; Image reconstruction; Spatial resolution; Contrast recovery; Signal-to-noise ratio; TOF; PSF; Q.Clear; GE Discovery MI

Permalink: https://www.hzdr.de/publications/Publ-31141
Publ.-Id: 31141


Start-to-end simulations Modeling hybrid plasma accelerator experiments with PIConGPU

Pausch, R.; Bachmann, M.; Garten, M.; Hübl, A.; Steiniger, K.; Widera, R.; Kurz, T.; Schöbel, S.; Chang, Y.-Y.; Couperus Cabadağ, J. P.; Köhler, A.; Zarini, O.; Heinemann, T.; Ding, H.; Döpp, A.; Gilljohann, M. F.; Kononenko, O.; Raj, G.; Corde, S.; Hidding, B.; Karsch, S.; Assmann, R.; Martinez De La Ossa, A.; Irman, A.; Schramm, U.; Debus, A.

A brief summary of the evolution of LPWFA hybrid simulations and why start-to end simulations are needed to model the LPWFA setup.

Keywords: LPWFA; hybrid; PIConGPU

  • Lecture (Conference) (Online presentation)
    DMA meeting, 20.05.2020, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-31140
Publ.-Id: 31140


Electric and magnetic dipole strength in 66Zn

Schwengner, R.; Massarczyk, R.; Scheck, M.; Tornow, W.; Brown, B. A.; Battaglia, G.; Beck, T.; Bemmerer, D.; Benouaret, N.; Beyer, R.; Butterling, M.; Fiedler, F.; Finch, S. W.; Fransen, C.; Friman-Gayer, U.; Frotscher, A.; Gonzalez, R.; Grieger, M.; Hartmann, A.; Hensel, T.; Hoemann, E.; Hoffmann, H.; Isaak, J.; Janssens, R. V. F.; Johnson, S.; Jones, M. D.; Junghans, A.; Kelly, N.; Kleemann, J.; Krishichayan, F.; Little, D. R.; Ludwig, F.; Müller, S.; Odonnell, D.; Pirovano, E.; Savran, D.; Sinclair, J.; Takacs, M. P.; Turkat, S.; Urlaß, S.; Wagner, A.; Wieland, O.; Wilhelmy, J.

The dipole strength of the nuclide 66Zn was studied in photon-scattering experiments using bremsstrahlung produced with electron beams of energies of 7.5 and 13.4 MeV at the γELBE facility as well as using quasi-monoenergetic and linearly polarized photon beams of 30 energies within the range from 4.3 to 9.9 MeV at the HIγS facility. About 140 J = 1 states were identified, out of them 9 with 1+ and 84 with 1- assignments. The quasicontinuum of unresolved transitions was included in the analysis of the spectra and the intensities of branching transitions were estimated on the basis of simulations of statistical γ-ray cascades. As a result, the photoabsorpton cross section up to the neutron-separation energy was determined and compared with predictions of the statistical reaction model. The experimental M1 strengths from resolved 1+ states are compared with results of large-scale shell-model calculations.

Keywords: Photon scattering; nuclear resonance fluorescence; dipole excitations; photoabsorption cross section; electromagnetic transitions; statistical reaction model; shell model

Permalink: https://www.hzdr.de/publications/Publ-31139
Publ.-Id: 31139


Nonlocal stimulation of three-magnon splitting in a magnetic vortex

Körber, L.; Schultheiß, K.; Hula, T.; Verba, R.; Faßbender, J.; Kakay, A.; Schultheiß, H.

We present a combined numerical, theoretical and experimental study on stimulated three-magnon splitting in a magnetic disk in the vortex equilibrium state. Our micromagnetic simulations and Brillouin-light-scattering results confirm that three-magnon splitting can be triggered even below threshold by exciting one of the secondary modes by magnons propagating in a waveguide next to the disk. The experiments show that stimulation is possible over an extended range of excitation powers and a wide range of frequencies around the eigenfrequencies of the secondary modes. Rate-equation calculations predict an instantaneous response to stimulation and the possibility to prematurely trigger three-magnon splitting even above threshold in a sustainable manner. These predictions are confirmed experimentally using time-resolved Brillouin-light-scattering measurements and are in a good qualitative agreement with the theoretical results. We believe that the controllable mechanism of stimulated three-magnon splitting could provide a possibility to utilize magnon-based nonlinear networks as hardware for reservoir or neuromorphic computing.

Here, we briefly describe how the archived data for the publication "Nonlocal stimulation of three-magnon splitting in a magnetic vortex", submitted to PRL, is structured.

"rate-equations"
- theoretical data of the temporal evolution of the spin wave modes in Fig. 4

"micromagnetic-simulation"
- MuMax3 simulation recipes (.go files) and sample-layout masks for the
simulations performed for Fig. 2(a,b,c).
- corresponding power spectra obtained with our "mumax3-pwsp" program
- mode profiles for stimulated and spontaneous splitting (Fig. 1(c) and Fig. 2(d))
- dispersion of the spin waves, calculated by micromagetnic simulation, shown in Fig. 1(b)

"experiments"
- electron beam microscopy image of the sample
- intensity spectrum of the waveguide, used to calculate the approximate
frequency/wave-vector region where the waveguide is effective (inset in Fig. 1(c))
- non-time-resolved BLS measurements, including spectra, power sweeps, etc. for
Figs 2,3 in "i3MS" folders, in more detail described by "i3MS_V1_KS_logbook.pdf"
- time-resolved BLS measurements, further explained in the corresponding subfolders
 

Keywords: spin wave; nonlinear; three-magnon splitting; stimulation; micromagnetic simulation; BLS

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-06-11
    DOI: 10.14278/rodare.364
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-31137
Publ.-Id: 31137


Treatment of brain metastases in small cell lung cancer: Decision-making amongst a multidisciplinary panel of European experts

Putora, P. M.; Fischer, G. F.; Früh, M.; Califano, R.; Faivre-Finn, C.; van Houtte, P.; Mcdonald, F.; Nestle, U.; Dziadziuszko, R.; Le Pechoux, C.; Ramella, S.; Belderbos, J.; Slotman, B. J.; Troost, E. G. C.; Peeters, S.; Widder, J.; Pöttgen, C.; Reck, M.; Blackhall, F.; Cappuzzo, F.; Besse, B.; Novello, S.; Garrido, P.; Felip, E.; O'Brien, M.; Paz Ares, L.; de Marinis, F.; Westeel, V.; de Ruysscher, D.

Background: Brain metastases (BM) are common in patients with small cell lung cancer (SCLC). In recent years, the role of whole brain radiotherapy (WBRT) for brain metastases in lung cancer is being reevaluated, especially in the context of new systemic treatments available for SCLC. With this analysis, we investigate decision-making in SCLC patients with BM among European experts in medical oncology and radiation oncology. Methods: We analyzed decision-making from 13 medical oncologists (selected by IASLC) and 13 radiation oncologists (selected by ESTRO) specialized in SCLC. Management strategies of individual experts were converted into decision trees and analyzed for consensus. Results and conclusion: In asymptomatic patients, chemotherapy alone is the most commonly recommended first line treatment. In asymptomatic patients with limited volume of brain metastases, a higher preference for chemotherapy without WBRT among medical oncologists compared to radiation oncologists was observed. For symptomatic patients, WBRT followed by chemotherapy was recommended most commonly. For limited extent of BM in symptomatic patients, some experts chose stereotactic radiotherapy as an alternative to WBRT. Significant variation in clinical decision-making was observed among European SCLC experts for the first line treatment of patients with SCLC and BM.

Keywords: Brain metastases; Chemotherapy; Decision-making; Small cell lung cancer; Stereotactic radiotherapy; Whole brain radiotherapy

Permalink: https://www.hzdr.de/publications/Publ-31136
Publ.-Id: 31136


Local void fraction and pressure drop data for horizontal annular flow through orifice

Porombka, P.; Boden, S.; Lucas, D.; Hampel, U.

This dataset combines multiple measurements form air-water horizontal annular flow experiments in a pipe (case A) and a pipe with circular orifice with \(d^2 / D^2 = 0.6\)  (case B). Measurements where taken at superficial Reynolds numbers of Re=25000 for the gas phase and Re =4090 for the liquid phase. The following data are included for each case:

  • linear pressure drop between two points (case A), four points (case B) measured with split-range differential pressure transducers at 5Hz
  • time-averaged local liquid volume fraction distribution in cylindrical and Cartesian coordinates reconstructed from X-ray microtomography projections
  • reconstructed pipe axis coordinates and pipe radius
  • Python code to calculate secondary validation parameters (e.g. film thickness distribution) from primary data

The detailed 3D data is intended for validation of computational fluid dynamics codes based on phase-averaged variables such as the Euler-Euler approach.

Keywords: X-ray microtomography; film thickness; circular orifice; annular flow

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-06-09
    DOI: 10.14278/rodare.361

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-31135
Publ.-Id: 31135


Hydrodynamic forces on a clean spherical bubble translating in a wall-bounded linear shear flow

Shi, P.; Rzehak, R.; Lucas, D.; Magnaudet, J.

The three-dimensional flow around a spherical clean bubble translating steadily in a wall-bounded linear shear flow is studied numerically. The present work is concerned with the drag and lift forces experienced by the bubble over a wide range of Reynolds number (0.1 ≤ Re ≤ 10^3, Re being based on the bubble diameter and relative velocity with respect to the ambient fluid), wall distance (1.5 ≤ LR ≤ 8, LR being the distance from the bubble center to the wall normalized by the bubble radius), and relative shear rate -0.5 ≤ Sr ≤ 0.5, Sr being the ratio between the velocity difference across the bubble and the relative velocity).Based on the above range of parameters, situations where the bubble is repelled from or attracted to the wall are both covered. The flow structure and vorticity field are analyzed to obtain qualitative insight into the interaction mechanisms at work. The drag and lift forces are computed as well. Their variations agree well with theoretical predictions available in the limit of low-but-finite Reynolds number and, when the fluid is at rest, in the potential flow limit. Numerical results and analytical expressions are combined to provide accurate semi-empirical expressions for the drag and lift forces at arbitrary Reynolds number and separation distance.

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Permalink: https://www.hzdr.de/publications/Publ-31134
Publ.-Id: 31134


Olfactory dysfunction correlates with putaminal dopamine turnover in early de novo Parkinson’s disease

Löhle, M.; Wolz, M.; Beuthien-Baumann, B.; Oehme, L.; van den Hoff, J.; Kotzerke, J.; Reichmann, H.; Storch, A.

Although olfactory dysfunction is one of the most well-established prodromal symptoms in Parkinson’s disease (PD), its correlation with clinical disease progression or dopaminergic dysfunction still remains unclear. We here evaluated the association of striatal dopamine metabolism and olfactory function in a homogenous cohort of 30 patients with early untreated de novo PD. Striatal dopamine metabolism was assessed by the extended 18Fluorodopa PET scanning protocol to measure 18Fluorodopa uptake (Kocc) and the effective dopamine distribution volume ratio (EDVR) as the inverse of dopamine turnover. Olfactory function was estimated by the “Sniffin’ Sticks” test including odor threshold (T), discrimination (D) and identification (I) assessment. We detected moderate correlations of the EDVR in the posterior putamen with the TDI composite score (r = 0.412; p = 0.024; Pearson’s correlation test) and the odor identification score (r = 0.444; p = 0.014). These correlations were confirmed by multivariate regression analyses using age, sex, symptom duration and disease severity as measured by UPDRSIII motor score as candidate covariates. No other associations were observed between olfaction measures and Kocc and EDVR in all striatal regions. Together, olfactory dysfunction in early PD is not correlated with striatal 18Fluorodopa uptake as a measure for dopaminergic degeneration, but with putaminal dopamine turnover as a marker for dopaminergic presynaptic compensatory processes in early PD. These results should be treated as hypothesis generating and require confirmation by larger multicenter studies.

Permalink: https://www.hzdr.de/publications/Publ-31133
Publ.-Id: 31133


Predicting the dominating factors during heat transfer in magnetocaloric composite wires

Krautz, M.; Beyer, L.; Funk, A.; Waske, A.; Weise, B.; Freudenberger, J.; Gottschall, T.

Magnetocaloric composite wires have been studied by pulsed-field measurements up to μ0ΔH = 10 T with a typical rise time of 13 ms in order to evaluate the evolution of the adiabatic temperature change of the core, ΔTad, and to determine the effective temperature change at the surrounding steel jacket, ΔTeff, during the field pulse. An inverse thermal hysteresis is observed for ΔTad due to the delayed thermal transfer. By numerical simulations of application-relevant sinusoidal magnetic field profiles, it can be stated that for field-frequencies of up to two field cycles per second heat can be efficiently transferred from the core to the outside of the jacket. In addition, intense numerical simulations of the temperature change of the core and jacket were performed by varying different parameters, such as frequency, heat capacity, thermal conductivity and interface resistance in order to shed light on their impact on ΔTeff at the outside of the jacket in comparison to ΔTad provided by the core.

Permalink: https://www.hzdr.de/publications/Publ-31131
Publ.-Id: 31131


The influence of different artificial extracellular matrix implant coatings on the regeneration of a critical size femur defect in rats

Förster, Y.; Schulze, S.; Penk, A.; Neuber, C.; Möller, S.; Hintze, V.; Scharnweber, D.; Schnabelrauch, M.; Pietzsch, J.; Huster, D.; Rammelt, S.

Resorbable biomaterials based on artificial extracellular matrices (aECM) represent promising scaffolds for the treatment of large bone defects. Here, we investigated various glycosaminoglycan (GAG) derivatives of varying sulfation degree with respect to their influence on in vivo bone healing. The materials used in this study consisted of GAG-coated degradable polycaprolactone-co-lactide (PCL). Critical size femur defects in rats were filled with autologous bone serving as positive control or the respective coated or uncoated PCL scaffolds. After 2 and 12 weeks, progress in the healing process was investigated by analyzing the new bone matrix formation, the collagen content and hydroxyapatite formation by using micro-computed tomography (μCT), biomechanical testing, nuclear magnetic resonance spectroscopy (NMR) and histology. The sulfated GAG coating contributed substantially to bone regeneration, increased collagen synthesis and initiated mineralization of the organic matrix. Most substantial collagen production was detected in scaffolds coated with chondroitin sulfate. Scaffolds coated with hypersulfated hyaluronan induced formation of new bone volume comparable to what was observed in the positive control. GAG differing in the sugar backbone and degree of sulfation modulate the healing process at different times, eventually leading to improved bone healing.

Keywords: Artificial extracellular matrices; Glycosaminoglycans; Chondroitin sulfate; Sulfated hyaluronan; Bone healing

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  • Secondary publication expected from 05.06.2021

Permalink: https://www.hzdr.de/publications/Publ-31130
Publ.-Id: 31130


Software for: Characterization of blood coagulation dynamics and oxygenation in ex-vivo retinal vessels by fluorescence hyperspectral imaging

Podlipec, R.; Iztok, U.

The Mathematica software for the analysis of blood oxygenation in the intact or damaged retinal vessel from the fluorescence hyperspectral data using optimized two-component empirical asymmetric log-normal lineshape (LN) spectral model (Urbancic et al, Opt. Express 21, 2013) modified with hemoglobin absorbance correction. 

Related publications

  • Software in the HZDR data repository RODARE
    Publication date: 2020-06-03
    DOI: 10.14278/rodare.359
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-31129
Publ.-Id: 31129


Compositional modelling of the impact of source lithology on the plant ionome

Pospiech, S.; van den Boogaart, K. G.; Tolosana Delgado, R.; Middleton, M.

The plant ionome is used for many applications for which it is important to understand and model how the elemental composition in the plants or plant organs evolved based on the available element sources, e.g. the effect of the soils or the underlying lithologies. Since the uptake and translocation of elements is influenced by a multitude of non-controllable parameters it is very challenging to relate a certain element pattern specifically to one parameter and quantify the effect of the parameter. Additionally, the applied modelling tools often do not take into account that both, the plant ionome and the element source, are multi-element concentrations. Concentrations are compositional data which represent the relative importance of some parts of a whole, and thus they are constrained and typically might suffer from problems of spurious correlations and negative bias, which disturbs our models of plant uptake.
In this contribution, we are presenting a statistical approach to describe the relation between geochemical composition of plants and the bedrock lithology while taking the multi-variate and constrained nature of concentrations into account. Modern compositional data analysis relies on log-ratio transforms and the Aitchison geometry. Most of the processes building the plant ionome from the element sources can be understood as linear modifications in the log-ratio space. A selective element transport would correspond to a shift of log-ratios. If this selectivity varies randomly this shift can be modelled by a multivariate normal distribution in log-ratio space. Selective element uptake by plants can thus be modelled by a downscaling of variability in the form of regression coefficients in log-ratio space. This allows to model many geochemical phenomena through a multivariate linear model in log-ratios.
To demonstrate the statistical method an exploration data set of lithologies and plant data from Northern Finland is used.

Keywords: plant geochemistry; ionome; compositional data; regression model; plant uptake; North Finland; gold mining; exploration

  • Open Access Logo Lecture (Conference) (Online presentation)
    Goldschmidt Virtual Conference 2020, 21.-26.06.2020, Online, USA

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Permalink: https://www.hzdr.de/publications/Publ-31128
Publ.-Id: 31128


Transport signatures of a junction between a quantum spin Hall System and a chiral topological superconductor

Novik, E. G.; Trauzettel, B.; Recher, P.

We investigate transport through a normal-superconductor (NS) junction made from a quantum spin Hall (QSH) system with helical edge states and a two-dimensional (2D) chiral topological superconductor (TSC) having a chiral Majorana edge mode. We employ a two-dimensional extended four-band model for HgTe-based quantum wells in a magnetic (Zeeman) field and subject to s-wave superconductivity. We show using the Bogoliubov-de Gennes scattering formalism that this structure provides a striking transport signal of a 2D TSC. As a function of the sample width (or Fermi energy) the conductance resonances go through a sequence of 2e2/h (nontrivial phase) and 4e2/h plateaux (trivial phase) which fall within the region of a nonzero Chern number (2D limit) as the sample width becomes large. These signatures are a manifestation of the topological nature of the QSH effect and the TSC.

Permalink: https://www.hzdr.de/publications/Publ-31127
Publ.-Id: 31127


Enhanced Ferromagnetism and Tunable Magnetism in Fe3GeTe2 Monolayer by Strain Engineering

Hu, X.; Zhao, Y.; Shen, X.; Krasheninnikov, A.; Chen, Z.; Sun, L.

Recent discovery of intrinsic ferromagnetism in Fe3GeTe2 (FGT) monolayer [Deng, Y.; et al. Nature 2018, 563, 94−99; Fei, Z.; et al. Nat. Mater. 2018, 17, 778−782] not only extended the family of two-dimensional (2D) magnetic materials but also stimulated further interest in the possibility to tune their magnetic properties without changing the chemical composition or introducing defects. By means of density functional theory computations, we explore strain effects on the magnetic properties of the FGT monolayer. We demonstrate that the ferromagnetism can be largely enhanced by the tensile strain in the FGT monolayer due to the competitive effects of direct exchange and superexchange interaction. The average magnetic moments of Fe atoms increase monotonically with an increase in biaxial strain from −5 to 5% in FGT monolayer. The intriguing variation of magnetic moments with strain in the FGT monolayer is related to the charge transfer induced by the changes in the bond lengths. Given the successful fabrication of the FGT monolayer, the strain-tunable ferromagnetism in the FGT monolayer can stimulate the experimental effort in this field. This work also suggests an effective route to control the magnetic properties of the FGT monolayer. The pronounced magnetic response toward the biaxial strain can be used to design the magnetomechanical coupling spintronics devices based on FGT.

Keywords: 2D materials; first-principles simulations

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  • Secondary publication expected from 05.05.2021

Permalink: https://www.hzdr.de/publications/Publ-31126
Publ.-Id: 31126


Simulating Raman spectra by combining first-principles and empirical potential approaches with application to defective MoS2

Kou, Z.; Hashemi, A.; Puska, M.; Krasheninnikov, A.; Komsa, H.-P.

Successful application of two-dimensional transition metal dichalcogenides in optoelectronic, catalytic, or sensing devices heavily relies on the materials’ quality, that is, the thickness uniformity, presence of grain boundaries, and the types and concentrations of point defects. Raman spectroscopy is a powerful and nondestructive tool to probe these factors but the interpretation of the spectra, especially the separation of different contributions, is not straightforward. Comparison to simulated spectra is beneficial, but for defective systems first-principles simulations are often computationally too expensive due to the large sizes of the systems involved. Here, we present a combined first-principles and empirical potential method for simulating Raman spectra of defective materials and apply it to monolayer MoS2 with random distributions of Mo and S vacancies. We study to what extent the types of vacancies can be distinguished and provide insight into the origin of different evolutions of Raman spectra upon increasing defect concentration. We apply to our simulated spectra the phonon confinement model used in previous experiments to assess defect concentrations, and show that the simplest form of the model is insufficient to fully capture peak shapes, but a good match is obtained when the type of phonon confinement and the full phonon dispersion relation are accounted for.

Keywords: Raman spectra; 2D materials; simulaitons

Permalink: https://www.hzdr.de/publications/Publ-31125
Publ.-Id: 31125


Two-Pion Intensity-Interferometry in Non-Central Collisions of Au + Au @ 1.23 A GeV

Greifenhagen, R.

High-statistics π-, π- and π+, π+ HBT data for non-central Au + Au collisions at 1.23 A GeV, measured with HADES at SIS18/GSI, are presented. The three-dimensional emission source is studied in dependence on pair transverse momentum and beam energy. A tilt of the source with respect to the reaction plane is observed. The spatial extension and the tilt magnitude of the source decrease with transverse momentum. A clear charge-sign difference is observed for the spatio-temporal variances, but not for the tilt angle of the source. Derived geometrical and temporal parameters do well complement the trend over several orders of magnitude in beam-energy provided that consistent transverse momenta are selected.

Keywords: femtoscopy; HBT

Related publications

  • Contribution to proceedings
    XIV Workshop on Particle Correlations and Femtoscopy, 03.-07.06.2019, Dubna, Russian Federation
    Physics of Particles and Nuclei Volume 51, Issue 3, Berlin: Springer, 1063-7796, 288-292
    DOI: 10.1134/S1063779620030132

Permalink: https://www.hzdr.de/publications/Publ-31124
Publ.-Id: 31124


Origin of the metamagnetic transitions in Y1− xErxFe2(H,D)4.2 compounds

Paul-Boncour, V.; Isnard, O.; Shtender, V.; Scurschii, I.; Guillot, M.

The structural and magnetic properties of Y1−xErxFe2 intermetallic compounds and their hydrides and deuterides Y1−xErxFe2H(D)4.2 have been investigated using X-ray diffraction and magnetic measurements under static and pulsed magnetic field up to 60 T. The intermetallics crystallize in the C15 cubic structure (Fd-3m space group), whereas corresponding hydrides and deuterides crystallize in a monoclinic structure (Pc space group). All compounds display a linear decrease of the unit cell volume versus Er concentration; the hydrides have a 0.8% larger cell volume compared to the deuterides with same Er content. They are ferrimagnetic at low field and temperature with a compensation point at x=0.33 for the intermetallics and x=0.57 for the hydrides and deuterides. A sharp first order ferromagnetic-antiferromagnetic (FM-AFM) transition is observed upon heating at TFM−AFM for both hydrides and deuterides. These compounds show two different types of field induced transitions, which have different physical origin. At low temperature (T < 50 K), a forced ferri-ferromagnetic metamagnetic transition with Btrans1 ≈8 T, related to the change of the Er moments orientation from antiparallel to parallel Fe moment, is observed. Btrans1 is not sensitive to Er concentration, temperature and isotope effect. A second metamagnetic transition resulting from antiferromagnetic to ferrimagnetic state is also observed. The transition field Btrans2 increases linearly versus temperature and relates to the itinerant electron metamagnetic behavior of the Fe sublattice. An onset temperature TM0 is obtained by extrapolating TFM−AFM (B) at zero field. TM0 decreases linearly versus the Er content and is 45 ± 5 K higher for the hydrides compared to the corresponding deuteride. The evolution of TM0 versus cell volume shows that it cannot be attributed exclusively to a pure volume effect and that electronic effects should also be considered.

Permalink: https://www.hzdr.de/publications/Publ-31123
Publ.-Id: 31123


Germetry dependent beam dynamics of a 3.5-cell SRF Ggun cavity at ELBE

Zhou, K.; Arnold, A.; Teichert, J.; Xiang, R.; Ma, S.; Schaber, J.

In order to optimize the next generation SRF gun at HZDR ELBE radiation source, the impact on beam dynamics from the SRF cavity geometry needs to be investigated. This paper presents an analysis on the electromagnetic fields and output electron beam qualities, by changing the geometry parameters of a 3.5-cell SRF gun cavity. The simulation results show the higher electric field ratio in the first half cell to the TESLA like cell, the better beam parameters we can obtain, which, however, will also lead to a higher Emax/E0 and Bmax/E0.

Keywords: SRF gun; superconducting cavity

  • Open Access Logo Poster
    The 19th International Conference on RF Superconductivity(SRF2019), 30.06.-05.07.2019, Dresden, Germany
    DOI: 10.18429/JACoW-SRF2019-THP082
  • Open Access Logo Contribution to proceedings
    The 19th International Conference on RF Superconductivity(SRF2019), 30.06.-05.07.2019, Dresden, Germany
    Proceedings of the 19th International Conference on RF Superconductivity: JACoW, 978-3-95450-211-0
    DOI: 10.18429/JACoW-SRF2019-THP082

Permalink: https://www.hzdr.de/publications/Publ-31122
Publ.-Id: 31122


Raw data: Quantification of peptide-particle interactions: A phage mimicking approach via site-selective immobilization on glass

Schrader, M.

This set contains the raw data of the fluorescence scanning experiments used in the publication of Quantification of peptide-particle interactions: A phage mimicking approach via site-selective immobilization on glass

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-06-05
    DOI: 10.14278/rodare.357
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-31121
Publ.-Id: 31121


SRF Gun and SRF Linac Driven THz at ELBE Successfully in User Operation

Xiang, R.; Arnold, A.; Evtushenko, P.; Kovalev, S.; Lehnert, U.; Lu, P.; Ma, S.; Michel, P.; Murcek, P.; Ryzhov, A.; Schaber, J.; Schneider, C.; Teichert, J.; Vennekate, H.; Will, I.

The first all-SRF accelerator driven THz source has been operated as a user facility since 2018 at ELBE radiation center. The CW electron beam is extracted from SRF gun II, accelerated to relativistic energies and compressed to sub-ps length in the ELBE SRF linac with a chicane. THz pulses are produced by passing the short electron bunches through a diffraction radiator (CDR) and an undulator. The coherent THz power increases quadratically with bunch charge. The pulse energy up to 10 μJ at 0.3 THz with 100 kHz has been generated.

Keywords: all-SRF accelerator; THz user facility; CW electron beam; SRF gun

  • Open Access Logo Poster
    The 19th International Conference on RF Superconductivity(SRF2019), 30.06.-05.07.2019, Dresden, Germany
    DOI: 10.18429/JACoW-SRF2019-THP032
  • Open Access Logo Contribution to proceedings
    The 19th International Conference on RF Superconductivity(SRF2019), 30.06.-05.07.2019, Dresden, Germany
    Proceedings of the 19th International Conference on RF Superconductivity: JACoW, 978-3-95450-211-0
    DOI: 10.18429/JACoW-SRF2019-THP032

Permalink: https://www.hzdr.de/publications/Publ-31120
Publ.-Id: 31120


Nonlinear compositional and morphological evolution of ion irradiated GaSb prior to nanostructure formation

Lively, M. A.; Holybee, B.; Toriyama, M.; Facsko, S.; Allain, J. P.

Low-energy ion irradiation of III-V semiconductor surfaces can lead to the formation of regular hexagonal dot patterns at the surface. We present experimental and computational results for ion irradiation of GaSb surfaces which elucidate the nature of the coupled compositional and morphological pattern-formation mechanisms. We demonstrate by in-situ grazing-incidence small-angle x-ray scattering (GISAXS) and angle-resolved Auger electron spectroscopy (ARAES) that the emergence of an altered compositional depth profile is essential to induce morphological changes at the surface. This morphological evolution of the surface follows nucleation-and-growth kinetics. Furthermore, we show from massive-scale molecular dynamics (MD) simulations that the compositional depth profile evolution leads to thermodynamic phase separation, providing a lateral compositional instability that drives pattern formation. Additionally, high-fluence simulations elucidate the irradiation-induced mechanisms of compositional depth profile formation. Prompt ion effects drive formation of single-element “protoclusters”, predominantly of Sb. Structural and energetic characterization of the simulation results indicate that Sb may be more mobile than Ga, providing a diffusional pathway for long-temporal-scale compositional evolution of the irradiated surface. Our findings motivate the development of new, comprehensive models which consider the total spatial and temporal complexity of multicomponent systems evolving under ion irradiation.

Keywords: nanostructures; ion beam irradiation; nanopatterning

Permalink: https://www.hzdr.de/publications/Publ-31118
Publ.-Id: 31118


Preliminary geometry optimization of a 3.5-cell SRF Gun cavity at ELBE based on beam dynamics

Zhou, K.; Li, P.; Arnold, A.; Schaber, J.; Xiang, R.; Teichert, J.; Ma, S.

At present, ELBE radiation source at HZDR is optimizing the SRF cavity for the next generation ELBE SRF GUN. This paper presents a preliminary study on the geometry optimization of a 3.5-cell SRF gun cavity based on beam dynamics. By changing the lengths of the half cell and the first TESLA like cell, two new cavity models with higher electric field in the half cell are built and their RF fields are compared with SRF GUN I and SRF GUN II. Through the scanning of the RF phases and the electric fields, the simulation results indicate that new models have smaller transverse emittance at relatively lower electric field gradients and better performance on longitudinal emittance than SRF GUN I and SRF GUN II.

Keywords: SRF cavity; SRF gun; transverse emittance

  • Open Access Logo Poster
    39th International Free-Electron Laser Conference (FEL19), 26.-30.08.2019, Hamburg, Germany
  • Open Access Logo Contribution to proceedings
    39th International Free-Electron Laser Conference (FEL19), 26.-30.08.2019, Hamburg, Germany
    Proceedings of the 39th International Free-Electron Laser Conference: JACoW, 978-3-95450-210-3
    DOI: 10.18429/JACoW-FEL2019-WEP026

Permalink: https://www.hzdr.de/publications/Publ-31117
Publ.-Id: 31117


Metal and semiconductor photocathodes in HZDR SRF gun

Xiang, R.; Arnold, A.; Murcek, P.; Teichert, J.; Schaber, J.

Quality of photocathode in a photoinjector is one of the critical issues for the stability and reliability of the whole accelerator facility. In April 2013, the IR FEL lasing was demonstrated for the first time with the electron beam from the SRF gun with Cs2Te at HZDR. Cs2Te photocathode worked in SRF gun-I for more than one year without degradation. Currently, Mg photocathodes with QE up to 0.5% are applied in SRF Gun-II, generating e- beam with bunch charge up to 300 pC in CW mode with sub-ps bunch length for the high power THz radiation. It is an excellent demonstration that SRF guns can work reliably in a high power user facility.

Keywords: photocathode; Cs2Te; Mg; photoinjector; SRF gun

  • Invited lecture (Conferences)
    ICFA Advanced Beam Dynamics Workshop on Energy Recovery Linacs (ERL’19), 15.-20.09.2019, Berlin, Germany
  • Open Access Logo Contribution to proceedings
    Workshop on Energy Recovery Linacs (ERL2019), 15.-20.09.2019, Berlin, Germany
    Proceedings of workshop on Energy Recovery Linacs (ERL2019)

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Permalink: https://www.hzdr.de/publications/Publ-31116
Publ.-Id: 31116


Robust Mg cathodes in SRF gun II

Xiang, R.; Jochen, T.

we present here the status of ELBE SRF gun II and the application of Mg photocathodes in SRF gun. In order to improve the QE of Mg cathodes, we appy the ps- UV laser cleaning for bulk Mg photocathodes. Furthermore, several alternative preparation methods of Mg are also under studying.

Keywords: Mg photocathode; SRF gun; laser cleaning

  • Open Access Logo Invited lecture (Conferences)
    European Workshop on Photocathodes for Particle Accelerator Applications (EWPAA 2019), 11.-13.09.2019, Villigen PSI, Switzerland

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Permalink: https://www.hzdr.de/publications/Publ-31115
Publ.-Id: 31115


Development and Implementation of Beam-Based Feedback Algorithms for Continuous Wave Superconducting Linear Accelerators

Maalberg, A.; Zenker, K.; Schwarz, A.; Evtushenko, P.; Kuntzsch, M.

The superconducting linear accelerator ELBE at Helmholtz-Center Dresden-Rossendorf is a versatile light source operated in continuous wave mode. New experiments and beam modes have a higher demand on the beam stability and reproducibility of accelerator settings. These requirements are addressed by an upgrade of the existing digital MicroTCA.4 based LLRF control by a beam-based feedback scheme. This poster gives an overview of the current control scheme, presents the planned beam diagnostics and discusses the possible ways of incorporating the beam-based feedback at the ELBE facility and a future light source.

  • Open Access Logo Poster
    19th International Conference on RF Superconductivity, 04.07.2019, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-31114
Publ.-Id: 31114


Spectral and spatial shaping of laser-driven proton beams using a pulsed high-field magnet beamline

Brack, F.-E.; Kroll, F.; Gaus, L.; Bernert, C.; Beyreuther, E.; Cowan, T.; Karsch, L.; Kraft, S.; Kunz-Schughart, L. A.; Leßmann, E.; Metzkes-Ng, J.; Obst-Hübl, L.; Pawelke, J.; Rehwald, M.; Schlenvoigt, H.-P.; Schramm, U.; Sobiella, M.; Rita Szabó, E.; Ziegler, T.; Zeil, K.

ntense laser-driven proton pulses, inherently broadband and highly divergent, pose a challenge to established beamline concepts on the path to application-adapted irradiation field formation, particularly for 3D. Here we experimentally show the successful implementation of a highly efficient (50% transmission) and tuneable dual pulsed solenoid setup to generate a homogeneous (laterally and in depth) volumetric dose distribution (cylindrical volume of 5 mm diameter and depth) at a single pulse dose of 0.7 Gy via multi-energy slice selection from the broad input spectrum. The experiments were conducted at the Petawatt beam of the Dresden Laser Acceleration Source Draco and were aided by a predictive simulation model verified by proton transport studies. With the characterised beamline we investigated manipulation and matching of lateral and depth dose profiles to various desired applications and targets. Using an adapted dose profile, we performed a first proof-of-technical-concept laser-driven proton irradiation of volumetric in-vitro tumour tissue (SAS spheroids) to demonstrate concurrent operation of laser accelerator, beam shaping, dosimetry and irradiation procedure of volumetric biological samples.

Keywords: Laser acceleration; Radiobiology; High field pulsed magnets

  • Open Access Logo Scientific Reports 10(2020), 9118
    DOI: 10.1038/s41598-020-65775-7
  • Lecture (Conference) (Online presentation)
    BLIN4: Beam Line and INstrumentation: Fourth Workshop, 29.06.2020, Dresden, Deutschland
  • Lecture (Conference) (Online presentation)
    LIGHT Collaboration Meeting, 30.06.2020, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-31113
Publ.-Id: 31113


The attempt of using GaN as a photocathode in SRF Gun II

Schaber, J.; Xiang, R.; Teichert, J.; Arnold, A.; Murcek, P.; Zwartek, P.; Ma, S.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green). An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
GaN is a semi-conductive material that is well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required. It has also a wide wavelength range from 100 to 380 nm.

Doping elements for n-type is silicon (Si) and for p-type magnesium (Mg). Mostly p-doped GaN promises better conditions because magnesium atoms increase the minority carrier diffusion length (about 200 nm). MOVPE is the most used technique to produce p-type GaN. Low temperatures are required in comparison to undoped or n-type GaN. Afterwards an annealing process is necessary to remove magnesium-bonded hydrogen. In p-type GaN electron are the minority carriers whereas holes are the majority carriers. The doping is assumed to lower the band bending around the surface. Therefore, the vacuum level is shifted to lower energy than the conductive band minimum in the flat band region.
Activated with a thin alkali metal layer, like caesium, GaN has the ability to lower the surface work function to produce a negative electron affinity (NEA). This effect originates from the surface band bending. Electrons excite over the bandgap and can easily enter into the vacuum.

Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
Like caesium telluride cathode it is possible to recover GaN(Cs) about 50% of the original QE with a simple bake out of 200°C and doing a Cs-reactivation to recover the degraded
cathode [2].
A big advantage of visible light cathodes instead of UV cathodes is to relax the drive laser requirements.

[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.
[2] Siegmund, O. et al. 2006. “Development of GaN Photocathodes for UV Detectors.” 567:89–92

Keywords: GaN(Cs) photocathode; III-V semiconductor; NEA photocathode; thin layer deposition

  • Open Access Logo Lecture (Conference)
    ECASIA 2019-European Conference on Applications of Surface and Interface Analysis, 15.-20.09.2019, Dresden, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31112
Publ.-Id: 31112


Emittance measurements comparison of slit-scan and quadrupole scan in simulation and experiments

Ma, S.; Arnold, A.; Evtushenko, P.; Ryzhov, A.; Schaber, J.; Teichert, J.; Xiang, R.

Three quadrupoles and one screen are used for beam transverse emittance measurements at HZDR ELBE. In this paper, the emittance calculated with two different methods, one with thin-lens approximation and the other one thick-lens no approximation, are compared and analized. To analyze the measurement error, quadrupole calibration is need. Two aspects about quadrupole analysis are made. The first one is quadrupole’s effective length and strength and the second one is quadrupole’s converged or diverged ability in reality.

  • Poster
    The 19th International Conference on RF Superconductivity, SRF2019, 30.06.-05.07.2019, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-31111
Publ.-Id: 31111


Study of using GaN(Cs) as a photocathode in SRF injector

Schaber, J.; Xiang, R.; Teichert, J.; Murcek, P.; Zwartek, P.; Arnold, A.; Ma, S.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green). An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.

Keywords: GaN photocathode; caesium activation; thin layer deposition, NEA photocathode

  • Open Access Logo Poster
    19th International Conference on RF Superconductivity, SRF2019, 30.06.-05.07.2019, Dresden, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31110
Publ.-Id: 31110


The attempt of using GaN(Cs) in SRF injector

Schaber, J.; Xiang, R.; Teichert, J.; Murcek, P.; Zwartek, P.; Arnold, A.; Ma, S.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green). An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.

Keywords: GaN; NEA activation; photocathode; thin layer deposition

  • Open Access Logo Poster
    EWPAA 2019: European workshop on photocathodes for particle accelerator applications, 11.-13.09.2019, Villingen, Schweiz

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Permalink: https://www.hzdr.de/publications/Publ-31109
Publ.-Id: 31109


Study of surface cleaning and Cs-activation on GaN photocathodes

Schaber, J.; Xiang, R.; Teichert, J.; Arnold, A.; Murcek, P.; Zwartek, P.; Ma, S.

Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams. With such a high intensity and short wavelengths, amorphous materials and chemical reaction steps nowadays could be studied.
GaN is a semi-conductive material that is well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is only used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
It has also a wide wavelength range from 100 to 380 nm.
The equilibrium phase of GaN is wutzite, which means gallium atoms are tetrahedrically surrounded by nitride atoms in a hexagonal closed crystal structure. The tetrahedrons build alternating bilayers of Ga and N in c-direction.
Doping elements for n-type is silicon (Si) and for p-type magnesium (Mg). Mostly p-doped GaN promises better conditions because magnesium atoms increase the minority carrier diffusion length (about 200 nm). MOVPE is the most used technique to produce p-type GaN. Low temperatures are required in comparison to undoped or n-type GaN. Afterwards an annealing process is necessary to remove magnesium-bonded hydrogen. In p-type GaN electron are the minority carriers whereas holes are the majority carriers. The doping is assumed to lower the band bending around the surface. Therefore, the vacuum level is shifted to lower energy than the conductive band minimum in the flat band region.
Activated with a thin alkali metal layer, like caesium, GaN has the ability to lower the surface work function to produce a negative electron affinity (NEA). This effect originates from the surface band bending. Electrons excite over the band gap and can easily enter into the vacuum.
Generally, the stability has also a great influence on the potential application in high brightness guns. GaN shows the promise of more significant stability and robustness against vacuum contaminations than alternate photocathodes.
Like caesium telluride cathode it is possible to recover GaN(Cs) about 50% of the original QE with a simple bake out of 200°C and doing a Cs-reactivation to recover the degraded
cathode [2].
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency GaN-Based Photocathodes with Extremely High Quantum Efficiency.” 103511(2005):1–4.
[2] Siegmund, O. et al. 2006. “Development of GaN Photocathodes for UV Detectors.” 567:89–92.

Keywords: photocathode; GaN; NEA activation

  • Open Access Logo Poster
    DPG Summer school 2019- Exciting nanostructures: Characterizing advanced confined systems, 22.-27.07.2019, Bad Honnef, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31108
Publ.-Id: 31108


The attempt of using GaN (Cs) as a photocathode in SRF injector

Schaber, J.; Xiang, R.; Teichert, J.; Arnold, A.; Murcek, P.; Zwartek, P.; Ma, S.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green).
An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.

Keywords: photocathode; semiconductor; NEA activation; surface analysis

  • Open Access Logo Poster
    DPG Frühjahrstagung, 18.-22.03.2019, München, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31107
Publ.-Id: 31107


The attempt of using GaN as a photocathode in SRF Gun II

Schaber, J.; Xiang, R.; Murcek, P.; Arnold, A.; Teichert, J.; Ma, S.; Zwartek, P.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green). An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.

  • Open Access Logo Lecture (Conference)
    5. Annual MT Meeting, 04.-07.03.2019, Jena, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31106
Publ.-Id: 31106


KLOE hadronic cross section data in the HepDATA repository

Müller, S.

Presentation at (remote) Kick-Off-Meeting of the PrecisionSM-Working group of the STRONG2020 EU Project.

Keywords: KLOE; HEPdata

  • Open Access Logo Lecture (Conference) (Online presentation)
    Kick-Off meeting for PrecisionSM working group of STRONG2020 project, 03.06.2020, ZOOM (Sweden), Sweden

Permalink: https://www.hzdr.de/publications/Publ-31105
Publ.-Id: 31105


Dataset for dynamic simulation of the CEFR control rod drop experiments

Fridman, E.

Dataset for dynamic simulation of the CEFR control rod drop experiments 

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-06-03
    DOI: 10.14278/rodare.353

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Permalink: https://www.hzdr.de/publications/Publ-31104
Publ.-Id: 31104


Biomineralization of uranium-phosphates fueled by microbial 1 degradation of isosaccharinic acid (ISA)

Kuippers, G.; Morris, K.; Townsend, L. T.; Bots, P.; Kvashnina, K.; Bryan, N.; Lloyd, J. R.

Geological disposal is the preferred long-term solution for higher activity radioactive wastes (HAW) including Intermediate Level Waste (ILW). In a cementitious disposal system, cellulosic waste items present in ILW could undergo alkaline hydrolysis, producing significant quantities of isosaccharinic acid (ISA), a chelating agent for radionuclides. Although microbial degradation of ISA has been demonstrated, its impact upon the fate of radionuclides in a GDF is a topic of ongoing research. This study investigates the fate of U(VI) in pH neutral, anoxic, microbial enrichment cultures, approaching conditions similar to the far field of a GDF, containing ISA as the sole carbon source, and elevated phosphate concentrations, incubated both (i) under fermentation and (ii) Fe(III)-reducing conditions. In the fermentation experiment, U(VI) was precipitated as insoluble U(VI)-phosphates, whereas under Fe(III)-reducing conditions, the majority of the uranium was precipitated as reduced U(IV)-phosphates, potentially via enzymatic reduction (mediated by metal-reducing bacteria including Geobacter species detected by 16S rRNA gene sequencing). Overall, this suggests the potential for the establishment of a microbially-mediated “bio-barrier” extending into the far field geosphere surrounding a GDF which has the potential to evolve in response to aspects of a GDF and can have a controlling impact on the fate of radionuclides.

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  • Secondary publication expected from 23.03.2022

Permalink: https://www.hzdr.de/publications/Publ-31103
Publ.-Id: 31103


ESFR-SMART WP1.2.1 dataset

Fridman, E.

ESFR-SMART WP1.2.1 dataset

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-06-03
    DOI: 10.14278/rodare.351

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Permalink: https://www.hzdr.de/publications/Publ-31102
Publ.-Id: 31102


Helmholtz AI For Matter at Helmholtz-Zentrum Dresden-Rossendorf

Steinbach, P.; Hoffmann, N.

This poster summarizes the Helmholtz AI local unit for Matter Research installed at HZDR. The poster was presented at the Helmholtz AI Kick-Off Meeting on March 5th, 2020, in Munich, Germany.

Keywords: Helmholtz AI; FWCC; Deep Learning; Machine Learning; Data Science; Kick-Off

  • Open Access Logo Poster (Online presentation)
    Helmholtz AI Kick-Off Meeting, 05.03.2020, München, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-31099
Publ.-Id: 31099


Neutronic analysis of the European Sodium Fast Reactor: Part II - burnup results

Fridman, E.; Álvarez-Velarde, F.; Romojaro-Otero, P.; Tsige-Tamirat, H.; Jiménez-Carrascosa, A.; García-Herranz, N.; Bernard, F.; Gregg, R.; Krepel, J.; Massara, S.; Poumerouly, S.; Girardi, E.; Mikityuk, K.

In the framework of the Horizon 2020 project ESFR-SMART, the European Sodium Fast Reactor (ESFR) core was updated through a safety-related modification and optimization of the core design from the earlier FP7 CP-ESFR project.

This study is dedicated to neutronic analysis of the new SFR core. The conducted work is reported in two parts. Part I dealt with the evaluation of the safety-related neutronic parameters of the fresh core carried out by 8 organizations using both continuous energy Monte Carlo and deterministic computer codes. A special emphasis was put on the calibration and verification of the computational tools involved in the analyses.

Part II is devoted to once-through and realistic batch-wise burnup calculations aiming at the establishing of the equilibrium core state, which will later serve as a basis for detailed safety analyses.

Keywords: ESFR; safety; Horizon 2020

Related publications

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-31098
Publ.-Id: 31098


Neutronic analysis of the European Sodium Fast Reactor: Part I - fresh core results

Fridman, E.; Álvarez-Velarde, F.; Romojaro-Otero, P.; Tsige-Tamirat, H.; Jiménez-Carrascosa, A.; García-Herranz, N.; Bernard, F.; Gregg, R.; Krepel, J.; Massara, S.; Poumerouly, S.; Girardi, E.; Mikityuk, K.

In the framework of the Horizon 2020 project ESFR-SMART (2017-2021), the European Sodium Fast Reactor (ESFR) core was updated through a safety-related modification and optimization of the core design from the earlier FP7 CP-ESFR project (2009-2013).

This study is dedicated to neutronic analyses of the improved ESFR core design. The conducted work is reported in two parts. Part I deals with the evaluation of the safety-related neutronic parameters of the fresh Beginning-of-Life (BOL) core carried out by 8 organizations using both continuous energy Monte Carlo and deterministic computer codes. In addition to the neutronics characterization of the core, a special emphasis was put on the calibration and verification of the computational tools involved in the analyses.

Part II is devoted to once-through and realistic batch-wise burnup calculations aiming at the establishing of the equilibrium core state, which will later serve as a basis for detailed safety analyses.

Keywords: ESFR; Safety; Horizon 2020

Related publications

Permalink: https://www.hzdr.de/publications/Publ-31097
Publ.-Id: 31097


Dynamic simulation of the CEFR control rod drop experiments with the Monte Carlo code Serpent

Fridman, E.; Huo, X.

The China Experimental Fast Reactor (CEFR) is the first SFR operated in China. The CEFR physical start-up tests, conducted in 2010, included control rod (CR) worth (CRW) measurements by the rod drop method.
In this study, the transient simulations of the actual course of the CR drop experiments have been performed with the Monte Carlo code Serpent using a detailed 3D heterogeneous model of the CEFR core. The estimated time-depended neutron population, dynamic reactivity, and CRWs have been compared to the measurements. The experimental and calculated reactivity curves have shown a very close behavior for the entire simulated time interval. With regard to the CRW results, a very good compliance between the experiment and simulations as well as among the applied computational approaches has been observed. The obtained results indicate that Serpent can be routinely applied to transient simulations, the area which until recently was limited to deterministic methods.

Keywords: CEFR; Serpent; dynamic Monte Carlo; rod drop experiments

Related publications

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  • Secondary publication expected from 20.07.2021

Permalink: https://www.hzdr.de/publications/Publ-31096
Publ.-Id: 31096


Laboratory study of stationary accretion shock relevant to astrophysical systems

Mabey, P.; Albertazzi, B.; Falize, E.; Michel, T.; Rigon, G.; van Box Som, L.; Pelka, A.; Brack, F.-E.; Kroll, F.; Filippov, E.; Gregori, G.; Kuramitsu, Y.; Lamb, D. Q.; Li, C.; Ozaki, N.; Pikuz, S.; Sakawa, Y.; Tzeferacos, P.; Koenig, M.

Accretion processes play a crucial role in a wide variety of astrophysical systems. Of particular interest are magnetic cataclysmic variables, where, plasma flow is directed along the star’s magnetic field lines onto its poles. A stationary shock is formed, several hundred kilometres above the stellar surface; a distance far too small to be resolved with today’s telescopes. Here, we report the results of an analogous laboratory experiment which recreates this astrophysical system. The dynamics of the laboratory system are strongly influenced by the interplay of material, thermal, magnetic and radiative effects, allowing a steady shock to form at a constant distance from a stationary obstacle. Our results demonstrate that a significant amount of plasma is ejected in the lateral direction; a phenomenon that is under-estimated in typical magnetohydrodynamic simulations and often neglected in astrophysical models. This changes the properties of the post-shock region considerably and has important implications for many astrophysical studies.

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Permalink: https://www.hzdr.de/publications/Publ-31094
Publ.-Id: 31094


Helmholtz AI Consultants at Helmholtz-Zentrum Dresden-Rossendorf

Steinbach, P.

This poster summarizes the dedicated Helmholtz AI consultant team installed at HZDR. The poster was presented at the Helmholtz AI Kick-Off Meeting on March 5th, 2020, in Munich, Germany.

Keywords: Helmholtz AI; consultants; Local Unit; Matter; Kick-Off

  • Open Access Logo Poster
    Helmholtz AI Kickoff, 05.03.2020, München, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-31093
Publ.-Id: 31093


Directed, elliptic and higher order flow harmonics of protons, deuterons and tritons in Au+Au collisions at sqrt(s_NN)=2.4 GeV

Adamczewski-Musch, J.; Arnold, O.; Behnke, C.; Belounnas, A.; Belyaev, A.; Berger-Chen, J. C.; Blanco, A.; Blume, C.; Böhmer, M.; Bordalo, P.; Chernenko, S.; Chlad, L.; Ciepal, I.; Deveaux, C.; Dreyer, J.; Epple, E.; Fabbietti, L.; Fateev, O.; Filip, P.; Fonte, P.; Franco, C.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Gernhäuser, R.; Golosov, O.; Golubeva, M.; Greifenhagen, R.; Guber, F.; Gumberidze, M.; Harabasz, S.; Heinz, T.; Hennino, T.; Hlavac, S.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Kämpfer, B.; Karavicheva, T.; Kardan, B.; Koenig, I.; Koenig, W.; Kohls, M.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kornas, F.; Kotte, R.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Lorenz, M.; Mahmoud, T.; Maier, L.; Malige, A.; Mamaev, M.; Mangiarotti, A.; Markert, J.; Matulewicz, T.; Maurus, S.; Metag, V.; Michel, J.; Mihaylov, D. M.; Morozov, S.; Müntz, C.; Münzer, R.; Naumann, L.; Nowakowski, K.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petukhov, O.; Piasecki, K.; Pietraszko, J.; Przygoda, W.; Pysz, K.; Ramos, S.; Ramstein, B.; Rathod, N.; Reshetin, A.; Rodriguez-Ramos, P.; Rosier, P.; Rost, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schuldes, H.; Schwab, E.; Scozzi, F.; Seck, F.; Sellheim, P.; Selyuzhenkov, I.; Siebenson, J.; Silva, L.; Singh, U.; Smyrski, J.; Sobolev, Y. G.; Spataro, S.; Spies, S.; Ströbele, H.; Stroth, J.; Sturm, C.; Svoboda, O.; Szala, M.; Tlusty, P.; Traxler, M.; Tsertos, H.; Usenko, E.; Wagner, V.; Wendisch, C.; Wiebusch, M. G.; Wirth, J.; Wójcik, D.; Zanevsky, Y.; Zumbruch, P.

Flow coefficients vn of the orders n=1−6 are measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI for protons, deuterons and tritons as a function of centrality, transverse momentum and rapidity in Au+Au collisions at sqrt(s_NN)=2.4 GeV. Combining the information from the flow coefficients of all orders allows to construct for the first time, at collision energies of a few GeV, a complete, multi-differential picture of the emission pattern of these particles. The ratio v4/v22 at mid-rapidity is found to be remarkably close to the value 0.5, as might be indicative for an ideal fluid scenario.

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Permalink: https://www.hzdr.de/publications/Publ-31092
Publ.-Id: 31092


Recent insights in barium-131 as a diagnostic match for radium-223: cyclotron production, separation, labeling and imaging

Reissig, F.; Bauer, D.; Ullrich, M.; Kreller, M.; Pietzsch, J.; Mamat, C.; Kopka, K.; Pietzsch, H.-J.; Walther, M.

Barium-131 is a promising SPECT-compatible radionuclide for nuclear medicine and a promising diagnostic match for the alpha emitters radium-223/-224 by providing similar chemical properties as well as physical half-lives. Methods: Herein, we report on the sufficient production route 133Cs(p,3n)131Ba by using 28 MeV proton beams. Moreover, a sufficient purification process, based on SR Resin, was applied. For the first time, radiolabeling of macropa (literature-known chelator) with barium-131 was performed. Biodistribution studies and small animal SPECT/CT measurements were carried out with [131Ba]Ba(NO3)2 as reference and 131Ba-labeled macropa. Results: An average of 190 MBq barium-131 per irradiation was obtained. The purification process led to barium-131 in high radiochemical purity. Only an isotopic impurity of 0.01% barium-133 was detectable. Radiolabeling methods under mild conditions and reaction controls based on TLC systems were successfully applied for the labeling of the chelator macropa. For the first time, small animal SPECT imaging was performed using [131Ba]Ba(NO3)2 and 131Ba-labeled macropa in healthy mice. Biodistribution studies revealed the expected rapid bone uptake of [131Ba]Ba2+ ions, whereas 131Ba-labeled macropa showed a fast clearance from the blood, thereby showing a significantly (P < 0.001) lower accumulation in the bone. Conclusion: Barium-131 is a promising SPECT radionuclide and delivers appropriate imaging qualities in small animals. Furthermore, the relative stability of the 131Ba-labeled macropa complex in vivo forms the basis for the development of sufficient new chelators for heavy alkaline earth metal ions, especially for radium isotopes. Those radionuclides and the necessary stable chelation are of great interest in the research field of targeted alpha therapy. Thereby, barium-131 will reveal its meaning as diagnostic match to the alpha emitters radium-223 and radium-224.

Keywords: barium-131; cyclotron production; radionuclide separation; macropa; small animal SPECT

Permalink: https://www.hzdr.de/publications/Publ-31091
Publ.-Id: 31091


Corrigendum to “Controls on strath terrace formation and evolution: The lower Guadiana River, Pulo do Lobo, Portugal”

Ortega-Becerril, J. A.; Garzón, G.; Tejero, R.; Meriaux, A.-S.; Delunel, R.; Merchel, S.; Rugel, G.

The authors regret publishing the original article while omitting four authors. The correct author list and affiliations have now been corrected.
We would also like to make the clarifications and corrections listed below on the cosmogenic radionuclide (CRN) analysis.
1) All ¹⁰Be samples were collected in 2010 and prepared at the Newcastle Cosmogenic Isotope Laboratory. Accelerator mass spectrometry (AMS) of ¹⁰Be was performed in 2011 at the DREAMS-facility at the Helmholtz-ZentrumDresden-Rossendorf (HZDR) (Akhmadaliev et al., 2013).
2) All the ¹⁰Be model ages were calculated similarly to Mériaux et al. (2012). Spallation and muon production rate schemes are compatible with the CRONUS-Earth calculator v2.2 using the mid-latitude attenuation length of Farber et al. (2008). Ζero erosion model ages were calculated similarly than the Stone/Lal scaling scheme of Balco et al. (2008) with a constant production rate “St” for ¹⁰Be of 4.49 ± 0.39 atoms/g·year instead of the updated 4.01 ± 0.32 atoms/g·year for that scheme by Phillips et al. (2016). The “St” model ages are corrected for the production rate update. Thickness corrections assume a density of ρ = 2.65 g/cm³ for each sample.
The topographic shielding is derived from topographic data collected in the field. The propagated analytical uncertainties include
error blank, carrier, counting statistics and the uncertainty of the standard-like material SMD-Be-12 (Akhmadaliev et al., 2013). The propagated uncertainties include statistical uncertainties from the AMS, 8% uncertainty on the production rate, 0.87% for the decay constants of ¹⁰Be (Korschinek et al., 2010), as well as uncertainty of 5% on the density and 2.25% on the attenuation length of 177 ± 4 g/cm² (Farber et al., 2008). The ages are given in ka. Table 2 has been corrected and completed with the time-dependent model ages calculated using the “LSDn” scaling model (Lifton et al., 2014).
These “LSDn” model ages integrate the variation of the magnetic field over time together with the non-dipole field components and up-to-date spallation and muon scaling schemes with elevation, latitude and longitude, and production rate of 3.92 ± 0.31 atoms/g·year for this LSDn scaling (see Borchers et al., 2016, Marrero et al., 2016 and Phillips et al., 2016 for details). In both cases, all the CRN model ages are calculated assuming no erosion, therefore all these models are minimum ages for that of the strath terraces.
The authors would like to apologise for any inconvenience caused.

Keywords: AMS; geomorphology

Permalink: https://www.hzdr.de/publications/Publ-31090
Publ.-Id: 31090


Effects of pillar size modulation on the magneto-structural coupling in self-assembled BiFeO3–CoFe2O4 heteroepitaxy

Amrillah, T.; Chen, Y.-X.; Ngoc Duong, M.; Abdussalam, W.; Mangasa Simanjuntak, F.; Chia-Hao, C.; Ying-Hao, C.; Jenh-Yih, J.

The magneto-structural coupling of BiFeO3 (BFO)–CoFe2O4 (CFO)/LaAlO3 (LAO) heteroepitaxy with various lateral sizes of CFO pillars embedded in a BFO matrix was investigated. A struc- tural phase transformation of the BFO matrix was observed when the pillar size of CFO was increased to exceed 200 nm. Such structural transformation led to modification of magneto-elastic coupling behavior and magnetic anisotropy in the BFO–CFO/LAO system. The flexibility of tuning the pillar size of CFO, and hence, the strain and interfacial effect on the multiferroic system have significant application implications in these functional oxide nanocomposites.

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Permalink: https://www.hzdr.de/publications/Publ-31089
Publ.-Id: 31089


Revealing the Role of Epithelial Mechanics and Macrophage Clearance during Pulmonary Epithelial Injury Recovery in the Presence of Carbon Nanotubes

Septiadi, D.; Abdussalam, W.; Rodriguez-Lorenzo, L.; Spuch-Calvar, M.; Bourquin, J.; Petri-Fink, A.; Rothen-Rutishauser, B.

Wound healing assays are extensively used to study tissue repair mechanisms; they are typically performed by means of physical (i.e., mechanical, electrical, or optical) detachment of the cells in order to create an open space in which live cells can lodge. Herein, an advanced system based on extensive photobleaching-induced apoptosis; providing a powerful tool to understand the repair response of lung epithelial tissue, consisting of a small injury area where apoptotic cells are still intact, is developed. Notably, the importance of epithelial mechanics and the presence of macrophages during the repair can be understood. The findings reveal that individual epithelial cells are able to clear the apoptotic cells by applying a pushing force, whilst macrophages actively phagocytose the dead cells to create an empty space. It is further shown that this repair mechanism is hampered when carbon nanotubes (CNTs) are introduced: formation of aberrant (i.e., thickening) F-actins, maturation of focal adhesion, and increase in traction force leading to retardation in cell migration are observed. The results provide a mechanistic view of how CNTs can interfere with lung repair.

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Permalink: https://www.hzdr.de/publications/Publ-31087
Publ.-Id: 31087


Two-photon retinal theranostics by adaptive compact laser source

Podlipec, R.; Mur, J.; Petelin, J.; Štrancar, J.; Petkovšek, R.

To avoid a devastating effect of eye vision impairment on the information flow from the eye to our brain, enormous effort is being put during the last decades into the development of more sensitive diagnostics and more efficient therapies of retinal tissue. While morphology can be impressively imaged by optical coherence tomography, molecular-associated pathology information can be provided almost exclusively by auto-fluorescence-based methods. Among the latter, the recently developed fluorescence lifetime imaging ophthalmoscopy (FLIO) has the potential to provide both structural information and interacting pictures at the same time. The requirements for FLIO laser sources are almost orthogonal to the laser sources used in phototherapy that is expected to follow up the FLIO diagnostics. To make theranostics more effective and cheaper, the complete system would need to couple at least the modalities of low-power high-repetition-rate FLIO and precision high-pulse energy-adjustable repetition rate phototherapy. In addition, the intermediate-power high repetition rate for two-photon excitation would also be desired to increase the depth resolution. In our work, compact fiber-laser based on high-speed gain-switched laser diode has been shown to achieve adaptable/independently tunable repetition rate and energy per pulse allowing coupled fluorescence lifetime diagnostics via two-photon excitation and phototherapy via laser-induced photodisruption on a local molecular environment in a complex ex vivo retinal tissue.

Keywords: adaptable fiber laser; retinal tissue; theranostics; multimodal imaging; fluorescence lifetime imaging

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  • Secondary publication expected from 11.05.2021

Permalink: https://www.hzdr.de/publications/Publ-31086
Publ.-Id: 31086


Material assignment for proton range prediction in Monte Carlo patient simulations using stopping-power datasets

Fibiani-Permatasari, F.; Eulitz, J.; Richter, C.; Wohlfahrt, P.; Lühr, A.

Motivation and objective: For each institute, the selection and calibration of the most suitable approach to assign material properties for Monte Carlo (MC) patient simulation in proton therapy is a major challenge. Current conventional approaches based on computed tomography (CT) depend on CT acquisition and reconstruction settings. This study proposes a material assignment approach, referred to as MATA (MATerial Assignment), which is independent of CT scanner properties and, therefore, universally applicable by any institute. Materials and methods: The MATA approach assigns material properties to the physical quantity stopping-power ratio (SPR) using a set of 40 material compositions specified for human tissues and linearly determined mass density. The application of clinically available CT-number-to-SPR conversion avoids the need for any further calibration. The MATA approach was validated with homogeneous and heterogeneous SPR datasets by assessing the SPR accuracy after material assignment obtained either based on dose scoring or determination of water-equivalent thickness. Finally, MATA was applied on patient datasets to evaluate dose differences induced by different approaches for material assignment and SPR prediction. Results: The deviation between the SPR after material assignment and the input SPR was close to zero in homogeneous datasets and below 0.002 (0.2% relative to water) in heterogeneous datasets, which was within the systematic uncertainty in SPR estimation. The comparison of different material assignment approaches revealed relevant differences in dose distribution and SPR. The comparison between two SPR prediction approaches, a standard look-up table and direct SPR determination from dual-energy CT, resulted in patient-specific mean proton range shifts between 1.3 mm and 4.8 mm. Conclusion: MATA eliminates the need for institution-specific adaptations of the material assignment. It allows for using any SPR dataset and thus facilitates the implementation of more accurate SPR prediction approaches. Hence, MATA provides a universal solution for patient modeling in MC-based proton treatment planning.

Keywords: Monte Carlo simulation; TOPAS; stopping-power ratio; dual-energy CT; proton radiotherapy

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  • Secondary publication expected from 11.09.2021

Permalink: https://www.hzdr.de/publications/Publ-31085
Publ.-Id: 31085


Thermal neutron radiography of a passive proton exchange membrane fuel cell for portable hydrogen energy systems

M. Chaparro, A.; Ferreira-Aparicio, P.; Folgado, M. A.; Hübscher, R.; Lange, C.; Weber, N.

A proton exchange membrane fuel cell (PEMFC) for portable applications is studied with thermal neutron radiography. The PEMFC operates under passive conditions, with air-breathing cathode and dead-end anode supplied with static ambient air and dry hydrogen, respectively. A columnar cathodic plate favors the mobility of water drops over the cathode surface and their elimination. Thermal neutron images show liquid water build-up during operation of the cell in vertical and horizontal position, i.e. aligned parallel and perpendicular to the gravity field, respectively. Polarization curves and impedance spectroscopy show orientation dependent cell response that can be related with the water profiles. In vertical position, the elimination of drops sliding over the cathode surface as well as natural convection favor lower water contents in the cathode and improve oxygen transport. The vertical cell can be operated for hours in ambient conditions, providing steady power densities above 100 mW cm-² . In horizontal position, natural forces are less effective for water removal leading to 17% decrease in peak power density. The horizontal position is especially adverse if the upper electrode is the cathode, because anode flooding causes cell failure after production of a small amount of water (5 mg cm-²).

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  • Secondary publication expected from 06.09.2021

Permalink: https://www.hzdr.de/publications/Publ-31084
Publ.-Id: 31084


Element- and orbital-selective magnetic coherent rotation at the first-order phase transition of a hard uniaxial ferrimagnet

Yamamoto, S.; Gorbunov, D.; Akai, H.; Yasumura, H.; Kotani, Y.; Nakamura, T.; Kato, T.; Mushnikov, N. V.; Andreev, A. V.; Nojiri, H.; Wosnitza, J.

3d-4 f intermetalic compounds with heavy rare-earth elements show first-order phase transitions in high magnetic fields due to the competition between the exchange interaction and the magnetocrystalline anisotropy. However, the microscopic picture of the field-induced noncollinear magnetic structures remains elusive. Here we report the direct experimental observation of the coherent stepwise rotation of the 3d and 4 f magnetic moments of the uniaxial hard ferrimagnet TmFe5Al7 by using soft x-ray magnetic circular dichroism in pulsed magnetic fields up to 25 T. The element- and shell-selective moments show a transition from the collinear ferrimagnet toward the forced ferromagnetic state via a canted phase, which is explained by a two-sublattice model.

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Permalink: https://www.hzdr.de/publications/Publ-31083
Publ.-Id: 31083


Advanced characterization of multicaloric materials in pulsed magnetic fields

Gottschall, T.; Bykov, E.; Gràcia-Condal, A.; Beckmann, B.; Taubel, A.; Pfeuffer, L.; Gutfleisch, O.; Manosa, L.; Planes, A.; Scurschii, I.; Wosnitza, J.

The multicaloric effect is described by a temperature or entropy change of a material triggered by external stimuli applied or removed simultaneously or sequentially. The prerequisite for this is a material exhibiting multiple ferroic states. However, direct measurements of the effect are rarely reported. Now, for this reason, we built a measurement device allowing to determine the adiabatic temperature change in pulsed magnetic fields and, simultaneously, under the influence of a uniaxial load. We selected the all-d-metal Heusler alloy Ni–Mn–Ti–Co for our first test because of its enhanced mechanical properties and enormous magneto- and elastocaloric effects. Ni–Mn–Ti–Co was exposed to pulsed magnetic fields up to 10 T and uniaxial stresses up to 80 MPa, and the corresponding adiabatic temperature changes were measured. With our new experimental tool, we are able to better understand multicaloric materials and determine their cross-coupling responses to different stimuli.

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Permalink: https://www.hzdr.de/publications/Publ-31082
Publ.-Id: 31082


Unexpected magnetic phase in the weakly ordered spin-1/2 chain cuprate Sr2CuO3

Sergeicheva, E. G.; Sosin, S. S.; Gorbunov, D.; Zherlitsyn, S.; Gu, G. D.; Zaliznyak, I. A.

The magnetic phase diagram of a spin- 1/2 chain antiferromagnet Sr2CuO3 is studied by an ultrasound phase-sensitive detection technique. The system is in the extreme proximity of the Luttinger-liquid quantum-critical point and we observe an unusually strong effect of magnetic field, which is very weak compared to the in-chain interaction, on the Néel ordering temperature. Inside the ordered phase, we detect an unexpected, field-induced continuous phase transition. The transition is accompanied by softening of magnetic excitation observed by electron-spin resonance, which in previous work [E. G. Sergeicheva et al., Phys. Rev. B 95, 020411(R) (2017)] was associated with a longitudinal (amplitude) mode of the order parameter. These results suggest a transition from a transverse collinear antiferromagnet to an amplitude-modulated spin-density-wave phase in a very weak magnetic field, which is unexpected for a system of weakly coupled Heisenberg spin- 1/2 chains.

Permalink: https://www.hzdr.de/publications/Publ-31081
Publ.-Id: 31081


Effect of curvature on the eigenstates of magnetic skyrmions

Korniienko, A.; Kakay, A.; Sheka, D. D.; Kravchuk, V. P.

Spectrum of spin eigenmodes localized on a ferromagnetic skyrmion pinned by a geometrical defect (bump) of magnetic films is studied theoretically. By means of direct numerical solution of the corresponding eigenvalue problem and finite element micromagnetic simulations we demonstrate, that the curvature can induce localized modes with higher azimuthal and radial quantum numbers, which are absent for planar skyrmions (for the same parameters). The eigenfrequencies of all modes, except the breathing and gyromodes decreases with increasing curvature. Due to the translational symmetry break, the zero translational mode of the skyrmion gains a finite frequency and forms the gyromode, which describes the uniform rotation of skyrmions around the equilibrium position. In order to treat the gyromotion analytically we developed a Thiele-like collective variable approach. We show that Neel skyrmions in curvilinear films experience a driving force originating from the gradient of the mean curvature. The gyrofrequency of the pinned skyrmion is proportional to the second derivative of the mean curvature at the point of equilibrium.

Keywords: skyrmions; curvature; eigenmodes; Thiele equation

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Permalink: https://www.hzdr.de/publications/Publ-31080
Publ.-Id: 31080


Multidimensional characterization of separation processes – Part 2: Comparability of separation efficiency

Buchmann, M.; Schach, E.; Leißner, T.; Kern, M.; Mütze, T.; Rudolph, M.; Peuker, U.; Tolosana Delgado, R.

Following the proposal of deriving statistical entropy maps from multidimensional separation curves, an extension is proposed to allow to compare the separation efficiency of various separation processes. This is achieved by integrating the entropy map weighted by the mass distribution of the particles in the feed. This proposal has several advantages: its straightforward extension to multidimensional partition curves, its scalar value (which allows for a natural ranking of processes), its flexibility to adapt to each and every feed, and its non-parametric character. A typical dynamic air classification process of an iron ore is presented as an example.

Keywords: Multidimensional partition curves; Weighted entropy; Particle tracking; Kernel density estimates; Mineral processing

Permalink: https://www.hzdr.de/publications/Publ-31079
Publ.-Id: 31079


Generating a tide-like flow in a cylindrical vessel by electromagnetic forcing

Jüstel, P.; Röhrborn, S.; Frick, P.; Galindo, V.; Gundrum, T.; Schindler, F.; Stefani, F.; Stepanov, R.; Vogt, T.

We show and compare numerical and experimental results on the electromagnetic generation of a tide-like flow structure in a cylindrical vessel which is filled with the eutectic liquid metal alloy GaInSn. Fields of various strengths and frequencies are applied to drive liquid metal flows. The impact of the field variations on amplitude and structure of the flows are investigated. The results represent the basis for a future Rayleigh-Bénard experiment, in which a modulated tide-like flow perturbation is expected to synchronize the typical sloshing mode of the large-scale circulation. A similar entrainment mechanism for the helicity in the Sun may be responsible for the synchronization of the solar dynamo with the alignment cycle of the tidally dominant planets Venus, Earth and Jupiter.

Keywords: electromagnetic forcing; impinging jets; magnetohydrodynamics; helicity synchronization

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Permalink: https://www.hzdr.de/publications/Publ-31078
Publ.-Id: 31078


Magnetic Effects on Microstructure and Solute Plume Dynamics of Directionally Solidifying Ga-In Alloy

Kao, A.; Shevchenko, N.; He, S.; Lee, P. D.; Eckert, S.; Pericleous, K.

The effects of applying a 0.2 T transverse magnetic field to a solidifying Ga-25%wt.In alloy were investigated through a joint experimental and numerical study. The magnetic field introduced significant changes to both the microstructure and the dynamics of escaping high concentration Ga plumes. Plume migration across the interface was quantified and correlated to simulations to demonstrate that Thermoelectric Magnetohydrodynamics (TEMHD) is the underlying mechanism. TEMHD introduced macro segregation within the dendritic structure leading to the formation of a stable ‘chimney’ channel by increasing solutal buoyancy in the flow direction. The resulting pressure difference across the solidification front, introduced a secondary hydrodynamic phenomenon that subsequently causes solute plume migration.

Keywords: Microstructure; Solidification; Magnetic Field; Freckle Defects; X-ray imaging; In situ observations

Permalink: https://www.hzdr.de/publications/Publ-31077
Publ.-Id: 31077


Silicon Surface Passivation by ALD-Ga₂O₃: Thermal vs. Plasma-Enhanced Atomic Layer Deposition

Hiller, D.; Julin, J. A.; Chnani, A.; Strehle, S.

Silicon surface passivation by gallium oxide (Ga2O3) thin films deposited by thermal- and plasma-enhanced atomic layer deposition (ALD) over a broad temperature range from 75 °C to 350 °C is investigated. In addition, the role of oxidant (O3 or O-plasma) pulse lengths insufficient for saturated ALD-growth is studied. The material properties are analyzed including the quantification of the incorporated hydrogen. We find that oxidant dose pulses insufficient for saturation provide for both ALD methods generally better surface passivation. Furthermore, different Si surface pretreatments are compared (HF-last, chemically grown oxide, and thermal tunnel oxide). In contrast to previous reports, the annealing time to activate the surface passivation is found to be significantly shorter. The best surface saturation current densities (JOs) or surface recombination velocities (Seff) are 6 and 9 fA/cm² or 0.6 and 1.5 cm/s for n- and p-type Si, respectively. We correlate the surface passivation with the negative fixed charge density (Qfix; field-effect passivation) and the interface defect density (Dit; chemical passivation). It turns out that a high Qfix is present, irrespective of the utilized ALD-method, deposition temperature, or postannealing, whereas low Dit is only achieved fo rplasma-enhanced ALD at low temperatures. A critical H-density of∼10¹⁶ cm−2 is identified as a necessary but not sufficient condition for excellent surface passivation. Finally, contact resistivities are measured to investigate the possibility of using ALD-Ga2O3 as passivating contact material. In order to understand the current-voltage measurements, the energetic positions of the band edges and the Fermi level are determined by ultraviolet photoelectron spectroscopy and Kelvin probe.

Keywords: Atomic layer deposition (ALD); gallium oxide(Ga2O3); hydrogen; silicon surface passivation

Permalink: https://www.hzdr.de/publications/Publ-31076
Publ.-Id: 31076


The integration of structural mechanics into microstructure solidification modelling

Soar, P.; Kao, A.; Djambazov, G.; Shevchenko, N.; Eckert, S.; Pericleous, K.

In situ structural mechanics are an often neglected area when modelling alloy microstructure during solidification, despite the existence of practical examples and studies which seem to indicate that the interaction between thermal or mechanical stresses and microstructure can have a significant impact on its evolution and hence the final properties at a macroscopic level. A bespoke structural mechanics solver using the finite volume method has been developed to solve the linear elasticity equations, with design choices being made to facilitate the coupling of this solver to run in situ with an existing solidification model. The accuracy of the structural mechanics solver is verified against an analytic solution and initial results from a fully coupled system are presented which demonstrate in a fundamental example that the interaction between structural mechanics and a solidifying dendrite can lead to a significant change in growth behaviour.

Keywords: Structural Mechanics; Microstrcture Solidification; Multi-Physics

  • Lecture (Conference) (Online presentation)
    MCWASP XV: Modelling of Casting, Welding and Advanced Solidification Processes, 22.-23.06.2020, Jönköping, Sweden
  • Open Access Logo IOP Conference Series: Materials Science and Engineering 861(2020)1, 012054
    DOI: 10.1088/1757-899X/861/1/012054

Permalink: https://www.hzdr.de/publications/Publ-31075
Publ.-Id: 31075


Controlling Freckle Defect Formation with Magnetic Fields During Directional Solidification of GaIn Alloy

Kao, A.; Krastins, I.; Shevchenko, N.; Eckert, S.; Pericleous, K.

Segregation of alloying components during solidification leads to stable solute channels, that solidify into defects called freckles. Freckles are caused by buoyancy driving lighter liquid elements, forming a macroscale channel that is fed by inter-dendritic flow. When fully solidified this channel represents a discontinuity in material properties and can lead to the failure of components. The application of a magnetic field, B, adds two physical phenomena to the process: the first is Electromagnetic Damping (EMD) of the liquid metal motion, the second is interstitial flow due to Thermoelectric (TE) Magnetohydrodynamics (MHD). TE effects translate temperature variations at the junction of two conductive materials into electric current, in this case between the solid and liquid.
The current, j¸ interacts with the magnetic field producing a Lorentz force F=j×B. Both the orientation and magnitude of the magnetic field determine the direction and strength of EMD and TEMHD effects.
Consider directional solidification of a solutal unstable buoyant alloy, namely Ga-25wt. %In. Both high velocity plumes of solute and the TE currents will be predominantly aligned to the thermal gradient (∇T), while the feeding inter-dendritic flow is primarily perpendicular to ∇T. A magnetic field orientated perpendicular to ∇T introduces EMD effects on the channel and also interacts with TE currents driving TEMHD flow. To capture these phenomena a parallel Cellular Automata Lattice Boltzmann Method that solves for microstructure solidification, fluid dynamics and electromagnetism using 100s millions of computational cells is used to simulate the freckle formation process at the sample scale. The results indicate that the channel formation can be significantly altered, showing the magnetic field as a potential technique for defect mitigation.

Keywords: Microstructure Solidification; Magnetic Field; Freckle Defects

  • Poster (Online presentation)
    MCWASP XV: Modelling of Casting, Welding and Advanced Solidification Processes, 22.-23.06.2020, Jönköping, Sweden

Permalink: https://www.hzdr.de/publications/Publ-31074
Publ.-Id: 31074


Volt-per-Ångstrom terahertz fields from X-ray free-electron lasers

Tanikawa, T.; Karabekyan, S.; Kovalev, S.; Casalbuoni, S.; Askegar, V.; Bonetti, S.; Wall, S.; Laarmann, T.; Turchinovich, D.; Zalden, P.; Kampfrath, T.; Fisher, A. S.; Stojanovic, N.; Gensch, M.; Geloni, G.

The electron linear accelerators driving modern X-ray free-electron lasers can emit intense, tunable, quasi-monochromatic terahertz (THz) transients with peak electric fields of V Å−1 and peak magnetic fields in excess of 10 T when a purpose-built, compact, superconducting THz undulator is implemented. New research avenues such as X-ray movies of THz-driven mode-selective chemistry come into reach by making dual use of the ultra-short GeV electron bunches, possible by a rather minor extension of the infrastructure.

Keywords: superradiant emission; terahertz control; terahertz radiation; ultrafast phenomena; X-ray free-electron laser

Permalink: https://www.hzdr.de/publications/Publ-31073
Publ.-Id: 31073


In situ observation of directional solidification in Ga-In alloy under a transverse DC magnetic field

He, S.; Shevchenko, N.; Eckert, S.

The directional solidification of a Ga-25wt.%In alloy under the effect of a transverse DC magnetic field is investigated by X-ray radiography. The magnetic field pointing parallel to the X-ray beam is generated by two ring-shaped permanent magnets. The magnetic field reaches values up to ~0.19 T in the field of view. The dendritic growth and the flow patterns of Ga-rich plumes migrating along the solidification front are captured and analyzed. It shows that the local fluctuations of solute concentration are partially damped by the magnetic field. At the temperature gradient of 1 K/mm, the growth velocities of solidification front and plumes are not affected. In the case of higher temperature gradient (~2 K/mm), the magnetic field causes an increase of the plume velocity in the horizontal direction and a decrease in the vertical direction while the velocity of the solidification front remains constant. Additionally, it is found that the magnetic field damps the fluctuations of tip velocity and refines the primary arm spacing. Above phenomena are discussed based on the thermoelectric magnetic and electromagnetic braking effects. The in situ experimental data are important for verification and improvement of the existing numerical simulations of solidification under the magnetic field.

Keywords: X-ray radiography; directional solidification; transverse magnetic field; dendritic growth; Ga-rich plumes

  • Poster (Online presentation)
    MCWASP XV: Modelling of Casting, Welding and Advanced Solidification Processes, 22.-23.06.2020, Jönköping, Sweden
  • Open Access Logo IOP Conference Series: Materials Science and Engineering 861(2020)1, 012025
    DOI: 10.1088/1757-899X/861/1/012025

Permalink: https://www.hzdr.de/publications/Publ-31072
Publ.-Id: 31072


Evolution of dendritic morphology in a solidifying Ga-In alloy studied by in-situ synchrotron radiography

Shevchenko, N.; Neumann-Heyme, H.; Grenzer, J.; Keplinger, O.; Rack, A.; Eckert, K.; Eckert, S.

The local dynamics of dendritic tips and side arms during the growth and coarsening stages are studied by X-ray synchrotron radiography and by numerical simulation. The direct investigation of dendritic side arm evolution appears to be rather complex and impose high requirements with respect to the spatial and temporal resolution and sensitivity of the detector. The synchrotron imaging experiments were performed at the ID19 beamline (ESRF, France) at a spatial resolution of < 1 µm. A flat sample of a Ga-In alloy is solidified from top to down applying a vertical temperature gradient. The present measurements provide real-time in-situ data on three phenomena that are of major importance in dendrite morphology evolution: side arm coarsening, side arm-splitting and dendrite tip evolution. The combination of numerical modeling and synchrotron experiments has allowed to improve the understanding of coarsening of dendritic side arms and to obtain material information that is relevant for quantitative modeling. Another interesting effect can be observed during in situ solidification experiments: a transition from a four-fold symmetry to a hyperbranched dendritic morphology. This morphological transition originating from the splitting of dendrite side arms has been detected.

Keywords: X-ray radiography; synchrotron experiments; side arms; dendrite tip; coarsening

  • Poster (Online presentation)
    MCWASP XV: Modelling of Casting, Welding and Advanced Solidification Processes, 22.-23.06.2020, Jönköping, Sweden

Permalink: https://www.hzdr.de/publications/Publ-31071
Publ.-Id: 31071


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