Publication database - Helmholtz-Zentrum Dresden-Rossendorf

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Only approved publications

25559 Publications
Magnetic stirring and sonication of liquid metals
Gerbeth, G.
  • Invited lecture (Conferences)
    International Workshop MHD-Days 2015, 07.-09.12.2015, Ilmenau, Germany
Registration No. 23303 - Permalink

Thermohydraulic safety issues for liquid metal cooled system
Gerbeth, G.
Abstract: A review is given on recent developments for liquid metal measurement techniques and their application in liquid metal cooled systems.
  • Invited lecture (Conferences)
    1st Sino-German Symposium on Fundamentals of Advanced Nuclear Safety Technology, 08.-12.03.2015, Shanghai, China
Registration No. 23302 - Permalink

Wertorientierung im Technologiemanagement von Krankenhäusern
Gurtner, S.; Gurtner, K.
Abstract: Neue innovative Technologien bieten zahlreiche Möglichkeiten, die Qualität der Behandlung von Patienten und den Behandlungserfolg zu steigern [1]. Neue technologiebasierte Diagnosemethoden, wie z. B. die Computertomografie oder die Magnet-Resonanz-Tomografie ebneten den Weg zur frühzeitigen Erkennung kritischer Erkrankungen wie Krebs oder Durchblutungsstörungen. Die Einführung neuer Methoden und Technologien für die Behandlung akuter Erkrankungen reduzierte die Mortalität und verbesserte die Lebensqualität zahlloser Patienten [2]. Auf der anderen Seite stiegen die Gesundheitsausgaben im Vergleich zum Bruttosozialprodukt in nahezu allen Industrieländern [3]. Der Grund für diesen unverhältnismäßigen Anstieg liegt in der steigenden Lebenserwartung, einer durch den demografischen Wandel verursachten zunehmenden Anzahl an Patienten, häufiger auftretenden Langzeit- oder chronischen Erkrankungen und einer zunehmenden Spezialisierung der Medizin [4]. Als einer der bedeutendsten Treiber von steigenden Gesundheitsausgaben wird häufig die Entwicklung und Implementierung von innovativen Medizintechnologien genannt [5, 6, 7]. Als Resultat der Einführung neuer Technologien kann eine stetige Steigerung des Angebotes medizinischer Dienstleistungen beobachtet werden, was insbesondere bei Krankenhäusern Auswirkungen auf das erforderliche Budget hat. Krankenhäuser als wichtiger Bestandteil des Gesundheitssystems müssen sich dabei einer Reihe strategischer Herausforderungen stellen. Wie jedes andere Unternehmen müssen sie qualitativ hochwertige Dienstleistungen anbieten und gleichzeitig auf ihre Kosten achten. Die Adoption neuer Technologien ist notwendig, um mit anderen Krankenhäusern und Gesundheitsversorgern zu konkurrieren, gleichzeitig müssen sie aber auch mit schrumpfenden Investitions-Budgets und steigenden Kosten umgehen [8].
Im Verlauf dieses Beitrages werden zwei Konzepte näher beleuchtet, die helfen können, mit diesem Dilemma umzugehen. Zum einen wird ein Modell des Technologiemanagementprozesses im Krankenhaus vorgestellt, welcher hilft, strukturierte Entscheidungen im Zusammenhang mit der Beschaffung und Bewirtschaftung von Technologien zu treffen. Zum zweiten werden die zentralen Gesichtspunkte der wertorientierten Gesundheitsversorgung vorgestellt und es wird diskutiert, wie diese dazu beitragen können, sowohl die Qualität der Versorgung zu erhöhen als auch Kosten zu senken.
Die Verbindung beider Konzepte beschreibt abschließend, welchen Herausforderungen sich die einzelnen Akteure im Gesundheitswesen stellen müssen.

Keywords: Technologiemanagement, Value Based Healthcare, Gesundheitsversorgung, Krankenhaus
  • mt-medizintechnik 2(2015), 57-60
    Button zum Volltext
Registration No. 23294 - Permalink

Magnetic Nanoparticles in tumour xenografts detected and quantified by Micro-Computer Tomography
Bayer, K.; Eckert, H.; Wiekhorst, F.; Trahms, L.; Krause, M.; Odenbach, S.
Abstract: In this work we focus on the imaging of magnetic nanoparticles in tumor tissue. The spatial distribution of magnetic nanoparticles in tumor tissue is an essential parameter in the evaluation of the efficiency of magnetic drug targeting (MDT). We developed a volume-based imaging method for x-ray-micro tomography calibrated by magnetorelaxometry to determine the concentration of magnetic nanoparticles in a certain tissue. With this technique, the x-ray absorption information contained in a μ-CT image can be directly related to an absolute mass of magnetic nanoparticles in a certain volume element of the tumor. In contrast to other related methods reported in the literature, the procedure described here is capable of a mass resolution of 0.044μgmm−3, making it possible to map the particle distribution in tumors with extremely low magnetic particle content, such as are usually found in mouse experiments on MDT.
Keywords: magnetic drug targeting, magnetorelaxometry, micro-computer tomography, particle-imaging

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Registration No. 23286 - Permalink

Magnetic domain walls as reconfigurable spin-wave nanochannels
Wagner, K.; Kakay, A.; Schultheiss, K.; Henschke, A.; Sebastian, T.; Schultheiss, H.
Abstract: In the research field of magnonics, it is envisaged that spin waves will be used as information carriers, promoting operation based on their wave properties. However, the field still faces major challenges. To become fully competitive, novel schemes for energy-efficient control of spin-wave propagation in two dimensions have to be realized on much smaller length scales than used before. In this Letter, we address these challenges with the experimental realization of a novel approach to guide spin waves in reconfigurable, nano-sized magnonic waveguides. For this purpose, we make use of two inherent characteristics of magnetism: the non-volatility of magnetic remanence states and the nanometre dimensions of domain walls formed within these magnetic configurations. We present the experi- mental observation and micromagnetic simulations of spin- wave propagation inside nano-sized domain walls and realize a first step towards a reconfigurable domain-wall-based magnonic nanocircuitry.
Keywords: magnetism, magnons, spin waves, domain walls, magnonics, spin wave logic, Brillouin light scattering, Registration No. 23285 - Permalink

NTCP reduction for advanced head and neck cancer patients using proton therapy for complete or sequential boost treatment versus photon therapy
Jakobi, A.; Stützer, K.; Bandurska-Luque, A.; Löck, S.; Haase, R.; Wack, L.-J.; Mönnich, D.; Thorwarth, D.; Perez, D.; Lühr, A.; Zips, D.; Krause, M.; Baumann, M.; Perrin, R.; Richter, C.
Abstract: Background.To determine by treatment plan comparison differences in toxicity risk reduction for patients with head
and neck squamous cell carcinoma (HNSCC) from proton therapy either used for complete treatment or sequential
boost treatment only.
Materials and methods. For 45 HNSCC patients, intensity-modulated photon (IMXT) and proton (IMPT) treatment
plans were created including a dose escalation via simultaneous integrated boost with a one-step adaptation strategy
after 25 fractions for sequential boost treatment. Dose accumulation was performed for pure IMXT treatment, pure
IMPT treatment and for a mixed modality treatment with IMXT for the elective target followed by a sequential boost
with IMPT. Treatment plan evaluation was based on modern normal tissue complication probability (NTCP) models for
mucositis, xerostomia, aspiration, dysphagia, larynx edema and trismus. Individual NTCP differences between IMXT
and IMPT ( Δ NTCP IMXT-IMPT ) as well as between IMXT and the mixed modality treatment ( Δ NTCP IMXT-Mix ) were
calculated.
Results. Target coverage was similar in all three scenarios. NTCP values could be reduced in all patients using IMPT
treatment. However, Δ NTCP IMXT-Mix values were a factor 2 – 10 smaller than Δ NTCP IMXT-IMPT . Assuming a threshold of
>= 10% NTCP reduction in xerostomia or dysphagia risk as criterion for patient assignment to IMPT, less than 15% of
the patients would be selected for a proton boost, while about 50% would be assigned to pure IMPT treatment. For
mucositis and trismus, Δ NTCP >= 10% occurred in six and four patients, respectively, with pure IMPT treatment, while
no such difference was identifi ed with the proton boost.
Conclusions. The use of IMPT generally reduces the expected toxicity risk while maintaining good tumor coverage
in the examined HNSCC patients. A mixed modality treatment using IMPT solely for a sequential boost reduces the
risk by 10% only in rare cases. In contrast, pure IMPT treatment may be reasonable for about half of the examined
patient cohort considering the toxicities xerostomia and dysphagia, if a feasible strategy for patient anatomy changes is
implemented.
Registration No. 23284 - Permalink

Increase in tumor control and normal tissue complication probabilities in advanced head-and-neck cancer for dose-escalated intensity-modulated photon and proton therapy
Jakobi, A.; Lühr, A.; Stützer, K.; Bandurska-Luque, A.; Löck, S.; Krause, M.; Baumann, M.; Perrin, R.; Richter, C.
Abstract: Introduction: Presently used radiochemotherapy regimens result in moderate local control rates for patients with advanced head-and-neck squamous cell carcinoma (HNSCC). Dose escalation (DE) may be an option to improve patient outcome, but may also increase the risk of toxicities in healthy tissue. The presented treatment planning study evaluated the feasibility of two DE levels for advanced HNSCC patients, planned with either intensity-modulated photon therapy (IMXT) or proton therapy (IMPT).

Materials and methods: For 45 HNSCC patients, IMXT and IMPT treatment plans were created including DE via a simultaneous integrated boost (SIB) in the high-risk volume, while maintaining standard fractionation with 2 Gy per fraction in the remaining target volume. Two DE levels for the SIB were compared: 2.3 and 2.6 Gy. Treatment plan evaluation included assessment of tumor control probabilities (TCP) and normal tissue complication probabilities (NTCP).

Results: An increase of approximately 10% in TCP was estimated between the DE levels. A pronounced high-dose rim surrounding the SIB volume was identified in IMXT treatment. Compared to IMPT, this extra dose slightly increased the TCP values and to a larger extent the NTCP values. For both modalities, the higher DE level led only to a small increase in NTCP values (mean differences <2%) in all models, except for the risk of aspiration, which increased on average by 8 and 6% with IMXT and IMPT, respectively, but showed a considerable patient dependence.

Conclusion: Both DE levels appear applicable to patients with IMXT and IMPT since all calculated NTCP values, except for one, increased only little for the higher DE level. The estimated TCP increase is of relevant magnitude. The higher DE schedule needs to be investigated carefully in the setting of a prospective clinical trial, especially regarding toxicities caused by high local doses that lack a sound dose–response description, e.g., ulcers.

Keywords: photon radiotherapy, proton radiotherapy, tumor control probability, normal tissue complication probability, head-and-neck cancer

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Registration No. 23282 - Permalink

Ion irradiated Er:YAG ceramic cladding waveguide amplifier in C and L bands
Tan, Y.; Ma, L.; Akhmadaliev, Sh.; Zhou, S.; Chen, F.
Abstract: We report on the optical-signal amplification in a cladding waveguide that was fabricated in Er:YAG ceramic by multiple carbon-ion irradiation. The waveguide has a multilayer structure that assures good overlap between the pump beam and the input signal. Under the pump at 980 nm with a fiber-coupled diode laser, the cladding waveguide possess a peak internal gain of 2.6 dB/cm at 1550 nm and of 4.0 dB/cm at 1585 nm. This work demonstrates the potential use as amplifier in the C and L communication bands of cladding waveguides fabricated in Er:YAG by carbon ion irradiation technique.
Keywords: Ion irradiation, Cladding waveguide, Er:YAG

Downloads:

Registration No. 23274 - Permalink

A synchronous Gigabit Ethernet protocol stack for high-throughput UDP/IP applications
Födisch, P.; Lange, B.; Sandmann, J.; Büchner, A.; Enghardt, W.; Kaever, P.
Abstract: State of the art detector readout electronics require high-throughput data acquisition (DAQ) systems. In many applications, e. g. for medical imaging, the front-end electronics are set up as separate modules in a distributed DAQ. A standardized interface between the modules and a central data unit is essential. The requirements on such an interface are varied, but demand almost always a high throughput of data. Beyond this challenge, a Gigabit Ethernet interface is predestined for the broad requirements of Systems-on-a-Chip (SoC) up to large-scale DAQ systems. We have implemented an embedded protocol stack for a Field Programmable Gate Array (FPGA) capable of high-throughput data transmission and clock synchronization. A versatile stack architecture for the User Datagram Protocol (UDP) and Internet Control Message Protocol (ICMP) over Internet Protocol (IP) such as Address Resolution Protocol (ARP) as well as Precision Time Protocol (PTP) is presented. With a point-to-point connection to a host in a MicroTCA system we achieved the theoretical maximum data throughput limited by UDP both for 1000BASE-T and 1000BASE-KX links. Furthermore, we show that the random jitter of a synchronous clock over a 1000BASE-T link for a PTP application is below 60 ps.
Keywords: Data acquisition circuits, Data acquisition concepts

Downloads:

Registration No. 23259 - Permalink

Ein VHDL basierter Gigabit Ethernet Protokollstapel für FPGAs
Födisch, P.; Lange, B.; Kaever, P.
Abstract: Mit diesem Beitrag wird ein Protokollstapel für einen ethernet-basierten Datenaustausch mit einem FPGA vorgestellt. Für den schnellen und verbindungslosen Datenaustausch ist das User Datagram Protocol (UDP) ein schlankes Protokoll der Transportschicht. Die dynamische Erzeugung der UDP Paketrahmen benötigt eine vollständige Abbildung der zugrunde liegenden Netzwerkschichten (Internetschicht und Netzwerkschicht). Es wird eine VHDL basierte Architektur für einen Protokollstapel vorgestellt, welche die Protokolle UDP, IP, ICMP und ARP in einem FPGA integriert. Der Schichtenaufbau soll den maximalen Datendurchsatz ermöglichen. Es werden die Ergebnisse der Implementierung und Tests auf unterschiedlichen FPGA Plattformen gezeigt.
  • Contribution to proceedings
    106. Tagung der Studiengruppe elektronische Instrumentierung im Frühjahr 2015, 02.-04.03.2015, Zeuthen, Deutschland, Hamburg: Verlag Deutsches Elektronen-Synchrotron, 978-3-935702-96-6, 52-76

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Registration No. 23257 - Permalink

Early and late effects of radiochemotherapy on cerebral blood flow in glioblastoma patients measured with non-invasive perfusion MRI
Petr, J.; Platzek, I.; Seidlitz, A.; Mutsaerts, H. J. M. M.; Hofheinz, F.; Schramm, G.; Maus, J.; Beuthien-Baumann, B.; Krause, M.; van den Den, J.
Abstract: Background and purpose: To provide a systematic measure of changes of brain perfusion in healthy tissue following a fractionated radiotherapy of brain tumors.
Materials and methods: Perfusion was assessed before and after radiochemotherapy using arterial spin labeling in a group of 24 patients (mean age 54.3±14.1 years) with glioblastoma multiforme. Mean relative perfusion change in gray matter in the hemisphere contralateral to the tumor was obtained for the whole hemisphere and also for six regions created by thresholding the individual dose maps at 10 Gy steps.
Results: A significant decrease of perfusion of -9.8 ± 20.9% (p = 0.032) compared to the pre-treatment baseline was observed 3 months after the end of radiotherapy. The decrease was more pronounced for high-dose regions above 50 Gy (-16.8 ± 21.0%, p = 0.0014) than for low-dose regions below 10 Gy (-2.3 ± 20.0%, p = 0.54). No further significant decrease compared to the post-treatment baseline was observed 6 months (-0.4 ± 18.4%, p = 0.94) and 9 months (2.0 ± 15.4%, p = 0.74) after the end of radiotherapy. Conclusions: Perfusion decreased significantly during the course of radiochemotherapy. The decrease was higher in regions receiving a higher dose of radiation. This suggests that the perfusion decrease is at least partly caused by radiotherapy. Our results suggest that the detrimental effects of radiochemotherapy on perfusion occur early rather than later.

Keywords: ASL Arterial spin labeling Cerebral blood flow Radiotherapy Brain tumor Perfusion Registration No. 23255 - Permalink

Application of Si3N4/SiC composite for particle detectors in harsh radiation environment
Naumann, L.; Laso Garcia, A.; Akindinov, A.; Dreyer, J.; Fan, X.; Kämpfer, B.; Kotte, R.; Kugler, A.; Malkevich, D.; Martin, H. P.; Naumann, B.; Stach, D.; Svoboda, O.; Sultanov, R.
Abstract: Si3N4/SiC composite is a possible candidate for floating electrodes in resistive plate chambers (RPC).
This detector type has been used in different nuclear physics experiments with soda lime glass electrodes at particle fluxes below 10E3 cm-2 s-1. Future experiments, e.g. at CBM-FAIR, demand a two orders of magnitude higher rate capability. This implies a proportional reduction of the RPC time constant. A manufacturing process has been developed to produce ceramic electrodes with a bulk resistivity varying between 10E8 and 10E12 Ω cm [2].
RPC detector prototypes of different sizes from 2x2 cm2 up to 20x20 cm2 and different bulk resistivity have been exposed with relativistic electrons, protons and ions. Detection efficiencies of 95% have been obtained for minimum ionizing particles at fluxes of up to 5x10E5 cm-2 s-1. The design of different ceramic RPC detectors and their working characteristics will be presented.
Finally, the radiation hardness of the ceramics electrodes has been investigated by neutron exposure with fluxes from 10E10 to 10E14 neq cm-2.

Keywords: Si3N4/SiC , RPC, neutron exposure, radiation hardness
  • Invited lecture (Conferences)
    Application of Si3N4/SiC Composite for Particle Detectors in Harsh Radiation Environment/ Energy Materials Nanotechnology - EMN Ceramics Meeting 2016, 25.-28.01.2016, Hong Kong, Hong Kong/SAR China
Registration No. 23245 - Permalink

Atomistic simulation of copper-vacancy clusters in bcc-Fe
Talati, M.; Al-Motasem, A. T.; Bergner, F.; Bonny, G.; Posselt, M.
Abstract: We have investigated how the lattice vibrations affect the thermodynamics of nanosized coherent clusters in bcc-Fe consisting of vacancies and/or copper. The study is carried out within the harmonic approximation. We have applied a combination of on-lattice simulated annealing based on Metropolis Monte Carlo simulations and off-lattice relaxation by molecular dynamics in order to find the most stable cluster configurations at 0 K. We have used the most recent interatomic potential built within the framework of the embedded-atom method for the Fe–Cu system. For finite temperatures, we determined the total free energy of pure bcc-Fe and fcc- Cu as well as the total formation free energy and the total binding free energy of the vacancy–copper clusters. Our results are compared with the available data from previous investigations performed using many-body interatomic potentials and first-principles methods.
Keywords: Atomistic simulation, nanoclusters
  • Lecture (Conference)
    International Conference: Women in Science & Technology: Creating Sustainable Career, 28.-30.01.2016, Ahmedabad, India
Registration No. 23241 - Permalink

Surface sealing using self-assembled monolayers and its effect on metal diffusion in porous low-k dielectrics studied using monoenergetic positron beams
Uedono, A.; Armini, S.; Zhang, Y.; Kakizaki, T.; Krause-Rehberg, R.; Anwand, W.; Wagner, A.
Abstract: Surface sealing effects on the diffusion of metal atoms in porous organosilicate glass (OSG) films were studied by monoenergetic positron beams. For a Cu(5 nm)/MnN(3 nm)/OSG(130 nm) sample fabricated with pore stuffing, C4F8 plasma etch, unstuffing, and a self-assembled monolayer (SAM) sealing process, it was found that pores with cubic pore side lengths of 1.1 and 3.1 nm coexisted in the OSG film. For the sample without the SAM sealing process, metal (Cu and Mn) atoms diffused from the top Cu/MnN layer into the OSG film and were trapped by the pores. As a result, almost all pore interiors were covered by those metals. For the sample damaged by an Ar/C4F8 plasma etch treatment before the SAM sealing process, self-assembled molecules diffused into the OSG film, and they were preferentially trapped by larger pores. The cubic pore side lengths in these pores containing self-assembled molecules was estimated to be 0.7 nm. Through this work, we have demonstrated that monoenergetic positron beams are a powerful tool for characterizing capped porous films and the trapping of atoms and molecules by pores.
Keywords: Positron annihilation low-k OSG SAM Registration No. 23235 - Permalink

Laser Cooling of Ion Beams at Relativistic Energies
Bussmann, M.
Abstract: Laser cooling of ion beams can achieve unprecedented low momentum spreads and is strong enough to overcome intra-beam scattering and induce beam crystallization. When compared to stochastic cooling and electron cooling, laser cooling promises to show better performance than the latter two in cooling highly relativistic ion beams.

Thus, laser cooling at future facilities such as FAIR and HIAF has come into the focus of ion accelerator research.
This work is intended to give the reader a comprehensive overview of laser cooling at relativistic energies and related experiments at the storage rings ESR at GSI Darmstadt, S-LSR at ICR Kyoto and CSRe at IMP Lanzhou.

Keywords: laser, cooling, storage, ring
  • Contribution to external collection
    Y. Zhang, W. Zhou: ICFA Beam Dynamics Newsletter No. 65, Newport News, CA, USA: International Committee for Future Accelerators, 2014, 8-21
Registration No. 23234 - Permalink

Steering laser plasma simulations towards reliable predictions: how to use accelerated computing for particle accelerators
Bussmann, M.
Abstract: Overview on HZDR simulation codes
Keywords: laser, plasma, simulation
  • Invited lecture (Conferences)
    SPIE Optics + Optoelectronics, 13.-16.04.2016, Praha, Ceska republika
Registration No. 23233 - Permalink

Data- and hardware-independent methods for parallel analysis algorithms: Alpaka, GrayBat and other strange animals
Bussmann, M.
Abstract: We present abstract methods for parallel algorithms developed at HZDR
Keywords: hpc
  • Lecture (Conference)
    PNI-HDRI Spring meeting 2015, 13.-14.04.2015, Hamburg, Deutschland
Registration No. 23232 - Permalink

High performant, staged data I/O and analysis: Say ADIOS to your data
Bussmann, M.
Abstract: Overview on data intensive computing at HZDR
Keywords: big data, hpc
  • Lecture (Conference)
    PNI-HDRI Spring meeting 2015, 13.-14.04.2015, Hamburg, Deutschland
Registration No. 23231 - Permalink

Compact Cancer Killers ─ Simulating Next-Generation Laser-Driven Ion Accelerators
Bussmann, M.; Huebl, A.
Abstract: We present recent results on simulations of laserd riven ion acceleration for cancer therapy
Keywords: simulation, gpu, picongpu, titan, cancer, radiation, therapy
  • Lecture (Conference)
    GPU Technology Conference 2015, 17.-20.03.2015, San Jose, CA, United States of America
Registration No. 23230 - Permalink

Breaking the Simulation/Analysis Chain
Bussmann, M.; Huebl, A.; Schmitt, R. Widera F.; Podhorszki, S. Grottel N.; Pugmire, D.; Klasky, S.
Abstract: We discuss the future of simulation and data analysis
Keywords: hpc, data analysis, simulation
  • Invited lecture (Conferences)
    Supercomputing Frontiers 2015, 17.-20.03.2015, Singapore, Singapore
Registration No. 23229 - Permalink

Femtosecond probing of fast transient plasma processes in high-power laser interaction with solids
Kluge, T.; Huang, L.; Gutt, C.; Bussmann, M.; Chung, H.; Zacharias, M.; Schramm, U.; Cowan, T.
Abstract: Ultra-intense laser-matter interactions are a major research area in in modern plasma physics. One of the essential elements is the relativistic electron generation and transport dynamics. At present, a predictive understanding of high-intensity laser-matter interactions is severely hampered by the lack of self-consistent models for the ionization dynamics, coupled with the complex electron transport.

We establish the feasibility of using XFEL femtosecond X-ray sources to probe the spatial correlations inside of the solid-density plasma using small angle X-ray scattering (SAXS) and resonant SAXS, to obtain for the first time information on the spatial and temporal evolution of the electron density and ionization dynamics with few fs and few nm resolution. The local and instantaneous ionization state can be measured when the X-ray beam is tuned to a bound-bound resonance of a particular charge state. The atomic scattering factor at the threshold of core electron excitation increases for example at Kα excitations in highly ionized Cu to a magnitude of more than 100 times the Thomson cross section per ion.

Keywords: xfel, saxs, laser, plasma
  • Lecture (Conference)
    DPG-Frühjahrstagung Bochum, 02.-05.03.2015, Bochum, Deutschland
Registration No. 23228 - Permalink

Laser Cooling of High Energy Ion Beams - from ESR and CSRe to FAIR and HIAF
Bussmann, M.; Wen, W.; Winters, D.; Dimopoulou, C.; Nolden, F.; Steck, M.; Sanjari, S.; Giacomini, T.; Litvinov, Y.; Kozhuharov, C.; Kühl, T.; Lochmann, M.; Ullmann, J.; Sanchez, R.; Nörtershäuser, W.; Stöhlker, T.; Beck, T.; Rein, B.; Walther, T.; Tichelmann, S.; Birkl, G.; Wang, H.; Zhang, D.; Huang, Z.; Hai, B.; Yuan, Y.; Ma, X.; Löser, M.; Siebold, M.; Schramm, U.
Abstract: We present results from laser cooling experiments at ESR, GSI Darmstadt and CSRe, IMP Lanzhou. We show that with a cw laser system it is possible to cool ion beams with large initial momentum spread and that laser cooling can overcome intra-beam scattering, regardless of the initial ion beam current.

We furthermore discuss first laser cooling tests with a pulsed laser system and present an outlook on how to optimize laser cooling for heavy ion beams at highly-relativistic energies, focusing not only on laser technologies but also on optical beam diagnostics.

Keywords: laser cooling, relativistic, ion beam, storage rings
  • Lecture (Conference)
    DPG-Frühjahrstagung Wuppertal, 09.-13.03.2015, Wuppertal, Deutschland
Registration No. 23227 - Permalink

Don’t forget the wire
Bussmann, M.; Zacharias, M.; Schöne, S.; Jung, F.; Vogt, S.; Widera, R.; Lieber, S.; Konrad, U.; Kaever, P.; Bieberle, A.; Wagner, A.; Fiedler, F.
Abstract: Overview of HZDR DTS Activities in Parallel Data Analyis
Keywords: dts, data, analysis, parallel
  • Lecture (Conference)
    Matter and Technologies Kickoff Meeting, 23.-26.02.2015, Hamburg, Deutschland
Registration No. 23226 - Permalink

Laser Cooling of Relativistic Ion Beams Recent Results and Future Perspectives
Bussmann, M.; Löser, M.; Seltmann, M.; Siebold, M.; Schramm, U.; Beck, T.; Rein, B.; Walther, T.; Tichelmann, S.; Birkl, G.; Sanchez-Alarcon, R.; Ullmann, J.; Lochmann, M.; Nörtershäuser, W.; Eidam, L.; Boine-Frankenheim, O.; Winters, D.; Kozhuharov, C.; Sanjari, S.; Litvinov, Y.; Giacomini, T.; Steck, M.; Dimopoulou, C.; Nolden, F.; Shevelko, S.; Stöhlker, T.; Spiller, P.; Wen, W.; Yang, J.; Zhang, D.; Ma, X.; Hannen, V.
Abstract: We discuss recent results and future perspectives of laser cooling of relativistic ion beams
Keywords: laser cooling, storage ring, relativistic, ion, beam
  • Invited lecture (Conferences)
    COOL Workshop 2015, 28.09.-02.10.2015, Newport News, VA, United States of America
Registration No. 23225 - Permalink

Synthetic Diagnostics for kinetic Laser Plasma Interaction Resonant Coherent X-Ray Diffraction
Bussmann, M.; Kluge, T.; Huebl, A.; Chung, H. K.; Gutt, C.; Huang, L. G.; Schramm, U.; Zacharias, M.; Cowan, T. E.
Abstract: Overview on Resonant Coherent X-Ray Diffraction Simulations of Laser Plasma Interaction
Keywords: rcxdi, cfel, laser, plasma
  • Poster
    XFEL User Meeting, 28.-30.01.2015, Hamburg, Deutschland
  • Poster
    3rd International Conference on “Correlation Effects in Radiation Fields”, CERF'15, 13.-18.09.2015, Rostock, Deutschland
Registration No. 23224 - Permalink

Alpaka, GrayBat and other spiritual animals that will help you survive in the dangerous world of HPC
Bussmann, M.; Eckert, C.; Huebl, A.; Jung, F.; Widera, R.; Worpitz, B.; Zacharias, M.; Zenker, E.; Juckeland, G.; Knüpfer, A.; Nagel, W.
Abstract: Implementing codes for simulations or large-scale, high rate data analysis on modern compute hardware can take much of the time that you initially wanted to spend on something entirely else. We present our tool box of simple yet powerful solutions for writing hardware-independent, scalable and performant codes that are maintanable and can survive the next compute hardware update. We show that with modern programming techniques it is possible to implement abstract interfaces that provide sustainable concepts for parallel programming while at the same time allowing for performance optimization. This talk is about real life applications that need to work. But it will also be cool.
Keywords: hpc, c++, simulation, plasma, imaging, abstraction
  • Invited lecture (Conferences)
    ZIH-Kolloquium, 28.01.2016, Dresden, Deutschland
Registration No. 23223 - Permalink

Titan Targets Tumors
Gedenk, E.; Bussmann, M
Abstract: German team makes large computational gains in laser-driven radiation therapy of cancer
Keywords: titan, supercomputer, radiation therapy, tumor, laser, ion, acceleration Registration No. 23222 - Permalink

Graphene-based fibers for supercapacitor applications
Chen, L. L.; Liu, Y.; Zhao, Y.; Chen, N.; Qu, L. T.
Abstract: Energy conversion and storage devices play an important role in industry and society with the rapid growth of energy consumption. Supercapacitors are very attractive due to their superior power density, fast charge/discharge rates and long cycle lifetime. Graphene fiber (GF), a fascinating material, has drawn considerable attention and shown great potential as an active material in the field of supercapacitors owing to its unique and tunable nanostructure, high electrical conductivity, excellent mechanical flexibility, light weight, and ease of functionalization. This review focuses on the recent significant advances in the fabrication and application of graphene-based fiber as electrode material in supercapacitors. The synthetic strategies and application in the supercapacitor are presented, accompanied with the summary and outlook for the future development of GFs.
Keywords: flexible electronics; graphene fiber; supercapacitor Registration No. 23221 - Permalink

Efficient laser-driven proton acceleration for radiobiological studies using ultra short laser pulses
Zeil, K.; Schlenvoigt, H.-P.; Brack, F.; Metzkes, J.; Kluge, T.; Bussmann, M.; Cowan, T. E.; Kraft, S. D.; Sauerbrey, R.; Schramm, U.; Becker, G.; Hornung, M.; Lötzsch, R.; Kaluza, M.; Kämpfer, T.; Reislöhner, J.; Uschmann, I.
Abstract: Presentation about laser-proton acceleration at HZDR with 100 TW Laser, cell irradiation experiments, study on filamented proton beam profiles and reduced mass targets.
  • Invited lecture (Conferences)
    Laser Plasma Acceleration Workshop, 15.5.2015, Guadeloupe, France
Registration No. 23220 - Permalink

Laser proton acceleration of mass-limited-targets of different materials
Zeil, K.; Schlenvoigt, H.-P.; Brack, F.; Metzkes, J.; Kluge, T.; Bussmann, M.; Cowan, T. E.; Kraft, S. D.; Sauerbrey, R.; Schramm, U.; Becker, G.; Hornung, M.; Lötzsch, R.; Kaluza, M.; Kämpfer, T.; Reislöhner, J.; Uschmann, I.
Abstract: Reproducible series of mass-limited targets, manufactured with lithographic techniques, and varying in size, thickness, and mounting geometry were irradiated at the 150 TW Draco Laser facility of the Helmhotz-Zentrum Dresden-Rossendorf with ultrashort (30 fs) laser pulses of intensities of about 8 · 10^20 W/cm^2. A robust maximum energy enhancement of almost a factor of two was found when compared to reference irradiations of plain foils of the same thickness and material. The performance gain was, however, restricted to lateral target sizes of about 50 μm which was attributed to edge and mounting structure influences. In a recent experiments these mass-limited targets of similar size and thickness but different materials, such as Al, Ti and Au were irradiated at the diode-pumped high-power laser system POLARIS at the Helmholtz-Zentrum Jena, in order to study the influence of the material on to the laser proton acceleration performance. The effect of target size dependent bulk heating was studied with characteristic X-ray imaging and spectroscopy.
  • Lecture (Conference)
    Laser Plasma Targetry Workshop, 21.4.2015, Paris, France
Registration No. 23219 - Permalink

Effect of superimposed DC magnetic field on an AC induction semi-levitated molten copper droplet
Bojarevics, A.; Beinerts, T.; Grants, I.; Kaldre, I.; Sivars, A.; Gelfgat, Y.; Gerbeth, G.
Abstract: While a piece of copper on a ceramic substrate was inductively melted by a 9 to 18 kHz AC magnetic field with an axial magnetic DC field superimposed, the liquid metal stably semi-levitated in the expected free surface shape. The diameter of the liquid metal at the base was 30 mm, the volume more than 20 cm3. Replacing the ceramic substrate with a non-wetted glassy carbon crucible causes instability of the semi-levitated copper droplet. In the absence of the DC field severe chaotic instabilities of the liquid metal shape occurred, causing splashes and uncontrolled contact with the crucible walls. When an axial DC magnetic field with induction 0.35T was superimposed, the liquid metal droplet exhibited a harmonic azimuthal wave deformation of the free surface. Higher frequencies lead to smaller characteristic wavelength. The transverse DC magnetic field direction suppressed the travelling wave deformations of the droplet shape. The stabilizing effect of the DC magnetic field during induction melting has been shown for axial and transverse directions of the DC magnetic field. These results experimentally demonstrate the possibilities to improve the stability of levitated metal volumes by a superimposed DC magnetic.
  • Magnetohydrodynamics 15(2015), 437-443
    Button zum Volltext
Registration No. 23218 - Permalink

Lithium/Sulfur Batteries Upon Cycling: Structural Modifications and Species Quantification by In Situ and Operando X-Ray Diffraction Spectroscopy
Walus, S.; Barchasz, C.; Bouchet, R.; Leprêtre, J.-C.; Colin, J.-F.; Martin, J.-F.; Elkaïm, E.; Baehtz, C.; Alloin, F.
Abstract: A quantitative analysis of in situ and operando X-ray diffraction studies allows for deeper insight into the mechanism of Li2S formation and consumption. A two-step reaction process is proposed for both discharge and charge. Changing selectivity for Li2S formation is estimated, with solely Li2S being formed during the earliest step, followed by possible concurrent formation of Li2S2 intermediate in the further step of discharge.
Keywords: Lithium/Sulfur Battery; x-Ray diffraction, XRD, EXAFS, in operando Registration No. 23215 - Permalink

Pulsed Power Technology in the Field of Laser Plasma Physics
Kroll, F.
Abstract: The presented work will summarize the development of pulsed high-field magnets and power converter technology at HZDR in 2014 for application in laser-plasma physics. The talk will focus on miniature magnetic solenoids, pulsed multipole magnets and the generation of high-current pulses.
  • Lecture (others)
    Annual Meeting of the LIGHT collaboration, 12.-13.01.2015, GSI Darmstadt, Deutschland
Registration No. 23214 - Permalink

Influence of microstructure and mechanical stress on behavior of hydrogen in 500 nm Pd films
Vlcek, M.; Lukác, F.; Vlach, M.; Wagner, S.; Uchida, H.; Baehtz, C.; Shalimov, A.; Pundt, A.; Cízek, J.
Abstract: Pd films can be used as a model system to examine the influence of microstructure and stress on the hydrogen absorption. In this work we study 500 nm Pd films deposited on different substrates with different binding strengths. The films were electrochemically loaded with hydrogen up to hydride concentration. Development of lattice constant during hydrogen loading of Pd films was investigated by in situ X-ray diffraction using synchrotron radiation. The influence of microstructure and mechanical stress in the films on the phase transition from Pd to Pd hydride was examined.
Keywords: Hydrogen Palladium Thin films Registration No. 23213 - Permalink

Thermal expansion of polycrystalline gallium nitride: an X-ray diffraction study
Minikayev, R.; Paszkowicz, W.; Piszora, P.; Knapp, M.; Bähtz, C.; Podsiadlo, S.
Abstract: Gallium nitride is studied at ambient and nonambient temperatures by powder X-ray diffraction followed by Rietveld refinement of the structure. The structure is reported for the ambient temperature on the basis of laboratory data. The diffraction data collected using a synchrotron beam serve for derivation of the lattice parameter and thermal expansion dependencies on temperature. The variation of unit-cell size on temperature was studied in detail in a broad range 11 K < T < 1073 K. The obtained dependencies of a, c and V and thermal expansion coefficients are smooth, and the results are consistent with previously collected data. The c/a ratio shows an almost linear decreasing trend with rising temperature. The magnitude of thermal expansion obtained in the described experiments is similar to a recently reported theoretical one.
Keywords: Thermal expansion, x-ray diffraction, gallium nitride Registration No. 23212 - Permalink

Characterization of laser driven ions
Brack, F.-E.; Kraft, S. D.; Kroll, F.; Metzkes, J.; Obst, L.; Rehwald, M.; Schlenvoigt, H.-P.; Zeil, K.; Schramm, U.
Abstract: Durch die Fokussierung eines ultrakurzen und hochintensiven Laserpulses auf ein Festkörpertarget können Pulse von Protonen und anderen positiv geladenen Ionen erzeugt werden. Auf Basis des etablierten TNSA (target-normal sheath acceleration) Prozesses konnten am Helmholtz-Zentrum Dresden-Rossendorf mit dem 150 TW Ultrakurzpulslaser Draco Protonenpulse mit Energien bis zu 20 MeV erzeugt und charakterisiert werden. Die Charakterisierung dieser Teilchenstrahlung erfordert die Identifizierung der Ionenspezies und die Bestimmung ihrer spektralen Verteilung möglichst nach jedem Puls, wofür standardmäßig Thomsonspektrometer verwendet werden. In den letzten Jahren wurde das DRACO-Lasersystem bis zu einer Pulsleistung über 500 TW erweitert. Aufbauend auf dem bisherigen Spektrometerdesign wurde in dieser Arbeit ein kompaktes Spektrometer für einen höheren Energiebereich bis über 80 MeV entworfen. Besonders wichtig dabei ist die Identifizierung möglicher das Messergebnis verfälschender Sekundärstrahlungsquellen, die mit Hilfe von Monte-Carlo Simulation analysiert werden müssen.
  • Lecture (Conference)
    DPG-Frühjahrstagung Wuppertal 2015, 09.-13.03.2015, Wuppertal, Deutschland
Registration No. 23211 - Permalink

Reflective probing of laser-driven plasma for ion acceleration
Rehwald, M.; Metzkes, J.; Zeil, K.; Kraft, S.; Schramm, U.
Abstract: Plasmas driven by intense, ultra-short laser pulses can support electrical field strengths of up to TV/m, making this concept promising for compact particle accelerators in which ions can gain MeV energies on a micrometer scale. For the acceleration, the laser pulse is focused onto a thin target which quickly ionized and transformed into a plasma in which electrons gain MeV energies in the laser field. These electrons leave the target volume and thereby create quasi-static charge-separation fields along the target surfaces in which the ion acceleration takes place. The acceleration is strongly influenced by the plasma conditions at the target during the main pulse interaction, which are determined by light preceding the intense main pulse or by the rising edge of the main pulse itself.

In this talk, we present a reflective pump probe method which allows to temporally resolve the lateral and longitudinal expansion of the critical plasma density. First experimental results with a pure imaging technique will be shown, in which the front and rear surface plasma were characterized. This technique is currently developed to include interferometry, in that way increasing the sensitivity in longitudinal direction. We will discuss the simulation results and a corresponding experimental setup.
  • Lecture (Conference)
    DPG-Frühjahrstagung Wuppertal 2015, 09.-13.03.2015, Wuppertal, Deutschland
Registration No. 23210 - Permalink

Phase transformations in Ni/Ti multilayers investigated by synchrotron radiation-based x-ray diffraction
Cavaleiro, A. J.; Ramos, A. S.; Martins, R. M. S.; Braz Fernandes, F. M.; Morgiel, J.; Baehtz, C.; Vieira, M. T.
Abstract: X-ray diffraction using synchrotron radiation was used for real-time investigation of the phase evolution of Ni/Ti multilayer thin films during annealing. These multilayers were deposited onto Tie6Ale4V substrates by dc magnetron sputtering from pure Ni and Ti targets. The deposition parameters were adjusted in order to obtain a near equiatomic chemical composition and modulation periods (L) below 25 nm. Along the entire thickness of the films, well-defined structures with alternate Ni- and Ti-rich layers are observed, even for L ¼ 4 nm. In this case, a halo characteristic of an amorphous structure is obtained, while for L of 12 and 25 nm the as-deposited thin films are nanocrystalline being possible to identify the (111) Ni and (002) Ti diffraction peaks. The nanolayered structure vanishes during annealing due to interdiffusion followed by reaction. The reaction between Ni and Ti to produce NiTi in the cubic B2 structure occurs in a short delay of time and within a narrow temperature range. For L of 25, 12 and 4 nm, the reaction temperature is close to 320, 350 and 385 C, respectively. For higher temperatures, in addition to the austenitic phase, the NiTi2 phase is identified. The diffusion of Ti from the substrate and Ni towards the substrate could favour the precipitation of NiTi2.
Keywords: Thin films Transition metal alloys and compounds Vapour deposition Phase transition Synchrotron radiation Transmission electron microscopy Registration No. 23209 - Permalink

High-repetition-rate laser-proton acceleration employing a cryogenic hydrogen jet as a target
Rehwald, M.; Göde, S.; Obst, L.; Sommer, P.; Brack, F.; Schramm, U.; Gauthier, M.; Macdonald, M.; Roedel, C.; Glenzer, S.; Zeil, K.; Metzkes, J.; Schumaker, W.; Schlenvoigt, H.-P.
Abstract: Applications of laser-accelerated protons demand a stable, high-energy and high-repetition rate particle source. We present the results of our experimental campaign in cooperation with the HED group at SLAC, performed at the 10 Hz Ti:Sa laser Draco of Helmholtz-Zentrum Dresden-Rossendorf (HZDR), employing a cryogenic Hydrogen jet as a renewable target. Draco delivers pulses of 30 fs and 5 J at 800 nm, focussed to a 3 µm spot by a F/2.5 off-axis parabolic mirror. The cylindrical jet has a diameter of 2 µm or 5 µm and a nominal electron density of 30 times the critical density. Preliminary results show a mono-species proton acceleration in a solid angle of at least +/-45° with respect to the incoming laser beam and proton energies exceeding 10 MeV. Radiochromic film stacks in forward direction show signatures of two acceleration mechanisms, one being the conventional TNSA and a second one leading to filament-like structures, possibly stemming from an instability within the plasma. Among other results, an on-shot monitoring of the stability of the jet by means of a temporally synchronized probe beam will be shown in the presentation.
  • Lecture (Conference)
    2nd European Advanced Accelerator Concepts Workshop, 13.-19.09.2015, La Biodola, Isola d'Elba, Italien
Registration No. 23208 - Permalink

Nucleation Control for Large, Single Crystalline Domains of Monolayer Hexagonal Boron Nitride via Si-Doped Fe Catalysts
Caneva, S.; Weatherup, R. S.; Bayer, B. C.; Brennan, B.; Spencer, S. J.; Mingard, K.; Cabrero-Vilatela, A.; Baehtz, C.; Pollard, A. J.; Hofmann, S.
Abstract: The scalable chemical vapor deposition of monolayer hexagonal boron nitride (h-BN) single crystals, with lateral dimensions of ∼0.3 mm, and of continuous h-BN monolayer films with large domain sizes (>25 μm) is demonstrated via an admixture of Si to Fe catalyst films. A simple thin-film Fe/SiO 2/Si catalyst system is used to show that controlled Si diffusion into the Fe catalyst allows exclusive nucleation of monolayer h-BN with very low nucleation densities upon exposure to undiluted borazine. Our systematic in situ and ex situ characterization of this catalyst system establishes a basis for further rational catalyst design for compound 2D materials.
Keywords: Hexagonal boron nitride (h-BN), chemical vapor deposition (CVD), borazine (HBNH)3, in situ X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), Fe catalyst Registration No. 23207 - Permalink

Spin waves going 3D - chiral effects in curved magnetic nanowires
Otalora, J. A.; Yan, M.; Lindner, J.; Fassbender, J.; Hertel, R.; Kakay, A.
Abstract: Recent progress in material science has enabled the first experimental studies concerning the static magnetization characterization of samples with tubular geometry to be carried out [1]. Although investigating spin-wave and domain-wall dynamics remains a challenge from an experimental point of view, theory predicts that it is fundamentally different than in previously investigated flat geometries. Here, we discuss the effect of the curvature on the dynamics of domain walls and spin waves. Using extensive finite element micromagnetic simulations, we demonstrate that a typical vortex-type domain wall formed in a ferromagnetic tube exhibits advantageous properties regarding the domain wall speed and stability. For topological reasons, these robust domain walls do not encounter the Walker breakdown in certain nanotubes and can propagate with velocities faster than the spin wave phase velocity [2]. Above a critical velocity, the domain wall triggers a Cherenkov-type spin wave radiation. A characteristic of ferromagnetic nanotubes is that the chiral symmetry of the domain wall propagation is broken [3]. This is attributed to the lack of local inversion symmetry due to the curved surface of the nanotube [4]. Our micromagnetic as well as analytical studies show that this lack of inversion symmetry leads to a non-reciprocal dispersion relation for the spin waves with regards to the sign of the propagation vector k. The split in the frequencies for spin waves traveling in opposite directions is of the order of several GHz for tubes below 100 nm in diameter. This effect is the largest when the nanotube radius is comparable with the wavelength of the traveling spin waves and is already present for bended thin films that form a half or even less than a half nanotube only. The split and the minima of the dispersion, however, can be tuned with a circular field. The analytical formula obtained for the dispersion allows for a systematic study of the dispersion relation of nanotubes with different geometry, material parameters, applied circular and/or axial fields, without the need for the expensive 3 dimensional finite element micromagnetic simulations.
References
[1] R. Streubel, et al., Nano Lett. 14, 3981 (2014)
[2] M. Yan et al., Appl. Phys. Lett. 99, 122505 (2011)
[3] M. Yan et al., Appl. Phys. Lett. 100, 25402 (2012)
[4] R. Hertel, SPIN 3, 1340009 (2013)

Keywords: Nanotube, chiral, curved, spin waves, Cherenkov, non-reciprocal
  • Invited lecture (Conferences)
    603. WE-Heraeus-Seminar: Magnonics – Spin Waves Connecting Charges, Spins and Photons, 05.-08.01.2016, Bad Honnef, Deutschland
Registration No. 23206 - Permalink

Non-reciprocal spin-wave dispersion in bent thin-film stripes
Zahn, F.; Lindner, J.; Fassbender, J.; Kakay, A.
Abstract: Spin waves are considered as promising candidates to carry information in future technology applications, therefore in the last decades they have been studied intensively in ferromagnetic thin films. Recent developments in material research enabled the manufacturing of more complex structures than planar thin films; especially nanotubes and bent structures of varying curvature can be produced. It has recently been shown by theory that in nanotubes the curvature has an impact on both the domain wall and spin-wave propagation [1][2]. Moreover, the dispersion relation in nanotubes is non-reciprocal regarding the sign of the propagation vector. These effects are attributed to the lack of local inversion symmetry due to the curved surface of the nanotube [3]. As predicted by theory the spin-wave dynamics is fundamentally different from that known from thin films. Here, we studied the spin-wave propagation and the spin-wave dispersion in bent Permalloy thin-film stripes in the form of quarter-tubes, half-tubes and threequarter tubes. Compared to nanotubes, these systems only posses the curvature but not the specific boundary condition of nanotubes. For the simulations we used our GPU accelerated Finite Element micromagnetic code TetraMag [4]. The partial tubes had a homogenous magnetization along the circumference or azimuthal direction in cylindrical coordinates. The spin waves are excited with an external field applied in the radial direction at the middle of the sample. Therefore the spin waves propagate toward the ends of the considered structures, in a Damon-Eshbach geometry. For a given frequency the simulation is run until the steady state is reached. The wave vector correponding to this excitation frequency is determined by a Fourier analysis of the radial component of the magnetization along the z-axis, using a given snapshot in time. The resulting dispersion relations show a non-reciprocity regarding the sign of the propagation vector, similarly to those reported for nanotubes. The spin wave assymetry, defined as the ratio between the difference of the frequencies and their sum for a given wave vector but with opposite signs, can be as high as 5%. This is equivalent to a difference of about 500MHz for spin waves travelling with a given wave vector but opposite signs. We believe this assymetry can be verified experimentally, providing further prospects for research.
[1] M. Yan et al., Appl. Phys. Lett. 99, 122505 (2011)
[2] M. Yan et al., Appl. Phys. Lett. 100, 25402 (2012)
[3] R. Hertel, SPIN 3, 1340009 (2013)
[4] A. Kakay et al., IEEE Trans. Magn. 46, 2303 (2010)

Keywords: Spin waves, non-reciprocal, dispersion, curvature induced
  • Poster
    603. WE-Heraeus-Seminar: Magnonics – Spin Waves Connecting Charges, Spins and Photons, 05.-08.01.2016, Bad Honnef, Deutschland
Registration No. 23205 - Permalink

Liquid metal two-phase flows
Strumpf, E.; Roshchupkina, O.; Shevchenko, N.; Eckert, S.; Gerbeth, G.
Abstract: The ascents of single Argon bubbles and bubble chains are investigated by means of Ultrasound Doppler Vecolimetry and X-ray radiography. A cuboid benchmark experiment of dimensions 144 x 144 x 12 mm³ is used and filled with eutectic alloy GaInSn. Furthermore the effects on the bubble behaviour and flow structure is investigated by superimposing a strong magnetic transversal DC field up to 1.1 T.
Keywords: liquid metal, two phase flow, bubble, magnetic field, UDV, X-ray
  • Poster
    LIMTECH midterm evaluation, 28.-30.09.2015, Dresden, Deutschland
Registration No. 23201 - Permalink

Liquid metal two-phase flows
Strumpf, E.; Roshchupkina, O.; Shevchenko, N.; Eckert, S.; Gerbeth, G.
Abstract: The ascents of single Argon bubbles and bubble chains are investigated by means of Ultrasound Doppler Vecolimetry and X-ray radiography. A cuboid benchmark experiment of dimensions 144 x 144 x 12 mm³ is used and filled with eutectic alloy GaInSn. Furthermore the effects on the bubble behaviour and flow structure is investigated by superimposing a strong magnetic transversal DC field up to 1.1 T.
Keywords: liquid metal, two phase flow, bubble, magnetic field, UDV, X-ray
  • Poster
    LIMTECH annual meeting 2015, 16.-17.11.2015, Hannover, Deutschland
Registration No. 23200 - Permalink

Magnetische Momente und mächtige Magnete
Wosnitza, J.
Abstract: es hat kein Abstract vorgelegen
  • Invited lecture (Conferences)
    „Physik am Samstag“ der Fachrichtung Physik der TU Dresden, 05.12.2015, Dresden, Deutschland
Registration No. 23199 - Permalink

AIDA – Apparatus for In-situ Defect Analysis
Trinh, T. T.
Abstract: AIDA – Apparatus for In-situ Defect Analysis
  • Lecture (Conference)
    PhD-Seminar of HZDR, 06.10.2015, Altenberg, Germany
Registration No. 23198 - Permalink

Spin-lattice interactions of frustrated magnets in high magnetic fields
Wosnitza, J.
Abstract: es hat kein Abstract vorgelegen
  • Invited lecture (Conferences)
    SFB 1143 Retreat workshop, 21.-23.09.2015, Krippen, Deutschland
Registration No. 23197 - Permalink

Apparatus for In-situ Defect Analysis (AIDA) Investigations by Positron Annihilation Spectroscopy
Trinh, T. T.; Liedke, M. O.; Anwand, W.; Wagner, A.; Potzger, K.; Krause-Rehberg, R.
Abstract: A unique high vacuum system for defect manipulation and analysis has been developed and installed at the Helmholtz-Zentrum Dresden-Rossendorf. The setup combines several experimental techniques for that purpose, e.g., material evaporation, ion beam modifications, and temperature treatment with the positron annihilation spectroscopy, and sheet resistance measurements.

AIDA utilizes a monoenergetic positron beam which is tungsten moderated, magnetically guided and pre-accelerated in the range of 30 eV to 35 keV. The positron beam is extracted from an intense 22Na source and enables sample depth profiling by Doppler broadening spectroscopy. The coincidence Measurements are performed by two HPGe detectors with energy resolution of (780 ± 20) eV at 511 keV, whereas the standard single HPGe detector Doppler broadening with energy resolution of (1.09 ± 0.001) keV is applicable for the varied energy scans. AIDA consist of a load lock chamber mechanism for halogen preliminary heating up to 150°C and loading a sample holder through a linear transfer to the MBE chamber by a basic pressure of 10-7 mbar. The sample holder is then mounted on a sophisticated 5 axis manipulator which is available for resistometry investigations by a 4-point probe module during isochronal annealing by a resistive heater at a base pressure of about 10-8 mbar. Thus, defects can be annealed up to 1300 K or stabilized down to 50 K and meanwhile residual resistivity measurements can be performed. In order to determine influence of vacancy complexes and their distribution onto magnetic, structural, and morphological sample properties, simultaneously ion irradiation by an energy range from (0.001 – 5) keV can be realized. The Ion Source is suitable for depth profiling and enables operation with reactive and noble gases by a current density of <200 µA/cm2. A Quartz oscillator provides a useful and progressive indication of coating thickness during the deposition process. Eventual, defect role during a dynamic formation of nanostructures on the semiconductor surface, e.g. Si or Ge, can be investigated during ion irradiation.

Keywords: Positron Annihilation Spectroscopy, In-situ
  • Poster
    28th International Conference on Defects in Semiconductors, 27.07.2015, Espoo, Finland
Registration No. 23196 - Permalink

Magnetic and structural studies of Mg2Fe(x)Si(1-x) – hydrides
Trinh, T. T.; Yildirim, O.; Anwand, W.; Liedke, O. M.; Grenzer, J.; Potzger, K.; Lindner, J.; Asano, K.; Dam, B. (Editors)
Abstract: Mg2Fe(x)Si(1-x) – hydride is a promising multifunctional material in terms of magnetic applications due to a dramatic change in their magnetic, optical and electronic properties upon hydrogen loading. Therefore they are capable of potential applications, e.g. hydrogen sensors for use as safety monitors wherever hydrogen is used, stored, or produced and storage devices.
In order to understand the physical background of Mg2(FeSi) based systems as well as their hydrides, comprehensive investigations were performed on as-grown and hydrogen loaded 250 nm thick Mg2Fe(x)Si(1-x) (x= 0; 0.25; 0.50; 0.75; 0.90; 1.00) films using magnetometry, X-ray diffraction (XRD) and positron annihilation spectroscopy (PAS).
Magnetometry results revealed that upon hydrogen loading volume magnetic properties of the system transforms from superparamagnetic- and spin glass-like behavior to ferromagnetic behavior with high Curie temperature. Likewise, it is found that the hydrogen loading and Fe concentration have direct consequences on the structural properties, these can be explained either by an amorphisation process or by the formation of very small nanocrystalline particles probed by XRD measurements. Furthermore, different sizes and chemical decoration of open-volume defects has been observed by PAS.
The knowledge gained from these studies can be use for monitoring those characteristics that change in the presence of hydrogen.

Keywords: Magnetic application, positron annihilation spectroscopy
  • Poster
    Gordon research conference on hydrogen-metal systems, 12.-17.07.2015, Easton, MA, USA
Registration No. 23195 - Permalink

Mg2FexSi1-x thin films: The interplay between the defects and magnetic structure properties of hydrogenation
Trinh, T. T.; Munnik, F.
Abstract: Mg2Fe hydride belongs to the most promising candidates for application as light weight storage material in a future hydrogen economy. Recently, it has also been shown that due to chemochromism, Mg2Fe is a low-cost and rare-earth-free candidate for switchable mirrors upon hydrogen loading. Besides the Mg2Fe hydride, a new compound of Mg2FexSi1-x will be presented. The additional content of Si promises an optimization of hydrogen absorption and desorption processes. Comprehensive investigations at the facilities of HZDR on Mg2FexSi1-x system showed that hydrogen induced changes in structure, electronic, optical and magnetic properties. I.e., volume magnetic properties transform from superparamagnetism to ferromagnetism with a high Curie temperature.
As a member of the Helmholtz Association, HZDR provides a unique infrastructure for researchers. Large scale research facilities, i.e. the ion beam center and the linear electron accelerator ELBE of the HZDR are also briefly presented. A suite of materials analysis techniques based on ion beams and the generated radiation of the electron beam is available. A few methods are introduced such as Rutherford Backscattering Spectrometry (RBS), Resonant Nuclear Reaction Analysis (NRA) and Positron annihilation spectroscopy (PAS), which enable the cross-disciplinary collaboration between researchers.

Keywords: Metal hydride, switchable mirror, Superparamagnetism
  • Invited lecture (Conferences)
    ENERGYPOLIS Seminar, 12.11.2015, Sion, Switzerland
Registration No. 23194 - Permalink

Luminescence mechanism for Er3+ ions in a silicon-rich nitride host under electrical pumping
Berencén, Y.; Illera, S.; Rebohle, L.; Ramírez, J. M.; Wutzler, R.; Cirera, A.; Hiller, D.; Rodríguez, J. A.; Garrido, B.; Skorupa, W.
Abstract: A combined experimental and theoretical study on the electroluminescent excitation mechanism for trivalent erbium (Er3+) ions in a silicon-rich nitride (SiNx) host is presented. Direct impact by hot electrons is demonstrated to be the fundamental excitation mechanism. The Er3+ excitation by energy transfer from silicon nanostructures and/or defects is shown to be marginal under electrical pumping. A bilayer structure made of a SiO2 electron-accelerating layer and an Er-implanted SiNx layer has been sandwiched between a metal–insulator–semiconductor structure with a highly doped N-type silicon substrate and an indium–tin–oxide window functioning as a transparent electrode. Monte Carlo (MC) simulations are used to model hot electron transport in the proposed device structure. Acoustic, polar and non-polar optical electron–phonon scattering mechanisms are considered as well as a new scattering process related to the trapping/detrapping on energetically shallow traps in the band gap of silicon nitride. For SiO2 layers around 20 nm-thick and beyond, the number and kinetic energy of hot electrons before entering the SiNx layer are maximal. A significant enhancement of the 1.54 μm electroluminescence power efficiency of two orders of magnitude is observed in devices composed of a 20 nm-thick SiO2 layer compared to those composed of 10 nm-thick SiO2. We demonstrate by MC simulations that such a difference, in terms of power efficiency, is ascribed to the high-energy tail of the hot electron energy distribution, which becomes more pronounced as the SiO2 electron-accelerating layer thickness increases. It is also unveiled that direct excitation of the 1.54 μm Er3+ main radiative transition requiring an excitation energy of only 0.8 eV is inefficient, and that the major part of the Er3+ ions are excited via higher level energy states. The obtained results are sufficiently consistent to be extended to other trivalent rare-earth ions inside similar insulating material environments.
Keywords: erbium, silicon-rich nitride, hot electrons, electroluminescence, direct impact excitation, Monte Carlo, light emitting devices Registration No. 23193 - Permalink

Die Jagd nach dem Feldrekord - Europas höchste Magnetfelder
Wosnitza, J.
Abstract: es hat kein Abstract vorgelegen
  • Lecture (others)
    Dresden-Open-Minded, Culture Container Festival, 12.-23.02.2015, Dresden, Deutschland
Registration No. 23192 - Permalink

Investigation of single bubbles and bubble chains in liquid metal under the influence of magnetic fields
Strumpf, E.; Roshchupkina, O.; Shevchenko, N.; Eckert, S.
Abstract: In the present study the ascents of single bubbles and of bubble chains in a liquid metal are investigated. For this purpose a benchmark experiment is set up, a cuboid vessel of the dimensions 144 x 144 x 12 mm³, which is filled with eutectic alloy GaInSn. A transversal magnetic field up to 1.1 T is imposed to this vessel. Ultrasound Doppler Velocimetry (UDV) is used to map the flow in the continuous phase of bubble chain regimes as well as the ascent velocity of single bubbles. X-ray radioscopy is applied to obtain detailed information within the disperse phase of bubble chains, such as bubble diameter, shape, trajectory etc.
Keywords: liquid metal, bubble, magnetic field, UDV, X-ray, two-phase flows
  • Lecture (Conference)
    MHD Days 2015, 07.-09.12.2015, Ilmenau, Deutschland
Registration No. 23191 - Permalink

Mono-energetic Positron Source (MePS) – a large-scale facility for Porosimetry at ELBE
Trinh, T. T.; Liedke, M. O.; Anwand, W.; Wagner, A.; Krause-Rehberg, R.
Abstract: Positron annihilation lifetime spectroscopy serves as an excellent tool for studies of open-volume defects in solid materials such as vacancies, vacancy agglomerates, dislocations, pores and voids. The intense mono-energetic positros beamline (MePS) at the ELBE accelerator developed for positron life-time and conventional Doppler Broadening experiments offers a non-destructive investigation method to study of porous media as well as thin film as a function of thickness.
Keywords: Positron annihilation lifetime spectroscopy, Doppler Broadening, Porous
  • Poster
    Porosimetry Workshop, 21.10.2015, HZDR, Germany
Registration No. 23190 - Permalink

From anti‐dots to sponge: Positron Annihilation Spectroscopy of Ge+ irradiated Ge
Liedke, M. O.; Böttger, R.; Liedke, B.; Facsko, S.; Anwand, W.; Wagner, A.
Abstract: Ion irradiation of Ge drives the surface morphology throughout a rich variety of nanostructure formations, i.e., from ordered nanohole and nanodot patterns to nanoporous and sponge-like structures [1]. Moreover, due to ion energy depth resolution functional modifications of Ge are not only limited to the surface but extend easily to several tens of nm depth. That is especially relevant for fuel [2], and solar cells [3], as well as for filters [4], and gas sensors [5] applications. Possible fundamental implications are under a debate as well, e.g., does the mechanism for porous Ge formation originate mainly from the vacancy clustering [1] or microexplosions [6]? In addition, surprisingly porous structures have not been found in ion irradiated Si that is in appearance virtually a very similar material to Ge.
The driving force for the irradiation induced morphology evolution is mainly related to the kinetics of ion beam induced defects. For Ge+ self-irradiation with low ion energies the sample surface remains first (i) smooth (EGe<4keV), followed by (ii) the self-organized formation of nanoholes (EGe=5-7keV), and finally (iii) at EGe>8keV porous/sponge structures develop. Increasing ion energy allows to tailor depth and porosity. For Bi+ irradiation surface morphology evolves in a similar fashion besides for EBi=7-12keV, where initial hexagonally ordered nanohole patterns reorganize into homogeneously distributed nanodots [1]. Again for larger ion energies porous and sponge-like structures evolve. The kinetics beneath ion irradiation of Ge can be drawn as follows: (i) defect distribution and number at a certain sample depth scales with ion energy, whereas (ii) increasing ion fluence forms amorphous Ge layer due to continuous creation of interstitials and vacancies. The former (iii) because of their mobility, formation volume and energy compare to interstitials can cluster and grow into pores. Once, such a small void is created and is far enough from the surface it grows by attracting additional vacancies [7]. The overall surface morphology evolution has been simulated by means of kinetic Monte Carlo (kMC) modeling [1]. Both hole and sponge structures have been visualized without, however, hexagonal ordering of patterns nor the nanodot formation found from Bi+ irradiation could be realized.
Positron annihilation lifetime spectroscopy (PALS) and Doppler Broadening (DB) measurements will allow to probe the open-volume distribution and its complexes as well as the pores size as a function of depth. Thus, it should give an insight into the evolution of surface morphology during ion irradiation of semiconductors. These results can be of importance for further kMC modeling. Preliminary investigations by DB will be performed at the SPONSOR/AIDA setup in order to estimate positron annihilation line parameters as a function of positron energy.
  • Lecture (Conference)
    Treffen deutscher Positronengruppen (TdP‐2015), 12.-13.11.2015, München, Deutschland
Registration No. 23189 - Permalink

Open volume defects and magnetic phase transition in Fe60Al40 transition metal aluminide
Liedke, M. O.; Anwand, W.; Bali, R.; Cornelius, S.; Butterling, M.; Trinh, T. T.; Wagner, A.; Salamon, S.; Walecki, D.; Smekhova, A.; Wende, H.; Potzger, K.
Abstract: Magnetic phase transition in the Fe60Al40 transition metal aluminide from the ferromagnetic disordered A2-phase to the paramagnetic ordered B2-phase as a function of annealing up to 1000°C has been investigated by means of magneto-optical and spectroscopy techniques, i.e., Kerr effect, positron annihilation and Mössbauer spectroscopy. The positron annihilation spectroscopy (PAS) has been performed in-situ sequentially after each annealing step at the Apparatus for In-situ Defect Analysis (AIDA) that is a unique tool combining positron annihilation spectroscopy with temperature treatment, material evaporation, ion irradiation, and sheet resistance measurement techniques. The overall goal was to investigate importance of the open volume defects onto the magnetic phase transition.
Magneto-optical measurements of the ordered Fe60Al40 as well as disordered sample after each annealing step have been done ex-situ at room temperature. A set of magnetization reversal loops is presented in Figure 1(a). The ordered sample shows no magnetic signal at room temperature at all, whereas the disordered one is represented by a magnetic reversal curve with coercivity of about 65 Oe. Due to annealing both the remanence and coercivity drop significantly and already at 500°C the magnetic signal vanishes. The SEM images [see inset of Fig. 1(a)] reveal continuous film surface at 500°C, whereas at 1000°C darker and bright island-like regions were found that possibly correspond to the former FeAl film and Al-AlO segregations, respectively. The light gray color surrounding the island-like regions in the 1000°C case represents most probably the SiO2 substrate.

Two different positron annihilation spectroscopy (PAS) measurement types have been utilized for defect analysis after each temperature step: (i) room temperature standard Doppler broadening as a function of positron energy E for depth profiling, (ii) RT coincident Doppler broadening measurements at fixed energy after each temperature step that can in detail reveal information of the chemical environment of defects with higher energy resolution [Fig. 1(b)]. In both cases two specific annihilation line parameters have been extracted: (i) the shape parameter S that corresponds to the fraction of positrons annihilating with the low-momentum electrons localized close to the middle of the annihilation line, and (ii) the wing parameter W that takes into appoint positron annihilation with high-momentum electrons at the outer region of the annihilation line. In general, the S parameter is sensitive to the open volume defects amount and their size, whereas the W parameter is a fingerprint of the annihilation site chemical environment, thus defects decoration by neighboring matrix elements [1].

cDB results are summarized in Figure 1(b), where the annihilation line parameters are plotted as a function of the annealing temperature. We can clearly see that up to 600°C both S and W parameters are more or less constant, whereas a jump followed by another plateau in the S parameter value for higher temperatures is visible. The jump of the S parameter can correspond to a slight increase of the open volume number and/or its size, whereas the decrease of W shifts the defect decoration in direction of Al. The S parameter difference at the jump is of about 1.5% that can be considered as low, nevertheless a step-like dependence is visible. A drop of about 5.5% in W cannot be neglected. Moreover W recovers to its original value at 1000°C that suggests larger occupation of the neighboring defect sites with Fe as well as a slight change of film stoichiometry due to annealing.

Summarizing, no evidence of variation in the vacancy concentration in matching the magnetic phase transition temperature range (400-600°C) has been found, whereas higher temperatures showed an increase in the vacancy concentration. Still, in the surface region of the sample reasonably large annihilation line parameters variations have been found showing sufficient sensitivity of our experimental tools, and ruling out possible signal saturation due to too high vacancies concentration. At higher temperatures a slightly larger defect concentration as well as different defect decorations were found that is likely a result of temperature driven material decomposition leading to a complete film melt at 1000°C. Magnetic and structural changes have been tracked using PAS, XRD, and CEMS measurements. The magnetic phase transition from para- to ferro-magnetic behavior appears to be driven by chemical disordering alone, and is independent of the vacancy concentration. These results help understand the role of defects in materials that show disorder-induced ferromagnetism.

Acknowledgments
This work has been partially financed by the Initiative and Networking Fund of the German Helmholtz Association, Helmholtz Virtual Institute MEMRIOX (VH-VI-442).

References
[1] - R. Krause-Rehberg and H. Leipner, Positron Annihilation in Semiconductors, Solid-State Sciences. Berlin: Springer, vol. 127 (1999)
  • Poster
    22nd International Colloquium on Magnetic Films and Surfaces, 12.-17.07.2015, Kraków, Polska
Registration No. 23188 - Permalink

Synthesis and characterization of modified ultrasmall nanoparticles as multimodal imaging agents
Singh, G.
Abstract: The synthesis of multimodal imaging agents is indeed a growing field and a lot of research is currently being done in this area because of its wide biomedical applications.[1] The idea behind this research is to prepare a single molecule/nanoparticle which is suitable for two or more imaging techniques and thus can act as a multimodal imaging agent, for example, the combination of optical and nuclear imaging modalities may provide complementary information for improving diagnosis as well as the treatment of diseases. These imaging agents combat the limitations of sensitivity, spatial and temporal resolution and also tissue penetrability. The high hydrophilicity of the nanoparticles and fast renal clearance of the complex from the body are the major highlights.
Amine terminated ultrasmall Silicon nanoparticles[2] of size <4 nm were synthesized by hydrothermal method and purified by dialysis. Sulfo-Cy5[3] and NOTA-Bn-SCN was attached selectively to the amine terminated Si USNPs. Next step would be the radiolabeling of the particles by 64Cu and could be used for the in vitro and in vivo studies. Bispidines[4] can also be tried as a copper chelator in the complex. Further, we could also attach single domain antibodies via PEG linkers bearing maleimide group.
The substituents after coupling with the USNPs are assumed to act as excellent multimodal imaging agent which can be used for the cancer diagnosis and therapy.

References
[1] G. J. Cheon, Y. Chang, J. Yoo, J. Cheon, Angew. Chem. 2008, 120, 6355 –6358.
[2] Y. Zhong, F. Peng, F. Bao, S. Wang, X. Ji, L. Yang, Y. Su, S. Lee, Y. He, J. Am. Chem. Soc. 2013, 135, 8350−8356.
[3] K. Viehweger, L. Barbaro, K. P. García, T. Joshi, G. Geipel, J. Steinbach, H. Stephan, L. Spiccia, B. Graham, Bioconjugate Chem. 2014, 25, 1011−1022.
[4] H. Stephan, M. Walther, S. Fähnemann, P. Ceroni, J. Molloy, G. Bergamini, F. Heisig, C. E. Müller, W. Kraus, P. Comba, Chem. Eur. J. 2014, 20, 17011-17018.

Keywords: multimodal imaging agent, ultrasmall silicon nanoparticles, bispidines
  • Poster
    2nd International Symposium on Nanoparticles/Nanomaterials and Applications, 18.-21.01.2016, Lisbon/Caparica, Portugal
Registration No. 23185 - Permalink

Local probe of disorder-induced magnetism in Fe60Al40 thin films by CEMS
Smekhova, A.; Walecki, D.; Salamon, S.; Bali, R.; Potzger, K.; Cornelius, S.; Liedke, M. O.; Lindner, J.; Wende, H.
Abstract: The phenomenon of chemical disorder-induced magnetism in the bulk FeAl system is known for decades [e.g. Ref.1] and has been intensively studied by Mössbauer spectroscopy. The majority of literature reports are dedicated to studies of ball-milled FeAl alloys of different stoichiometry that exhibit a hyperfine field splitting depending on the milling time and temperature. Nowadays it is possible to create such a disorder in a much more controlled and delicate manner also in thin films: the ion beam irradiation technique allows to effectively vary the number of Fe nearest-neighbors and interatomic distances by increasing either the ion energy or the irradiation dose.
Fe60Al40 (40nm and 250nm)/SiO2/Si thin films have been prepared by magnetron sputtering with further annealing and 20 keV Ne+ irradiation as reported in [2]. XRD scans demonstrate that the irradiation destroys the chemical ordering but preserves the structural integrity. MOKE and VSM magnetometry measurements confirm that chemically disordered films (A2 phase) are clearly ferromagnetic contrary to the annealed ones (B2 phase).
CEMS studies of as-prepared, annealed and irradiated thin films of 40nm were performed at room and low (80K) temperatures in normal or “magic angle” incidence geometry. The evident paramagnetic-ferromagnetic phase transition is shown in Fig.1: the experimental single line from an annealed sample (B2 phase) is replaced by a sextet with a hyperfine field distribution from the irradiated one (A2 phase). Measurements performed at 80K revealed further transformation of the subspectra: the subspectrum related to the paramagnetic phase almost vanishes while the subspectrum related to the ferromagnetic phase exhibits an enlarged hyperfine field splitting. Such a behavior may be attributed to the enhanced contribution of ferromagnetic Fe-rich areas in the sample [as in Ref. 3] that could have different Curie temperatures below RT. For 250nm thick samples annealed at 500°C or 1000°C, the parameters of the CEMS subspectra (isomer shifts, quadrupole splitting and doublet intensity ratio) obtained within a model suggested in [4] could be interpreted as an indication of different amounts of thermal vacancies in the samples studied. A comparison of results from CEMS and X-ray element-specific spectroscopy is in progress and will be reported.
References
[1] G. P. Huffman et al., J.Appl. Phys. 38, 735 (1967).
[2] R. Bali et al, Nano Lett. 14, 435 (2014).
[3] L. Zamora et al., Phys. Rev. B 79, 094418 (2009).
[4] J. Bogner et al., Phys. Rev. B 58, 14922 (1998).
  • Poster
    The International Conference on the Applications of the Mössbauer Effect (ICAME), 13.-18.09.2015, Hamburg, Deutschland
Registration No. 23184 - Permalink

Electron beam final focus system for Thomson scattering
Krämer, J.; Jochmann, A.; Lehnert, U.; Budde, M.; Irman, A.; Schramm, U.
Abstract: Electron beam final focus system for Thomson scattering experiments is presented.
  • Poster
    2nd European Advanced Accelerator Concepts Workshop, 13.-19.09.2015, La Biodola, Isola d'Elba, Italia
Registration No. 23183 - Permalink

Developing the current experimental research into laser acceleration to a pre-commercial level
Krämer, J.; Lehnert, U.; Irman, A.; Budde, M.; Schramm, U.
Abstract: One of the main challenges in the field of laser acceleration is the beam transport of laser accelerated beams with a large energy spread. The same applies to a final focus system (FFS) for the high-flux laser-Thomson x-ray source at the conventional electron accelerator ELBE, where beams are chirped for longitudinal bunch compression. We found a telescope system consisting of four permanent quadrupole magnets to address the energy spread significantly better than a quadrupole triplet. We present the design of the system, magnet test results and emittance measurements at the interaction point.
  • Lecture (Conference)
    Laser Applications at Accelerators, 24.-27.03.2015, Palmanova, Spain
Registration No. 23182 - Permalink

Linear and nonlinear Thomson scattering from the PHOENIX xray source
Krämer, J.; Jochmann, A.; Couperus, J. P.; Köhler, A.; Zarini, O.; Pausch, R.; Debus, A.; Wagner, A.; Lehnert, U.; Budde, M.; Bødker, F.; Kristensen, J.; Michel, P. ; Irman, A.; Schramm, U.
Abstract: Development of advanced x-ray sources based on the laser-Thomson scattering mechanism is becoming important pushed by a strong demand for ultrashort hard x-ray pulses. These can serve as a tool for structural analysis of complex systems with unprecedented temporal and spatial resolution. We explored the spectral shape and bandwidth of the x-ray beam as a result from the interaction of electron and laser beam. The intensity dependence of the backscattered photon spectrum is investigated and compared to full-physics 3D ab-initio simulations. The realization of a non-linear Thomson scattering source qualifies as an initial step towards strong field physics research.
  • Lecture (Conference)
    International Conference on Extreme Light (ICEL), 23.-27.11.2015, Bucharest, Romania
  • Lecture (Conference)
    2nd European Advanced Accelerator Concepts Workshop, 13.-19.09.2015, La Biodola,Isola d'Elba, Italia
Registration No. 23181 - Permalink

Al in ZnO - From doping to alloying: An investigation of Al electrical activation in relation to structure and charge transport limits
Cornelius, S.; Vinnichenko, M.
Abstract: The electrical activation of Al in ZnO thin films grown by pulsed reactive magnetron sputtering is quantified experimentally for a wide range of Al concentrations. We find that the activation does not exceed 35% remaining constant for growth temperatures below a certain optimum value at which the highest free electron density and mobility are achieved. Above this temperature, the Al activation decreases rapidly, while Al is accumulating in the films and their micro-structure as well as electrical properties deteriorate significantly. The analysis of possible mechanisms of Al deactivation suggests that the observed effects may be explained only by considering Al doped ZnO as metastable solid solution showing a tendency to segregation of Al into secondary phases
Keywords: Sputtering; Transparent conductive oxide Registration No. 23175 - Permalink

Neue Lasermaterialien für Petawatt – Laser: Anforderungen und Erkenntnisstand
Röser, F.; Löser, M.; Albach, D.; Siebold, M.; Schramm, U.
  • Lecture (others)
    2. Projekttreffen des VP5 „Hochreine Gläser“ im Rahmen des Wachstumskerns Pades, 04.03.2015, Dresden, Deutschland
Registration No. 23174 - Permalink

Laserlab Europe – ILAT kick-off
Siebold, M.; Röser, F.; Löser, M.; Albach, D.; Harzendorf, G.; Nehring, H.; Eiselt, P.; Schramm, U.
Abstract: Laserlab Europe – ILAT kick-off presentation HZDR
  • Lecture (others)
    Laserlab Europe, 24.11.2015, Mailand, Italien
Registration No. 23173 - Permalink

Stereotactic radiotherapy augments the immune response / Die stereotaktische Strahlentherapie unterstützt die Immunantwort
Troost, E. G.
Abstract: there ist no abstract Registration No. 23172 - Permalink

Plug Transfer System for GaAs Photocathodes
Murcek, P.; Arnold, A.; Teichert, J.; Xiang, R.; Burrill, A.
Abstract: The transport and exchange technology of Cs2Te photocathode for the ELBE superconducting rf photoinjector (SRF gun) has been successfully developed and tested at HZDR. The next goal is to realize the transport of GaAs photocathode into SRF gun, which will need a new transfer system with XHV 10-11 mbar. The key component of the system is the transfer chamber and the load-lock system that will be connected to the SRF-gun. In the carrier four small plugs will be transported, and one of them will be plug on the cathode-body and inserted into the cavity. The new transport chamber allows the transfer and exchange of plugs between HZDR, HZB and other cooperating institutes. In HZDR this transfer system will also provide a direct connection between the SRFGUN and the GaAs preparation chamber in the Elbe-accelerator hall.
Keywords: SRf gun, photo injector, GaAs photo cathode
  • Poster
    17th International Conference on RF Superconductivity SRF 2015, 13.-18.09.2015, Whistler, Canada
Registration No. 23171 - Permalink

Preclinical Assessment of Efficacy of Radiation Dose Painting Based on Intratumoral FDG-PET Uptake.
Trani, D.; Yaromina, A.; Dubois, L.; Granzier, M.; Peeters, S. G.; Biemans, R.; Nalbantov, G.; Lieuwes, N.; Reniers, B.; Troost, E. E.; Verhaegen, F.; Lambin, P.
Abstract: PURPOSE:

We tested therapeutic efficacy of two dose painting strategies of applying higher radiation dose to tumor subvolumes with high FDG uptake (biologic target volume, BTV): dose escalation and dose redistribution. We also investigated whether tumor response was determined by the highest dose in BTV or the lowest dose in gross tumor volume (GTV).
EXPERIMENTAL DESIGN:

FDG uptake was evaluated in rat rhabdomyosarcomas prior to irradiation. BTV was defined as 30% of GTV with the highest (BTVhot) or lowest (BTVcold) uptake. To test efficacy of dose escalation, tumor response (time to reach two times starting tumor volume, TGTV2) to Hot Boost irradiation (40% higher dose to BTVhot) was compared with Cold Boost (40% higher dose to BTVcold), while mean dose to GTV remained 12 Gy. To test efficacy of dose redistribution, TGTV2 after Hot Boost was compared with uniform irradiation with the same mean dose (8 or 12 Gy).
RESULTS:

TGTV2 after 12 Gy delivered heterogeneously (Hot and Cold Boost) or uniformly were not significantly different: 20.2, 19.5, and 20.6 days, respectively. Dose redistribution (Hot Boost) with 8 Gy resulted in faster tumor regrowth as compared with uniform irradiation (13.3 vs. 17.1 days; P = 0.026). Further increase in dose gradient to 60% led to a more pronounced decrease in TGTV2 (10.9 days; P < 0.0001).
CONCLUSIONS:

Dose escalation effect was independent of FDG uptake in target tumor volume, while dose redistribution was detrimental in this tumor model for dose levels applied here. Our data are consistent with the hypothesis that tumor response depends on the minimum intratumoral dose. Clin Cancer Res; 21(24); 5511-8. ©2015 AACR.
Registration No. 23170 - Permalink

HPV and beyond-looking out for biomarkers for distinguishing the good prognosis from the bad prognosis group in locally advanced and clinically high risk HNSCC.
Lohaus, F.; Linge, A.; Baumann, M.
Abstract: There is no abstract

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Registration No. 23169 - Permalink

Cancer stem cell related markers of radioresistance in head and neck squamous cell carcinoma.
Kurth, I.; Hein, L.; Mäbert, K.; Peitzsch, C.; Koi, L.; Cojoc, M.; Kunz-Schughart, L.; Baumann, M.; Dubrovska, A.
Abstract: Despite recent advances in understanding of the molecular pathogenesis and improvement of treatment techniques, locally advanced head and neck squamous cell carcinoma (HNSCC) remains associated with an unfavorable prognosis. Compelling evidence suggests that cancer stem cells (CSC) may cause tumor recurrence if they are not eradicated by current therapies as radiotherapy or radio-chemotherapy. Recent in vitro studies have demonstrated that CSCs may be protected from treatment-induced death by multiple intrinsic and extrinsic mechanisms. Therefore, early determination of CSC abundance in tumor biopsies prior-treatment and development of therapeutics, which specifically target CSCs, are promising strategies to optimize treatment. Here we provide evidence that aldehyde dehydrogenase (ALDH) activity is indicative for radioresistant HNSCC CSCs. Our study suggests that ALDH+ cells comprise a population that maintains its tumorigenic properties in vivo after irradiation and may provide tumor regrowth after therapy. We found that ALDH activity in HNSCC cells can be attributed, at least in part, to the ALDH1A3 isoform and inhibition of the ALDH1A3 expression by small interfering RNA (siRNA) decreases tumor cell radioresistance. The expression dynamic of ALDH1A3 upon irradiation by either induction or selection of the ALDH1A3 positive population correlates to in vivo curability, suggesting that changes in protein expression during radiotherapy are indicative for tumor radioresistance. Our data indicate that ALDH1A3+ HNSCC cells may contribute to tumor relapse after irradiation, and inhibition of this cell population might improve therapeutic response to radiotherapy.
Keywords: aldehyde dehydrogenase; cancer stem cells; head and neck squamous cell carcinoma (HNSCC); radioresistance

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Registration No. 23167 - Permalink

Acceleration of volume decomposition of supersaturated Al+4 wt.% Cu solid solution under irradiation with Ar+ ions
Gushchina, N. V.; Ovchinnikov, V. V.; Mücklich, A.
Abstract: Effect of irradiation with Ar+ ions on the decomposition processes of model precipitation-hardening alloy Al+4wt.% Cu has been studied. Using X-ray diffraction, high-resolution electron microscopy methods and micro hardness measurements, it was established, that, already at low temperatures (T<60°C), ion irradiation causes accelerated decomposition of solid solution, with precipitation of θ′- and θ-phase particles at a depth greatly exceeding the Ar+ ions projected range.
Keywords: Aluminum alloy; Ion irradiation; Long-range effect; Supersaturated solid solution decomposition Registration No. 23166 - Permalink

Global Task Force on Radiotherapy for Cancer Control.
Jaffray, D. A.; Knaul, F. M.; Atun, R.; Adams, C.; Barton, M. B.; Baumann, M.; Lievens, Y.; Lui, T. Y.; Rodin, D. L.; Rosenblatt, E.; Torode, J.; van Dyk, J.; Vikram, B.; Gospodarowicz, M.
Abstract: there is no abstract Registration No. 23165 - Permalink

SRF Gun Characterization – Phase Space and Dark Current Measurement at ELBE
Panofski, E.; Jankowiak, A.; Kamps, T.; Lu, P.; Teichert, J.
Abstract: RF photoelectron sources with superconducting cavities provide the potential to generate high quality, high brightness electron beams for future accelerator applications. At Helmholtz-Zentrum Dresden Rossendorf, such an electron source was operated for many years. The commissioning of an improved SRF Gun with a new high-performance gun cavity with low field emission and a superconducting solenoid inside the gun cryomodule (SRF Gun II) has started in June 2014. Simulations of the experimental set-up with ASTRA and ELEGANT were performed. First low current measurements as well as studies of unwanted beam transport using SRF Gun II with Cu photocathode and an acceleration gradient up to 9 MV/m will be presented. First beam characterization of the SRF Gun in combination with ELBE, a two-stage superconducting linear accelerator will be discussed.
Keywords: electron source, SRF gun, photo injector, superconducting RF
  • Poster
    International Beam Instrumentation Conference IBIC2015, 13.-17.09.2015, Melbourne, Australia
  • Contribution to proceedings
    International Beam Instrumentation Conference IBIC2015, 13.-17.09.2015, Melbourne, Australia
    Proceedings of the IBIC 2015: Jacow
Registration No. 23164 - Permalink

Increased evidence for the prognostic value of primary tumor asphericity in pretherapeutic FDG PET for risk stratification in patients with head and neck cancer.
Hofheinz, F.; Lougovski, A.; Zöphel, K.; Hentschel, M.; Steffen, I. G.; Apostolova, I.; Wedel, F.; Buchert, R.; Baumann, M.; Brenner, W.; Kotzerke, J.; van den Hoff, J.
Abstract: PURPOSE:

In a previous study, we demonstrated the first evidence that the asphericity (ASP) of pretherapeutic FDG uptake in the primary tumor provides independent prognostic information in patients with head and neck cancer. The aim of this work was to confirm these results in an independent patient group examined at a different site.
METHODS:

FDG-PET/CT was performed in 37 patients. The primary tumor was delineated by an automatic algorithm based on adaptive thresholding. For the resulting ROIs, the metabolically active part of the tumor (MTV), SUVmax, SUVmean, total lesion glycolysis (TLG) and ASP were computed. Univariate Cox regression with respect to progression free survival (PFS) and overall survival (OS) was performed. For survival analysis, patients were divided in groups of high and low risk according to the parameter cut-offs defined in our previous work. In a second step, the cut-offs were adjusted to the present data. Univariate and multivariate Cox regression was performed for the pooled data consisting of the current and the previously described patient group (N = 68). In multivariate Cox regression, clinically relevant parameters were included.
RESULTS:

Univariate Cox regression using the previously published cut-off values revealed TLG (hazard ratio (HR) = 3) and ASP (HR = 3) as significant predictors for PFS. For OS MTV (HR = 2.7) and ASP (HR = 5.9) were significant predictors. Using the adjusted cutoffs MTV (HR = 2.9/3.3), TLG (HR = 3.1/3.3) and ASP (HR = 3.1/5.9) were prognostic for PFS/OS. In the pooled data, multivariate Cox regression revealed a significant prognostic value with respect to PFS/OS for MTV (HR = 2.3/2.1), SUVmax (HR = 2.1/2.5), TLG (HR = 3.5/3.6), and ASP (HR = 3.4/4.4).
CONCLUSIONS:

Our results confirm the independent prognostic value of ASP of the pretherapeutic FDG uptake in the primary tumor in patients with head and neck cancer. Moreover, these results demonstrate that ASP can be determined unambiguously across different sites.
Registration No. 23163 - Permalink

Proton therapy of pediatric rhabdomyosarcoma: Same tumor control as photon therapy, with less adverse effects / Protonentherapie von Rhabdomyosarkompatienten im Kindesalter: Gleiche lokale Tumorkontrolle wie bei Photonentherapie mit weniger Nebenwirkungen
Gurtner, K.; Baumann, M.
Abstract: there is no abstract Registration No. 23162 - Permalink

Comprehensive analysis of signal transduction in three-dimensional ECM-based tumor cell cultures.
Eke, I.; Hehlgans, S.; Zong, Y.; Cordes, N.
Abstract: Analysis of signal transduction and protein phosphorylation is fundamental to understanding physiological and pathological cell behavior and identifying novel therapeutic targets. Despite the fact that the use of physiological three-dimensional cell culture assays is increasing, 3D proteomics and phosphoproteomics remain challenging due to difficulties with easy, robust and reproducible sample preparation. Here, we present an easy-to-perform, reliable and time-efficient method for the production of 3D cell lysates that does not compromise cell adhesion before cell lysis. The samples can be used for western blotting as well as phosphoproteome array technology. This technique will be of interest for researchers working in all fields of biology and drug development.
Keywords: 3D cell culture; extracellular matrix; phosphoproteomics; protein analysis; signaling

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Registration No. 23161 - Permalink

Cell-ECM interactions control DDR
Dickreuter, E.; Cordes, N.
Abstract: there ist no abstract
Keywords: KEYWORDS: DNA repair; cell-ecm interactions; integrins
  • Oncoscience 2(2015)8, 679-680
    Button zum Volltext

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Registration No. 23160 - Permalink

Hyperfractionated accelerated radiation therapy (HART) of 70.6 Gy with concurrent 5-FU/Mitomycin C is superior to HART of 77.6 Gy alone in locally advanced head and neck cancer: long-term results of the ARO 95-06 randomized phase III trial.
Budach, V.; Stromberger, C.; Poettgen, C.; Baumann, M.; Budach, W.; Grabenbauer, G.; Marnitz, S.; Olze, H.; Wernecke, K. D.; Ghadjar, P.
Abstract: PURPOSE:

To report the long-term results of the ARO 95-06 randomized trial comparing hyperfractionated accelerated chemoradiation with mitomycin C/5-fluorouracil (C-HART) with hyperfractionated accelerated radiation therapy (HART) alone in locally advanced head and neck cancer.
PATIENTS AND METHODS:

The primary endpoint was locoregional control (LRC). Three hundred eighty-four patients with stage III (6%) and IV (94%) oropharyngeal (59.4%), hypopharyngeal (32.3%), and oral cavity (8.3%) cancer were randomly assigned to 30 Gy/2 Gy daily followed by twice-daily 1.4 Gy to a total of 70.6 Gy concurrently with mitomycin C/5-FU (C-HART) or 16 Gy/2 Gy daily followed by twice-daily 1.4 Gy to a total dose of 77.6 Gy alone (HART). Statistical analyses were done with the log-rank test and univariate and multivariate Cox regression analyses.
RESULTS:

The median follow-up time was 8.7 years (95% confidence interval [CI]: 7.8-9.7 years). At 10 years, the LRC rates were 38.0% (C-HART) versus 26.0% (HART, P=.002). The cancer-specific survival and overall survival rates were 39% and 10% (C-HART) versus 30.0% and 9% (HART, P=.042 and P=.049), respectively. According to multivariate Cox regression analysis, the combined treatment was associated with improved LRC (hazard ratio [HR]: 0.6 [95% CI: 0.5-0.8; P=.002]). The association between combined treatment arm and increased LRC appeared to be limited to oropharyngeal cancer (P=.003) as compared with hypopharyngeal or oral cavity cancer (P=.264).
CONCLUSIONS:

C-HART remains superior to HART in terms of LRC. However, this effect may be limited to oropharyngeal cancer patients.
Registration No. 23159 - Permalink

Expanding global access to radiotherapy
Atun, R.; Jaffray, D. A.; Barton, M. B.; Bray, F.; Baumann, M.; Vikram, B.; Hanna, T. P.; Knaul, F. M.; Lievens, Y.; Lui, T. Y.; Milosevic, M.; O'Sullivan, B.; Rodin, D. L.; Rosenblatt, E.; van Dyk, J.; Yap, M. L.; Zubizarreta, E.; Gospodarowicz, M.
Abstract: Radiotherapy is a critical and inseparable component of comprehensive cancer treatment and care. For many of the most common cancers in low-income and middle-income countries, radiotherapy is essential for effective treatment. In high-income countries, radiotherapy is used in more than half of all cases of cancer to cure localised disease, palliate symptoms, and control disease in incurable cancers. Yet, in planning and building treatment capacity for cancer, radiotherapy is frequently the last resource to be considered. Consequently, worldwide access to radiotherapy is unacceptably low. We present a new body of evidence that quantifies the worldwide coverage of radiotherapy services by country. We show the shortfall in access to radiotherapy by country and globally for 2015-35 based on current and projected need, and show substantial health and economic benefits to investing in radiotherapy. The cost of scaling up radiotherapy in the nominal model in 2015-35 is US$26·6 billion in low-income countries, $62·6 billion in lower-middle-income countries, and $94·8 billion in upper-middle-income countries, which amounts to $184·0 billion across all low-income and middle-income countries. In the efficiency model the costs were lower: $14·1 billion in low-income, $33·3 billion in lower-middle-income, and $49·4 billion in upper-middle-income countries-a total of $96·8 billion. Scale-up of radiotherapy capacity in 2015-35 from current levels could lead to saving of 26·9 million life-years in low-income and middle-income countries over the lifetime of the patients who received treatment. The economic benefits of investment in radiotherapy are very substantial. Using the nominal cost model could produce a net benefit of $278·1 billion in 2015-35 ($265·2 million in low-income countries, $38·5 billion in lower-middle-income countries, and $239·3 billion in upper-middle-income countries). Investment in the efficiency model would produce in the same period an even greater total benefit of $365·4 billion ($12·8 billion in low-income countries, $67·7 billion in lower-middle-income countries, and $284·7 billion in upper-middle-income countries). The returns, by the human-capital approach, are projected to be less with the nominal cost model, amounting to $16·9 billion in 2015-35 (-$14·9 billion in low-income countries; -$18·7 billion in lower-middle-income countries, and $50·5 billion in upper-middle-income countries). The returns with the efficiency model were projected to be greater, however, amounting to $104·2 billion (-$2·4 billion in low-income countries, $10·7 billion in lower-middle-income countries, and $95·9 billion in upper-middle-income countries). Our results provide compelling evidence that investment in radiotherapy not only enables treatment of large numbers of cancer cases to save lives, but also brings positive economic benefits. Registration No. 23157 - Permalink

First beam characterization of SRF gun II at ELBE with a Cu photocathode
Teichert, J.; Arnold, A.; Lu, P.; Murcek, P.; Vennekate, H.; Xiang, R.
Abstract: An improved SRF gun has been installed and commissioned at HZDR since 2014. This new gun replaces the first SRF gun at the superconducting linear accelerator ELBE which had been in operation since 2007. The new SRF gun II has an improved 3.5-cell niobium cavity and a superconducting solenoid inside the gun cryostat. The gun has been tested first with a Cu photocathode. Using the standard high repetition rate laser system, this allows low bunch charge beams of a few pC only. The beam parameters for these low charges have been measured, and the first beam has been guided into the ELBE accelerator. Since 2015 the photocathode transfer system is installed for future use of Cs2Te photocathodes with high quantum efficiency photocathodes.
Keywords: electron source, photo injector, photo cathode, superconducting RF
  • Invited lecture (Conferences)
    Workshop on Energy Recovery Linacs (ERL2015), 07.-12.06.2015, Stony Brook, USA
  • Contribution to proceedings
    Workshop on Energy Recovery Linacs (ERL2015), 07.-12.06.2015, Stony Brook, USA
    Proceedings of the ERL 2015: Jacow
Registration No. 23156 - Permalink

Laser Cooling of Relativistic Ion Beams at FAIR. From ESR to SIS100 and HESR
Bussmann, M.; Löser, M.; Seltmann, M.; Siebold, M.; Schramm, U.; Beck, T.; Rein, B.; Walther, T.; Tichelmann, S.; Birkl, G.; Sanchez-Alarcon, R.; Ullmann, J.; Lochmann, M.; Nörtershäuser, W.; Eidam, L.; Boine-Frankenheim, O.; Winters, D.; Kozhuharov, C.; Sanjari, S.; Litvinov, Y.; Giacomini, T.; Steck, M.; Dimopoulou, C.; Nolden, F.; Shevelko, S.; Stöhlker, T.; Spiller, P.; Wen, W.; Yang, J.; Zhang, D.; Ma, X.; Hannen, V.
Abstract: We present recent results and future perspectives on laser cooling of relativistic storage beams
Keywords: laser cooling, storage ring, relativistic, ion beam
  • Invited lecture (Conferences)
    Kick-off Meeting für APPA-Verbundforschung, 14.-15.01.2016, Darmstadt, Deutschland
Registration No. 23154 - Permalink

The Power of Performant Code Abstraction in Real World HPC Applications
Bussmann, M.; Eckert, C.; Huebl, A.; Jung, F.; Widera, R.; Zacharias, M.; Zenker, E.
Abstract: Many-core architectures are going to stay for a while. Thus, scaling real world applications on HPC systems with thousands of nodes and hybrid architectures will be important to application developers. We present two real world applications, plasma simulations and high repetition rate data analysis, that strongly benefit from speed ups seen with accelerator hardware. From our viewpoint as users with real-world problems we discuss our path towards scalable, hardware-independent, performant application codes. Our focus is not to reinvent the wheel, but to make full use of the power of existing C++ codes by fully abstracting all parts of a code that require optimization, separating concepts used in the code from their optimized implementation. We do this by providing light-weight, single-purpose, zero-overhead interfaces to central code components. In the talk I will discuss our experiences with this approach, the reusable interfaces that have come out of this and the vision behind putting everything together.
Keywords: many core, picongpu, simulation, hpc
  • Invited lecture (Conferences)
    SPPEXA Annual Plenary Meeting, 25.-27.01.2016, Garching b. München, Deutschland
Registration No. 23153 - Permalink

The fastest code in the field of laser-plasma physics
Döring, C
Abstract: Ultra fast, scalable and free of charge – what began as a “youth conducts research” project, is today one of the most powerful programme codes for calculations in the field of astrophysics and plasma physics.
Keywords: picongpu, laser plasma, cancer therapy, acceleration Registration No. 23152 - Permalink

Laser focus Simulations explore how a tumor-killing laser’s high-energy fields can rip matter apart.
Bussmann, M.
Abstract: Laser physicists are tantalizingly close to building a device that delivers highly focused beams of tumor-killing ionized particles and packing it in a compact unit that would fit in a doctor’s office. OncoRay, a research center in Dresden, Germany, is designing what would be the first prototype compact particle therapy units.
Keywords: cancer therapy, laser, simulation, picongpu Registration No. 23151 - Permalink

Hot electron currents in ultra-intense laser-solid interactions
Kluge, T.
Abstract: The generation and propagation of strong currents of laser-accelerated hot electrons in solid density foils is of importance in many applications such as resistive heating, generation of resistive magnetic fields and ion acceleration. We present results from particle-in-cell simulations for the scaling of hot electron currents in solids and demonstrate the importance of a full description of the currents with respect to its spectral distribution and spatio-temporal structure. Taking them into account, we derive analytic scalings from first principle conservation laws that as an input to models for heating, magnetic field generation or ion acceleration prove to be consistent with the simulations in contrast to simple expressions such as j=\gamma n_c.
  • Lecture (Conference)
    2nd European Advanced Accelerator Concepts Workshop, 13.-19.09.2015, La Biodola, Italien
Registration No. 23150 - Permalink

Nanometer-scale characterization of laser-driven plasmas, compression, shocks and phase transitions, by coherent small angle x-ray scattering
Kluge, T.
Abstract: Combining ultra-intense short-pulse and high-energy long-pulse lasers, with brilliant coherent hard X-ray FELs, such as the Helmholtz International Beamline for Extreme Fields (HIBEF) [1] under construction at the HED Instrument of European XFEL [2], or MEC at LCLS [3], holds the promise to revolutionize our understanding of many High Energy Density Physics phenomena. Examples include the relativistic electron generation, transport, and bulk plasma response [4], and ionization dynamics and heating [5] in relativistic laser-matter interactions, or the dynamics of laser-driven shocks, quasi-isentropic compression, and the kinetics of phase transitions at high pressure [3,6]. A particularly promising new technique is the use of coherent X-ray diffraction to characterize electron density correlations [4], and by resonant scattering to characterize the distribution of specific charge-state ions [5], either on the ultrafast time scale of the laser interaction, or associated with hydrodynamic motion. As well one can image slight density changes arising from phase transitions inside of shock-compressed high pressure matter. The feasibility of coherent diffraction techniques in laser-driven matter will be discussed. including recent results from demonstration experiments at MEC. Among other things, very sharp density changes from laser-driven compression are observed, having an effective step width of 10 nm or smaller. This compares to a resolution of several hundred
nm achieved previously [6] with phase contrast imaging.
[1] www.hibef.eu
[2] www.xfel.eu/research/instruments/hed
[3] B. Nagler et al., J. Synchrotron Rad. 22, 520 (2015).
[4] T. Kluge et al, Phys. Plasmas 21, 033110 (2014).
[5] T. Kluge et al., http://arxiv.org/abs/1508.03988
[6] A. Schropp et al., Sci. Rep. 3, 1633 (2013).

Author T. Kluge on behalf of HIBEF User Consortium, for the Helmholtz International Beamline for Extreme Fields at the European XFEL.
  • Invited lecture (Conferences)
    57th Annual Meeting of the APS Division of Plasma Physics, 16.-20.11.2015, Savannah, GA, USA
Registration No. 23148 - Permalink

Proton and electron Irradiation in oxynitrided gate 4H-SiC MOSFET: A recent open issue
Michel, P.; Florentin, M.; Alexandru, M.; Constant, A.; Monserrat, J.; Millan, J.; Godignon, P.
Abstract: Long-term degradation of MOS devices has to be avoided in different harsh irradiated environments, especially for aerospace or military applications. In this paper, an overview of the irradiation experiments recently performed on 4H-SiC MOSFETs having an oxynitrided gate oxide is given, with a special focus on the threshold voltage and the effective channel mobility drifts. The general mechanisms taking place during irradiation and post-annealing treatments are described. Finally, new open issues recently observed by performing the temperature measurement on irradiated MOSFETs are introduced and discussed.
Keywords: Charge trapping; Electron; Irradiation; Mobility; Proton; SiC MOSFET; SiO2/SiC interface; Threshold voltage; Time bias stress instability Registration No. 23146 - Permalink

PET imaging for the monitoring of particle therapy: from GSI experience to new developments
Rohling, H.
Abstract: History and current challenges of PET for particle therapy with the focus on GSI experiences.
  • Invited lecture (Conferences)
    Arbeitstreffen Kernphysik, 19.-26.02.2015, Schleching / Oberbayern, Deutschland
Registration No. 23145 - Permalink

Aqueous chemistry of tetravalent cerium (Ce(IV)): Characterisation of polymer and cluster complexes formed via hydrolysis
Ikeda-Ohno, A.
Abstract: Because of their high charge density, the aqueous chemistry of f-elements with lower valences (i.e. tri- and tetravalent) is predominantly controlled by strong hydrolysis producing a variety of hydroxide species. Interestingly enough, this strong hydrolysis often induces the intrinsic formation of polymer and nano-sized cluster complexes which are stable even in aqueous solutions. This talk will provide a recent overview of the hydrolysis-induced polymer/cluster formation of tetravalent f-elements, with a special focus on tetravalent cerium (Ce(IV)), primarily from the viewpoint of structural chemistry, as well as the associated characterisation techniques (e.g. X-ray absorption spectroscopy or X-ray scattering).
Keywords: Actinides, lanthanides, f-elements, tetravalent, aqueous chemistry, hydrolysis, characterisation, X-ray, synchrotron
  • Invited lecture (Conferences)
    Internal Scientific Seminar at Joint Research Centre - Institute for Transuranium Elements, 02.02.2016, JRC-ITU, Karlsruhe, Germany
Registration No. 23144 - Permalink

Broadband(UV-VIS), Single-shot spectometer for fs electron bunches
Zarini, O.; Debus, A.; Köhler, A.; Couperus, J. P.; Seidel, W.; Irman, A.; Schramm, U.
Abstract: Broadband(UV-VIS), Single-shot spectometer for fs electron bunches is presented.
Keywords: Broadband(UV-VIS), Single-shot spectometer, electron bunch
  • Lecture (Conference)
    The 4.annual meeting of the LAOLA collaboration, 23.-24.06.2015, Wismer, Deutschland
Registration No. 23143 - Permalink

Broadband (UV - mid-IR) spectrometer for single-shot femtosecond electron bunch duration measurement
Zarini, O.; Debus, A.; Couperus, J. P.; Köhler, A.; Jochmann, A.; Seidel, W.; Irman, A.; Schramm, U.
Abstract: Measurement of coherent transition radiation (CTR) spectra of ultrashort electron bunches from LWFA by using a high-resolution, broadband spectrometer for single-shot bunch duration measurements.
Keywords: broadband spectrometer, Single-shot bunch length measurement, coherent transition radiation, absolute calibration
  • Poster
    3rd ARD ST3 workshop, 15.-17.07.2015, Karlsruhe, Deutschland
Registration No. 23142 - Permalink

Studies of a Proton Phase Beam Monitor for Range Verification in Proton Therapy
Werner, T.; Dreyer, A.; Golnik, C.; Hueso-Gonzalez, F.; Enghardt, W.; Straessner, A.; Petzoldt, J.; Roemer, K.; Pausch, G.; Kormoll, T.
Abstract: A primary subject of the present research in particle therapy is to ensure the precise irradiation of the target volume. The prompt gamma timing (PGT) method provides one possibility for in vivo range verification during the irradiation of patients. Prompt gamma rays with high energies are emitted promptly due to nuclear reactions of protons with tissue. The arrival time of these gammas to the detector reflects the stopping process of the primary protons in tissue and are directly correlated to the range. Due to the time resolution of the detector and the proton bunch time spread, as well as drifts of the bunch phase with respect to the accelerator frequency, timing spectra are smeared out and compromise the accuracy of range information intended for future clinical applications. Nevertheless, counteracting this limitation and recovering range information from the PGT measured spectra, corrections using a phase beam monitor can be performed. A first prototype of phase beam monitor was tested at GSI Darmstadt, where measurements of the energy profile of the ion bunches were performed. At the ELBE accelerator Helmholtz-Zentrum Dresden-Rossendorf (HZDR), set up to provide bremsstrahlung photons in very short pulses, a constant fraction algorithm for the incoming digital signals was evaluated, which is for optimizing the time resolution. Studies of scattering experiments with different thin targets and detector positions are accomplished at Oncoray Dresden, where a clinical proton beam is available. These experiments allow a basic characterization of the proton bunch structure and the detected yield.
Keywords: Range Verification, Proton Therapy
  • Lecture (Conference)
    ANIMMA 2015, 20.-24.04.2015, Lisboa, Portugal
Registration No. 23141 - Permalink

Measurements of the Time Spread of Proton Pencil Beams at a Clinical Therapy Facility
Petzoldt, J.; Roemer, K. E.; Kormoll, T.; Enghardt, W.; Fiedler, F.; Helmbrecht, S.; Hueso-González, F.; Golnik, C.; Rohling, H.; Werner, T.; Pausch, G.
Abstract: In proton therapy, high dose conformality and the finite range of the projectiles are exploited to reduce the dosage to healthy tissue while increasing the dose inside the tumor volume compared to conventional radiotherapy. However, those benefits can be diminished by range uncertainties. An online range verification and in-vivo dosimetry is therefore highly desired.
The prompt gamma ray timing (PGT) method utilizes the detection time of high energetic photons emitted during treatment. The time distribution of the gamma rays contains essential information about the range of the protons. However, PGT spectra are smeared by the time spread of the proton bunches. Knowledge about this time spread would help to disentangle the PGT data and to give better input parameters to simulation procedures.
At the UniversitaetsProtonenTherapieDresden (Dresden, Germany), a dedicated experiment was realized to measure the time spread of a clinical proton pencil beam created by a Cyclone 230 fixed energy cyclotron from Ion Beam Applications. Two phoswich detectors each made out of plastic scintillator and BGO were placed under 90 degrees to detect coincident protons originating from elastic pp-scattering at a thin slice of PMMA. The time spread was measured for incident proton energies between 70 MeV and 225 MeV as well as for several positions of the momentum limiting slits of the energy selection system. Additionally, the absolute transmission of protons from point of extraction to beam exit was determined.
Summarizing, the measured data will help to create reasonable range verification procedures using the PGT method in clinical routine.

Keywords: proton therapy, prompt gamma ray timing
  • Lecture (Conference)
    2015 IEEE Nuclear Science Symposium & Medical Imaging Conference, 31.10.-07.11.2015, San Diego, USA
Registration No. 23140 - Permalink

Determination of the carrier envelope phase for short, circularly polarized laser pulses
Titov, A. I.; Kämpfer, B.; Hosaka, A.; Nousch, T.; Seipt, D.
Abstract: We analyze the impact of the carrier envelope phase on the differential cross sections of the Breit-Wheeler and the generalized Compton scattering in the interaction of a charged electron (positron) with an intensive ultra-short electromagnetic (laser) pulse. The differential cross sections as a function of the azimuthal angle of the outgoing electron have a clear bump structure, where the bump position coincides with the value of the carrier phase. This effect can be used for the carrier envelope phase determination.

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Registration No. 23138 - Permalink

Quantum processes in short and intensive electromagnetic fields
Titov, A. I.; Kämpfer, B.; Hosaka, A.; Takabe, H.
Abstract: This work provides an overview of our recent results in studying two most important and widely discussed quantum processes: electron-positron pairs production off a probe photon propagating through a polarized short-pulsed electromagnetic (e.g.\ laser) wave field or generalized Breit-Wheeler process, and a single a photon emission off an electron interacting with the laser pules, so-called non-linear Compton scattering. We show that the probabilities of particle production in both processes are determined by interplay of two dynamical effects, where the first one is related to the shape and duration of the pulse and the second one is non-linear dynamics of the interaction of charged fermions with a strong electromagnetic field. We elaborate suitable expressions for the production probabilities and cross sections, convenient for studying evolution of the plasma in presence of strong electromagnetic fields. Registration No. 23137 - Permalink

Strange hadron production at SIS energies: an update from HADES
Lorenz, M.; Adamczewski-Musch, J.; Arnold, O.; Atomssa, E. T.; Behnke, C.; Berger-Chen, J. C.; Biernat, J.; Blanco, A.; Blume, C.; Böhmer, M.; Bordalo, P.; Chernenko, S.; Deveaux, C.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Fonte, P.; Franco, C.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzon, J. A.; Gill, K.; Golubeva, M.; Guber, F.; Gumberidze, M.; Harabasz, S.; Hennino, T.; Hlavac, S.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Karavicheva, T.; Kardan, B.; Koenig, I.; Koenig, W.; Kolb, B. W.; Korcy, G.; Kornakov, G.; Kotte, R.; Krasa, A.; Krebs, E.; Kuc, H.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Mahmoud, T.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michel, J.; Müntz, C.; Münzer, R.; Naumann, L.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petousis, V.; Pietraszko, J.; Przygoda, W.; Ramstein, B.; Rehnisch, L.; Reshetin, A.; Rost, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schmidt-Sommerfeld, K.; Schuldes, H.; Sellheim8, P.; Siebenson, J.; Silva, L.; Sobolev, Yu. G.; Spataro, S.; Ströbele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Tsertos, H.; Vasiliev, T.; Wagner, V.; Wendisch, C.; Wirth, J.; Wüstenfeld, J.; Zanevsky, Y.; Zumbruch, P.
Abstract: We present and discuss recent experimental activities of the HADES collaboration on open and hidden strangeness production close or below the elementary NN threshold. Special emphasis is put on the feed-down from φ mesons to antikaons, the presence of the Ξ- excess in cold nuclear matter and the comparison of statistical model rates to elementary p+p data. The implications for the interpretation of heavy-ion data are discussed as well.

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Registration No. 23136 - Permalink

RF-bunching of relativistic 12 C 3+ ion beam for laser cooling experiment at the CSRe
Wang, H. B.; Wen, W. Q.; Ma, X.; Huang, Z. K.; Zhang, D. C.; Bussmann, M.; Winters, D. F. A.; Yuan, Y. J.; Zhu, X. L.; Zhao, D. M.; Mao, R. S.; Li, J.; Mao, L. J.; Yang, J. C.; Zhao, H. W.; Xu, H. S.; Xiao, G. Q.; Xia, J. W.
Abstract: To prepare the upcoming experiment of laser cooling of relativistic 12 C 3+ ion beams at the experimental cooler storage ring (CSRe), a test experiment was performed with 12 C 3+ ion beams at an energy of 122 MeV/u on the CSRe, at the Institute of Modern Physics, Lanzhou, China. In this experiment, the main storage ring of CSRm was employed to accumulate and accelerate the ion beam which was injected into the CSRe for the experiments. The number of 12 C 3+ ions at the CSRe reached 5×10 8 for every injection, which satisfied the experimental requirement. To fulfil the laser cooling experiment, the 12 C 3+ ion beams were bunched by sinusoidal waveforms with fixed and sweeping frequencies, respectively. A resonant Schottky pick-up was employed to record the Schottky spectra of these ion beams. The test experimental results demonstrated that the RF-buncher and diagnostic systems at the CSRe worked well and the CSRe was very stable with 12 C 3+ ion beams, hereby the CSRe is suitable for laser cooling experiment.
Keywords: rf bunching, relativistic, ion beam, storage ring, dynamics

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Registration No. 23135 - Permalink

Broadband(UV- mid-IR) spectrometer for single-shot femtosecond electron bunch measurement first experiment @ HZDR
Zarini, O.; Debus, A.; Couperus, J. P.; Köhler, A.; Jochmann, A.; Irman, A.; Schramm, U.
Abstract: Laser-wakefield accelerators (LWFA) feature electron bunch durations ranging from several fs to tens of fs. Precise knowledge of the longitudinal profile of such ultra-short electron bunches is essential for the design of future table-top Xray light-sources and remains a big challenge due to the resolution limit of existing diagnostic techniques.
Measurement of broadband coherent and incoherent transition radiation produced when LWFA electron bunches pass a metal foil is a promising way to analyze longitudinal characteristics of these bunches.
Because of the limited reproducibility due to the nonlinear nature of the electron source this characterization requires single-shot capability.
Our ultra-broadband spectrometer combines the TR spectrum in UV/VIS (200-1000nm), NIR (0.9-1.7µm) and mid-IR (1.6-12µm). A high spectral sensitivity, dynamic bandwidth and spectral resolution are realized by three optimized dispersion and detection systems to a single-shot spectrometer.
A complete characterization and calibration of the spectrometer has been done with regard to wavelengths, relative spectral sensitivities and absolute photometric sensitivity, also taking into account for the light polarization.
Our spectrometer is able to characterize electron bunches with charges as low as 1 pC and resolve time-scales from 0.7 to 40 fs.

Keywords: Broadband spectrometer, coherent transition radiation, electron bunch duration, longitudinal profile, absolute calibration
  • Lecture (Conference)
    2nd European Advanced Accelerator Concepts Workshop (EAAC), 13.-19.09.2015, La Biodola, Isola d'Elba, Italien
  • Lecture (Conference)
    DoKDoK 2015, 10.-15.10.2015, Eisenach, Deutschland
Registration No. 23134 - Permalink

5-Chloro-1-phenylpentan-1-one
Bechmann, N.; Kniess, T.; Pietzsch, J.; König, J.; Köckerling, M.
Abstract: kein Abstract verfügbar
Keywords: crystal structure; d-chlorobutyl; phenyl ketone; hyrogen bonding

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Registration No. 23133 - Permalink

Dynamics of bulk electron heating and ionization in solid plasmas driven by ultra-short relativistic laser pulses
Huang, L. G.; Kluge, T.; Bussmann, M.; Chung, H. K.; Cowan, T. E.
Abstract: We investigate the dynamics of bulk electron heating and ionization in solid density plasmas driven by ultra-short relativistic laser pulses. During laser-plasma interactions, the solid plasma absorbs a fraction of laser energy and converts it into kinetic energy of electrons. A part of the electrons with high kinetic energy travels through the solid plasma and transfers energy into bulk electrons, which results in bulk electron heating by return current. The bulk electron temperatures in the interest of bulk region agrees very well with the theory based on Ohmic heating mechanism by treating the return current correctly. The bulk electron heating is finally translated into bulk ionization dynamics, which is modeled by Thomas-Fermi ionization mechanism in our studies.
Keywords: bulk heating, ionization, high power laser, solid plasmas
  • Poster
    Novel Light Sources from Laser-Plasma Interactions, 20.-24.04.2015, Dresden, Germany
Registration No. 23131 - Permalink

Scintillator-Based High-Throughput Fast Timing Spectroscopy for Real-Time Range Verification in Particle Therapy
Pausch, G.; Petzoldt, J.; Berthel, M.; Enghardt, W.; Fiedler, F.; Golnik, C.; Hueso-González, F.; Lentering, R.; Römer, K.; Ruhnau, K.; Stein, J.; Wolf, A.; Kormoll, T.
Abstract: Range verification of particle beams in real time is considered a key for tapping the full potential of radiooncological particle therapies. The novel technique of prompt gamma-ray timing (PGT), recently proposed and explored in first proof-of-principle experiments, promises range assessment at reasonable expense but challenges detectors, electronics, and data acquisition. Energy-selected time distributions have to be measured at very high throughput rates to obtain the statistics necessary for range verification with single pencil beam spots. Clinically applicable systems should provide a time resolution of about 200 ps, to be obtained with large (about 2” diameter) scintillators, detector loads in the few-Mcps range, and data acquisition rates around 1 Mcps, if possible with compact and inexpensive systems. Such requirements can be met best with CeBr3 scintillators read out with conventional photomultiplier tubes, coupled to commercial but customized electronics featuring high-resolution pulse digitization and fast digital signal processing. The paper deduces design parameters from the constraints given by typical treatment conditions, and presents first results obtained with prototype detectors and electronics developed in accordance with the derived specifications.
Keywords: Hadron therapy, proton beams, range monitoring, gamma rays, gamma-ray spectroscopy, gamma ray detectors, fast timing, inorganic scintillators, cerium bromide, photomultipliers, digital signal processing, medical applications
  • Lecture (Conference)
    13th International Conference on Scintillators and their Applications (SCINT), 07.-12.06.2015, Berkeley, USA
Registration No. 23130 - Permalink
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