Detector technologies: Experimental nuclear astrophysics and ultrafast timing detectors
Nuclear reactions power our Sun, and they create the chemical elements that are necessary for human life.
We study radiative-capture reactions that are important for astrophysics, in precision experiments: in Dresden using ion beams at the surface of the Earth, in the Felsenkeller shallow underground laboratory, and at LUNA deep underground in the Gran Sasso/Italy. We plan to upgrade the Felsenkeller underground laboratory in Dresden by installing a high-current 5MV accelerator there (local link to 5 MV Pelletron technical page).
- We develop time-of-flight detectors of 0.1 ns time resolution, enabling kinematically complete experiments. To this end we study silicon photomultiplier (SiPM) based readout for a scintillator-based NeuLAND detector. We use the dedicated electron-beam timing detector station at ELBE.
This page shows our ongoing projects and a brief motivation. For more details on the astrophysics, please see our review papers on LUNA and on the nuclear physics of the Sun. Some possible topics for Master's and Bachelor's theses are listed here. Further detailed information is linked through the web page you are reading now!
Hydrogen burning in novae: 22Ne(p,γ)23Na
PhD project Marcell Takács (2013-2016), Diploma project Marie-Luise Menzel (2011-2012, thesis)
22Ne(p,γ)23Na working group coordinator at LUNA: Daniel Bemmerer.
Motivation: The stable nuclide 22Ne plays an important role in astrophysical novae, and in supernovae where it provides neutrons for neutron-capture driven nucleosynthesis. In a hydrogen-rich scenario, 22Ne is mainly destroyed by the 22Ne(p,γ)23Na reaction. Only upper limits exist on the cross section of this reaction at relevant energies.
Experiment at HZDR: The strengths of several resonances in the 0.4-1.2 MeV energy range are redetermined using implanted 22Ne targets and high-purity germanium detectors at the HZDR 3 MV Tandetron.
Experiment at LUNA: The experiment is being performed in two phases, both using windowless gas target systems. The first phase concentrated on the study of selected low-energy resonances using two high-purity germanium detectors and runs from fall 2013 until October 2014. The second phase, using a 4π bismuth germanate summing crystal, will push the lowest energy limit even further down and should start late 2014 / early 2015.
- Eur. Phys. J. A 2014 Cavanna et al.
Nucleosynthesis in supernovae: 40C(α,γ)44Ti and 44Ti(α,p)47V
Master's project Konrad Schmidt (2010-2011, thesis), PhD project Konrad Schmidt (2011-2015, thesis)
Motivation: The radioactive nucleus 44Ti (halflife 60 years) is created in supernovae. Gamma-rays from the decay of 44Ti have been observed in satellite-based observatories. Together with precise nuclear data, the observations can be used to calibrate supernova models.
Experiment at HZDR ion beam center and Felsenkeller: A study of resonance strengths in the 44Ti-producing reaction 40Ca(α,γ)44Ti has recently been concluded. More info on the science here.
Hydrogen burning in our Sun: 14N(p,γ)15O and 15N(p,αγ)12C
PhD project Louis Wagner (2013-2016), B. Sc. thesis Martin Serfling (2014), Diplom theses Louis Wagner (2012-2013) and Stefan Reinicke (2012-2014).
Motivation: The 14N(p,γ)15O reaction controls the rate of the carbon-nitrogen-oxygen (CNO) cycle, first proposed in 1938 by Bethe and Weizsäcker. The CNO rate affects low-energy solar neutrinos (under study at the SNO+ detector in Canada and at the Borexino detector in Italy), carbon stars and last not least the age of our universe. It has attracted recent interest because it may help to directly measure the content of carbon and nitrogen in the solar core.
Study of resonances at HZDR: Improved data on resonance strengths in the 14N(p,γ)15O and 15N(p,αγ)12C have been measured at the HZDR 3 MV Tandetron.
Off-resonance data at HZDR: After some preliminary off-resonance 14N(p,γ)15O data from 2008-2009, two beam times have been performed at the HZDR 3 MV Tandetron to address the cross section in the 0.4-1.5 MeV energy range (January 2013 and March 2014).
Experimental setup at Tandetron.
Experiment at LUNA: The LUNA study of this reaction showed that the CNO rate was only half the previously accepted value:
- Phys. Lett. B 2004 Formicola et al.
- Astron. Astrophys. 2004 Imbriani et al.
- Phys. Lett. B 2006 Lemut et al.
- Nucl. Phys. A 2006 Bemmerer et al.
- Phys. Rev. C 2008 Marta et al.
- Phys. Rev. C 2011 Marta et al.
Experiment at Agata demonstrator Legnaro/Italy: The lifetime of the exited state at 6.79 MeV in 15O is studied by the Doppler shift attenuation method (collaboration with INFN Padova and GANIL Caen/France).
Hydrogen burning out of equilibrium: 12C(p,γ)13N reaction in inverse kinematics
PhD project Tobias Reinhardt (2012-2015), Diplom project Klaus Stöckel (2014-2015)
Motivation: In the outer and cooler parts of the solar core, the CNO cycle is not yet in equilibrium, and its onset is controlled by the 12C(p,γ)13N reaction. Furthermore, this reaction controls the production of 13C (decay product of radioactive 13N). 13C, in turn, fuels the neutron source reaction 13C(α,n)16O that creates heavy chemical elements in the astrophysical s-process. The last comprehensive experiment on this reaction dates back to the 1970s, and precise new data is needed.
Experiment at HZDR: The reaction is studied in inverse kinematics, using intensive 12C beam from the HZDR 3 MV Tandetron accelerator and solid hydrogen targets.
SiPM-based photosensors for fast scintillator readout, motivated by NeuLAND @ FAIR
PhD projects Tobias Reinhardt (2012-2015) and Stefan Reinicke (2014-2017); Diplom project Stefan Gohl (2013-2014)
We are developing ultrafast timing detectors for research. The scientific motivation for our work is to study astrophysically important nuclear reactions at the R3B experiment. R3B is part of the NuSTAR branch of FAIR, the future accelerator complex under construction at GSI Darmstadt.
For scintillator-based time-of-flight detectors like NeuLAND @ FAIR, it is necessary to read out the scintillating light with high resolution. This is traditionally done with timing photomultipliers, which are however costly and need to be replaced from time to time. Currently there is a large industry effort to develop so-called silicon photomultipliers (SiPM's) as new photosensors.r facility at Darmstadt/Germany. Our development work flows into the NeuLAND neutron time-of-flight detector at R3B. NeuLAND is currently under construction and will in its final shape consist of a fully active setup of 250 x 250 x 300cm of plastic RP408 scintillators.
We are currently studying how and which SiPMs can be used to read out the NeuLAND bars.
The image shows our detector test station at the ELBE 40 MeV electron accelerator, where we can test timing devices of 2 m size and more (in the image, our 2 m x 0.5 m MRPC prototype for NeuLAND).
Technical experiment pages (password protected)
- Tandetron electronic logbooks: 40Ca(α,γ)44Ti ELOG, 14N(p,γ)15O ELOG, 12C(p,γ)13N ELOG, feasibility study 44Ti(α,p)47V ELOG
- ELBE electronic logbooks: NeuLAND, NEDENSAA, and GSI ELOG
- NeuLAND data acquisition manual, RIO type III and type IV (FPGA version 2.4; by Mathias Kempe)
- Electronics list and scaler+QDC+TDC channels (FPGA version; by Mathias Kempe)
People, astrophysics and detector development
- PD Dr. Daniel Bemmerer
- Dr. Francesca Cavanna (postdoc, six-month DAAD fellowship)
- Dr. rer. nat. Marko Röder (postdoc: NeuLAND detector and 20,21N(γ,n)20,19N at GSI)
- Dr. Tamás Szücs (postdoc, NAVI)
- Dipl.-Phys. Tobias Reinhardt (PhD student, TU Dresden, NEDENSAA: SiPMs for NeuLAND and 12C(p,γ)13N)
- Dipl.-Phys. Stefan Reinicke (PhD student, DTSP: SiPMs for NeuLAND and astrophysics)
- M. Sc. Marcell Takács (PhD student, NAVI: 22Ne(p,γ)23Na at HZDR and at LUNA and 3He(α,γ)7Be data evaluation)
- Dipl.-Phys. Louis Wagner (PhD student, NAVI: 14N(p,γ)15O)
- cand. phys. Marcel Grieger (Master's student: Monte Carlo simulations of neutron transport in Felsenkeller)
- Ferdinand Rath (Bachelor's student: Radio frequency ion source for Felsenkeller)
People, detector development
- Dr. Andreas Wagner (HZDR)
- Dipl.-Ing. (FH) Klaus Heidel (HZDR)
- Dipl.-Ing. (FH) Daniel Stach (HZDR)
- M. Sc. David Weinberger (HZDR)
- LUNA collaboration
- NAVI, Helmholtz Association Nuclear Astrophysics Virtual Institute
- EuroGENESIS MASCHE (associated project, jointly with K. Zuber / TU Dresden)
- TU Dresden: K. Zuber
- VKTA Dresden: M. Köhler, D. Degering (low-level γ-counting in Felsenkeller shallow-underground laboratory)
- ATOMKI, Debrecen/Hungary: Zs. Fülöp, Gy. Gyürky, T. Szücs
- INFN Padua/Italy: C. Broggini, A. Caciolli, R. Menegazzo, R. Depalo
- Hashemite University, Zarqa/Jordan (DFG incoming fellowship for Prof. Dr. Tariq Al-Abdullah)
- Paul-Scherrer-Institut, Switzerland: D. Schumann, R. Dressler (long-lived radioisotopes for astrophysics)
- Helmholtz Detector Technology and Systems Platform (DTSP)
- NEDENSAA collaboration: INFN Italy, CIEMAT and IFIC Spain, CNRS/IN2P3 and CEA/DRT/LIST/DCSI/LCAE France, University of Jyväskylä Finland, ATOMKI Hungary, Institute for Nuclear Research and Nuclear Energy (INRNE) Bulgaria, Uppsala University Sweden, TÜBİTAK Turkey
- GSI Darmstadt: T. Aumann (TU Darmstadt), K. Boretzky, M. Heil
- Uni Köln: M. Elvers, V. Maroussov, A. Zilges
- SINP Kolkata/India: U. Datta Pramanik
Financial support (ongoing; see history page for concluded projects)
- Helmholtz Association, partner in NAVI (Nuclear Astrophysics Virtual Institute, 2011-2016)
- NupNET NEDENSAA (TU Dresden, Prof. T. Cowan, 2012-2015)
- GSI FuE DR-ZUBE (TU Dresden, Prof. K. Zuber, 2014-2016)
- DAAD, six-month fellowship for Dr. Francesca Cavanna (2015)
- INFN Italy, Fondo Affari Internazionali (2009-2014)
- TU Dresden, Graduiertenakademie (4-month scholarship for Konrad Schmidt, 2014)
- Recent papers and talks (links to HZDR library).
- List of completed, ongoing, and possible future PhD, Diploma, Master's, and Bachelor's theses.
- History page, showing past and recently finished projects and alumni.
- List of past experiments.
- Description of the dedicated electron-beam timing detector station at ELBE.
- Nuclear Astrophysics Meetings (local access only).
- Felsenkeller Pelletron technical page (local access only).