Meiko Volknandt
A5081742983- Nuclear Physics and Applications
- Nuclear physics research studies
- Nuclear reactor physics and engineering
- Radiation Detection and Scintillator Technologies
- Atomic and Molecular Physics
- Astronomical and nuclear sciences
- Radiation Therapy and Dosimetry
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced NMR Techniques and Applications
- Atomic and Subatomic Physics Research
- Astro and Planetary Science
- Medical Imaging Techniques and Applications
- Quantum Chromodynamics and Particle Interactions
- Electromagnetic Compatibility and Measurements
- Radiopharmaceutical Chemistry and Applications
- Advanced Chemical Physics Studies
- Mass Spectrometry Techniques and Applications
- International Science and Diplomacy
- Electron and X-Ray Spectroscopy Techniques
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Medical Imaging and Pathology Studies
- Superconducting Materials and Applications
- Particle Detector Development and Performance
- Muon and positron interactions and applications
Goethe University Frankfurt
2016-2025
Institute of Space Science - INFLPR Subsidiary
2021
GSI Helmholtz Centre for Heavy Ion Research
2020
We report the first measurement of low-energy proton-capture cross sections $^{124}\mathrm{Xe}$ in a heavy-ion storage ring. ${^{124}\mathrm{Xe}}^{54+}$ ions five different beam energies between 5.5 and 8 AMeV were stored to collide with windowless hydrogen target. The $^{125}\mathrm{Cs}$ reaction products directly detected. interaction are located on high energy tail Gamow window for hot, explosive scenarios such as supernovae x-ray binaries. results serve an important test predicted...
NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility Antiproton and Ion Research). detects neutrons energies from 100 to 1000 MeV, featuring a high detection efficiency, spatial time resolution, large multi-neutron reconstruction efficiency. This achieved by highly granular design of organic scintillators: 3000 individual submodules size 5 × 250 cm3 are arranged in 30 double...
We report the application of new elimination Rutherford elastic scattering technique for measurement proton-induced reaction cross sections utilizing stored ions decelerated to astrophysical energies. This approach results in a background reduction factor about 1 order magnitude, enabling first (p, n) section storage ring. Here, channels ^{124}Xe(p,n) and ^{124}Xe(p,γ) have been studied just above neutron threshold energy. The data provide valuable constraints Hauser-Feshbach theory...
The electron capture process was studied for Xe$^{54+}$ colliding with H$_2$ molecules at the internal gas target of ESR storage ring GSI, Darmstadt. Cross section values into excited projectile states were deduced from observed emission cross Lyman radiation, being emitted by hydrogen-like ions subsequent to a electron. ion beam energy range varied between 5.5 MeV/u and 30.9 applying deceleration mode ESR. Thus, data recorded intermediate in particular low collision regime, well below...
Abstract We present the design, prototype developments and test results of new time-of-flight detector (ToFD) which is part R $$^3$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow/> <mml:mn>3</mml:mn> </mml:msup> </mml:math> B experimental setup at GSI FAIR, Darmstadt, Germany. The ToFD able to detect heavy-ion residues all charges relativistic energies with a relative energy precision $$\sigma _{\varDelta E}/{\varDelta E}$$ <mml:mrow> <mml:msub>...
Activations with neutrons in the keV energy range were routinely performed at Karlsruhe Institute of Technology (KIT) Germany order to simulate stellar conditions for neutron-capture cross sections. A quasi-Maxwell-Boltzmann neutron spectrum kT = 25 keV, being interest astrophysical s-process, was produced by 7 Li(p,n) reaction utilizing a 1912 proton beam Van de Graaff accelerator. Activated samples resulting long-lived nuclear products half-lives yr 100 Myr analyzed Accelerator Mass...
The slow neutron capture process produces heavy elements in different stellar sites at temperatures. Neutron cross sections for temperatures between k B T = 5 keV and 100 are crucial a quantitative understanding of the s-process abundance distribution. Over last decade activation measurements were performed Goethe University Frankfurt to study temperature 25 keV. We developed new method measure 6
Abstract A new detector setup (NICE-detector) based on an organic plastic scintillator is presented. It will be used during experiments measuring neutron-induced reactions with a charged particle in the exit channel. The proposed design was tested at Goethe University Frankfurt. One of test cases capture cross-section 209 Bi different astrophysically important energies, including thermal and resonance integral. This research presents performance setup, as well preliminary results for...
Abstract We measured the Coulomb dissociation of 16 O into 4 He and 12 C at R 3 B setup in a first campaign within FAIR Phase 0 GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve accuracy experimental data for C( α,γ ) fusion reaction reach lower center-ofmass energies than so far. experiment required beam intensities 10 9 ions per second an energy 500 MeV/nucleon. rare case breakup posed another challenge: magnetic rigidities particles are close because same...
The capture cross section of $^{209}$Bi(n,$\gamma$)$^{210g}$Bi was measured at different astrophysically energies including thermal (25 meV), resonance integral, and the Maxwellian averaged a energy $kT$ = 30 keV. partial ($\sigma_g$) determined using activation technique by measuring $^{210}$Po activity. newly developed tested NICE detector setup used to measure $\alpha$-activity $^{210}$Po. Using this integral sections were be $16.2\;\pm\;0.97$~mb $89.81\;\pm\;8.0$~mb, respectively. And...
The 124Xe(p,γ) reaction has been measured for the first time at energies around Gamow window by using stored ions ESR facility. desired beam below 10 MeV/u introduce new experimental challenges like windowless detection under UHV conditions, extremely short lifetimes and efficient deceleration cooling, all of which have successfully met.
The determination of the involved reaction cross sections is essential for understanding how big bang nucleosynthesis and nuclear reactions in stars contribute to observed abundances. One those, which has not been measured so far, 10Be(n,<i>γ<i>) section.
The neutron activation technique is a well established method to measure capture cross sections relevant for the s-process. 7 Li(p,n) reaction at E p = 1912 keV often used as source since energy distribution of emitted neutrons closely resembles Maxwell-Boltzmann spectrum k B T 25 keV, mimicking 22 Ne( α ,n) phase in TP-AGB stars. weak s-process, which takes place massive stars, can reach energies up 90 keV. Neutron spectra corresponding with > cannot be produced by directly. We developed...
Abstract Heavy nuclei are mainly synthesised by a sequence of neutron captures and β -decays. The corresponding energies in the different astrophysical sites range from 1keV to 1MeV. By using activation technique, small capture cross sections can be studied. A sample is irradiated quasi-stellar spectrum order produce radioactive isotopes. decay detected their characteristic gamma rays. For this purpose, sensitive experimental detector equipment needed. Two Broad Energy Germanium Detectors...
Abstract The neutron activation method has been proven to be a well-suited tool for the investigation of capture cross sections relevant main component s-process. Neutrons produced via 7 Li(p,n) Be reaction at proton energy E p = 1912 keV can used recreate quasi-stellar distribution mimicking astrophysical s-process scenario k B T 25keV. For weak s-process, which takes place in massive stars temperatures between 25 and 90 keV, not yet successful recreating spectra. However, simulations show...
The neutron activation method is well-suited to investigate neutron-capture cross sections relevant for the main s-process component. Neutrons can be produced via 7 Li(p,n) reaction with proton energies of 1912 keV at e.g. Van de Graaff accelerators, which results in a quasi-Maxwellian spectrum neutrons corresponding temperature k B T = 25 keV. However, weak takes place massive stars temperatures between and 90 Simulations using PINO code [2] suggest that Maxwellian higher energies, keV,...
About 50% of the elements heavier than iron are produced during slow neutron capture process. This process occurs in different stellar sites at various energies. To understand ongoing nucleosynthesis, probability a for temperatures and therefore is essential. Activation experiments using 7 Li(p,n) reaction as source were performed. At temperature k B T = 25 keV cross sections determined 27 Al, 37 Cl 41 K. A new method was developed to perform activation even lower temperatures. For proof...
To determine the neutron flux in activation experiments, a commonly used monitor is zirconium and particular stable isotopes 94,96Zr. 96Zr very sensitive to epithermal neutrons. Despite its widespread application, most gamma intensities of radioactive capture product, 97Zr, yield large uncertainties. With help new γ spectroscopy setup GEANT simulations, we succeeded determining set γ-ray with significantly reduced