A5010683515- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Nuclear physics research studies
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- Advanced NMR Techniques and Applications
- Atomic and Subatomic Physics Research
- Particle Detector Development and Performance
- Radiation Detection and Scintillator Technologies
- Quantum, superfluid, helium dynamics
- Nuclear reactor physics and engineering
- Astronomical and nuclear sciences
- Dark Matter and Cosmic Phenomena
- Advanced Chemical Physics Studies
- Superconducting Materials and Applications
- Cold Atom Physics and Bose-Einstein Condensates
- X-ray Spectroscopy and Fluorescence Analysis
- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Medical Imaging Techniques and Applications
- Nuclear Materials and Properties
- Electron and X-Ray Spectroscopy Techniques
- Crystallography and Radiation Phenomena
- Radioactive Decay and Measurement Techniques
Justus-Liebig-Universität Gießen
2015-2024
Giessen School of Theology
2009-2024
GSI Helmholtz Centre for Heavy Ion Research
1994-2023
University of Groningen
2023
Joint Institute for Nuclear Research
2004-2021
Florida State University
2007-2020
Institute of Physics of the Slovak Academy of Sciences
2018-2019
Slovak Academy of Sciences
2018-2019
Johannes Gutenberg University Mainz
2018
University of Bonn
2007-2017
Information on the size and shape of neutron skin (208)Pb is extracted from coherent pion photoproduction cross sections measured using Crystal Ball detector together with Glasgow tagger at MAMI electron beam facility. On exploitation an interpolated fit a theoretical model to sections, half-height radius diffuseness distribution are found be c(n)=6.70±0.03(stat.) fm a(n)=0.55±0.01(stat.)(-0.03)(+0.02)(sys.) fm, respectively, corresponding thickness...
We have measured precise total and differential cross sections for the reaction $\ensuremath{\gamma}p\ensuremath{\rightarrow}p\ensuremath{\eta}$ from threshold to 790 MeV at MAMI accelerator in Mainz with neutral meson spectrometer TAPS. Resonance parameters of ${S}_{11}$(1535) resonance electromagnetic coupling $\ensuremath{\gamma}p\ensuremath{\rightarrow}{S}_{11}$ been extracted data. Contributions ${D}_{13}$(1520) $\ensuremath{\eta}$ photoproduction region identified first time via...
The photoproduction of $\ensuremath{\omega}$ mesons on nuclei has been investigated using the Crystal Barrel/TAPS experiment at ELSA tagged photon facility in Bonn. aim is to study possible in-medium modifications meson via reaction $\ensuremath{\gamma}+A\ensuremath{\rightarrow}\ensuremath{\omega}+X\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}+{X}^{\ensuremath{'}}$. Results obtained for Nb are compared a reference measurement ${\mathrm{LH}}_{2}$ target. While recoiling,...
We present phase space distributions and multiplicities of K+, K−, ϕ mesons produced in Ar+KCl reactions at a kinetic beam energy 1.756 GeV/nucleon measured with the HADES spectrometer. The inverse slope parameters yields kaons supplement systematics previous measurements. percentage K− coming from decay is found to be 18±7%.6 MoreReceived 9 March 2009DOI:https://doi.org/10.1103/PhysRevC.80.025209©2009 American Physical Society
We present transverse momentum spectra, rapidity distribution and multiplicity of $ \Lambda$ -hyperons measured with the HADES spectrometer in reaction Ar(1.76AGeV) + KCl . The yield \Xi^{{-}}_{}$ is calculated from our previously reported /( \Sigma^{{0}}_{}$ ) ratio compared to other strange particle multiplicities. Employing a strangeness balance equation multiplicities yet unmeasured \Sigma^{{\pm}}_{}$ can be estimated. Finally statistical hadronization model used fit yields \pi^{-}_{}$ ,...
We report first results on a deep subthreshold production of the doubly strange hyperon Xi;{-} in heavy-ion reaction. At beam energy 1.76A GeV reaction Ar + KCl was studied with High Acceptance Di-Electron Spectrometer at SIS18/GSI. A high-statistics and high-purity Lambda sample collected, allowing for investigation decay channel --> Lambdapi;{-}. The deduced Xi;{-}/(Lambda Sigma;{0}) ratio (5.6 +/- 1.2_{-1.7};{+1.8}) x 10;{-3} is significantly larger than available model predictions.
We present a search for the e+e− decay of hypothetical dark photon, also named U vector boson, in inclusive dielectron spectra measured by HADES p(3.5 GeV) + p, Nb reactions, as well Ar (1.756 GeV/u) KCl reaction. An upper limit on kinetic mixing parameter squared ϵ2 at 90% CL has been obtained mass range MU=0.02–0.55 GeV/c2 and is compared with world data set. For masses 0.03–0.1 GeV/c2, lowered respect to previous results, allowing now exclude large part region favored muon g−2 anomaly....
We present an analysis of proton number fluctuations in $\sqrt{s_{NN}}$ = 2.4 GeV Au+Au collisions measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI. With help extensive detector simulations done IQMD transport model events including nuclear clusters, various nuisance effects influencing observed cumulants have been investigated. Acceptance and efficiency corrections applied as a function fine grained rapidity transverse momentum bins, well considering local track...
The photoproduction of η-mesic 3He has been investigated using the TAPS calorimeter at Mainz Microtron accelerator facility MAMI. total inclusive cross section for reaction γ3He→ηX measured photon energies from threshold to 820 MeV. and angular differential coherent η sections have extracted up 745 A resonancelike structure just above production with an isotropic distribution suggests existence a resonant quasibound state. This is supported by studies competing decay channel such nucleus...
The photon decay of the relativistic Coulomb excitation single and double giant dipole resonance (GDR) in target has been observed system 1A GeV $^{209}\mathrm{Bi}$ on $^{208}\mathrm{Pb}$. For peripheral events which are dominated by excitation, a large Lorentzian structure energy spectrum is peaked at 13.3\ifmmode\pm\else\textpm\fi{}0.1 MeV with width 4.1\ifmmode\pm\else\textpm\fi{}0.1 MeV, corresponding to GDR $^{208}\mathrm{Pb}$ target. sum coincident...
Differential and absolute cross sections for the reaction p(\ensuremath{\gamma},${\mathrm{\ensuremath{\pi}}}^{0}$) have been measured with energy-defined photons in threshold region (${\mathit{E}}_{\ensuremath{\gamma}}$=131.4--157.2 MeV). The ${\mathit{E}}_{0+}$ amplitude has extracted out of data. values found are disagreement predictions low-energy theorems.
The invariant-mass spectrum of $e^+ e^-$ pairs produced in $^{12}$C+$^{12}$C collisions at an incident energy 2 GeV per nucleon has been measured for the first time. pair production probabilities span over five orders magnitude from $\pi^0$-Dalitz to $\rho/\omega$ region. Dalitz decays $\pi^0$ and $\eta$ account all yield up 0.15 GeV/c$^2$, but only about 50% above this mass. A comparison with model calculations shows that excess is likely due baryon-resonance vector-meson decays. Transport...
We review the current status of theories and experiments aiming at an understanding a determination properties light vector scalar mesons inside strongly interacting hadronic matter. Starting from discussion relevant symmetries QCD their connection with description through sum rules we then discuss models used to calculate in-medium self-energies hadrons spectral functions. The difficulties link these calculated actual observables are emphasized. Finally, in detail all running searching for...
The gp-->etap reaction has been measured with the Crystal Ball and TAPS multiphoton spectrometers in energy range from production threshold of 707 MeV to 1.4 GeV (1.49 =< W >= 1.87 GeV). Bremsstrahlung photons produced by 1.5-GeV electron beam Mainz Microtron MAMI-C momentum analyzed Glasgow Tagging Spectrometer were used for eta-meson production. Our accumulation 3.8 x 10^6 gp-->etap-->3pi0p-->6gp events allows a detailed study dynamics. differential cross sections determined 120 bins full...
Total and differential cross sections for η η′photoproduction off the proton have been determined with CBELSA/TAPS detector photon energies between 0.85 2.55 GeV. The mesons are detected in their two neutral decay modes, η→γγ η→3π0→6γ, first time, cover full angular range cosθc.m. of meson. These new photoproduction data consistent earlier CB-ELSA results. η′ observed to π0π0η→6γ also extend coverage range.8 MoreReceived 8 September 2009DOI:https://doi.org/10.1103/PhysRevC.80.055202©2009...
We present the transverse momentum spectra and rapidity distributions of ${\ensuremath{\pi}}^{\ensuremath{-}}$ ${\mathrm{K}}_{S}^{0}$ in Ar $+$ KCl reactions at a beam kinetic energy $1.756$ $A$ GeV measured with High Acceptance Di-Electron Spectrometer (HADES). The reconstructed sample is characterized by good event statistics for wide range rapidity. compare experimental to predictions Isospin Quantum Molecular Dynamics (IQMD) model. model calculations show that low momenta constitute...
Information on hadron properties in the nuclear medium has been derived from photoproduction of $\ensuremath{\omega}$ mesons nuclei C, Ca, Nb, and Pb using Crystal Barrel/TAPS detector at ELSA tagged photon facility Bonn. The dependence $\ensuremath{\omega}$-meson cross section mass number compared with three different types models: a Glauber analysis, Boltzmann-Uehling-Uhlenbeck analysis Giessen theory group, calculation by Valencia group. In all cases, inelastic width is found to be...
Quasifree photoproduction of eta mesons off nucleons bound in the deuteron has been measured with CBELSA/TAPS detector for incident photon energies up to 2.5 GeV at Bonn ELSA accelerator. The have detected coincidence recoil protons and neutrons, which allows a detailed comparison quasifree n(gamma,eta)n p(gamma,eta)p reactions. excitation function production neutron shows pronounced bumplike structure W=1.68 (E{gamma} approximately 1 GeV), is absent proton.