H. Schmieden
A5106031185- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Nuclear physics research studies
- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Quantum, superfluid, helium dynamics
- Advanced NMR Techniques and Applications
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Atomic and Molecular Physics
- Scientific Research and Discoveries
- Dark Matter and Cosmic Phenomena
- Advanced Chemical Physics Studies
- Medical Imaging Techniques and Applications
- Particle Detector Development and Performance
- X-ray Spectroscopy and Fluorescence Analysis
- Radiation Detection and Scintillator Technologies
- Computational Physics and Python Applications
- Particle accelerators and beam dynamics
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Advanced Graph Theory Research
- Advanced X-ray Imaging Techniques
- Astronomical and nuclear sciences
University of Bonn
2015-2024
University of Aveiro
2021-2023
A. Alikhanyan National Laboratory
2023
European Organization for Nuclear Research
2016-2019
Deutsches Archäologisches Institut, Zentrale
2016
Justus-Liebig-Universität Gießen
2013-2014
Johannes Gutenberg University Mainz
1998-2008
Technical University of Darmstadt
2003
Old Dominion University
1998
Institut Laue-Langevin
1998
Precise data on the neutron magnetic form factor G_{mn} have been obtained with measurements of ratio cross sections D(e,e'n) and D(e,e'p) up to momentum transfers Q^2 = 0.9 (GeV/c)^2. Data typical uncertainties 1.5% are presented. These allow for first time extract a precise value radius neutron.
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,...
The electric form factor of the neutron ${G}_{E,n}$ has been measured in quasifree ${}^{2}\mathrm{H}(\stackrel{\ensuremath{\rightarrow}}{e}{,e}^{\ensuremath{'}}\stackrel{\ensuremath{\rightarrow}}{n})p$ reaction using 855 MeV polarized cw electron beam Mainz Microtron MAMI. polarization scattered neutrons was analyzed a polarimeter consisting two walls plastic scintillators. precession spin magnetic field used for first time to circumvent measurement effective analyzing power and...
We have measured the neutron electric form factor Gen via 3He→(e→,e′n)pp at Q2=0.67(GeV/c)2 using 3-spectrometer facility of A1 Collaboration Mainz Microtron and a dedicated detector. High pressure polarized 3He→ gas was used as target neutrons. is determined from ratio asymmetries A⊥/A∥ in quasifree kinematics with spin perpendicular parallel to momentum transfer. find Gen=0.052±0.011±0.005.Received 30 April 1999DOI:https://doi.org/10.1103/PhysRevLett.83.4257©1999 American Physical Society
Total and differential cross sections for the reaction p(gamma,eta)p have been measured photon energies in range from 750 MeV to 3 GeV. The low-energy data are dominated by S11 wave which has two poles energy region below 2 Eleven nucleon resonances observed their decay into peta. At medium we find evidence a new resonance N(2070)D15 with (M,Gamma)=(2068+/-22, 295+/-40) MeV. gamma above 1.5 GeV, strong peak forward direction develops, signaling exchange of vector mesons t channel.
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.
The photoproduction of \eta'-mesons off different nuclei has been measured with the CBELSA/TAPS detector system for incident photon energies between 1500 - 2200 MeV. transparency ratio deduced and compared to theoretical calculations describing propagation in nuclei. comparison indicates a width \eta' -meson order \Gamma= 15-25 MeV at \rho =\rho_0 an average momentum p_{\eta'} = 1050 MeV/c, which \eta'-meson is produced nuclear rest frame. inelastic N cross section estimated be 3 10 mb....
The γ+p→K0+Σ+ photoproduction reaction is investigated in the energy region from threshold to Eγ=2250 MeV. differential cross section exhibits increasing forward-peaking with energy, but only up K⁎ threshold. Beyond, it suddenly returns a flat distribution forward dropping by factor of four. In total pronounced structure observed between K⁎Λ and K⁎Σ thresholds.
The charge form factor of the neutron has been determined from asymmetries measured in quasi--elastic pol.3He(pol e,e'n) at a momentum transfer 0.67(GeV/c)^2. In addition, target analyzing power, A_y^o, to study effects final state interactions and meson exchange currents.
The first measurement is reported of the double-polarization observable G in photoproduction neutral pions off protons, covering photon energy range from 620 to 1120 MeV and full solid angle. describes correlation between polarization plane scattering for protons polarized along direction incoming photon. highly sensitive contributions baryon resonances. new results are compared predictions SAID, MAID, BnGa partial wave analyses. In spite long-lasting efforts understand γp→pπ0 as simplest...
The first measurement of the helicity dependence photoproduction cross section single neutral pions off protons is reported for photon energies from 600 to 2300 MeV, covering nearly full solid angle. data are compared predictions SAID, MAID, and BnGa partial wave analyses. Strikingly large differences between observed, which traced in amplitudes well-known established resonances. Precise values several resonances reported.