Ph. Hoffmeister - The CBELSA/TAPS Collaboration

Ph. Hoffmeister
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Name
Ph. Hoffmeister
Affiliation
The CBELSA/TAPS Collaboration
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Nuclear Experiment (12)
 
Physics - Instrumentation and Detectors (1)

Publications Authored By Ph. Hoffmeister

Photoproduction of $\eta$ mesons from neutrons} \abstract{Results from measurements of the photoproduction of $\eta$ mesons from quasifree protons and neutrons are summarized. The experiments were performed with the CBELSA/TAPS detector at the electron accelerator ELSA in Bonn using the $\eta\to3\pi^{0}\to6\gamma$ decay. A liquid deuterium target was used for the measurement of total cross sections and angular distributions. Read More

2015Jun
Affiliations: 1The CBELSA/TAPS Collaboration, 2The CBELSA/TAPS Collaboration, 3The CBELSA/TAPS Collaboration, 4The CBELSA/TAPS Collaboration, 5The CBELSA/TAPS Collaboration, 6The CBELSA/TAPS Collaboration, 7The CBELSA/TAPS Collaboration, 8The CBELSA/TAPS Collaboration, 9The CBELSA/TAPS Collaboration, 10The CBELSA/TAPS Collaboration, 11The CBELSA/TAPS Collaboration, 12The CBELSA/TAPS Collaboration, 13The CBELSA/TAPS Collaboration, 14The CBELSA/TAPS Collaboration, 15The CBELSA/TAPS Collaboration, 16The CBELSA/TAPS Collaboration, 17The CBELSA/TAPS Collaboration, 18The CBELSA/TAPS Collaboration, 19The CBELSA/TAPS Collaboration, 20The CBELSA/TAPS Collaboration, 21The CBELSA/TAPS Collaboration, 22The CBELSA/TAPS Collaboration, 23The CBELSA/TAPS Collaboration, 24The CBELSA/TAPS Collaboration, 25The CBELSA/TAPS Collaboration, 26The CBELSA/TAPS Collaboration, 27The CBELSA/TAPS Collaboration, 28The CBELSA/TAPS Collaboration, 29The CBELSA/TAPS Collaboration, 30The CBELSA/TAPS Collaboration, 31The CBELSA/TAPS Collaboration, 32The CBELSA/TAPS Collaboration, 33The CBELSA/TAPS Collaboration, 34The CBELSA/TAPS Collaboration, 35The CBELSA/TAPS Collaboration, 36The CBELSA/TAPS Collaboration, 37The CBELSA/TAPS Collaboration, 38The CBELSA/TAPS Collaboration, 39The CBELSA/TAPS Collaboration, 40The CBELSA/TAPS Collaboration, 41The CBELSA/TAPS Collaboration, 42The CBELSA/TAPS Collaboration, 43The CBELSA/TAPS Collaboration, 44The CBELSA/TAPS Collaboration, 45The CBELSA/TAPS Collaboration, 46The CBELSA/TAPS Collaboration, 47The CBELSA/TAPS Collaboration, 48The CBELSA/TAPS Collaboration, 49The CBELSA/TAPS Collaboration, 50The CBELSA/TAPS Collaboration, 51The CBELSA/TAPS Collaboration, 52The CBELSA/TAPS Collaboration, 53The CBELSA/TAPS Collaboration, 54The CBELSA/TAPS Collaboration, 55The CBELSA/TAPS Collaboration, 56The CBELSA/TAPS Collaboration, 57The CBELSA/TAPS Collaboration, 58The CBELSA/TAPS Collaboration, 59The CBELSA/TAPS Collaboration, 60The CBELSA/TAPS Collaboration, 61The CBELSA/TAPS Collaboration, 62The CBELSA/TAPS Collaboration, 63The CBELSA/TAPS Collaboration, 64The CBELSA/TAPS Collaboration, 65The CBELSA/TAPS Collaboration, 66The CBELSA/TAPS Collaboration, 67The CBELSA/TAPS Collaboration, 68The CBELSA/TAPS Collaboration, 69The CBELSA/TAPS Collaboration, 70The CBELSA/TAPS Collaboration, 71The CBELSA/TAPS Collaboration, 72The CBELSA/TAPS Collaboration, 73The CBELSA/TAPS Collaboration, 74The CBELSA/TAPS Collaboration, 75The CBELSA/TAPS Collaboration, 76The CBELSA/TAPS Collaboration, 77The CBELSA/TAPS Collaboration, 78The CBELSA/TAPS Collaboration, 79The CBELSA/TAPS Collaboration

Data on the polarization observables T, P, and H for the reaction $\gamma p\to p\pi^0$ are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. Read More

The first measurements of the beam-target-helicity-asymmetries $E$ and $G$ in the photoproduction of $\omega$-mesons off protons at the CBELSA/TAPS experiment are reported. $E$ ($G$) was measured using circularly (linearly) polarised photons and a longitudinally polarised target. $E$ was measured over the photon energy range from close to threshold ($E_\gamma = 1108$~MeV) to $E_\gamma = 2300$~MeV and $G$ at a single energy interval of $1108 < E_\gamma <1300$~MeV. Read More

New data on the polarization observables T, P, and H for the reaction $\gamma p \to p\pi^0$ are reported. The results are extracted from azimuthal asymmetries when a transversely polarized butanol target and a linearly polarized photon beam are used. The data were taken at the Bonn electron stretcher accelerator ELSA using the CBELSA/TAPS detector. Read More

The first measurement of the helicity dependence of the photoproduction cross section of single neutral pions off protons is reported for photon energies from 600 to 2300\,MeV, covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, and BnGa partial wave analyses. Strikingly large differences between data and predictions are observed which are traced to differences in the helicity amplitudes of well known and established resonances. Read More

The OLYMPUS experiment was designed to measure the ratio between the positron-proton and electron-proton elastic scattering cross sections, with the goal of determining the contribution of two-photon exchange to the elastic cross section. Two-photon exchange might resolve the discrepancy between measurements of the proton form factor ratio, $\mu_p G^p_E/G^p_M$, made using polarization techniques and those made in unpolarized experiments. OLYMPUS operated on the DORIS storage ring at DESY, alternating between 2. Read More

The first measurement is reported of the double-polarization observable G in photoproduction of neutral pions off protons, covering the photon energy range from 620 to 1120 MeV and the full solid angle. G describes the correlation between the photon polarization plane and the scattering plane for protons polarized along the direction of the incoming photon. The observable is highly sensitive to contributions from baryon resonances. Read More

The polarization observable I^s, a feature exclusive to the acoplanar kinematics of multi-meson final states produced via linearly polarized photons, has been measured for the first time. Results for the reaction g p -> p pi0 eta are presented for incoming photon energies between 970 MeV and 1650 MeV along with the beam asymmetry I^c. The comparably large asymmetries demonstrate a high sensitivity of I^s to the dynamics of the reaction. Read More