0000000001320140
AUTHOR
O. Selke
showing 6 related works from this author
Compton scattering by the proton through θcms = 75° and 90° in the Δ-resonance region
1997
Abstract Differential cross sections for Compton scattering by the proton have been measured in the energy interval between 200 and 500 MeV at scattering angles of θcms = 75° and θcms = 90° using the CATS, the CATS/TRAJAN, and the COPP setups with the Glasgow Tagger at MAMI (Mainz). The data are compared with predictions from dispersion theory using photo-meson amplitudes from the recent VPI solution SM95. The experiment and the theoretical procedure are described in detail. It is found that the experiment and predictions are in agreement as far as the energy dependence of the differential cross sections in the Δ-range is concerned. However, there is evidence that a scaling down of the reso…
A high angular-resolution and time-of-flight detector system for recoil protons from the reactions p(γ, γ)p and p(γ, π0)p
1996
Using the Mainz NaI(Tl)BaF2 photon spectrometer CATS (Compton And Two photon Spectrometer) together with the prototype of a universal spectrometer for recoil protons TRAJAN (TRAjectory ANalyser) we have studied different methods to disentangle Compton scattering by the proton from the large π0 background through the energy range of the Δ resonance. CATS is a modular 48 cm ⊘ × 64 cm NaI(Tl) detector with an energy resolution of 1.5% combined with a 2π array of 61 BaF2 detectors. TRAJAN consists of a hodoscope with two planes, a wire chamber with horizontal and vertical wires and a grid of horizontal and vertical plastic scintillator strips, followed by a wall of nine NaI(Tl) detectors. By t…
Beam Asymmetry of Coherentπ° Photoproduction on4Hein theΔ(1232) Range Measured using Coherent Bremsstrahlung
1997
Using coherent bremsstrahlung at MAMI (Mainz), the beam asymmetry of the differential cross sections for coherent $\ensuremath{\pi}\ifmmode^\circ\else\textdegree\fi{}$ photoproduction on ${}^{4}\mathrm{He}$ has been measured in the energy interval from 200 to 500 MeV at an angle of ${\ensuremath{\theta}}_{\mathrm{lab}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}37\ifmmode^\circ\else\textdegree\fi{}$. The coherent ( $\ensuremath{\gamma},\ensuremath{\pi}\ifmmode^\circ\else\textdegree\fi{}$) reaction is used as a precise linear polarimeter for the first time. Agreement with predictions has been obtained on a $\ensuremath{\gtrsim}3%$ level of precision.
Photoemission of protons from4He in theΔ-resonance region
1996
High resolution proton energy spectra from the4He(γ,p) reaction have been measured with tagged photons in the range Eγ = 130−525 MeV using the large Mainz NaI(T1) spectrometer atΘplab=37.1°. Three separate reaction channels were identified, viz.4He(γ,p)t two-body breakup,4He photodisintegration via two-nucleon photon absorption processes and the quasifree pion production channel. Differential cross sections are presented for each of these channels as a function of photon energy. The sum of the two-nucleon photon absorption and the quasifree pion production differential cross sections, in the CM system, resembles that of the corresponding free-nucleon differential cross section when Fermi mo…
Angular and polarization dependence of Compton scattering from in the Δ-resonance region
1998
Abstract Using linearly polarized tagged photons from coherent bremsstrahlung, differential cross sections and beam asymmetries for Compton scattering by 4 He have been measured at MAMI in the energy interval between 150 MeV and 500 MeV for scattering angles of θ γ lab =37°, 93° and 137°, thus largely increasing the available data base. Improved calculations in terms of the Δ -hole model completely fail to describe the data at large scattering angles. The same proved to be true for a schematic model, even after taking into account properties of nuclear photo-absorption in very detail.
"Table 1" of "Angular and polarization dependence of Compton scattering from He-4 in the Delta resonance region"
1999
Axis error includes +- 0.0/0.0 contribution.