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Proton compton scattering at backward angles in the energy range from 400 MeV to 1050 MeV

Authors
Journal
Nuclear Physics B
0550-3213
Publisher
Elsevier
Publication Date
Volume
247
Issue
2
Identifiers
DOI: 10.1016/0550-3213(84)90552-2
Disciplines
  • Physics

Abstract

Abstract Differential cross sections of proton Compton scattering have been measured in the energy range between 400 MeV and 1050 MeV at C.M.S. angles of 150° and 160°. The recoil proton was detected with a magnetic spectrometer using multi-wire proportional chambers and multi-wire spark chambers. The scattered photon was detected with a lead glass Čerenkov counter of the total absorptive type with two layers of multi-wire proportional chambers which measured the horizontal and vertical positions of the scattered photon. The proton Compton scattering was differentiated from the background of the π 0 photoproduction events with the use of angular correlations between the recoil proton and the scattered photon. The cross-section data show the clear second resonance peak at E γ = 750 MeV and a bump around E γ = 925 MeV at both angles. Also the angular distributions show the backward peak in the energy range between 700 MeV and 950 MeV. The data are compared with theoretical calculations based on an isobar model with some phases for the resonances. In this calculation, the proton Compton data were fitted varying the photocouplings of the nucleon resonances around the bump and the phases below the third resonances as free parameters. The calculation reproduced the angular distribution of differential cross sections well. However, it was inevitable that we use large photocouplings of P 33(1600) in order to fit the bump.

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