BREMSSTRAHLUNG PRODUCTION IN 48-MeV p–p COLLISIONS

Abstract

Measurements of the cross section d2σ/dΩ1dΩ2 for the bremsstrahlung reaction p + p → p + p + γ were made with 48 ± 1 MeV incident protons. Both final protons were detected in coincidence at equal angles on either side of the beam and coplanar with the beam, and bremsstrahlung events were identified kinematically. Cross sections of 2.12 ± 0.36 and 3.04 ± 0.44 μb/sterad2 were obtained at 30° and 35°, respectively. Both measured cross sections are smaller than the predictions of Signell and Marker by about a factor of 10; this discrepancy is considered to be well established, since various tests show that our detection efficiency is nearly 100%. It is concluded that further theoretical work, especially predictions of cross sections for noncoplanar events, is needed to determine whether the discrepancy results from a strong preference for coplanar events or from some basic defect in the theory.