Experimental investigation of the 4He(γ, p)3H reaction in the Δ -resonance region

Abstract The 4 He(γ, p) 3 H reaction was investigated in the photon energy region between 200 and 450 MeV and at proton c.m. angles between 30° and 150°. The outgoing particles were detected in coincidence in two time-ot-flight spectrometers consisting of scintillation counters; energies and angles of both particles were determined. The measured angular distributions show a strong forward peak. The differential cross sections and the total cross section fall off smoothly with increasing photon energy. However, the slope is not as steep as in the low energy region.