Photoproton Cross Sections for Mg, Al, Si and S

Abstract

Photoproton cross sections for Mg, Al 27 , Si 28 and S 32 were measured using a betatron. A vacuum chamber with six detectors, each of which consists of a ZnS(Ag) scintillator and a photomultiplier, was used for the detection of photoprotons. The protons having larger energies than about 1.5 Mev were measured. The obtained yield curves were converted into the cross sections by Penfold-Leiss' method. The results are as follows: the giant resonance energies are 20, 20, 19.7 and 19.3 Mev for Mg, Al 27 , Si 28 and S 32 respectively: the widths at half maximum are 6, 7, 4 and 6 Mev; the integrated cross sections up to 23 Mev are 0.070, 0.11, 0.14 and 0.26 Mev-barns.