Reactions of Cesium with Protons at 60, 80, 100, 150, and 240 Mev

Abstract

Absolute production cross sections have been determined for certain isotopes of barium, cesium, iodine, and tellurium produced by reactions of cesium with protons of energies 60, 80, 100, 150, and 240 Mev. The yields are based on the known cross section for the monitor reaction ${\mathrm{Al}}^{27}(p, 3pn){\mathrm{Na}}^{24}$. In the region up to 100 Mev the data indicate that the yields are largely explained on the basis of an evaporation mechanism which competes with the prompt knock-on optical model to an extent which decreases rapidly with increasing energy because of increasing nuclear transparency. The neutron pick-up reaction manifests itself in extraordinarily large yields of ${\mathrm{Cs}}^{132}$ and to a lesser extent in the yields of ${\mathrm{Cs}}^{131}$. Formation of small amounts of neutron-excess iodine isotopes argues for alpha-particle fragmentation especially at the lower bombardment energies.