Experimental investigation and nuclear model calculations for proton induced reactions on indium around thresholds

摘要

Proton reactions with natural indium were found to give biased reaction cross section due to self-induced accompanying neutron-induced reactions in the target. We gave state-of-art and provided original experimental measurement for combined proton-and proton-induced-neutron reactions on indium isotopes. Low-energy protons incident on targets of stacked metallic indium foils were used to investigate the cross section and reaction yield around threshold. Two equivalent targets were designed to compensate the effect of neutron fluctuation in the sample and to swap the energy range below 14 MeV. The presence of significant neutron had been probed through the variation of reaction rate for formation of In-116m fluence through-out the target foils; In-116m yield was dependent on the stack arrangement. The interplay between the proton reactions on target isotopes through the In-113(p,n) Sn113m+g In-113(p,p') In-113m, In-115(p,p'), In-115m, In-115(p,np)In-114m, and In-13(p,H-3) In-111m routes from one side and the reactions of proton-induced-neutrons from the other side alters the experimental results and strengthen the formation of Sn113m+g and In-114m on the expense of exhausting other reaction products. We stated the experimental values for the apparent reaction cross sections of these reactions in addition to the reaction cross section of short-lived isomeric level of Sn-113m (T-1/2 = 1284 s) through the decay gamma-line at 77.38 keV. Nuclear model calculations were performed for all the related reactions and used to adopt our hypothesized values concerning the combined proton-and proton-induced-neutron reaction cross sections. Two resonance states for the reaction In-113(p,H-3) In-111m were identified at 11.51 MeV (Gamma(t) = 0.961 MeV) and 14.12 MeV (Gamma(t) = 0.194 MeV).