Secondary nuclear reactions in the bombardment of tin by fast protons

Abstract

A radiochemical method has been used to study the capture of products arising in disintegration of target nuclei.

Using the measurements of yields of radioactive isotopes of tellurium (Z=52) and iodine (Z=53) obtained from tin (Z=50) irradiated by protons with energy from 170 to 660 Mev excitation curves are plotted for the secondary reactions which lead to the formation of products with charges 2 and 3 units greater than the charge of the original nucleus. The cross sections for these reactions increases with increasing energy of the incident protons: σ(α, x n) and σ(Li, xn) are respectively 18.5 ± 5 and 0.17 ± 0.1 mbarns for E_p=170 Mev and 50 ± 6.5 and 1.6 ± 0.5 mbarns for E_p=660 Mev. The cross sections for lithium capture by tin in a comparable proton energy interval are in good agreement with the results of investigations of similar reactions in copper, tin and lead but are found to be 50 times smaller than the cross sections obtained by Marquez and Perlman.

The observed cross sections for the secondary lithium capture can be explained only by assuming that these nuclei acquire energies greater than that which can be obtained In evaporation or fission of the target nuclei.

Secondary reactions of the (α, xn) type can be explained satisfactorily on the basis of an evaporation mechanism for the formation of the helium nuclei.