Study of Total Discrete Gamma Radiation from Aluminum under 14.9-MeV Neutron Bombardment

Abstract

Combining the usual prompt gamma radiation measurement technique and the lifetime correction method for delayed gamma radiation yield measurements allows the study of total discrete gamma radiation from 14.9-MeV neutron-induced 27Al(n,xγ) reactions. The following are identified: 21 prompt gamma lines from (n,n'γ), (n,αγ), (n, nαγ), (n,nαγ), (n,pnγ), (n,dγ), and (n,2nγ) reactions; 5 delayed gamma lines from one isomeric state produced in the (n, α) reaction; and the β-decay products of the residual nuclei in the (n,p) and (n, α) reactions. Their differential production cross sections at 55, 90, and 140 deg are determined simultaneously. Compared with previous experimental results, one sees a clear advantage in separating the delayed component from the mixed gamma-ray peaks, which consist of prompt and delayed gamma radiation; completely clean prompt gamma-ray production data are obtained. The accurate (n,p) cross sections and a preliminary (n, α) cross section are determined from relative differential production cross sections. They are in good agreement with the known activation data obtained from previous measurements and evaluations. The isomeric cross section for the 472.3-keV state of 24Na is also given. The present result shows that the total gamma radiation measurement method is valuable not only to acquire accurate gamma-ray production data but also to acquire accurate neutron activation data with a wide half-life range.