Measurements and Applications of the Excitation Functions for Fast Neutron Induced Reactions

Abstract

The concentric ring technique has been devised for the measurement of fast neutron fluxes and energies by using different standard materials and their measured excitation functions. It has been shown experimentally that for the determination of flux and energy in the 14 MeV region, this novel technique can yield accuracy values of the order of 1.0% and 1.2% respectively. An experimental cross-section ratio curve for the (n,2n) reaction on 63Cu and the (n,p) reaction on 27Al has been established as a standard reference for fast neutron energy measurement. The technique has been applied to the measurement of the excitation functions for the following nuclear reactions: a) The 12.9 to 15.9 MeV neutron energy region (1) 27Al(n,p)27Mg (2) 56Fe(n,p)56Mn (3) 59Co(n,α)56Mn (4) 64Zn(n,2n)63Zn (5) 63Cu(n,2n)62Cu 6) 121Sb(n,2n)120Sb b) The 13.4 to 14.9 MeV neutron energy region (7) 28Si(n,p)28Al (8) 27Al(n,α)24Na (9) 64Zn(n,p)64Cu (10) 65Cu(n,2n)64Cu The cross-section data obtained by using a 0.5 MeV Van de Graaff and 3.0 MeV Dynamitron accelerators are consistent and are in good general agreement with the published data. This investigation includes also detailed studies of fast neutron production by the T(d,n)4He reaction, fast neutron monitoring, activation analysis and cross-section data systematics. Some of the recommendations proposed include flux monitoring by the 121Sb(n,2n)120gSb reaction, further possible applications of the concentric ring technique, and a possible system for the standardization of neutron cross-section data