Measurements of Average Cross Sections for Some Threshold Reactions for Neutrons with Fission-type Reactor Spectrum

Abstract

The fast neutron spectrum in the core of the Kyoto University Reactor (KUR) was measured by using seven threshold reactions, a 6Li sandwich counter and also nuclear emulsion plates, and the results were compared with theoretical calculations by the Sn method. It was found that the shape of the fast neutron spectrum was approximately the same as that of fission neutrons. Making use of these neutrons with fission-type spectrum, measurements were made of the average cross sections for twelve threshold reactions (46Ti(n, p)46Sc, 47Ti(n, p)47Sc, 46Ti(n, p)48Sc, 28Si(n, p)28Al, 29Si(n, p)29Al, 30Si(n, α)27Mg, 51V(n, α)48Sc, 64Zn(n, p)64Cu, 92Mo(n, p) 92mNb(n, 2n)92mNb, 204Pb(n, n1 )204mPb and 204Pb(n, 2n)203Pb). For the purpose of comparison, the average cross sections for six among these reactions were measured also with neutrons from a fission plate. The results agreed within experimetal error with those obtained for neutrons in the KUR core. A Ge(Li) counter was mainly used for the measurement of γ-rays emitted from induced activities.