Measurement of fast neutron induced fission cross section of thorium using Lexan plastic track detector

Abstract

Fission-track registration characteristics of Lexan solid state nuclear track detectors have been used to measure the fast neutron induced fission cross section of232Th. The fast neutrons (≅14.2MeV) were produced with the help of an AN-400 model Van-de-Graaff accelerator at Banaras Hindu University laboratory using3H(2H,n)4He reaction and were used to irradiate the fissile target deposited on the plastic detector. The track densityT, registered on the plastic detector is related to the fission cross sectionσ f, through the relationT=knσ fot wheren is the number of fissile atoms per cm2 in the deposit, o is the neutron flux,k is fission track registration efficiency andt is the time of irradiation. The fission cross sectionσ f of232Th, relative to the well measured fission cross section of238U, was found to be 0.36±0.04 barn.