Indium as an absolute Neutron Yield Detector

Brian DeMarco and Alena Lieto
Faculty Advisor: Steve Padalino
LLE Collaborator Bob Kremens

Alena, Brian and their poster

Here is the abstract for the poster that Brian and Alena will be giving at the March 1996 APS meeting:

The recently completed OMEGA 64 upgrade at the Lab for Laser Energetics (LLE) at the University of Rochester required a recalibration of the DD neutron absolute yield detector. Measurement of DD neutron absolute yield is crucial to determining fuel densities. The method used to measure absolute DD yield is the gamma ray activity produced by neutron activation of indium, specifically the reaction ^₁₁₅In(n,n')^115mIn. This gamma ray activity can be used to infer the absolute neutron yield, provided a calibration factor has been obtained (incident neutrons/gamma count). Research is underway at the Nuclear Structure Lab at the State University of New York at Geneseo to determine this calibration factor for LLE. Indium activation is accomplished using Geneseo's 2 MV Van de Graaff accelerator to create the nuclear reaction d(d,n)³He. The neutron flux incident on the indium sample is inferred by measuring the associated ³He flux. The resulting gamma-ray activity is measured using a high-purity germanium detector. An analysis of neutron transport in the indium sample allows the calibration factor to be related to the incident neutron flux and the measured gamma-ray activity. Funded in part by the U.S. Department of Energy.