  The goal of this research project is to give quantitative information useful
for the design of a g-ray detector to investigate neutron capture (n, g)
reactions on radioactive nuclei at the Manuel Lujan Jr. Neutron Scattering
Center (MLNSC) moderated neutron source at LANSCE. Data for neutron energies
from thermal up to approximately 500 keV are desired. The radioactive nuclei
can have half-lives as short as a few months. With the sample sizes foreseen,
typically 1 mg, the radioactive decay rate can exceed tens of Curies (Ci).
