A compound detector based on the Na-23(n,gamma) reaction in a boron sh
ield is investigated. The detector cross section was calculated assumi
ng that the spectrum inside the shield is a sum of two components, one
due to direct penetration of neutrons through the shield wall and neu
trons scattered in the shield mass. Also investigated was the effect o
f hydrolyzing varnish in the shield and the size of the activation det
ector on the detector readings.