Fast Neutron Capture Cross Section Measurements Using a NaI Detector

摘要

We present the different ways the total capture cross section is determined starting from the pulse-height distribution as given by a NaI detector surrounded by an annulus. The time-of-flight technique associated with an improved shielding of the system is used to reduce background making capture cross sections as low as 1 mb measurable. The extrapolation of the capture gamma -ray energy distribution in the (n,n' gamma ) region is made using a simple statistical model calculation. The principle of energy conservation is also used. The unfolding stage can be avoided by applying the pulse-height weighting technique to the NaI pulse-height spectrum. The present method has also the advantage of giving the (n, gamma n') cross section as a byproduct. (Atomindex citation 13:698344)