Am-Be neutron irradiator used for nuclear instrumentation training

A neutron irradiator was assembled at IPEN (Nuclear and Energy Research Institute) facility to perform qualitative-quantitative analysis of materials, using thermal and fast neutrons. In order to determine the ^116mIn decay constant, a thermal flux obtained experimentally by Monte Carlo N-Particle Transport Code-MCNP, in a previous work, was used in the nuclear experiment. The activity calculated from the activation parameters was 13.51 ± 0.17 kBq and the activity determined experimentally was 12.51 ± 0.36 kBq. The decay constant determined by the pulse height analyzer (PHA) measures was 211.4 μ·s^-1, and that determined by fitting the data using a Multichannel Scaler (MCS) system was 200.3 ± 1.6 μ·s^-1. The half-life of ^116mIn found in the literature is 3256.8 s, which corresponds to a decay constant of 212.8 μ·s^-1. The present experiment does not intend to establish a new value for the decay constant: it solely aims students´ practical exercises in nuclear properties of elements. This experiment is part of the nuclear experimental course.