On the optimization of the isotopic neutron source method for measuring the thermal neutron absorption cross section: Advantages and disadvantages of BF3 and 3He counters

The effect of the detector characteristics on the performance of an isotopic neutron source device for measuring thermal neutron absorption cross section (Σ) has been examined by means of Monte Carlo simulations. Three specific experimental arrangements, alternately with BF3 counters and 3He counters of the same sizes, have been modelled using the MCNP-4C code. Results of Monte Carlo calculations show that devices with BF3 counters are more sensitive to Σ, but high-pressure 3He counters offer faster assays.