Response improved for neutron long counter

A low-sensitivity neutron long counter was designed as a standard directional flow detector to monitor neutron fluence reference values of an accelerator-based 14-MeV D-T neutron source with yield of 10(13) n s(-1). The energy response over 6 MeV was improved using a tungsten radiator, which acts as an energy converter via the (n, xn) reaction. Different parameters were optimised to flatten the neutron energy response over a wide energy range. A simulation of the designed neutron long counter was performed using the Monte Carlo codes SuperMC. The response function is relatively flat in the energy range of 1 keV-20 MeV. The results show that the maximal relative variation is ∼7.8 %.