Design of long neutron counter for intensified D-T neutron source

A low sensitivity long neutron 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 about 10¹³ n/s. 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 optimized to flatten the neutron energy response over a wide energy range. A simulation of the designed long neutron counter using the Monte Carlo codes MCNP was undergone. The response function is relatively flat in the energy range of 1 keV-20 MeV. The results show the maximal relative variation is about 7.8%. (author)