In this study, a reduced size neutron long counter with improved response
function was designed using SuperMC simulation code. The main parts of the
reduced size long counter are 3He proportional counter, cylindrical
moderators made of polyethylene, chromium metal converter, neutron absorber
material and outer aluminum cover. A 1.5 cm thick layer of chromium metal was
embedded into the hydrogen-rich moderator to enhance response of the long
counter at high neutron energies. The radius and length of the long counter
was reduced to 15 cm and 35 cm, respectively. In this design we managed to
obtain a flat response function from a few keV to 20 MeV energy range. The
angular response function, determined at 0.5 MeV and 14 MeV neutron energies,
confirmed that the reduced size long counter designed in this study is not
significantly affected by in-scattered neutrons. The reduced size long
counter is suitable for use as a standard transfer instrument for monitoring
neutron fluence in mono-energetic neutron fields.
Deriving the angular response function for backscattering sensors
