A comprehensive study of a wide energy range proportional counter neutron spectrometer fast neutron detector
Titre du congrès :International Workshop on Fast Neutron Detectors and Applications
Ville du congrès :Le Cap
Date du congrès :03/04/2006
The neutron spectrometer ROSPEC is made up of 6 spherical proportional counters with different gas fillings, on a rotating platform, and which covers the energy range 0.025 eV to 4.5 MeV. A complete study is performed within the framework of a French working group in order to improve the spectrometer performance.
First, the study of the devices performance in reference neutron fields was performed, with respect to the influence of rotation and disturbance from other counters. It appeared that the fluence scattered by other counters could represent between 7 and 40% of the total fluence, but with a slight influence on the initial spectrum.
Secondly, we determined the response matrix for each counter from two main parameters, the wall and the gas amplification effects. The wall effects were calculated using the Snidow algorithm and compared to the MCNPX simulation. The change in the electric field was calculated using a finite element method to define amplification region for simulation.
Finally, since the ROSPEC unfolding code sometimes gave negative fluences, the unfolding code UMG was used to correct this default. We compared the results from both unfolding codes.