Use of 4He-filled proportional counters as neutron spectrometers

Neutron response functions of two commercially available cylindrical He-4-filled proportional counters (filling pressure about 2 MPa) have been measured in the neutron energy range 144-14000 keV. Measurements were carried out using optimal settings for the detector high voltage and amplifier shaping time which were determined within the scope of this study. The experimental results have been analyzed and compared to calculated response functions using empirically determined energy and resolution calibration functions. The theoretically determined response functions show good agreement with the measured response except for energies above 10 MeV. The discrepancies are attributed to unsatisfactory electronics. The Monte-Carlo code Gas-filled neutron spectrometer response (GNSR) which has been developed for the calculation of response functions and efficiencies of gas-filled neutron detectors, is briefly described. (C) 1998 Elsevier Science B.V. All rights reserved.