G. Fehrenbacher et al., FAST-NEUTRON DETECTION WITH GERMANIUM DETECTORS - UNFOLDING THE 692 KEV PEAK RESPONSE FOR FISSION NEUTRON-SPECTRA, Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 397(2-3), 1997, pp. 391-398
A new method is proposed for obtaining information on the spectral dis
tribution of fast fission neutrons in the energy range from 0.7 MeV up
to about 6 MeV from the shape of the Ge 692 keV inelastic scattering
peak response e.g. in the pulse-height distribution measured with a po
rtable Ge detector. In order to reduce photon background events, a lea
d shielding is put around the active volume of the Ge detector. Peak r
esponses associated with the 692 keV peak are computed by Monte-Carlo
simulations including the lead shield. A set of 80 response functions
for neutron energies in the aforementioned energy range are used in an
unfolding procedure based on least-squares methods for the 692 keV pe
ak response. The procedure was used to determine shape and magnitude o
f a fission neutron spectrum from a Cf-252 source. In a numerical exam
ple, the procedure was also applied to unfolding the calculated peak r
esponse to spectra of fission neutron sources shielded by carbon, conc
rete enriched with iron, and a thick lead shield. It is shown that the
peak responses for such different spectra can be substantially differ
ent and, thus, used for a limited neutron spectrometry.