Determination of Slow-Neutron Fluence Rate Using Gamma-Ray Spectroscopy

In this work, the method of determination of the slow-neutron fluence rate using a gamma-ray spectroscopy with a high-purity germanium detector (HPGe) and Monte Carlo calculations was presented. The prompt gamma rays with energies of 595.9, 867.9, and 1204.2 keV, originating from the nuclear reaction Ge-73(n, gamma)Ge-74 in the germanium crystal of the HPGe detector, were registered. A special system composed of two neutron sources (Cf-252, PuBe), a lead shield and a HPGe detector was made to find correlations between net areas of the peaks from these prompt gamma rays in the measured spectra and the fluence rate of slow neutrons getting to the germanium crystal. The net areas of the peaks were related to the slow-neutron fluence rate using the Monte Carlo calculations based on the GEANT4 code. The presented method using the gamma-ray spectroscopy can be applied in laboratories which do not have detectors for neutron measurements.