Fast-Neutron Scattering from Germanium

Abstract

Elastic and inelastic neutron scattering cross sections of natural germanium were measured in the incident neutron energy range 0.3-1.5 MeV with incident energy resolutions of ^20 keV. Neutron-velocity and 7-ray spectroscopic methods were employed to resolve the scattering to individual low-lying states. The results were interpreted in terms of the optical model and the statistical compound-nucleus model including effects due to fluctuations and correlations of resonance widths. Measured cross sections for inelastic scattering to a number of excited states in even Ge isotopes were reasonably well described by the statistical model of Hauser and Feshbach without corrections for width fluctuations and correlations.

Neutron interactions as seen by a segmented germanium detector

“…If the excited state of a nucleus has the same spin as the ground state, internal conversion [11,12] is the predominant mode of the de-excitation. Since the mean free path of an electron emitted from internal conversion is about 1 mm in germanium, the energy of the electron and the recoil of the nucleus are deposited in the same segment.…”

SICANE: a detector array for the measurement of nuclear recoil quenching factors using a monoenergetic neutron beam

“…The simulation predicts that 82% of these γ escape detection, leaving only the neutron time-of-flight as a mean to discriminate these events from elastic scatters. The cross-sections for each of these states are of the order of 1 b [24], compared with an elastic cross-section of the order of 2 b [25]. Given the isotopic abundances in Ge, the 563 keV yield is only a fifth of the 596 keV one.…”

“…The end products of such a collision are i) a nuclear recoil with a kinetic energy inferior to that associated with elastic scattering, ii) a scattered neutron with a reduced energy and thus an increased time-offlight to the NE213 cells, and iii) a γ emission which may deposit some of its energy in the detector. Given the neutron energy, the most important γ's to be expected [24] are the 596 keV transition in 74 Ge, 835 keV in 72 Ge and 563 keV in 76 Ge. The simulation predicts that 82% of these γ escape detection, leaving only the neutron time-of-flight as a mean to discriminate these events from elastic scatters.…”

Measurement of Fast-Neutron Flux With a Lithium-Drifted Germanium Detector.

“…The presence of fluctuations in the efficiency from threshold to E n = 1400 keV is confirmed by the results of the present study and those of Lister and Smith. 16 Uncertainties in the data make it difficult to determine details of the structure in the efficiency calibration for the range E n = 2400-5000 keV. In any event, the results of the present work indicate that for neutron-energy resolutions of 20 keV or broader, there is very little structure in the efficiency over a wide range of neutron energy and this is favorable for detector applications.…”