MEASUREMENT OF 14 MEV NEUTRONS TRANSMISSION THROUGH LITHIUM HYDRIDE LAYERS WITH TIME-OF-FLIGHT METHOD

The results of experiments on transmission of 14 MeV neutrons through lithium hydride layers of thickness up to 25 cm are presented in the article. The measurements were performed with time-of-flight method on a pulse channel of neutron generator NG-12I. The operating mode of the neutron generator is pulse-periodic. Neutrons passing through the layers of Li hydrides were registered by detector based on a 70×70 mm stilbene crystal scintillator. NIM standard modules were used as measuring equipment. The neutron yield from the generator target was estimated by neutron monitor with a fluorine plastic activation detector. Activity of radiation-exposed neutron activation detectors was measured using a gamma spectrometer with high purity germanium detector (HPGe). The averaged 14 MeV neutrons flux from the target was ∼2⋅108 n/s. The measurement results were used to obtain instrumental neutron spectra for samples of various thicknesses and to estimate coefficients of 14 MeV neutrons passing through the layers of Li hydrides. The obtained results can be used for validation of neutron-physical calculations and for improvement of neutron constants libraries.