Silicon detector characterisation for monoenergetic neutron measurements using proton-recoil telescopes

초록

Precise absolute-neutron-flux measurements are critical in numerous applications, including cross-sectional measurements of neutron-induced reactions, characterisation of neutron beams, and dosimetric surveys. The cross-section of elastic scattering between neutrons and protons is a widely recognised indicator for accurate absolute-neutron-flux measurements, and elastically scattered protons can be detected using a proton-recoil telescope (PRT) equipped with silicon detectors. The present study was focused on the optimisation and characterisation of a PRT for establishing a standard monoenergetic neutron field at the Korea Research Institute of Standards and Science (KRISS) in Korea. To improve the reliability of the PRT characterisation results, its energy calibration was performed using a 20-MeV proton beam delivered by a cyclotron, instead of conventional alpha-radiation sources. The irradiation experiment was conducted using a proton beam with an energy of 14.8 MeV; this energy corresponds to the maximum energy transferred from a neutron, emitted from deuterium-tritium fusion, to an elastically recoiled proton during an elastic collision. In addition to energy calibration, the coincidence time resolution of the KRISS-PRT silicon detector under proton beam irradiation was confirmed to be 15.5 ns at 1 sigma, which could not be attained using conventional alpha-particle sources.

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