Lithium Gadolinium Borate in Plastic Scintillator as an Antineutrino Detection Material

摘要

Experiments and simulations were conducted to assess the use of lithium gadolinium-borate (LGB) crystals to identify neutron capture in a detector system intended to detect nuclear reactor antineutrinos. The experiments used two prototype detectors comprised of crushed LGB crystal mixed with plastic scintillator. Both detectors were 127 mm diameter cylinders, with heights of 123 mm and 348 mm. Each contained 1% by weight LGB crystal, but different LGB particle sizes. The experiments determined neutron capture efficiencies, interevent timing and scintillation light attenuation of the prototype detectors. Based only on the 6Li(n, )3H interaction, neutron capture efficiencies of 1.73% 0.24% for the smaller detector and 1.38% 0.14% for the larger detector were measured for a 252Cf fission neutron source. Indications of neutron captures on 10B were also evident, but accurate efficiency measurements were hampered by contamination from non-neutron capture events. Computer simulations using the GEANT4 toolkit were conducted to analyze detector performance. Comparisons between experiment and simulations were made to validate the detector modeling. Simulations of detector performance at inverse beta decay neutron energies were conducted to determine neutron detection efficiency in an antineutrino detection role. Variation of isotope content, LGB loading and LGB particle size were modeled to explore possible improvements in neutron capture efficiency at neutron energies associated with inverse beta decay.