Thermal neutron field characteristics in the neutron exposure accelerator system for biological effect experiments (NASBEE) facility

Abstract The neutron exposure accelerator system for biological effect experiments (NASBEE) facility was constructed to investigate the biological effects of fast neutrons produced by the  9Be(p, n)9B and  9B(D, n)10B reactions. In this work, we describe the modification of the NASBEE facility for the development of thermal neutron detectors and radiology applications. We characterized thermal neutron fields created with a polyethylene (PE) moderator. The maximum thermal neutron fluxes via proton (600 μ A) and deuteron (350 μ A) beams were estimated to be 5.7 × 107 and 1.2 × 108 cm−2 s−1, respectively, by using the 30-mm-thick PE moderator set in front of the irradiation sample The ratios of the gamma ray absorbed dose to thermal neutron fluence were 3.6 × 10−12 Gy cm2 for the  9Be(p, n)9B reaction and 6.1 × 10−11 Gy cm2 for the  9B(D, n)10B reaction. The thermal neutron field in the NASBEE facility can be used for various applications of thermal neutrons and is now open to external users.