Development of boron-based thermal neutron absorbers for short-pulsed MW-class neutron sources – how can the pre-decoupling function be enhanced?

Decouplers (thermal neutron absorbers) are used for pulse shaping of neutron beams in pulsed neutron sources, contributing to higher resolution of neutron instruments. We are developing a boron (B)-based decoupler material for MW pulsed neutron sources, focusing on the pre-decoupling function to suppress material embrittlement due to the (n, α) reaction of B by adding other higher thermal-neutron absorption material (gadolinium (Gd)). The challenge is to develop a material in which B and Gd are uniformly dispersed. In the development of sintered materials focusing on the hot isostatic pressing (HIP) method, the possibility of further enhancing the pre-decoupling function was obtained under HIP temperature conditions from above 893 K to below the melting point.