Direct detection of 14.1 MeV neutrons by multi-stacked <i>h</i> -BN detector

Reliable detection of 14.1 MeV neutrons from deuterium–tritium (DT) fusion reactions is vital for advancing nuclear energy, bolstering national security, and managing nuclear waste. Despite their importance, the effective detection of 14.1 MeV neutrons produced from these reactions remains a significant hurdle for semiconductor detectors, primarily due to their inherently low interaction cross section. We report here the development of a stacked detector constructed from hexagonal boron nitride (h-BN) quasi-bulk crystals produced by hydride vapor-phase epitaxy (HVPE) growth. The mean free path (λ) of 14.1 MeV fast neutrons in h-BN was determined to be 11.3 cm. By engineering an effective neutron interaction path length of 1 cm, we have achieved a notable neutron detection efficiency of 5.0% and a charge collection efficiency of 59% when exposed to 14.1 MeV fast neutrons. Furthermore, this stacked h-BN detector exhibits a substantial neutron-generated direct current, suggesting the feasibility for realizing portable and battery-powered DT neutron sensors. Our findings are a major step forward, with the potential to deliver highly sensitive, compact, scalable, and operationally efficient h-BN semiconductor fast neutron detectors that will benefit diverse scientific and industrial applications.