Response function measurement of layered type CVD single crystal diamond radiation detectors for 14 MeV neutrons

Abstract

Response function measurement of layered-type chemical vapor deposition single crystal diamond radiation detectors for 14 MeV neutrons was carried out. The detector had a layered structure that was composed of a boron-doped diamond layer of 0.5 μm in thickness and a nondoped diamond layer of 20 μm on an inexpensive high pressure and high temperature-type Ib diamond substrate. The detector had energy resolution of 2.6% for 5.5 MeV α particles. This experiment was mainly carried out in order to understand the present status of the detector as a 14 MeV neutron spectrometer and an extent of charge trapping. As result, a peak caused by the C12(n,α0)9Be reactions was clearly observed; the best energy resolution of 6% as for a synthetic diamond radiation detector was achieved. Detection efficiency was 3.2×10−7 counts/unit neutron fluence. However, taking the energy resolution for α particles, etc., into account, the energy resolution for 14 MeV neutrons was not so high. Further improvement based on better crystal growth is indispensable.