The effect of fast neutron irradiation on the performance of synthetic single crystal diamond particle detectors

Diamond is known for its extreme hardness which may allow it to operate as a particle detector in high fluence environments even after absorption of large radiation doses. We present a study of the deterioration of the charge collection efficiency (CCE) due to neutrons produced by U-235 fission, with irradiation fluences up to 1 x 10(16) n cm(-2). The planar devices were fabricated by thermal evaporation of Au onto approx. 300 mu m thick high purity chemical vapour deposited diamond produced by Element Six Ltd., UK. The detector performance was investigated as a function of bias voltage at room temperature using Am-241 alpha-particles and minimum ionising particles (MIPs) of a Sr-90 source. At low fluences up to 2 x 10(13) n cm(-2), the detectors reach the initial saturated signal amplitude after irradiation. However, the signal is less stable and deteriorates due to polarisation. This effect can be reduced by initial priming with X-rays. No peak could be distinguished in the detector response in the unprimed state after 10(16) n cm(-2) with bias voltages up to 1000 V (equivalent to 32 kV cm(-1)). However, a peak at about 18% CCE could be recovered after priming. (C) 2010 Elsevier B.V. All rights reserved