Priming effect on a polycrystalline CVD diamond detector under 60Co γ-rays irradiation

The priming effect on a polycrystalline chemical vapor deposition (CVD) diamond film detector caused by irradiation with 60Co γ-rays has been investigated. Charge collection efficiencies of the detector for α-particles and γ-rays detection were determined in both the normal state and the pumped state. The duration of the priming effect and its relationship with bias voltage were also studied. The results show that the priming effect may clearly improve charge collection efficiency, with an increase of 6% for α-particles and 13% for γ-rays at 600 V saturation bias voltage. The priming effect can be completely retained for 40 min after irradiation, and it begins to gradually disappear within 12 h. In addition, the effect is more easily induced when bias voltage is applied than in the absence of any bias voltage. The experiments also demonstrated that irradiation incident on the growth surface may induce higher charge collection efficiency than irradiation incident on the substrate surface.