Remediating neutron damage in large area planar Ge-DSSD with amorphous germanium contacts through annealing and pulse-height correction

Abstract

Large area, position sensitive planar germanium detectors offer new opportunities in γ-ray spectroscopy. For in-beam studies remediating neutron damage is important. This work studied a mechanically cooled circular planar 9 × 1 cm wafer with orthogonal 16 × 16 amorphous germanium strip electrodes. Before neutron irradiation the wafer was heated in-cryostat to above 373 K for more than 24 h in order to test the robustness of the contacts and the mechanical cooler. No deterioration in performance was observed. The detector was then exposed to controlled doses of 2.2 MeV neutrons, produced from the 7Li(p,n)7Be reaction until substantial damage was observed. Averaged over the surface of the wafer, a flux of 1.9(1)×109 n/cm2 was delivered. The detector then survived thermal cycling and 350 K (∼77°C) annealing for 70 h which substantially reduced hole trapping. pulse-height correction is investigated to further mitigate the neutron damage. Higher temperature annealing at 365 K was not successful.