Diamond detector irradiation tests at TRIUMF

Polycrystalline chemical vapour deposition (pCVD) diamond detectors are being considered for an upgrade of Forward Calorimetry in the ATLAS detector at the CERN LHC. In order to determine their radiation hardness, four detectors were continuously monitored during irradiation with 500 MeV protons at TRIUMF to a fluence of 2.25 x 1017 protons/cm2. All four detectors worked at the end of the irradiation period. The detector response A as a function of fluence has been fitted to a sum of two exponentials and to a function A = ao/(1+a1ϕ) where ao is the initial response and ϕ is the fluence with a1 = 9.8 x 10−17 ± 3.2 x 10−18 cm2/proton. At the end of irradiation the response had reduced to five percent of the original value. The time resolution was found to be ∼ 250 picoseconds.