Proton irradiation of CVD diamond detectors for high-luminosity experiments at the LHC

CVD diamond shows promising properties for use as a position-sensitive detector for experiments in the highest radiation areas at the Large Hadron Collider. In order to study the radiation hardness of diamond we exposed CVD diamond detector samples to 24 Gev/c and 500 Mev protons up to a fluence of 5×1015 p/cm2. We measured the charge collection distance, the average distance electron–hole pairs move apart in an external electric field, and leakage currents before, during, and after irradiation. The charge collection distance remains unchanged up to 1×1015 p/cm2 and decreases by ≈40% at 5×1015 p/cm2. Leakage currents of diamond samples were below 1 pA before and after irradiation. The particle-induced currents during irradiation correlate well with the proton flux. In contrast to diamond, a silicon diode, which was irradiated for comparison, shows the known large increase in leakage current. We conclude that CVD diamond detectors are radiation hard to 24 GeV/c and 500 MeV protons up to at least 1×1015p/cm2 without signal loss.