Study of polycrystalline and single crystal diamond detectors irradiated with pions and neutrons up to 3×1015 cm−2

Polycrystalline CVD (pCVD) diamond detectors are a viable candidate for the innermost tracking layer of experiments at the SLHC, where lifetime fluences are expected to exceed 10¹⁶ particles/cm². Irradiation data of diamonds in this fluence range are scarce, and mostly rely on high-energy protons. According to recent NIEL simulations radiation damage induced by fast reactor neutrons might be representative of degradation by high energy hadrons. Seven detector-grade pCVD and two single crystal CVD (scCVD) diamond 5times5 mm² pad detectors (0.5 mm thick) were acquired from Diamond Detectors Ltd. Four pCVDs were irradiated so far, two to fluences of 1, 3, 10 and 30 times 10¹⁴ fast n/cm² at the TRIGA research reactor in Ljubljana, and two to 3.2 and 6.1 times 10¹⁴ 200 MeV pions/cm² at PSI. Charge collection was measured with a ⁹⁰Sr source using fast electronics with 25 ns shaping in a charge sensitive TCT set-up. Effect of pumping (priming) upon long-time exposure to the 37 MBq beta source was studied. Preliminary results of the charge collection measurements are presented and discussed.