Assessment of single crystal diamond detector radiation hardness to 14 MeV neutrons

Single Crystal Diamonds (sCD) have been selected as neutron detectors for the ITER Radial Neutron Camera (RNC). This paper investigates experimentally the hardness of these detectors to 14 MeV neutrons in order to have indications of their limits of applicability in the RNC. The experiment has been performed at the Frascati Neutron Generator (FNG) facility using three sCDs of different thickness (500, 300,100 mu m). The degradation of the sCD Charge Collection Efficiency (CCE) with increasing 14 MeV neutron fluence has been found to be lower with decreasing sCD thickness. Strong polarization effects produced by the trapping of charge carriers in the defects produced by the neutron irradiation are observed already at about 4. 10(14) n/cm(2) in the 100 mu m thick sCD. A software correction of the polarization effect is proposed, which enables to extend the sCD range of operation up to higher fluences. Taking into account such correction, a 50 mu m thick sCD is expected to reach 10(15) n/cm(2) with a CCE greater than 0.7.