Fast Neutron Damage to Silicon Junction Particle Detectors

Two silicon junction charged-particle detectors were irradiated with fast neutrons distributed in energy from 1/2 to 6 Mev. Reverse current and pulse height spectra of U-234 ¿ particles were observed at several bias voltages as functions of neutron dosage. The reverse current of both detectors increased roughly five fold during exposure to 1.2 x 1013 fast neutrons per cm2. From the ¿ pulse heights the capacitance (at some fixed bias) of one detector vas found to increase roughly 25% per 1012 nvt. Approximately 50% of this change was restored by 1000 hours of annealing at room temperature. In the other detector, the ¿ pulse height decreased at a similar rate, but the data was obscured by the development of unusually large pulse rise times.