Measurement of strong gamma fields by silicon detectors working in a current-generation mode

The measurement system is designed to have a Si n+–p–p+ detector and current amplifier. It is examined in strong gamma fields. The detector works in a current-generation mode without applying reverse voltage. The amplifier measures currents in the range of 10−6–10−12 A. The output current is proportional to the gamma-ray intensity. By integrating the output current, the system can measure the radiation dose for a preliminary chosen time. A maximum integral irradiation dose of 59.9 Mrad is obtained for five consecutive periods. The I–V, C–V and α-spectrum measurements show that a self-annealing process of the gamma-ray generated defects occurs during the break time between the consecutive periods. Such an annealing can lead to an extended radiation tolerance in which the output current of the system is proportional to the gamma-ray intensity. Despite the density of the generated defects, a constant output current was observed up to the highest investigated dose of 59.9 Mrad. Since the irradiations are performed at relatively high gamma-ray intensity (25 krad/h), the current-generation rate is much higher than the recombination rate.