A Portable Dose-Rate Meter Using a Silicon p-n Junction as a Detector

The dose-rate meter comprises a small area p-n junction counter, charge and linear pulse amplifiers, a discriminator and a three decade logarithmic count rate circuit. It is designed to measure tissue dose rates from ß particles in the range 0.1 to 100 Rad/hour. It also measures, approximately, dose-rates from γ-rays in the same range. The design of the circuits and the application of the p-n junction, which is of commercial origin, are described. The mechanical design which features high component density, robustness, low weight and cost is also discussed. The, noise and stability under conditions of varying temperature and power supply voltage is reported. So also, is the dependence of the sensitivity on the nature, distance and direction of the beta source.