Electronic pocket dosimeter

Abstract

Small, light-weight portable radiation measurement apparatus provides accurate quantitative measurment of radiation dosage and dosage rates. Such apparatus, referred to as a dosimeter, is housed in a ruggedized housing that is only about 1/2 the volume of a package of cigarettes, may easily be clipped to clothing or carried in a shirt pocket, and is powered by a conventional alkaline AA-sized battery. Included in the housing are a geiger tube for detecting radiation, a high voltage power supply for providing power to the geiger tube, a counting circuit for counting geiger pulses generated by the geiger tube, a microprocessor circuit for processing the geiger pulses in accordance with a prescribed program to determine the does or dosage rate to which the geiger tube has been exposed, and a digital display that displays the dosage rates thus determined. The microprocessor program is stored in memory circuits, included as part of the microprocessor circuit. An audible alarm is generated whenever the dose or dosage rate exceeds a programmable threshold. The circuitry and display allow a wide range of radiation levels to be detected and displayed. All the circuits are designed for low power consumption, allowing 500-600 hours of continuous use before having to replace the battery. A dielectrically coupled communications port allows necessary data, e.g., calibration coefficients or dosage data, to be transferred to and from the dosimeter circuitry without direct physical contact.