An automated beta irradiator

To support the continuing effort of the US Department of Energy to maintain high-quality radiological calibrations, the Pacific Northwest Laboratory fabricated an automated beta irradiation system. The system hardware includes a microprocessor that controls the duration of the irradiation and records the input from environmental gauges that measure temperature, humidity, and barometric pressure. A bar-code reader is used to identify dosimeters. A thin-walled ionization chamber is mounted in the irradiation phantom, and its output is measured by a digital electrometer. Both the electrometer and the bar-code reader interface to the microprocessor. Alternating current power for the microprocessor is provided by an uninterruptible power supply. The system software collects the data necessary to perform the irradiation. This includes the source identification number, the delivered dose, and the dosimeter identification number. It also calculates their radiation duration time and generates the signals to open and close the source shutter. The operator is led through a series of parameter verifications and a printout summarizes all of the pertinent data. This paper describes the system in detail. 2 refs., 1 tab.