Electronics for low-level counting using a microcomputer

A low-cost electronic system for low-level radioactivity measurements is described. Counts of one or more detectors are handled by integrated amplifiers/quad-discriminators and anticoincidence units, interfaced to an 8-bit microcomputer with external printer which provide a maximum of 15 recording channels. Software effects a clock and counting timers, and furthermore data manipulation such as output tabulation and testing of counting statistics. Interrupt-controlled microprocessopr input is realized at 80 μs electronic dead time. This system was implemented to adopt three gas counter detectors, each equipped with its own guard counter, and with five recording channels per detector, and it has performed extremely well over more than a year of continuous operation. Its expected count rate loss of less than 0.2% has been verified by observation.