Design and development of a computer-based continuous monitor for the determination of the short-lived decay products of radon and thoron

A portable, rugged, monitor has been designed and built for measuring the short-lived decay products of radon and thoron. The monitor is computer-based and employs a continuous filter strip which can be advanced at programmable time intervals to allow unattended continuous operation with automatic sampling, analysis and recording of radiation levels. Radionuclide analysis is carried out by two silicon diffused-junction alpha-detectors and electronic circuitry with multichannel spectral analysis capabilities. Standard gross α-count methods and α-spectroscopy methods can easily be implemented. The built-in computer performs a variety of operations via a specially designed interface module, including control and data recording functions, and computations, program storage and display functions. Programs and data are stored in the built-in casette tape drive and the computer integrated CRT display and keyboard allow simple, prompted menu-type operation of standard software. Graphical presentation of α-spectra can be shown on the computer CRT and printed when required on the computer built-in thermal printer. In addition to implementing the specially developed radionuclide analysis software, the operator can interact and modify existing software, and program new ones, through BASIC language programming, or employ the computer in a totally unrelated, general purpose mode. Although the monitor is ideally suited for environmental radon (thoron) daughter monitoring, it could also be used in the determination of other airbone radionuclides provided adequate analytical procedures are developed or included in the already existing computer software.