A PULSE ANALYSIS SYSTEM AND COMPUTER PROGRAM FOR THE ROSSI LET COUNTER*
Review articleOpen access
1968/01/01 Simple chapter DOI: 10.1016/B978-1-4832-8312-8.50053-9
AbstractAcceptance of the Rossi LET counter for routine health physics use depends upon the degree to which data collection and analysis can be simplified. This paper describes an electronic system for recording counter events and a computer program prepared for data analysis that contribute toward this end.In developing this system, we found that spectral stability is significantly affected by voltage and gas purity through the mechanism of varying ion collection time. Circuitry has been developed which delays sampling of the pulse height until full charge collection has been achieved. Operation as a sealed chamber has thereby been achieved over useful periods.Since the spectra realized are typically exponential in shape, extremely long data collection times are required to achieve statistical significance for the large pulses. To ameliorate this problem, an analog pulse height computer is used to compress the high energy deposition end of the spectrum according to a selectable power function before pulse height analysis is performed.The data analysis program has been made as flexible as possible to allow further studies in interpretive procedure. The raw data for both radiation field and background (where applicable) are smoothed before determining net counts. The technique used has a minimum of bias as to the spectrum shape. The smoothed spectrum is then analyzed and a probable LET spectrum determined. Since the energy loss spectrum due to mono-LET particles traversing the chamber depends on questionable assumptions, options are included for triangular, exponential, and square stripping functions. From the LET spectrum, the dose and dose equivalent are calculated, and the LET spectrum is smoothed and plotted. Examples are given of the results produced by the system for typical radiation sources.
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