Investigation and Development of a High Accuracy Radiation Belt Weigher. Final Report for the Period 1 July 1982-30 June 1984

摘要

The aim of the project was to analyze the performances of presently existing radiation belt weighers and to propose and test ways for error reduction. It was shown that the main source of error is due to the non-uniform loading of the belt. The errors for the most commonly used types of weighers were estimated. Two ways for error reduction are suggested and discussed: a) linearization of the absorption exponent with variable dead time; and b) positioning of the scintillation detector. The principle of the dead time linearization is based on the higher number of surpressed counts for higher counting rates. Thus the error from transverse load irregularities can be reduced twice and the error from longitudinal irregularities for heavy load and ''bad'' load distribution ( mu d equivalent 1.) can be reduced below 1%. The detector positioning of one long scintillation detector makes possible the construction of a multi-channel weigher which is equivalent to a multi-detector system. A new type of radiation belt weigher is proposed and discussed. The proposed scanning radiation belt weigher combines the advantages of the ''classical'' radiation weighers - reliability, with the performance of a multi-channel weigher. The principle of operation of the scanning weigher is as follows: a point gamma source is positioned in a rotatory collimator which has several channels. It is constructed in such a way that only one beam at a time scans transversely the load on the belt. The rotation of the collimator is synchronized with the counting system thus ''splitting'' the scintillator into a number of detectors. (Atomindex citation 16:007228)