DESIGN OF TISSUE-EQUIVALENT PROPORTIONAL-COUNTERS

This paper deals with those factors which are of importance in the des ign of tissue equivalent proportional counters. Basic physical process es in the transport of ions and electrons through gases are discussed, as well as electron avalanche, but only from simple classical approxi mations. Monte Carlo techniques are dealt with elsewhere in this volum e. Emphasis is on practical design considerations, and therefore the i mportance of geometrical factors is considered in some detail, as is p hysical size. These design parameters are illustrated with some succes sful designs of both cylindrical and spherical types. Finally, some of the more exotic recent developments in proportional counters are illu strated.