Dependence of position signal on pulse height and gas gain for 3H .BETA.-rays observed with position sensitive proportional counter.

Abstract

Position information obtained with a charge division type position sensitive proportional counter for 3H β-rays emitted from a point source depends on the pulse height and the gas gain, because the gas gain for each β-ray is influenced by the direction of its track with respect to the anode wire. With the increase of the gas gain, position signals of pulses with large pulse height appear first in a single broad position, and then in two different positions. The reason is that the gas gain for 8-rays making the tracks perpendicular to the anode wire is smaller than that for those parallel to the wire owing to self-induced space charge effect at large gas gain. Consequently, the parallel tracks give the largest pulse height of all. When isobutane is used as counting gas, with the further increase of the gas gain position signals of pulses with large pulse height appear in three different positions and finally in a single position. The final phenomenon in isobutane means that the gas gain for β-rays making t...