A Sealed High Pressure Xenon-Carbon Dioxide Filled Position Sensitive Proportional Counter

A sealed position sensitive proportional counter, used in previously reported work with xenon-methane and intended for applications in X-ray astronomy, has been operated with xenon-carbon dioxide at 2 atmospheres pressure. As expected, the improved UV absorption of carbon dioxide limits the effect of secondary avalanches so that a position resolution of 230 microns FWHM is obtained compared with 360 microns in xenon-methane. The modulation of the position signal at the anode wire pitch, observed in xenon-methane is greater in xenon-carbon dioxide for the same amplifier shaping time constant. However, it does diminish for longer time constants and the position resolution improves, contrary to its behaviour in xenon-methane. Thus considerably improved position resolution with marginally degraded linearity are achieved with xenon-carbon dioxide.