GAS AMPLIFICATION IN HIGH-PRESSURE PROPORTIONAL-COUNTERS

We have made absolute gas gain measurements for proportional counters filled with argon/xenon at various pressure up to approximately 30 atm (3000 kPa). Our data show that of the various empirical formulae whic h give gas gain as a function of electric field and gas pressure, the relation proposed by Charles [J. Phys. E5 (1972) 95] gives the best fi t over a wide range of pressures for both argon and xenon. The measure ments further reveal that gas gain data at low pressures cannot be ext rapolated to higher pressures to explain the behaviour of proportional counters filled to such high pressures, because of the changing mobil ity of positive ions. The details of our measurements and the results obtained are described in this paper.