Ultra-high-pressure proportional counter. Pt. 1

Low-pressure argon/xenon-filled proportional counters have been used extensively for the detection of photons and charged particles in the fields of nuclear physics and X-ray astronomy. In general, gas counters have better energy resolution, lower background, simplicity of structure and lower cost compared to semiconductor and scintillation detectors but suffer from low detection efficiency at higher photon energies. To extend the use of gas detectors into the low-energy gamma-ray region, and examine their physical limitations, we have been pursuing a programme to develop and fabricate ultra-high-pressure argon/xenon-filled counting modules with pressures up to 2750 kPa (≅400 psi) for the detection of X-ray photons up to 1 MeV. This development is aimed at a new large-area balloon-borne detector system for low-energy gamma-ray astronomy. This paper concerns the detailed description of the gas multiplication behaviour and pulse properties for a detector filled with argon mixtures at high pressures. (orig.)