The Performance of a Multistep Proportional Counter for Use in X-Ray Astronomy

The addition of a parallel field preamplification region has been shown to dramatically improve the performance of a standard multiwire proportional counter, permitting high overall gas gains to be achieved, a prerequisite for good spatial resolution, without in any way compromising energy resolution. The resulting device, known as a multistep detector, has been tested over a wide range of operating conditions and fill gas mixtures. Results are presented here detailing the performance available with argon and xenon as the principle gases, these being of particular relevance to x-ray astronomy.