The escape gated proportional counter — A low background and high energy resolution hard X-ray detector

Abstract

Proportional counters, designed to detect X-rays, are generally filled with Xe or Kr or a mixture of Xe and Kr. In a large multichamber proportional counter the K-flourescent radiation of these gases, which escapes the cell of origin, but is absorbed in other cells of the counter, provides an additional signal. A coincidence technique, which makes use of this signal to reduce the charged particle background and to correct the energy spectrum for the escape peak, has been evaluated. The detector has an improved energy resolution over that of the conventional proportional counter and preliminary results indicate that a reduction in the background by a factor of about 1000 can be obtained. Its combined properties of very efficient background reduction and improved energy resolution make this type of instrument most suitable for spectroscopic studies of astronomical X-ray sources in the energy range 15–100 keV.