Position sensitive proportional counter

Abstract

We are developing a Position Sensitive Proportional Counter for X-rays in the energy range from 2 keV to 20 keV. With the sensitive circular area of 30 mm diameter, it can be used as an imaging detector at the focal plane of a soft X-ray optics. For two demensional position determination of an X-ray event, two multi wire cathode grids of 50 ?m wire spaced at 0.5 mm are used. The final position of the event is obtained by calculating the center of gravity of the charge spread. Accuracy of the order 50 ?m can be achieved by this method. The main anode grid made up of 25 ?m wire spaced at 1 mm gives the standard energy resolution of the proportional counter. Another anode grid is used as an anti-coincidence counter to achieve high degree of background rejection.