A Sealed High Pressure Xenon Filled Imaging Proportional Counter with a Sensitive Area 30cm Square

The performance of an imaging proportional counter (IPC) 30cm square is evaluated in this paper. The scaling effects involved in the construction of such a device were investigated using an electrode array alone and a xenon-methane filled IPC. In the IPC, a spatial resolution of 1.2mm FWHM was achieved; and as expected this limitation is shown not to be due to the electronic signal to noise ratio, but to the widely dispersed secondary avalanches initiated by ultra violet photons emitted by excited xenon atoms.