A desktop particle detector using the gas microstrip chamber

Abstract

The physics and operation of the gas microstrip chamber (GMC) is investigated. A recent addition to the family of gaseous ionization detectors the GMC is capable of resolving the x,y position of a charged particle or x-ray to a resolution of less than 200 microns. Improvements to previous designs include the first 100 micron resolution chamber with a low capacitance electrode geometry on ion-implanted spin-on-polyimide. The effect of the electrode voltages and gas pressures on the gas multiplication is measured and compared with an analytical expression for the First Townsend coefficient; the data and theory are in good agreement. A digital readout system capable of reading out a 128 channel GMC at a rate of 7 million samples / second has been designed and built using off-the-shelf, high speed discriminators, programmable logic devices and memory. This system was used to image a collimated x-ray source and an electrophoresis gel containing tritium labeled protein. Some applications for this detector include its use in high energy physics experiments as well as for x-ray crystallography and digital autoradiography.