A HIGHLY PARALLEL IMAGING GAS COUNTER FOR SYNCHROTRON-RADIATION DIFFRACTION

Multiwire proportional counters (MWPCs) currently in use for synchrotr on radiation diffraction offer unrivalled dynamic range and detection efficiency. Unfortunately they have, until recently, been somewhat lim ited in count rate performance and suffer from parallax problems with incoming photons at high angles of incidence. We report on the progres s of a fast 2-D proportional counter detector for use on the beamlines at the Synchrotron Radiation source at Daresbury. It utilises a highl y parallel data acquisition system in order to achieve photon counting rates in excess of 10(6) counts per second. This is coupled to a pres surised proportional counter to reduce the parallax errors. The detect or will have a 200 mm by 200 mm active area and the system will yield a real spatial resolution of approximately 200 mum (FWHM). A review of the system components is made, and a technique for further improving the performance is described.