X-RAY POSITION-SENSITIVE DETECTORS .6. ON SOME FACTORS CONTROLLING HIGH-ACCURACY MEASUREMENTS OF X-RAY QUANTA POSITIONS WITH MULTIWIRE PROPORTIONAL CHAMBERS

Multiwire proportional chambers (MWPC) may provide a useful tool for dealing with many problems concerned with the localization of X-ray quanta. The accuracy in the determination of the spatial coordinates of a single quantum in a chamber is controlled by several factors: • - the spatial extension of the secondary electrons produced by the absorption of the quantum; • - the mean free path of the secondary X-rays emitted by the absorbing atom; • - the chamber parameters: detection thickness and wire spacing; • - the read-out method. At LURE, we are trying to build large-size detectors, having a large angular aperture (≈ 90°), accuracies better than 1 mm (fwhm), high counting-rate capabilities (≈ 1 MHz), and high efficiencies (≈ 100% at 8 keV); in this paper we will discuss some problems encountered in this enterprise. © 1978.