A liquid xenon position sensitive gamma-ray detector for positron annihilation experiments

A liquid xenon position sensitive gamma-ray detector for positron annihilation experiments has been constructed. The detector is a single wire drift chamber filled with liquid xenon and consists of a drift space for electrons whose sensitive volume is 50 mm x 50 mm x 10 mm thick, and single wire proportional counter for detection of the drifted electrons. The incident position of gamma-rays is determined by measuring the time interval between the direct scintillation due to electrons produced by gamma-rays and the proportional scintillation initiated by drifted electrons near the anode wire of the proportional counter. The intrinsic spatial resolution of 0.6 mm at fwhm was achieved for collimated 662 keV gamma-rays with a high detection efficiency. (orig.)