A high-efficiency two-dimensional angular correlation spectrometer for positron studies

Abstract

A two-dimensional angular correlation spectrometer based on position sensitive Anger camera detectors is described. The specification of the machine includes an angular resolution of 0.65 mrad FWHM by 0.65 mrad FWHM over an angular field of order 21*21 mrad2 and an exceptionally high efficiency for counting coincidence events. The spectrometer design is discussed in the light of the basic measurement problem and its performance is illustrated with the aid of the results of explicit test measurements and some representative results.