INITIAL PERFORMANCE OF THE EXITE2 IMAGING PHOSWICH DETECTOR TELESCOPE FOR HARD X-RAY ASTRONOMY

We have developed, tested, and flown a large-area imaging phoswich detector/telescope for hard X-ray astronomy. This second-generation Energetic X-ray Imaging Telescope Experiment (EXITE) is designed to detect and image cosmic X-ray sources in the 20-600 keV energy range from a high-altitude balloon. Imaging is accomplished via the coded-aperture technique. Laboratory tests have shown that the detector achieves 14% (FWHM) energy resolution and approximately 10 mm (FWHM) spatial resolution at 60 keV, and that the pulse-shape discrimination (PSD) circuit effectively distinguishes between NaI(T1) and CsI(Na) events from approximately 40-400 keV. The first flight of the instrument was from Palestine, Texas, on 13-14 June 1993. In this paper, we present details of the laboratory performance of the system and some flight results.