NaI(Tl) - CsI(Na) Phoswich Detectors for X-Ray Astronomy

The design and performance of NaI(Tl) - CsI(Na) phoswich detectors for X-ray Astronomy applications are presented. Phoswich techniques enable the design of low-background, actively-shielded detectors of large sensitive area, while maintaining minimum weight and cost. Results from a balloon-borne test flight incorporating several detectors, including one with an effective area of 765 cm2, are discussed.