We are working on the development of a new balloon-borne telescope, MARGIE (Minute-of-Arc Resolution Gamma ray Imaging Experiment). It will be a coded aperture telescope designed to image hard X-rays (in various configurations) over the 20-600 keV range with an angular resolution approaching one arc minute. MARGIE will use one (or both) of two different detection plane technologies, each of which is capable of providing event locations with sub-mm accuracies. One such technology involves the use of Cadmium Zinc Telluride (CZT) strip detectors. We have successfully completed a series of laboratory measurements using a prototype CZT detector with 375 micron pitch. Spatial location accuracies of better than 375 microns have been demonstrated. A second type of detection plane would be based on CsI microfiber arrays coupled to a large area silicon CCD readout array. This approach would provide spatial resolutions comparable to that of the CZT prototype. In one possible configuration, the coded mask would be 0.5 mm thick tungsten, with 0.5 mm pixels at a distance of 1.5 m from the central detector, giving an angular resolution of 1 arc-minute and a fully coded field of view of 12 degrees. We review the capabilities of the MARGIE telescope and report on the status of our development efforts and our plans fora first balloon flight.

We report progress in ongoing measurements of the performance of a sub-millimeter pitch CdZnTe strip detector developed as a prototype for astronomical instruments. Strip detectors can be used to provide twodimensional position resolution with fewer electronic channels than pixellated arrays. Arrays of this type are under development for the position-sensitive image plane detector for a coded-aperture telescope operating in the hard x-ray range of 20-200 keV. The prototype is a 1 .5 mm thick, 64 x 64 orthogonal stripe CdZnTe detector of 0.375 mm pitch in both dimensions, approximately one square inch of sensitive area. In addition to energy and spatial resolution capabilities, as reported last year, we demonstrate the imaging capabilities and discuss uniformity of response across an 8 x 8 stripe, 64 "pixel", segment of detector. A technique for determination of the depth of photon interaction is discussed and initial results related to depth determination are presented. Issues related to the design and development of readout electronics, the packaging and production of strip detectors and the production of compact strip detector modules, including detector and readout electronics, are also discussed.

We are working on the development of a new balloon-borne telescope, MARGIE (Minute-of-Arc Resolution Gamma ray Imaging Experiment). It will be a coded aperture telescope designed to image hard X-rays (in various configurations) over the 20-600 keV range with an angular resolution approaching one arc minute. MARGIE will use one (or both) of two different detection plane technologies, each of which is capable of providing event locations with sub-mm accuracies. One such technology involves the use of Cadmium Zinc Telluride (CZT) strip detectors. We have successfully completed a series of laboratory measurements using a prototype CZT detector with 375 micron pitch. Spatial location accuracies of better than 375 microns have been demonstrated. A second type of detection plane would be based on CsI microfiber arrays coupled to a large area silicon CCD readout array. This approach would provide spatial resolutions comparable to that of the CZT prototype. In one possible configuration, the coded mask would be 0.5 mm thick tungsten, with 0.5 mm pixels at a distance of 1.5 m from the central detector, giving an angular resolution of 1 arc-minute and a fully coded field of view of 12 degrees. We review the capabilities of the MARGIE telescope and report on the status of our development efforts and our plans fora first balloon flight.