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D. Hullinger, S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, C. Markwardt, A. Parsons, J. Tueller, G. Weidenspointner (NASA/Goddard Space Flight Center, USA), E. Fenimore, D.M. Palmer (Los Alamos National Laboratory, USA), K. Nakazawa, G. Sato, T. Takahashi, S. Watanabe (Institute of Space and Astronautical Science, Japan), Y. Okada, H. Takahashi (University of Tokyo, Japan), M. Suzuki, M. Tashiro (Saitama University, Japan)
The Burst Alert Telescope (BAT), one of a trio of instruments aboard the Swift Gamma-ray Burst Explorer, will provide burst triggers and positions as well as light curves and spectra between 15 and ~150 keV. BAT is a coded aperture telescope with a wide (2 steradian) field of view. It consists of an array of 32,768 CdZnTe gamma ray detectors, each 4 mm x 4 mm x 2 mm, lying 1 meter below a coded mask of lead tiles. Raw BAT data will consist of counts recorded in three basic dimensions: time, detector plane position (pixel), and detector deposited energy. The counts recorded in the detector array are modulated by the coded mask, producing an image in the detector plane that can be transformed into a position on the sky. In order to produce the instrument response for this image, it is necessary to separate the mask-modulated portion of the detector plane counts (which contribute to the image) from the unmodulated portion resulting from scattering (which contribute to the background). Generating this instrument response requires both monte carlo simulations (to help separate background counts from those that form the image) and careful ground calibration to measure detector-specific properties such as charge-transport properties, threshold, ADC units-to-deposited energy conversion, and electronics noise, as well as for checking the monte carlo results. Techniques and results from these simulations and calibration measurements will be presented.
The author(s) of this abstract have provided an email address for comments about the abstract: derek@milkyway.gsfc.nasa.gov
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.