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J.D. Kurfess, W.N. Johnson, E.I. Novikova, B.F. Phlips, E.A. Wulf (Naval Research Laboratory), S.O. Nelson, C. Rowland (NRC-NRL Resident Research Associate)
An Advanced Compton Telescope (ACT) is under study for consideration as the next major mission in low/medium energy gamma ray astrophysics. ACT will have broad scientific objectives, but with an emphasis on nuclear astrophysics, especially the detailed investigations of Type Ia supernovae. To achieve the required sensitivity for these investigations, a broad line sensitivity (e.g. 30 keV FWHM for 847 keV line from 56Co) of ~ 3 x 10-7 gamma/cm2-s in 106 sec must be achieved. This represents an improvement of approximately 100 over the capabilities of CGRO and INTEGRAL instruments. Position-sensitive solid-state detectors appear to be the preferred detector technology. We have been pursuing the development of thick silicon detectors for this and other applications. Advantages of silicon include use of standard silicon processing techniques, near room temperature operation, high efficiency using a multiple Compton technique where good energy and angular resolution is achieved without full energy deposition of the incident gamma ray, and improved angular and energy resolution associated with the low Doppler broadening compared to higher-Z material. We will present laboratory performance of a 3-layer stack of silicon detectors, including the energy and imaging capabilities using the multiple Compton scatter technique and the status of a prototype instrument consisting of eight layers with a 2x2 array of detectors in each layer. We will also present plans for larger area and thicker detectors and the simulate performance for a silicon ACT.
This research funded by the Office of Naval Research, NASA and DTRA.
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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.