The GLAST Silicon-Strip Tracking System
R.P. Johnson, W.B. Atwood, V. Chen, H.A. Hernando,
M. Hirayama, W. Kroeger, G. Paliaga, H. Sadrozinski
E. Bloom, J. Broeder, E. do Couto e Silva,
G. Godfrey, T. Handa, M. Nordby
W. Miller, E. Ponslet
The GLAST instrument concept is a gamma-ray
pair conversion telescope that uses
silicon microstrip detector technology to
track the electron-positron pairs
resulting from gamma-ray conversions in thin
lead foils. A cesium iodide calorimeter
following the tracker is used to measure the energy.
Silicon strip technology is
mature and robust, with an excellent heritage in
space science and particle physics.
It has many characteristics important for optimal
performance of a pair conversion
telescope, including high efficiency in thin
detector planes, low noise, and excellent
resolution and two-track separation. The
large size of GLAST and high channel count in
the tracker puts demands on the technology
to operate at very low power, yet with
sufficiently low noise occupancy to allow self
triggering. A prototype system employing
custom-designed ASIC's has been built and tested
that meets the design goal of
approximately 200 microwatts per channel power
consumption with a noise occupancy of less
than one hit per trigger per 10,000 channels.
Detailed design of the full-scale tracker
is well advanced, with all components prototyped,
and a complete 50,000 channel
engineering prototype tower module is currently
under construction and will be tested in
particle beams in late 1999. The flight-instrument
conceptual design is for a 4×4 array
of tower modules with an aperture of 2.9 m2
and an effective area of greater than 8000 cm2.
File translated from TEX by TTH, version 2.32.
On 2 Aug 1999, 16:04.