Tracking, Imaging, and Polarimeter Properties of the TIGRE Instrument
T. J. O'Neill, A. Akyüz, D. Bhattacharya, G. L. Case, D. Dixon,
J. Samimi, O. T. Tümer, R. S. White, A. D. Zych
A&A Supplement, 120, C661 (1996)
Abstract
The Tracking and Imaging Gamma Ray Experiment (TIGRE) was designed to
observe cosmic gamma-ray sources at energies of 0.3 to 100 MeV.
It uses multilayer silicon strip detectors to track Compton recoil
electrons and positron-electron pairs and small CsI(Tl) crystals
to measure the position and energy of the scattered photon.
The energy and momentum of the scattered electron and the scattered
photon allows the determination of the incident direction uniquely.
Traditional Compton telescopes all use a time-of-flight between two
detectors, whereas TIGRE uses the electron track in the silicon strip
to distinguish between upward and downward moving photons. This allows
one to decrease the distance between the two detection arrays thereby
increasing the instrument efficiency significantly. TIGRE is also a
gamma-ray polarimeter, making use of the sensitivity of the Klein-Nishina
cross-section for large Compton scatter events. We discuss the results
of up/down tracking discrimination, CLAD imaging, and the polarimetry
properties of TIGRE.