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Calibration of the EGRET gamma-ray telescope with a backscattered laser beam

Thesis/Dissertation ·
OSTI ID:7197722
One of the three co-aligned gamma-ray telescopes to be placed in orbit aboard the Gamma Ray Observatory is EGRET, the energetic gamma-ray experiment telescope. EGRET will measure celestial gamma rays in the energy range 20-24,000 MeV. The telescope uses conversion foils and a spark chamber to resolve gamma-ray direction and is triggered by a directionally sensitive pair of plastic-scintillator arrays. An 8'' thick NaI(Tl) spectrometer below the spark chamber yields information about the gamma-ray energy. The sensitive area is 20 times larger than previous instruments of its type. A full-sky survey is expected to resolve approx. 10 extragalactic and approx. 100 galactic point gamma-ray sources. Diffuse gamma-ray emission will also be examined. A calibration of the telescope to determine efficiency, angular resolution and energy resolution as a function of gamma-ray energy and arrival direction is necessary to analyze the flight data. EGRET received a calibration gamma-ray exposure with a backscattered laser beam. Gamma rays were produced by the Compton scattering of frequency-doubled YAG laser photons from a high-energy electron beam. The SLAC beam was constructed originally to produce 20-GeV gamma rays. Modifications were made to operate over the energy range required for calibration.
Research Organization:
Stanford Univ., CA (USA)
OSTI ID:
7197722
Country of Publication:
United States
Language:
English