A Large Area VHE Gamma-Ray Detector for Super High Energies of 10 to 1000 GeV
O. T. Tümer, D. Bhattacharya, D. Dixon, T. J. O'Neill, R. S. White, A. D. Zych
Towards a Major Atmospheric Cerenkov Detector - II, R. C. Lamb, ed., 259, (1993)
Abstract
A new detector system is proposed that will open the unexplored Super High
Energy (SHE) gamma ray region (10 GeV to 1,000 GeV) between the High Energy
(HE) and Very High Energy (VHE) regimes. It is based on atmospheric Cherenkov
light detection from gamma-ray originated air showers and will observe gamma
rays in the transition energy region between the EGRET detector on the Compton
Gamma-ray Observatory (CGRO) (sensitive below 30 GeV) and the present very
high energy (VHE) Cherenkov detectors (sensitive above 500 GeV). SHE
measurements of the high energy end of the EGRET AGN source spectra are
crucial in the understanding of the AGN model. Further insight will also be
gained into the measurements of the VHE and ultra high energy (UHE) celestial
sources measured before with low statistical significance. The detector will
use a central tower system with reflector mirrors covering about 50% of the
ground within a 200 to 300 m diameter. The mirrors reflect the atmospheric
Cherenkov light to the top of the tower where a Fresnel lens or a mirror
system produces an image of the reflectors at its focal plane where an array
of PMTs observes the Cherenkov light cone. The effective area of this
detector is expected to be approximately 10^4 m^2. The cosmic ray background
cuts of rapidly below about 75 GeV allowing significantly lower background for
SHE gamma ray observations. The senitivity of such a detector is expected to
be about 27 milli Crab for a 2 week (4 hr/day) observation for > 10 GeV gamma
rays without any cosmic ray discrimination.