New Detector for Observing Very High Energy Gamma-Rays from Celestial Sources

摘要

The Keck Solar Two Gamma-Ray Observatory is a ground-based instrument is being developed to detect 20-300 GeV gamma rays by sampling the Cherenkov light generated as gamma rays and cosmic rays interact with the atmosphere. The observatory utilizes the Solar Two Pilot Power Plant in Barstow, California (Figure 1) which has the largest heliostat mirror area in the world. It has over 1.818 heliostats each with about 41 cm~2 mirror area. The total active area is over 75,000 m~2. Thus, Keck Solar Two Gamma Ray Observatory has the potential to be the most sensitive ground-based gamma-ray detector between 20-300 GeV. The secondary mirror systems, each capable of viewing 32 heliostats has been designed. The secondary mirror systems also include the photomultiplier tube (PMT) camera, electronics, and heliostat field. The first secondary camera system has been manufactured and it is being calibrated. Working on building the second secondary camera system with 32 helisotats has been started. When the second system is completed a 64 heliostat telescope will be ready to observe 50-300 GeV gamma rays. Further enlargement of the telescope to 128 or 256 heliostat is expected to lower the energy threshold to about 20 GeV.