チェレンコフ望遠鏡のための反射鏡の形状の評価

前田 昇平


Abstract


   Current conditions of mirror frame shape of Cherenkov Telescopes are mainly Davies-Cotton or parabolic one. In this time, we carried out Monte-Carlo simulation with several shapes of mirror frame and examined which is the most suited one. At the first time we made incident photons, which have uniform flux density, into the main mirror with angles 1 to 3 degrees to led focal images of reflected photons. Since the arrival time period of Cherenkov photons generated from air showers is only a few nsecs, so we must consider not only their shapes of focal image but also their timing properties. If we can apply main mirror frame that it has good timing properties, it reduce background photons because the capturing period will be able to shorten, and we can find incoming direction of air showers from the timing distribution. Next, we simulated Cherenkov photons generated from air showers using Monte-Carlo Simulation, and compared focal image's "image parameters" reflected at main mirrors with the case of not using main mirrors. Based on these results, we found the most optimized shapes of main mirror frame using for Cherenkov Telescope in F-value=0.8 is parabolic and adjusted each segment mirror's focal length to the focal plane.