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.