COMPUTER-SIMULATION METHODS FOR INVESTIGATING THE DETECTION CHARACTERISTICS OF TEV AIR CHERENKOV TELESCOPES

Determination of the energy thresholds and detection sensitivities of VHE (10 GeV to 20 TeV) gamma ray astronomy telescopes utilizing the atmospheric Cherenkov technique (ACT) requires the use of computer simulations of gamma ray and hadron induced air showers and their associated Cherenkov light production. We present in this paper methods to determine these parameters that utilize the DePauw-Purdue KASCADE shower simulation program for a variety of existing and proposed ACT telescopes. The KASCADE system is a detailed, three-dimensional computer simulation developed by us that generates the Cherenkov photons produced by VHE gamma ray and hadronic (usually proton) air showers. The KASCADE system has been specifically designed to be of general use as a tool in investigating a variety of ACT telescope designs with the goal of maximizing their gamma ray detection sensitivity. Specific methods for achieving these goals are presented. Also presented are detailed discussions of the various algorithms used by the KASCADE program to simulate air showers. Further, as a demonstration of the utility of these methods and the KASCADE programs we present results of a case study of the detection characteristics of the Haleakala Gamma Ray Observatory telescope.