Pachmarhi Array of Čerenkov Telescopes

Pachmarhi Array of Cerenkov Telescopes (PACT) has been designed to search for celestial TeV γ-rays using the wavefront sampling technique. PACT consists of 25 telescopes deployed over an area of 80 m×100 m. A telescope consists of 7 parabolic reflectors, each viewed by a fast phototube behind a 3° mask at the focus. The density and arrival time of photons at the PMT are measured. The energy threshold and collection area of the array are estimated, from Monte Carlo simulations, to be ∼1 TeV and 105 m2 respectively. The accuracy in determination of arrival angle of a shower was estimated to be 0.1° in the near vertical direction. About 99% of the off-axis hadronic events could be rejected from directional information alone. Further, nearly 75% of the on-axis hadronic events could be rejected using species sensitive measurements like the photon density fluctuations. These cuts on data to reject back-ground would retain ∼44% of the γ-ray signal. The sensitivity of the array for a 5σ detection of γ-ray signal ...