|
Author(s) |
Borwankar, C.; Sharma, M.; Bhatt, N.; Bhattacharyya, S.; Rannot, R. C.; Tickoo, A. K. (ApSD)
|
Source |
Nuclear Instruments & Methods in Physics Research-A, 2020. Vol. 953: Article no. 163182 |
ABSTRACT
|
MACE (Major Atmospheric Cherenkov Experiment) is a Very High Energy (VHE) 𝛾 ray telescope, under installation at Hanle (32o46′ 46′′ N, 78◦ 58′ 35′′ E) in the Himalayan ranges of North India. It is a 21 m diameter dish and 25 m focal length Imaging Atmospheric Cherenkov Telescope (IACT) located at an altitude of 4270 m, highest for any existing IACT. In this paper, we estimate 4 performance characteristics of the MACE telescope, namely the trigger rate, the integral flux sensitivity, the angular resolution and the energy resolution in the dynamic energy range of ∼ 30 GeV–10 TeV in the low zenith angle range (< 30o). We observe that the integral rate of the MACE telescope for the 4 closed clusters nearest neighbor (CCNN) trigger with single-channel photoelectron threshold of 9.0 photoelectrons is 1.03 kHz. The integral flux sensitivity of the telescope is expected to be 2.4 % with the threshold energy of 31 GeV. We employ the Random Forest method (RFM) and show that the MACE telescope is estimated to have an angular resolution, defined as the 𝜎 of a 2-dimensional Gaussian distribution, of ∼ 0.21◦ in the energy range of 30.0–47.0 GeV. The angular resolution improves with increasing 𝛾-ray energy and reaches to a value of ∼ 0.06o in the energy range of 1.8 TeV–3 TeV. We also evaluate 68% containment radius (𝜎0.68) for the distribution of reconstructed arrival directions as an alternative estimate of angular resolution. We find 𝜎0.68 to steadily improve from a value of 0.36o in the energy range of 30.0–47 GeV to a value of ∼ 0.09o in the energy range of 1.8–3 TeV. We also reconstructed 𝛾-ray energies using the regressive RFM and estimated the energy resolution, defined as the 𝜎 of the 1-D Gaussian fitted to distribution of fractional difference between the true and estimated energy, as a function of 𝛾-ray energy. The MACE telescope is estimated to have energy resolution of ∼ 40% in the energy range (30–47) GeV (close to the analysis energy threshold of the MACE telescope), which improves to ∼ 19.8% in the energy bin of 1.8–3 TeV. The bias in the corresponding energy ranges improves from ∼ 36% to ∼ −0.2%. |
|
|
|