12-20 July 2017
Asia/Seoul timezone
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BEXCO - Room F(201/202/203/204)

[GA225] Simulation study for the proposed wide field-of-view gamma-ray detector array ALTO


  • Satyendra THOUDAM

Primary authors

  • Satyendra THOUDAM (Department of Physics and Electrical Engineering, Linnaeus University, Växjö, Sweden)


  • Michael PUNCH (Department of Physics and Electrical Engineering, Linnaeus University, Växjö, Sweden; 2) APC, Univ Paris Diderot, CNRS/IN2)
  • Yvonne BECHERINI (Department of Physics and Electrical Engineering, Linnaeus University, Växjö, Sweden)


ALTO is a wide field-of-view air shower array for very-high-energy (VHE) gamma-ray astronomy, proposed to be installed in the Southern Hemisphere at an altitude of ~ 5.1 km above sea level. The array will use water Cherenkov detectors, as in the HAWC observatory, but combined with scintillator detectors, to detect air showers induced by VHE gamma rays in the atmosphere. It will be designed to attain a lower energy threshold, better energy and angular resolution, and improved sensitivity. The array will consist of ~1250 smaller-sized detector units distributed over a circular area of ~200 m in diameter. Each detector unit will consist of a water Cherenkov detector and a liquid scintillation detector underneath which will preferentially identify muons, facilitating the background (cosmic ray) rejection, thereby improving the sensitivity. The background rejection will be further enhanced by the close-packed arrangement and the small size of the detectors which will allow a fine sampling of air-shower footprints at the ground. In this contribution, we will describe the Monte-Carlo simulation of the experiment performed using CORSIKA and GEANT4 simulation packages, the reconstruction of air shower parameters, and the analysis for the signal/background discrimination based on the Boosted Decision Trees technique. We will also present the expected performance of the array in terms of reconstruction accuracies of the shower core, arrival direction, and energy of the primaries, as well as preliminary estimates of the energy threshold and sensitivity for a point-like gamma-ray source.