Detection of Gamma-Ray Bursts in the 1 GeV - 1 TeV energy range by ground based experiments

Ground based extensive air showers arrays can observe GRBs in the 1-1000 GeV energy range using the "single particle" techique. The sensitivity to detect a GRB as a function of the burst parameters and the detector characteristics are discussed. The rate of possible observations is evaluated, making reasonable assumptions on the high energy emission, the absorbtion of gamma-rays in the intergalactic space, the distribution of the sources in the universe and the bursts luminosity function. We show that a large area detector located at high mountain altitude has good prospects for positive detections, providing useful informations on the high energy components of GRBs.Comment: 14 pages, 9 figures, accepted by Astroparticle Physic

Expected sensitivity of ARGO-YBJ to detect point gamma-ray sources

ARGO-YBJ is a full coverage air shower detector currently under construction at the Yangbajing Laboratory (4300 m a.s.l., Tibet, China). First data obtained with a subset of the apparatus will be available in summer 2003 while the full detector operation is expected in 2005. One of the main aims of ARGO-YBJ is the observation of gamma-ray sources, at an energy threshold of a few hundreds GeV. In this paper we present the expected sensitivity to detect point gamma ray sources, with particular attention to the Crab Nebula. According to our simulations a Crab-like signal could be detected in one year of operation with a statistical significance of 10 standard deviations, without any gamma/hadron discrimination.Comment: 4 pages, 2 Postscript figure