Detection of GRB signals with fluorescence detectors

Gamma ray bursts are being searched in many ground based experiments detecting the high energy component (GeV-TeV energy range) of the photon bursts. In this paper, fluorescence detectors are considered as possible candidate devices for these searches. It is shown that GRB photons induce fluorescence emission of UV photons on a wide range of their spectrum. The induced fluorescence flux is dominated by GRB photons from 0.1 to about 100 MeV and, once the extinction through the atmosphere is taken into account, it is distributed over a wide angular region. This flux can be detected through a monitor of the diffuse photon flux, provided that its maximum value exceeds a threshold value, that is primarily determined by the sky brightness above the detector. The feasibility of this search and the expected rates are discussed on the basis of the current GRB observations. The basic requirements for fluorescence detectors to search for GRB signals are finally discussed. It is shown that these requirements are only partially fulfilled by the existing fluorescence detectors and therefore their GRB detection capability turns out to be marginal. (C) 2008 Elsevier B.V. All rights reserved.