Milagro is a water-Cherenkov detector capable of observing air showers produced by gamma- rays. The wide field of view (~2 sr) and high duty cycle (>90%) of Milagro make it ideal for searching for transient very high energy emission. We will report on the results of a blind search of the Milagro data for very high energy ranging from 160 μs to 6 minutes. While this analysis is primarily aimed at detecting -ray bursts (GRBs), it could also be sensitive to other phenomena like primordial black-hole evaporation and soft gamma -ray repeaters. No trigger from another instrument is required, instead the entire reconstructed data set is systematically searched in time, space and emission duration. Four years of Milagro data are searched, which corresponds to 2920 sr days of exposure. While the peak sensitivity of Milagro is above 1 TeV, the detector has substantial effective area at lower energies (~50 m^2 at 100 GeV, ~2500 m^2 at 1 TeV).

Milagro

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 3 (OG part 2), pages 1135-1138