Sensitivity of the HAWC observatory to Gamma-ray Bursts using the scaler system

Author: Dirk Lennarz

Abstract: The High Altitude Water Cherenkov (HAWC) observatory is a ground based very-high-energy gamma-ray detector under construction at Sierra Negra in Mexico at an altitude of 4100 m above sea level. Higher altitude, improved design and a larger physical size is used to more efficiently reject cosmic-ray background and make HAWC 10-20 times more sensitive than its predecessor Milagro. HAWC's large field of view (∼2sr) and over 90% duty cycle make it ideal to search for GRBs. We review the sensitivity of HAWC to GRBs and show that for GRBs similar to GRB 090510, which was observed by Fermi-LAT, HAWC will be able to make greater than 5 sigma discoveries. Limits on > 10 GeV emission from GRB 111016B, studied with HAWC's engineering array of 7 water Cherenkov detectors, are presented. Finally, we will summarize the construction status of HAWC-30.