부산대학교 도서관

The Fermi Large Area Telescope (LAT) has established the existence of emission above tens of GeV from GRBs but the sensitivity is limited by statistics. More data are needed to reveal the mechanism of the temporally extended high-energy emission. The LAT consists of a tracker, a calorimeter and an anti-coincidence detector. The standard event classes require that gamma rays convert in the tracker. To increase statistics above 20 GeV, we have developed the "Calorimeter-only" event classes which recover events without usable tracker information. Additionally, their field of view is broader than the regular one. In this talk, we report the performance of them for GRB photon search. I will present them in two cases, a GRB was being pointed by the telescope or was in the outer region of the field of view where the Calorimeter-only classes have larger effective area than the regular ones.