GRS consists of two identical BGO (bismuth germanate oxide) scintillators (GRS-1 and GRS-2). Each scintillator is 7.6 cm in diameter and 5.1 cm in thickness. The window of each BGO scintillator is covered with a 0.5 mm thick lead absorber to suppress low-energy gamma-rays associated with solar flares. GRS covers the photon energy band from 0.3 MeV to 100 MeV. The energy resolutions is 14 % at 0.662 MeV and 6 % at 4.07 MeV. Inflight energy calibration is achieved by detection of the 1.173 and 1.333 MeV lines emitted by a Co-60 radioactive source. Each GRS has a six-channel PC, a 128-channel PHL and a 16-channel PHH. The energy bands of the PC and PH are given in the table in section 4.5.
The GRS instrument calibration are stored in the following data files located in the directory $DIR_WBS_CAL (/ys/wbs/response) and in IDL programs.
