  The GLAST Burst Monitor (GBM) will augment the capabilities of GLAST for the
detection of cosmic gamma-ray bursts by extending the energy range (20 MeV to >
300 GeV) of the Large Area Telescope (LAT) towards lower energies by 2
BGO-detectors (150 keV to 30 MeV) and 12 NaI(Tl) detectors (10 keV to 1 MeV).
The physical detector response of the GBM instrument for GRBs is determined
with the help of Monte Carlo simulations, which are supported and verified by
on-ground calibration measurements, performed extensively with the individual
detectors at the MPE in 2005. All flight and spare detectors were irradiated
with calibrated radioactive sources in the laboratory (from 14 keV to 4.43
MeV). The energy/channel-relations, the dependences of energy resolution and
effective areas on the energy and the angular responses were measured. Due to
the low number of emission lines of radioactive sources below 100 keV,
calibration measurements in the energy range from 10 keV to 60 keV were
performed with the X-ray radiometry working group of the
Physikalisch-Technische Bundesanstalt (PTB) at the BESSY synchrotron radiation
facility, Berlin.
