BeppoSAX GRBM on-ground calibrations data analysis

We describe the analysis of BeppoSAX Gamma-Ray Burst Monitor on-ground calibrations performed after the full integration of the spacecraft in order to explore in detail the dependence of the detectors efficiency on the direction and energy of impinging photons. Analytical techniques have been used to determine with reasonable accuracy this function by fitting the angular response at different calibration energies with simple models partially derived from the underlying physics and partially semiempirical. Satisfactory results have been obtained for the two detectors which have almost clean field of view and are co-aligned with the Wide Field Cameras. Work is still in progress for the others. Preliminary results of ground calibration analysis have been already used to derive spectral information on gamma-ray bursts impinging parallel to the axis of the two best performing shields.