In order to evaluate the possible modifications induced in the source energy spectrum by the calibration environment (e.g. walls, measurement set-up, source supporting structures), as discussed in section 3.1.2, a calibration of the radioactive sources was performed using a 1.4 cm thick NaI scintillator located at the satellite position in a configuration similar to the GRBM calibration configuration.
Other measurements of calibration sources spectra were carried out before and after the ESTEC campaign with a Germanium (Beryllium window) detector at the ENEA and IAS/CNR laboratories (Frascati, ITALY) to study possible effects of the source support on the shape of the source spectra.