High-energy electron detection onboard DEMETER: The IDP spectrometer, description and first results on the inner belt

This paper gives a description and the first results of the electron spectrometer placed onboard the Demeter satellite. This detector with a large geometrical factor is aimed to measure trapped electron fluxes in the energy range from 70 keV to about 0.8 MeV and to provide information on the electron fluxes between 0.8 and 2.5 MeV. The energy resolution, better than 10 keV, and the 256 energy channels allow to obtain insights on the radiation belt structure. The data received during 2004 show for the first time that the low-energy component of the inner radiation belt (1.1