Speaker
Description
We give a detailed description and the main results of the electron spectrometer placed onboard the Demeter satellite. This detector with a large geometrical factor is aimed to measure electron fluxes close to 90° pitch-angles 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. In survey mode, the energy resolution, about 18 keV, and the 128 energy channels allow to obtain insights on the radiation belt structure and dynamics. The data were received from the DEMETER launch in 2004 up to 2011 when the data acquisition was stopped. Some results on the global effect of VLF transmitters and of atmospheric lightnings on radiation belt electrons are presented and discussed as well as global measurements of electron/proton energy structuring associated to drift modulations. We also emphasize some physical and electronics limitations of the measurement such as minimum ionization leading to an overestimation of low energy fluxes and impulses pile-up leading to an apparent increase of the high energy fluxes. We also discuss how the large geometrical factor of the instrument, allowing the detection of low fluxes of electrons and the collection of large count rates has the side effect of increasing the detector dead-time.
