JUICE, the Jupiter Icy Moons Explorer, ESA's next L-class mission to the Jovian system, will carry a radiation hard electron monitor (RADEM). It will be the first mission since Galileo to perform long-term measurements of the Jovian radiation environment. RADEM has challenging low mass and power constraints which required novel detector concepts. In this paper, we present a RADEM directionality detector and describe its capability to measure radiation angular variability.

ESAs next class-L mission to the Jovian system, the Jupiter Icy Moons Explorer (JUICE), will collect valuable data while orbiting Jupiter and three its moons for a period of three and a half years. RADEM, the Radiation Hard Electron Monitor is being developed to provide housekeeping information for the mission. It will also gather valuable scientific data on the energetic radiation environment of the Jovian system for its full duration. The Jovian radiation environment, dominated by electrons, results from Jupiter strong magnetic field and its interaction with the Galilean moons. So far, only the Galileo spacecraft performed long-term measurements of the radiation environment showing that it is extremely hazardous and complex. RADEM features four detector heads: the Proton Detector Head to measure protons energies, the Ion Detector Head to measure ion content up to oxygen; the Electron Detector head to perform electron spectral measurements; and the Directionality Detector Head to correct for electron flux angular dependences. The detectors readout are three newly custom designed ASIC IDE3466. In this work, RADEM overall properties and Engineering Model radiation tests results are presented.

The multifunctional spectrometer (MFS) is a radiation monitor installed on the X panel of the Alphasat satellite, in geostationary orbit (GEO) since July 2013. The MFS was specially tailored to characterize the space radiation environment in GEO and it is expected to acquire scientific data during a total lifetime of five years. An end-to-end Geant4 simulation of the MFS flight model based on the full geometry of the MFS, imported from computer-aided design (CAD) to geometry description markup language, was implemented and validated with the MFS ground-test results obtained in Paul Scherrer Institute facilities in 2010. The MFS simulation was then used to derive response functions for the MFS electron and proton channels. This paper describes the implementation of a maximum likelihood fit method to reconstruct particle spectra from MFS data, and its application to the reconstruction of the electron spectra for a 20-day period centered on the occurrence of January 2, 2014, solar energetic particle event. The obtained electron integral fluxes for this period are in reasonable agreement with GOES-15 public data and with the predictions of the AE8MIN update and IGE-2006 models.

The MFS (Multi-Functional Spectrometer) is a radiation monitor that together with CTTB (Component Technology Test Bed) make the AEEF-TDP8 (ESA Alphasat Environment and Effects Facility - Technology Demonstration Payload 8). The two units are hosted in the X panel of the Alphasat satellite in orbit since July 2013. MFS is an instrument specifically designed to characterise the Space Radiation environment while CTTB was built to monitor the effect of radiation on electrical components (GaN transistors, Memories and Optical Transceivers) in geostationary orbit. The mission lifetime of AEEF/TDP8 will be at least of three years and TDP8 is expected to be acquiring scientific data during the whole period. On ground, correlation between radiation environment and radiation effects can be established. Before launch, MFS was submitted to proton and electron beam tests at Paul Scherrer Institute in Switzerland in 2010. The main purpose was the validation and calibration of the MFS proto-flight model together with the estimation of particle energy resolution and identification capability. A full Geant4 simulation with CAD (Computer-aided design) geometry exported to GDML (Geometry Description Markup Language) description the MFS in-flight configuration was built. Ground tests results were validated with Geant4 simulation. The measurements of MFS proton channels and MFS proton response functions are evaluated using comparisons with INTEGRAL/IREM data during the Solar Proton Event (SPE) of January 2014. In addition, an Artificial Neural Network (ANN) unfolding method was developed in order to unfold MFS data. Comparisons show that the derived ANN Alphasat/MFS fluxes are in remarkable agreement with INTEGRAL/IREM proton fluxes.