In-flight calibration of RADEM, the JUICE mission radiation monitor

Fuente: arXiv
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Autori principali: Pinto, Marco, Santos, Francisca, Gomes, António, Gonçalves, Tomás, Arruda, Luísa, Gonçalves, Patrícia, Rodríguez-García, Laura, Vainio, Rami, Witasse, Olivier, Altobelli, Nicolas
Natura: Preprint
Pubblicazione: 2026
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author Pinto, Marco
Santos, Francisca
Gomes, António
Gonçalves, Tomás
Arruda, Luísa
Gonçalves, Patrícia
Rodríguez-García, Laura
Vainio, Rami
Witasse, Olivier
Altobelli, Nicolas
author_facet Pinto, Marco
Santos, Francisca
Gomes, António
Gonçalves, Tomás
Arruda, Luísa
Gonçalves, Patrícia
Rodríguez-García, Laura
Vainio, Rami
Witasse, Olivier
Altobelli, Nicolas
contents The RADiation-hard Electron Monitor (RADEM) aboard the Jupiter Icy Moons Explorer (JUICE), launched on 14 April 2023, measures high-energy protons and electrons during the cruise phase and will continue throughout the nominal mission. Initial in-flight observations could not be explained by pre-flight ground calibration, motivating an in-flight calibration campaign. We calibrated the RADEM sensors using galactic cosmic rays by progressively increasing detector thresholds, thereby modifying their response to high-energy particles. Threshold-dependent in-flight count rates were compared with theoretical expectations derived from the Badhwar-O'Neill 2020 galactic cosmic ray model and corresponding response functions. These results were used to derive new in-flight calibration coefficients and to develop a flux reconstruction algorithm based on the bow-tie method. In several cases, the in-flight calibration slopes differ by up to an order of magnitude from ground calibration values. Proton fluxes from solar energetic particle events reconstructed with this method agree within a factor of two with independent measurements from the Solar and Heliospheric Observatory. These results demonstrate that RADEM provides accurate proton flux measurements in interplanetary space and is well suited for both single-spacecraft analyses and coordinated multi-mission studies of solar energetic particles. While electrons were clearly detected during the JUICE Lunar-Earth gravity assist, reliable reconstruction of their fluxes requires further analysis.
format Preprint
id arxiv_https___arxiv_org_abs_2602_24246
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle In-flight calibration of RADEM, the JUICE mission radiation monitor
Pinto, Marco
Santos, Francisca
Gomes, António
Gonçalves, Tomás
Arruda, Luísa
Gonçalves, Patrícia
Rodríguez-García, Laura
Vainio, Rami
Witasse, Olivier
Altobelli, Nicolas
Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
Instrumentation and Methods for Astrophysics
The RADiation-hard Electron Monitor (RADEM) aboard the Jupiter Icy Moons Explorer (JUICE), launched on 14 April 2023, measures high-energy protons and electrons during the cruise phase and will continue throughout the nominal mission. Initial in-flight observations could not be explained by pre-flight ground calibration, motivating an in-flight calibration campaign. We calibrated the RADEM sensors using galactic cosmic rays by progressively increasing detector thresholds, thereby modifying their response to high-energy particles. Threshold-dependent in-flight count rates were compared with theoretical expectations derived from the Badhwar-O'Neill 2020 galactic cosmic ray model and corresponding response functions. These results were used to derive new in-flight calibration coefficients and to develop a flux reconstruction algorithm based on the bow-tie method. In several cases, the in-flight calibration slopes differ by up to an order of magnitude from ground calibration values. Proton fluxes from solar energetic particle events reconstructed with this method agree within a factor of two with independent measurements from the Solar and Heliospheric Observatory. These results demonstrate that RADEM provides accurate proton flux measurements in interplanetary space and is well suited for both single-spacecraft analyses and coordinated multi-mission studies of solar energetic particles. While electrons were clearly detected during the JUICE Lunar-Earth gravity assist, reliable reconstruction of their fluxes requires further analysis.
title In-flight calibration of RADEM, the JUICE mission radiation monitor
topic Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2602.24246