Thesis

A Directionality Detector for the JUICE mission Radiation Hard Electron Monitor

• Call:

  IDPASC Portugal - PHD Programme 2014

• Academic Year:

  2014 /2015

• Domain:

  Astroparticle Physics

• Supervisor:

  Patricia Goncalves

• Co-Supervisor:

  Bernardo Tomé

• Institution:

  Instituto Superior Técnico

• Host Institution:

  Laboratório de Instrumentação e Física Experimental de Partículas

• Abstract:

  The Jovian system is known to be outstandingly complex with its extremely hazardous and highly dynamic radiation environment. Therefore, its rigorous, accurate exploration, as well as profound understanding is enormously valuable for answering questions on planet formation and emergence of life. One of the biggest challenges for the ESA JUICE mission, is to measure and handle the compound, intense and highly penetrating radiation environment of Jupiter and its active moons. Based on previous data, it has been long understood that Jupiter radiation field plays a decisive role in radiation damage scenarios for the whole spacecraft and all its payloads. Due to its excessive features such us very high fluxes and wide range of energies, it also drives detection principles for science instruments and in particular for radiation monitors. In this context, a comprehensive, reliable and accurate monitoring of the radiation onboard of the JUICE mission is a major challenge and a high priority task. It is crucial for safe operation and continuity of the mission, as well as for the scientific data analysis support. RADEM is the Radiation Hard Electron Monitor, for JUICE, the next European Space Agency Large mission, which will be heading for JUICE in 2022. It is being developed by an international consortium, lead by EFACEC, and in which LIP, PSI(ch) and IDEAS (no) take part, under a contract with the European Space Agency. In the current phase of the development of RADEM, which started in May 2014 and will contibue untill September 2016, its design concept will be further optimised, and the detector will be calibrated and tested. RADEM is based on a design concept for which a first prototype already exists. The first design concept included an electron detector, the Magnetic Spectrometer (MS) and a proton and heavy ion dedicated sensor, the HEP. Given the dynamics of the Jovian magnetosphere, both the MS and HEP will hardly have their pointing directions aligned with the Jovian magnetic field. Moreover, their limited field of view will intercept a small fraction of the incoming electron and proton fluxes. Such local measurements may either over or underestimate the realistic fluxes and dose rates. The Directional Detector (DD) will allow for proper folding of the measured energy spectrum with the flux angular distribution, giving more accurate values of the averaged fluxes and dose rates. In addition, the comparison with the data from the MS and the redundancy of collected data will allow for the validation and verification of the performances of the detectors, as well as for better calibration. It will also provide better understanding of background and its processing for optimal retrieving of the clean data. The measurement of the electrons directionality along the JUICE trajectory is expected to give crucial and decisively important information for the analysis of the Jovian magnetosphere, inter-ference mechanisms with the moons magnetospheres and plasma diffusion mechanisms. The DD is specifically tailored to cope with very high fluxes of electrons with energies above 300keV. Its data, combined with the precise spectral measurement of the RADEM MS, will be valuable for the crosscorrelation with the measurements of the Particle Package: the plasma analyser for electrons from 1eV to 20keV and the particle analyser for 15keV to 1MeV. The DD is a valuable asset for the scientific data analysis and understanding of the complex Jovian Radiation Environment. The objective of the proposed program is to develop the Directional Detector concept and to study its performance, while integrated in the RADEM instrument, for the duration of the JUICE mission. The different radiation environment models that exist for the Jovian system will be used to study the response of RADEM under the radiation environment expected at the different locations of the JUICE mission orbit and under different spaceweather conditions.