PEP Particle Environment Package for JUICE - Design for the Jupiter radiation environment. Continuation of ST/N000161/1 2017-18

Particle Environment Package (PEP) is a complete, highly versatile and optimized, single-interface suite of nine sensors, which addresses all JUICE top level scientific objectives. Modelling radiation effects on the instruments, which is the responsibility of the Aberystwyth team, is crucial due to the harsh radiation environment at Jupiter. The solid radiation analysis of the resulting design, which employs smart design solutions to mitigate radiation: effective mutual shielding and the usage of single to triple coincidence detection schemes in all sensors, was called out by the ESA selection panel as one of the chief factors which led to PEP selection. Aberystwyth led the radiation design group during the proposal, and will continue in that role during the design phase. A crucial factor was an STFC funded PhD. The Aberystwyth group was able to run detailed GEANT4 radiation simulations for the real instrument design, as imported directly from CAD designs. This unique capability enables us to ensure the survivability of the instrument, and critically, to tune the design to maximise the signal to noise ratio for the 9 different sensor measurements. This is facilitated by the availability of major in-house supercomputing capabilities provided under EU and Welsh funding, which allows independence to undertake these large simulations. JUICE is unique in the dependence of measurement quality on radiation design, and our early appreciation of this requirement led to a new team approach to instrument optimisation. Although our role is not as conventional hardware providers, we are playing a leading role in the design of the entire suite of plasma instruments, with profound influence on the final configuration. The PEP consortium is based around the highly successful international team which produced the ASPERA3 and 4 instruments for Mars and Venus Express; Aberystwyth has a long heritage with this group, being core members of both ASPERA teams. One consequence of the degree of optimisation adopted is that the design of instruments should evolve according to the spacecraft configuration chosen by ESA - this is dependent on self-shielding to maximise the instrument performance in a given spacecraft configuration. We have maintained good contact with ESA, as evidenced by the recent workshop on JUICE radiation design hosted at Aberystwyth, which featured hands-on tutorials supported by three members of the ESTEC JUICE radiation design team. The plasma package measures positive and negative ions, electrons, neutral gas, and energetic neutral atoms from thermal to relativistic energies with full 3D coverage. It combines in-situ measurements with remote sensing using energetic neutral atoms to explore domains of the Jovian magnetosphere not directly sampled by JUICE. The science goals are especially targeted at understanding the corotating plasma environment of Jupiter, including its extremely efficient generation of relativistic electrons, and understanding the plasma environments of Europa and Ganymede. PEP surpasses the Galileo plasma package in energy range and angular coverage, and carries for the first time a neutral gas mass spectrometer and ENA imagers. These science questions are an excellent fit to the solar system science expertise at Aberystwyth, where we have a strong record for planetary magnetospheres and ionospheres, with an emphasis on energetic particles and plasma composition. Moreover, recent collaborations with the Earth Sciences glaciology group are leading to new insights into the icy surface of Europa, and its interaction with the plasma environment. Our intimate involvement in the design of the entire suite of sensors will place us in an ideal position to fully exploit the data set.