Piers Jiggens

SEPEM: A tool for statistical modeling the solar energetic particle environment

Solar energetic particle (SEP) events are a serious radiation hazard for spacecraft as well as a severe health risk to humans traveling in space. Indeed, accurate modeling of the SEP environment constitutes a priority requirement for astrophysics and solar system missions and for human exploration in space. The European Space Agencys Solar Energetic Particle Environment Modelling (SEPEM) application server is a World Wide Web interface to a complete set of cross-calibrated data ranging from 1973 to 2013 as well as new SEP engineering models and tools. Both statistical and physical modeling techniques have been included, in order to cover the environment not only at 1 AU but also in the inner heliosphere ranging from 0.2 AU to 1.6 AU using a newly developed physics-based shock-and-particle model to simulate particle flux profiles of gradual SEP events. With SEPEM, SEP peak flux and integrated fluence statistics can be studied, as well as durations of high SEP flux periods. Furthermore, effects tools are also included to allow calculation of single event upset rate and radiation doses for a variety of engineering scenarios.

SEP Protons in GEO Measured With the ESA MultiFunctional Spectrometer

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.

SEP protons in GEO measured with the ESA MultiFunctional spectrometer

The multifunctional spectrometer (MFS) is a new radiation monitor that together with component technology test bed makes the European Space Agency Alphasat Environment and Effects Facility—Technology Demonstration Payload 8 (AEEF-TDP8). 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 characterize the space radiation environment in geostationary orbit. The mission lifetime of AEEF/TDP8 will be at least three years and TDP8 is expected to be acquiring scientific data during the whole period. Before launch, MFS was submitted to proton and electron beam tests at the Paul Scherrer Institute in Switzerland in 2010. The main purpose was the validation and calibration of the MFS protoflight model together with the estimation of particle energy resolution and identification capability. A full Geant4 simulation with computer-aided design geometry exported to geometry description markup language description the MFS in-flight configuration was built. Ground test results were validated with Geant4 simulation. The measurements of MFS proton channels and MFS proton response functions are validated using comparisons with INTErnational Gamma-Ray Astrophysics Laboratory/INTEGRAL Radiation Environment Monitor data during the solar energetic particle event 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.

Defining the SEP environment for specifications using the SAPPHIRE model

Present standards for the solar energetic particle radiation environment in space prescribe a somewhat disparate set of methods for the determination of environment specifications. Herein a new model is presented to cover all SEP environment time-scales across all relevant species in a consistent, probabilistic manner; the Solar Accumulated and Peak Proton and Heavy Ion Radiation Environment (SAPPHIRE) model. This model builds on earlier work regarding the probabilistic modelling methodology but is greatly enhanced making use of updates to the ESAs SEPEM (Solar Energetic Particle Environment Modelling) Reference Data Set (RDS) for protons and an extension to include helium. A careful processing of heavier ion data has been carried out to extend the helium model to heavier ions. Model outputs include mission cumulative fluence, worst-case event fluence and peak fluxes for proton spectra, helium spectra and heavy ion spectra also included as a function of Linear Energy Transfer (LET). As a verification of the robustness of the procedure the proton model outputs are compared to a similar model based solely on data from neutron monitors.