Hugh Evans

MULASSIS: a Geant4-based multilayered shielding simulation tool

Radiation shielding analysis is a crucial process in the spacecraft and space instrument development cycle. Simple tools such as SHIELDOSE-2 are used traditionally. With advances in computer and network technology and in energetic particle transport simulation codes, detailed Monte Carlo (M-C) simulation is no longer an approach reserved for research scientists but is widely becoming an important engineering tool. In this paper, we report on the main features of the multilayered shielding simulation software tool (MULASSIS) developed as part of the European Space Agency (ESA) activities in the Geant4 collaboration. It is based on the Geant4 M-C simulation toolkit developed by a large international collaboration lead by CERN. The software will be used as a general tool within ESA for radiation fluence, dose, and effects analysis. It has been integrated into the ESA SPENVIS system, thus, making it accessible to the wider space community over the World Wide Web.

A model for Mars radiation environment characterization

A modeling framework for the prediction of the Martian radiation environment is presented. Features include input solar cycle modulated cosmic ray and solar particle event spectra, based both on CREME-96, the transport of this radiation in the Martian atmosphere and regolith, including creation of secondaries, using the Geant4 Monte Carlo toolkit. Details of the atmosphere are derived from the European Mars Climate Database with a dense topological grid and layering of the atmosphere. Seasonal and diurnal variations are considered. Surface topology is derived from the Mars Orbiter Laser Altimeter (MOLA) and geology is modeled. The outputs are full particle transport histories, maps of radiation fluxes, and doses. The model will be applied to future European Mars missions.

Radiation-belt and transient solar-magnetospheric effects on Hipparcos radiation background

The Hipparcos astrometry satellite operated in a near-geostationary transfer orbit between August 1989 and August 1993. Its telescopes were sensitive to background signals induced by energetic electrons and protons, and by bremsstrahlung. The observations yielded a long-term data-set which strongly reflects the structure of the radiation belts, their dynamics and the effects of solar particle events. Investigation of these data includes qualitative comparisons with GOES and CRRES data. >

SRAMs SEL and SEU in-flight data from PROBA-II spacecraft

This paper presents an analysis of the SEE in-flight data of SRAMs on board Proba-II spacecraft. Proba-II spacecraft has been flying on a LEO orbit for more than 3 years. Observed in-flight error rates are compared with predictions based on ground test data.

Unfolding and validation of SREM fluxes

The Standard Radiation Environment Monitor (SREM) belongs to a second generation of instruments in a program established by the European Research and Technology Centre of the European Space Agency (ESA) to provide minimum intrusive particle radiation detectors on ESA spacecraft for space weather applications, which are also suitable for scientific investigations.

Inner Belt Anisotropy Investigations Based on the Standard Radiation Environment Monitor (SREM)

The Standard Radiation Environment Monitor (SREM) is a particle detector developed for wide use on ESA spacecraft. It is flying on several ESA missions, most recently the Herschel and Planck space telescopes. Using data from the SREM unit on PROBA-1 in LEO, pitch angle anisotropics in the inner Van Allen belt are investigated. The sensitivity of the SREM to pitch angle induced flux anisotropics can be linked to the directional response function of the SREM, obtained using GRAS/Geant4 Monte-Carlo simulations. The directional response function is combined with an anisotropic version of the AP8 model (based on the Badhwar-Konradi anisotropy distribution) to yield improved count predictions. The importance of considering flux anisotropies is shown for both short-term data and long-term integrated counts. Significant improvements to the AP8 model can be realised.

Detailed Comparison of Monte Carlo and Sector-Shielding Analyses for Space Applications

Predictions of Total Ionizing Dose made using full 3-D Monte Carlo and simplified sector-shielding techniques for simple and complex geometries in a space environment are compared and differences between them analyzed in detail

Characterization of Solar Energetic H and He Spectra Measured by the Energetic Particle Telescope (EPT) On-Board PROBA-V During the January 2014 SEP Event

On January 6, 2014 a Solar Energetic Particle (SEP) event started that led to a 1030 cm

Characterization of solar energetic H and He spectra measured by the energetic particle telescope (EPT) on-board PROBA-V during the January 2014 SEP event

^{-2}