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We developed a new empirical model for corotating plasma in the Jovian magnetosphere. The model, named the corotation plasma environment model version 2 (CPEMv2), considers the charge density, velocity vector, and ion temperature based on Galileo/plasma system (PLS) ion data. In addition, we develop hot electron temperature and density models based on Galileo/PLS electron data. All of the models provide respective quantities in the magnetic equator plane of 9–30 $\mathrm {R}_{J}$ , while the charge density model can be extended to 3-D space. A characteristic feature of the CPEM is its support of the percentile as a user input. This feature enables us to model extreme conditions in addition to normal states. In this paper, we review the foundations of the new empirical model, present a general derivation algorithm, and offer a detailed formulation of each parameter of the CPEMv2. As all CPEM parameters are of the analytical form, their implementation is straightforward, and execution involves the use of a small number of computational resources. The CPEM is flexible; for example, it can be extended, as new data (from observations or simulation results) become available. The CPEM can be used for the mission operation of the European Space Agency’s mission to Jupiter, JUpiter ICy moons Explorer (JUICE), and for future data analyses.

A new probabilistic model aiming to cover all aspects of the solar energetic particle (SEP) environment required for mission specifications is presented; the solar accumulated and peak proton and heavy ion radiation environment model. This model includes an updated reference data set upon which the analysis is based, a thorough evaluation of fitting procedures for SEP fluxes, a probabilistic helium model not based on proton fluxes, an extension to heavier ions based on new analysis of the Advanced Composition Explorer/solar isotope spectrometer data set, and a careful extrapolation of all output spectra to cover energies from 0.1 MeV/nuc to 1 GeV/nuc. Also included in this paper are derivations of spectra for rare solar particle events, which would occur at a given mean frequency and a new description for implementing the model to make it accessible to the public through systems, such as SPace ENVironment Information System or OMERE.

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 Agency's 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.

The Solar Accumulated and Peak Proton and Heavy Ion Radiation Environment (SAPPHIRE) model provides environment specification outputs for all aspects of the Solar Energetic Particle (SEP) environment. The model is based upon a thoroughly cleaned and carefully processed data set. Herein the evolution of the solar proton model is discussed with comparisons to other models and data. This paper discusses the construction of the underlying data set, the modelling methodology, optimisation of fitted flux distributions and extrapolation of model outputs to cover a range of proton energies from 0.1 MeV to 1 GeV. The model provides outputs in terms of mission cumulative fluence, maximum event fluence and peak flux for both solar maximum and solar minimum periods. A new method for describing maximum event fluence and peak flux outputs in terms of 1-in-x-year SPEs is also described. SAPPHIRE proton model outputs are compared with previous models including CREME96, ESP-PSYCHIC and the JPL model. Low energy outputs are compared to SEP data from ACE/EPAM whilst high energy outputs are compared to a new model based on GLEs detected by Neutron Monitors (NMs)., 37 pages, 17 figures

In this work we present the development of the electron Slot Region Radiation Environment Model (e-SRREM). e-SRREM is a data-based statistical model which has been built on fifteen years of electron flux measurements. The model describes the trapped electron radiation in a region that includes the slot region between the inner and the outer electron radiation belts. The model provides energetic electron fluxes with their uncertainties determined by confidence levels for user-defined mission orbit and duration. First comparisons of e-SRREM with the AE8 and International Radiation Environment Near Earth (IRENE) AE9 models show that the aforementioned models underestimate the electron flux levels along highly elliptic orbit that crosses the slot region. Extensive testings and comparisons will follow in future work.

A statistical analysis comparing the number of CREME-96 worst-week environments to a space environment particle flux data analysis and the PSYCHIC model is presented. This analysis provides an indication of the number of worst-week environments that are required to obtain a particular confidence level and determine the associated risk of a destructive single event effect over a mission but highlights the drawback of such an approach compared to using a statistical model. A method for direct assessment of the number of Single Event Effects expected specific to components and shielding geometries using the European Space Agency SEPEM system is also presented.

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 ESA's 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.

The ‘Mars Energetic Radiation Environment Models’ (dMEREM and eMEREM) recently developed for the European Space Agency are herein used to estimate, for the first time, background Galactic Cosmic Ray (GCR) radiation and flare related solar energetic particle (SEP) events at three candidate martian landing sites under conditions where particle arrival occurred at solar minimum (December, 2006) and solar maximum (April, 2002) during Solar Cycle 23. The three landing sites were selected on the basis that they are characterized by significantly different hydrological conditions and soil compositions. Energetic particle data sets recorded on orbit at Mars at the relevant times were incomplete because of gaps in the measurements due to operational constraints. Thus, in the present study, comprehensive near-Earth particle measurements made aboard the GOES spacecraft were used as proxies to estimate the overall particle doses at each perspective landing site, assuming in each case that the fluxes fell off as 1/ r 2 (where r is the helio-radial distance) and that good magnetic connectivity always prevailed. The results indicate that the particle radiation environment on Mars can vary according to the epoch concerned and the landing site selected. Particle estimations obtained using MEREM are in reasonable agreement, given the inherent differences between the models, with the related NASA Heavy Ion–Nucleon Transport Code for Space Radiation/HZETRN. Both sets of results indicated that, for short (30 days) stays, the atmosphere of Mars, in the cases of the SEPs studied and the then prevailing background galactic cosmic radiation, provided sufficient shielding at the planetary surface to maintain annual skin and blood forming organ/BFO dose levels below currently accepted ionizing radiation exposure limits. The threat of occurrence of a hard spectrum SEP during Cruise-Phase transfers to/from Mars over 400 days, combined with the associated cumulative effect of prolonged GCR exposure, poses an as yet unsolved hazard to prospective onboard personnel.

Eight commercially available n-channel power MOSFETs were exposed to high energy spallation neutrons and thermal neutrons in separate experiments. Single event burnout (SEB) was observed in several of the devices in both environments. Measurements of SEB at derated drain-source voltages show very strong reductions in burnout cross-sections, but suggest that current recommendations for safe operation of devices may need updating for high voltage devices. In one device a different failure mode was observed, with subsequent investigations suggesting that single event gate rupture (SEGR) was responsible. This first observation of SEGR in accelerated neutron testing of power MOSFETs represents a new consideration for designers of high voltage control systems.

The Geant4-based PLANETOCOSMICS radiation simulation code has been extended to simulate the radiation environment in the vicinity of the Galilean moons. This software model treats in 3-dimensions the complex trajectories traced by charged particles in the combined effects of Jupiter's and the moon's intrinsic and induced fields. Furthermore, once the particles are incident upon the moon's surface, the detailed nuclear and electromagnetic interactions are modeled and secondary particle emission treated. Treatment of these complex processes allows more accurate prediction required for radiation environment and hardness assurance for future missions to these moons. This paper describes the basis of the PLANETOCOSMICS-J model and the simulation approach for the Galilean moons. The first results from applying the model to Europa are presented and show potentially 60-75% reduction in total ionizing dose for 500 km to 100 km circular orbits around the moon.

Various SRAM and MOSFET devices were exposed to 3 MeV and 14 MeV neutrons at a fusion facility and to a fission neutron spectrum with a californium-252 source. Single event burnout (SEB) was observed in several of the MOSFETs in all three environments-the first time this phenomenon has been observed at neutron energies below 10 MeV. In addition to observing single event upsets (SEU) and single event latchup (SEL) in the SRAMs, two devices experienced significant multiple cell upset (MCU) effects which dominated the upset rate. The physical mechanisms underlying these phenomena and the consequences for various radiation environments are discussed.

New radiation monitors based on solid-state detectors have been developed to perform wide-ranging measurements of the atmospheric environment and provide warnings of sudden increases during solar particle events. Results have been obtained during the current deep solar minimum across the full range of latitudes and from sea level to 13 km altitude. Results for ambient dose equivalent agree very closely with Tissue Equivalent Proportional Counters carried on the same flights. Values of 10 ?Sv/hr are being reached at 12 km altitude and high latitude. Comparisons are made with the QinetiQ Atmospheric Radiation Model and the need to include cosmic-ray heavy ions is demonstrated.

Geant4 is a software toolkit for the simulation of the passage of particles through matter. It is used by a large number of experiments and projects in a variety of application domains, including high energy physics, astrophysics and space science, medical physics and radiation protection. Over the past several years, major changes have been made to the toolkit in order to accommodate the needs of these user communities, and to efficiently exploit the growth of computing power made available by advances in technology. The adaptation of Geant4 to multithreading, advances in physics, detector modeling and visualization, extensions to the toolkit, including biasing and reverse Monte Carlo, and tools for physics and release validation are discussed here., Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 835, ISSN:0168-9002, ISSN:1872-9576

Models have been embodied within the QinetiQ atmospheric radiation model (QARM) to compute enhancements during major solar particle events and the influence of any concurrent geomagnetic storms that lower the cut-off rigidity. Predictions are compared with available in-flight measurements and extended to give worst case estimates for a number of aircraft routes. It is found that during solar particle events the gradients of particle fluxes with respect to altitude and geomagnetic latitude are so steep that doses and fluences are extremely sensitive to both geomagnetic conditions and the exact route.

Neutron test data on single event effects for a wide range of SRAMs, facilities (monoenergetic and continuum) and energies (thermal to 800 MeV) are compared. Many modern devices are found to be sensitive to thermal neutrons and rates from this source can dominate in many situations. A significant number of devices suffer latchup and the cross-sections increase with operating voltage and beam energy implying that most test facilities will underestimate the problem for the natural atmospheric environment. Upset sensitivity at 3-5 MeV varies from 5 to 600 less than at high energies and will be of most significance for sources of fission neutrons. These results are related to current and developing standards

The QinetiQ atmospheric radiation model (QARM) is a comprehensive model of the energetic radiation in the atmosphere. In this paper we report on the improvement and validation activities for this model. The improvements include the implementation of two additional cosmic ray models, new response matrix, dose rate and flight dose calculation facilities. Tests/validations of the model have been carried out at individual component level as well as at system level. We will also report on the web interface developed to allow easy access to the model.

A comprehensive model of the energetic radiation in the atmosphere has been developed. It is based on the use of a dynamic cosmic ray radiation model, an efficient rigidity cutoff calculation tool, and the use of detailed atmospheric response matrices to monochromatic cosmic ray particle incidences. The response matrices were produced by detailed Monte Carlo (MC) simulations of cosmic ray interactions with the atmosphere. This model can predict the secondary particle (proton, neutron, electron, gamma, charged pion, or charged muon) spectrum at any given location and time in the atmosphere.

A new physics process has been implemented in the Geant4 Monte Carlo code to treat the scattering of low-energy protons at grazing incidence angles. Experimental data has shown that this is a predominantly surface process where protons are reflected without entering the surface material hence the classical multiple scattering process is not applicable. The new model has been used to revise predictions of proton fluence at the focal plane of the XMM-Newton telescope obtained in earlier simulations.

The purpose of this work is to understand the interaction of high energy neutrons with CCDs with the aim of deploying them in flight experiments to gather a database of atmospheric neutron interaction events in silicon cells. The new results in this paper include: 1) early-time multilevel RTS signals from dark current spikes, which have never been resolved before and 2) improved resolution of the frequency distributions of event intensity and comparison with results from a radiation transport code. This work adds to the state of the art by providing a novel perspective on the formation and evolution (annealing) of displacement damage complexes in silicon and by demonstrating that CCDs can provide an attractive combination of spatial and intensity resolution for the interaction events of neutrons and other particles within silicon cells.

This paper examines the performance of the Geant4 radiation transport toolkit for the simulation of energy deposition from proton- and neutron-nuclear interactions in silicon microelectronics. The results show that for large (/spl sim/300 /spl mu/m) to small (/spl sim/0.5 /spl mu/m) feature-size devices, the nucleon-nuclear and electromagnetic interaction models within the toolkit provide energy deposition spectra and single event upset rate predictions that are in good agreement with experimental data. The new Binary Cascade and Classical Cascade models, together with the nuclear pre-equilibrium model in Geant4, do not significantly differ in the results they produce. For small feature-size devices, it is shown that it is necessary to consider the effects of ionization by particles produced by nuclear interactions several micrometers above the sensitive volume.

We present here a set of tools for space applications based on the Geant4 simulation toolkit, developed for radiation shielding analysis as part of the European Space Agency (ESA) activities in the Geant4 collaboration. The Sector Shielding Analysis Tool (SSAT) and the Materials and Geometry Association (MGA) utility will first be described. An overview of the main features of the MUlti-LAyered Shielding SImulation Software tool (MULASSIS) will follow. The tool is specifically addressed to shielding optimization and effects analysis. A Java interface allows the use of MULASSIS by the space community over the World Wide Web, integrated in the widely used SPENVIS package. The analysis of the particle transport output provides automatically radiation fluence, ionising and NIEL dose and effects analysis. ESA is currently funding the porting of this tools to a low-cost parallel processor facility using the GRID technology under the ESA SpaceGRID initiative. Other Geant4 present and future projects will be presented related to the study of space environment effects on spacecrafts.

Monte Carlo simulations are presented where protons are shown to propagate through X-ray telescope optics by grazing incidence scattering processes. If these protons reach charge coupled device (CCD) detectors in sufficient numbers, they can induce a radiation background, and at certain energies, the nonionising dose can cause degradation of the charge transfer efficiency (CTE). In the course of this work, the telescope optics of the Chandra and XMM-Newton observatories were simulated.

Results from the Cosmic Radiation Environment Monitors (CREAM and CREDO) have been reported from a range of platforms during the declining phase of solar cycle 22 and a number of implications drawn for radiation environment and shielding models. Since these reports, the CREAM monitor has flown on a number of Shuttle visits to MIR during 1997-1998 with an extended deployment on MIR during January to May 1998. In all cases an active monitor measured charge-deposition spectra at various locations, while passive packages comprising neutron activation foils, neutron bubble detectors and thermoluminescent dosimeters obtained integrated data at these and other sites. Movement of the South Atlantic Anomaly is observed and cannot be fitted by simply updating the geomagnetic field model. The data from MIR are compared with those from previous Shuttle missions and show comparable secondary neutron fluencies and dose rates. Meanwhile a CREDO-3 particle telescope has been included in the Microelectronics and Photonics Test Bed in highly eccentric, high inclination orbit and has been returning data since November 1997. This experiment measures proton fluxes greater than 38 MeV and linear energy transfer spectra of cosmic rays and solar particle events in the range 100-20000 MeV/(g cm-2). The data have been extended to July 2000 and are used both to correlate with device behavior and to compare with models of trapped radiation, cosmic rays and solar particles. A number of solar particle events have been observed as cycle 23 builds up. Following a relatively quiet year in 1999, the recent event of July 14, 2000 is observed to compete with the October 1989 events in terms of proton fluency but has a somewhat lower heavy ion fraction.

An ion microdosimetry extension to the Monte Carlo High Energy Transport Code (HETC) has been developed to allow tracking of all the reaction products and has been applied to model charge-deposition spectra in pin diodes caused by atmospheric neutron spectra, as well as upsets in DRAMs from ground and space irradiation by protons. These cases cover sensitive zone sizes ranging from hundreds of microns to sub-micron. Angular distributions of both incident particles and reaction products are found to be important, particularly for the prediction of multiple-bit upsets in devices of small feature size.

The earth is bombarded by a nearly isotropic flux of energetic charged particles called cosmic rays which interact with air nuclei to generate a cascade of secondary particles building up to a maximum intensity at 60 000 feet. At normal cruising altitudes, the radiation is still several hundred times the ground level intensity. These particles are sufficiently energetic and ionising that they can deposit enough charge in a small volume of semiconductor to change the state of a memory cell, while certain devices can be triggered into a state of high current drain, leading to burn-out and hardware failure. These deleterious interactions of individual particles are referred to as single event effects. The authors have flown Cosmic Radiation Effects detectors in a variety of spacecraft and aircraft and illustrative results will be presented together with a review of published instances of such phenomena in flight systems. In the future there is likely to be increased susceptibility due to growing reliance on high performance computers using smaller devices operated at lower voltages and flying at higher altitudes. The influence of cosmic rays will have to be properly considered in the assessment of reliability.

This anthology contains contributions from eleven different groups, each developing and/or applying Monte Carlo-based radiation transport tools to simulate a variety of effects that result from energy transferred to a semiconductor material by a single particle event. The topics span from basic mechanisms for single-particle induced failures to applied tasks like developing websites to predict on-orbit single event failure rates using Monte Carlo radiation transport tools.

A radiation transport suite has been used to simulate gamma-ray emissions produced in the X-ray Multi-Mirror Mission spacecraft by interactions of cosmic-rays and solar protons. Their energy deposition in charge coupled device detectors is a significant source of background.

GANIL/Applications industrielles; The effects of heavy-ion test conditions and beam energy on device response are investigated. These effects are illustrated with two types of test vehicles: SRAMs and power MOSFETs. In addition, GEANT4 simulations have also been performed to better understand the results. Testing to high fluence levels is required to detect rare events. This increases the probability of nuclear interactions. This is typically the case for power MOSFETs, which are tested at high fluences for single event burnout or gate rupture detection, and for single-event-upset (SEU) measurement in SRAMs below the direct ionization threshold. Differences between various test conditions (e.g., "in air" or vacuum irradiations, with or without degraders) are also explored. Nuclear interactions with any materials in the beam's path can increase the number of high collected charge events potentially impacting the experimental results. A "species" effect has been observed in the power MOSFET devices examined in this work. When the beam energy increases, the single-event-burnout (SEB) voltage is constant, such that the SEB voltage is determined only by the species of the ion beam. The species effect is shown to be due to high collected charge events induced by nuclear interactions, which can lead to premature SEB. If a device is sensitive to the species effect, the worst-case test conditions will be for the heaviest ion species, which can produce the largest linear-energy-transfer (LET) secondaries. SRAMs can also be sensitive to the species effect below the direct ionization threshold LET. For the devices used in this work, the worst-case energy for SEU characterization is $sim 10'{rm s}~{rm MeV/u}$ where the species dominates the device response. In the 10's MeV/u range the heaviest species result in the largest cross sections. However, at very high energies (100's MeV/u), the species is not the - ominant parameter because of differences in the population of secondaries created by nuclear interactions. At very high energies the SEU cross section below the direct ionization threshold LET decreases by several orders of magnitude compared to 10's MeV/u SEU data. The results of this work emphasize that there is no such thing as an "ideal" test facility. Nevertheless, these results can be used by experimenters to optimize the integrity of their results for given test conditions.

The new regime of trapped protons centered around L=2.5 and observed by CRRES (Combined Release and Radiation Effects Satellite) between March and October 1991 has been observed by CREAM (Cosmic Radiation Environment and Activation Monitor) on Shuttle missions at an altitude of 569 km in September 1991 (STS-48) and at altitudes of 385 km and 326 km in December 1992 on STS-53. CREDO (Cosmic Radiation Environment and Dosimetry instrument) on UOSAT-3 at 800 km observed the decay of the belt from March 1991 to March 1992. At high latitudes cosmic-ray fluxes have increases by a factor of two between June 1991 and March 1993. The effect of Shuttle shielding on cosmic rays is to increase the fluxes of low LET (linear energy transfer) secondaries and neutrons. Trapped protons and their dose contribution are attenuated, but again significant fluxes of secondary neutrons are produced. >

Charge collection is used as a non-destructive technique to analyze the statistical response of vertical power MOSFETs and their single-event burnout (SEB) rate as a function of the incident ion energy. Two effects are observed at either low or high energy. At low energy, the collected charge significantly decreases because of the limited ion range and energy straggling in the thick epitaxial layer. Because of this limited range effect, using low energy ions for SEB testing can significantly underestimate the SEB rate. At high energy, the presence of thick source bond wires, which partially cover the die area, as typically encountered in power MOSFETs, induce a large shadowing effect. When crossing the bond wires, high energy ions loose energy and can have a higher LET (but still a significant range) when they reach the active die. As a result, they can deposit more charge in the thick sensitive epitaxial layers of the transistors than the primary beam. A significant probability of high collected charge events is then observed at high energy. Contrary to the low energy (range) effect, the shadowing at high energy contributes to overestimating the SEB rate. General rules for the SEB radiation hardness assurance, related to the ion energy versus the power MOSFET voltage rating, are provided to avoid both range and shadowing effects.

The Cosmic Radiation Environment and Activation Monitor (CREAM) was successfully deployed in the middeck area on Shuttle missions STS-48 and STS-44 during September and November 1991 with the aim of monitoring those aspects of the primary and secondary radiation environment responsible for single event upsets in microelectronics and background noise in sensors. Results are compared with the outputs of standard radiation environment models. For the accurate location of trapped protons the choice of geomagnetic field model is shown to be critical, while results at high latitudes show the low-altitude manifestation of the new trapped proton belt observed to follow the March 1991 solar flare event. From deployment at a number of locations there is clear evidence for a significant build-up with shielding of secondary charged particles and neutrons. >

Although heavy ions constitute only ∼1% of the total cosmic ray flux, they can make a significant contribution to the radiation field in the upper atmosphere. This contribution is evaluated by MC simulations within the QARM framework.

Geant4 is a software toolkit for the simulation of the passage of particles through matter. It is used by a large number of experiments and projects in a variety of application domains, including high energy physics, astrophysics and space science, medical physics and radiation protection. Its functionality and modeling capabilities continue to be extended, while its performance is enhanced. An overview of recent developments in diverse areas of the toolkit is presented. These include performance optimization for complex setups; improvements for the propagation in fields; new options for event biasing; and additions and improvements in geometry, physics processes and interactive capabilities.

Comparisons arc presented between measured and predicted energy deposition spectra from neutron-nuclear events within a silicon semiconductor detector. Experiment data are from irradiations performed at the TRIUMF and TSL neutron beam facilities. Predictions are based on the Geant4 radiation transport toolkit, which is applied both to quantify the effects of interactions in the detector and scattering of the neutron source by other experiments upstream of the detector. The predictions highlight the importance of quantifying scattering effects in large experiment setups, the lower-energy neutrons in the continuum of the quasi-monoenergetic spectrum suffering greater scattering. The results are used to correct neutron-induced single event upset cross-section data.

Induced radioactivity has long been known to be the major factor in performance degradation of spaceborne gamma-ray detectors, such as those to be flown on the planned Gamma Ray Observatory mission, and hence accurate calculations of this induced activity are required for the execution of a successful mission. However, the different methods used for the estimation of these effects have given divergent answers depending on the assumptions made. An approach based on Monte Carlo simulation of the atomic and nuclear interactions of these energetic radiations is outlined, which incorporates the best current understanding of the composition, angular and energy dependence of these radiations, and of their interactions in complex, many-material geometries. >

Flight data obtained between 1995 and 1997 from the Cosmic Radiation Environment Monitors CREAM and CREDO carried on UoSat-3, Space Shuttle, STRV-1a (Space Technology Research Vehicle) and APEX (Advanced Photovoltaic and Electronics Experiment Spacecraft) have been added to the dataset affording coverage since 1990. The modulation of cosmic rays and evolution of the South Atlantic Anomaly are observed, the former comprising a factor three increase at high latitudes and the latter a general increase accompanied by a westward drift. Comparison of particle fluxes and linear energy transfer spectra is made with improved environment and radiation transport calculations which account for shield distributions and secondary particles. While there is an encouraging convergence between predictions and observations, significant improvements are still required, particularly in the treatment of locally produced secondary particles.

Radiation shielding analysis is a crucial process in the spacecraft and space instrument development cycle. A number of dedicated tools have been developed in the last decades for the study of the effects of radiation on materials and instruments in space. We present here a set of detailed analyses based on Monte Carlo radiation transport simulations, and new tools for space applications, both based on the Geant4 simulation toolkit, developed as part of the European Space Agency (ESA) activities in the Geant4 collaboration. Finally we present some activities initiated by ESA for the creation of a Geant4 space users' community.

Geant4 is a software toolkit for the simulation of the passage of particles through matter. It has abundant hadronic models from thermal neutron interactions to ultra relativistic hadrons. An overview of validations in Geant4 hadronic physics is presented based on thin‐target measurements. In most cases, good agreement is available between Monte Carlo prediction and experimental data; however, several problems have been detected which require some improvement in the models.