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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.

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.

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.