[en] The knowledge of the composition of the radiation environment is an important information for all the radiation safety issues needed for the planning of future long manned space missions. The ALTEA detector is on board the International Space Station since July 2006 and during this period it has performed a detailed measurement of the radiation environment. In this paper we present a summary of past measures and results.

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[en] LIDAL–ALTEA is a detector designed to study the radiation flux and energy spectra in the International Space Station (ISS). Its mission is manifested by NASA in 2019. The ALTEA subsystem, which took data on the ISS in the past Zaconte et al. (2010), is based on Silicon Strip detectors and will measure the released energy of the traversing particles, while the LIDAL subdetector is based on fast plastic scintillators, read by PMTs, will measure the particle Time Of Flight. A custom Front End electronics has been designed to reach a time resolution better than 120 ps. LIDAL is under construction while a prototype has been already tested with a proton beam. The measured time resolution fulfills the design expectation and is compatible with FLUKA simulations. The Monte Carlo results have also been validated by the comparison with a test measure where the ALTEA detector was exposed to proton beams.

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[en] In this work we presented a method to estimate a local shielding thickness of the International Space Station (USLab), expressed as equivalent of aluminum. The calculation took advantage of total and partial charge-changing cross sections, both measured experimentally and computed theoretically, to obtain the total survival fractions of ions with charge 5≤Z≤26 when transversing the space craft hull. The combination of these values with the measured relative abundances outside the space station provided the estimates of the internal relative abundances at several thicknesses. The results have been compared with data measured by ALTEA experiment in the USLab to find the thickness that minimizes the discrepancy between the calculated data and the measurements: the result yielded to an estimate of the shielding thickness at ALTEA site of about 5 cm of aluminum equivalent.

[en] The ALTEA program is an international and multi-disciplinary project aimed at studying particle radiation in space environment and its effects on astronauts' brain functions, as the anomalous perception of light flashes first reported during Apollo missions. The ALTEA space facility includes a 6-silicon telescopes particle detector, and is onboard the International Space Station (ISS) since July 2006. In this paper, the detector calibration at the heavy-ion synchrotron SIS18 at GSI Darmstadt will be presented and compared to the Geant 3 Monte Carlo simulation. Finally, the results of a neural network analysis that was used for ion discrimination on fragmentation data will also be presented

[en] Iron abundance in cosmic rays impinging on astronauts in space habitats is of paramount importance when calculating the radiation risk for human space exploration. The concurrent high relative abundance of iron in Galactic Cosmic Rays (GCR) and iron ability to produce damages at cellular and molecular levels, together with recent radiobiology results suggests iron as a major candidate to be studied in order to produce accurate radiation hazard assessments. Iron may be in fact responsible for a large percentage of cancer risk during a long interplanetary voyage, and therefore deserves a specific attention. We built a simple model based on CREME96 for the radiation in the International Space Station (ISS) and tested it against recently performed measurements with the ALTEA and Alteino particle detectors. While we can report a good agreement between 50m and 250 keV/μm (very good for several peaks such as Si, Mg, S) we show an overestimation by this model of iron abundances of about 25–80% when compared to the measurements. New analysis on previously published work, supporting this result, are also reported. Reasons for this overestimation are discussed, they are likely to be related to the not detailed enough transport through the multiplicity of the ISS shielding and to the often used simplification of “aluminum equivalent shielding”. The iron sources in LEO, possibly not yet accurate enough when transported in Low Earth Orbit, can also play a role. New concurrent measurements (inside–outside the ISS) are suggested to help resolving this issue. - Highlights: ► Overestimation of Fe in the ISS when modeling with CREME96 and Al-equivalent shielding. ► Radiation model based on CREME96 shows good agreement with measurements in the ISS. ► Anisotropy of high LET radiation in the ISS is due to the different amount shielding.

[en] The ALTEA-Space detector has been calibrated by testing its response to several monochromatic beams. These measurements provided energy-deposition spectra in silicon of 100, 600 and 1000 MeV/nucleon ¹²C and 200 and 600 MeV/nucleon ⁴⁸Ti. The results have been compared to three Monte Carlo transport codes, namely PHITS, GEANT4 and FLUKA. Median, full width at half maximum (FWHM) and interquartile range (IQR) have been calculated for all datasets to characterize location, width and asymmetry of the energy-deposition spectra. Particular attention has been devoted to the influence of δ rays on the shape of the energy-deposition spectrum, both with the help of analytical calculations and Monte Carlo simulations. The two approaches proved that, in this range of projectile charge, projectile energy and detector size, the leakage of secondary electrons might introduce a difference between the energy-loss and energy-deposition spectrum, in particular by changing the location, width and symmetry of the distribution. The overall agreement between the Monte Carlo predictions and the measurements is fair and makes PHITS, FLUKA and GEANT4 all possible candidates for simulating ALTEA-Space experiment.