As NASA missions extend beyond low Earth orbit, increasing reliance is placed on carbon fiber reinforced polymer (CFRP) composites for spacecraft structures where mass efficiency, durability, and long-term reliability are critical. In service, these materials are subjected to a combination of ultraviolet radiation, vacuum, ionizing radiation, atomic oxygen, and extreme thermal excursions under sustained mechanical loading. Flight systems such as the Boeing Starliner and SpaceX Dragon employ external composite structures that will experience these environments for extended durations. Although prior spaceflight and ground studies have reported limited changes in bulk mechanical properties, the synergistic effects of these environments on composite microstructure, particularly at the fiber matrix interphase, remain insufficiently characterized and represent a potential qualification and reliability risk. This study investigates the effects of short-term cryogenic exposure on a radiation shielding carbon epoxy composite, SC2020, as a ground-based analog for space relevant thermal extremes. The SC2020 material system has previously flown on the International Space Station under the Materials International Space Station Experiment (MISSE) program. Composite specimens were exposed to liquid nitrogen for 6 and 24 hours and evaluated using a multiscale characterization framework that combined ASTM D3039 tensile testing, Atomic Force Microscopy (AFM) based interphase analysis, and helium gas permeability measurements. Tensile testing showed no statistically significant or permanent degradation in global strength or modulus following cryogenic exposure. In contrast, AFM measurements revealed reductions in interphase modulus, weakened adhesion, and increased nanoscale heterogeneity, indicating localized degradation mechanisms not captured by conventional bulk testing. Gas permeability measurements showed a progressive increase in helium diffusion with exposure duration, consistent with micro-void formation or partial interfacial debonding. The results indicate that cryogenic exposure initiates degradation at the fiber matrix interphase while leaving global mechanical properties largely unchanged over short durations. These findings underscore the importance of multiscale diagnostics for identifying early-stage damage mechanisms that may influence long term performance and qualification margins for spaceflight composite structures. The data presented establish a cryogenic baseline for comparison with forthcoming MISSE flight exposure results and support ongoing NASA Established Program to Stimulate Competitive Research (EPSCoR) efforts aimed at improving composite qualification methodologies, risk assessment, and reliability prediction for space environments.

This study investigates the effects of short-term cryogenic exposure on the interfacial properties of carbon fiber-reinforced epoxy composites (CFRPs). Macro-scale tensile testing following ASTM D3039 standards revealed minimal change in tensile strength and modulus after 6- and 24- hour liquid nitrogen immersion. However, nanoscale analysis using Atomic Force Microscopy (AFM) revealed significant degradation in the interphase region. Modulus and adhesion mapping highlighted cryogen-induced changes not reflected in global mechanical performance. Complementary permeability and DSC testing support these findings, suggesting that interfacial sensitivity serves as an early indicator of degradation. These results provide insight into the long term performance of CFRPs in cryogenic and space-like environments.

The HIMAC (Heavy Ion Medical Accelerator in Chiba) was originally designed principally for carbon ion therapy, but heavy ion research projects in medicine, physics, chemistry and biology have been conducted under a collaborative research framework since 1994. One major application is space radiation research. The radiation in space of greatest interest for human space exploration consists of energetic protons and heavy ions which can affect the health of space crew and lead to the failure of electronic devices. Ground-based experiments at heavy ion accelerators are crucial for ensuring mission crew safety and for understanding the biological effects of long-term exposure to space radiation. HIMAC provides a range of linear energy transfer (LET) beams from protons to Xe ions at energies up to 800 MeV/u, representing the most biologically-significant components of the space radiation field. At HIMAC a variety of radiation detectors and instruments are characterized and calibrated for dosimetry using specific mono-energetic heavy ion beams, the performance of shielding materials for mitigating space radiation dose is evaluated, radiation hardness of electronic devices is tested to ensure their safe operation in space, and the radiobiological studies are conducted to understand biological effects in humans during long-term space activities. HIMAC is an indispensable simulator of space radiation for the new decade of space exploration.

In recent years there has been a growing interest from the aviation community for space weather radiation forecasts tailored to the needs of the aviation industry.In 2019 several space weather centers began issuing advisories for the International Civil Aviation Organization alerting users to enhancements in the radiation environment at aviation flight levels.Due to a lack of routine observations, radiation modeling is required to specify the dose rates experienced by flight crew and passengers.While mature models exist, support for key observational inputs and further modeling advancements are needed.Observational inputs required from the ground-based neutron monitor network must be financially supported for research studies, and operationally supported to ensure real-time data is available for forecast operations and actionable end user decision making.An improved understanding of the geomagnetic field is required to reduce dose rate uncertainties in regions close to the open/closed geomagnetic field boundary, important for flights such as those between the continental US and Europe which operate in this region.Airborne radiation measurements, which are crucial for model validation and improvement, are lacking, particularly during solar energetic particle events.New measurement campaigns must be carried out to ensure progress.Furthermore, solar energetic particle forecasting must be improved to move aviation radiation nowcasts to forecasts in order to meet customer requirements for longer lead times for planning and mitigation.

The data from two Bulgarian-German instruments with the basic name "Radiation Risk Radiometer-Dosimeter" (R3D) are discussed. The R3DR instrument worked inside the ESA EXPOSE-R facility (2009-2010), while R3DR2 worked inside the ESA EXPOSE-R2 facility (2014-2016). Both were outside the Russian Zvezda module on the International Space Station (ISS). The data from both instruments were used for calculation of the neutron dose equivalent rate. Similar data, obtained by the Russian "BTNNEUTRON" instrument on the ISS are used to benchmark the R3DR/R2 neutron dose equivalent rate. The analisys reveals that the "BTNNEUTRON" and R3DR/R2 values are comparable both in the equatorial and in the South Atlantic Anomaly (SAA) regions. The R3DR/R2 values are smaller than the "BTNNEUTRON" values in the high latitude regions. The comparison with the Monte Carlo simulations of the secondary galactic cosmic rays (GCR) neutron ambient dose equivalent rates (El-Jaby and Richardson, 2015, 2016) also shows a good coincidence with the R3DR/R2 spectrometer data obtained in the equatorial and high latitude regions.

The goal of this paper is to demonstrate the capability of the 1U CubeSat to study the radiation spectra on LEO. The research was realized by the Lucky-7 mission with the primary goal of testing electronics such as a power supply, piNAV L1 GPS receiver, UHF communication system, and other subsystems in the natural space environment, and the secondary goal of testing the possibility of using 1U CubSat class satellites for scientific tasks. The satellite is equipped with a piNAV GPS receiver and piDOSE radiation detector, silicon diode radiation spectrometer, camera, and other sensors. The on-board computer enables storage of 34 h of measurements of the radiation spectrum. These measurements can be downloaded by the UHF communication system during four satellite passes over the monitoring ground station. We successfully verified all necessary instruments and their cooperation and measurement procedure. The UHF communication was identified as the most critical subsystem because of its low capacity, which slowed down the satellite operation. We needed four zenith passes to upload 34 h of measurement.

The Active Tissue Equivalent Dosimeter (ATED) is a low-cost, easy-to-use and compact tissue equivalent proportional counter designed for use aboard spacecraft, satellites, aircraft, unmanned aerial vehicles and high-altitude balloons. ATED was rigorously tested at particle accelerator facilities utilizing heavy ions of charge and energy similar to Galactic Cosmic Rays (GCRs). Upon completion of the ground-based testing and calibration, the ATED was operated aboard the International Space Station (ISS) during July–August of 2018. ATED measurements from the ISS were then analyzed in terms of time, latitude, longitude, and altitude in order to correlate with the radiation fields in the ISS orbit. When ATED measurements were correlated with orbital position, elevated absorbed dose rates due to the South Atlantic Anomaly (SAA) were clearly evident. ATED measurements were also separated based on their orbital location into three different regions. The results from the July–August 2018 flight show that ATED functioned as designed while onboard the ISS. The hypothesis that lineal energy and linear energy transfer can be used interchangeably with measurements by a TEPC in Low Earth Orbit (LEO) was tested by ATED measurements. Lastly, a direct comparison was made between linear energy transfer (LET) converted from lineal energy spectra from a spherical TEPC in LEO and model-calculated LET values. Such a comparison is highly challenging with the TEPCs with cylindrical geometry previously used in space.

Calculation of radiation protection quantities in tissue equivalent material from measurements using semiconductor detectors requires correction factors for conversion of the measured values in the semiconductor material to the tissue equivalent material. This approach has been used many times in aircraft and for space dosimetry. In this paper, we present the results of Monte Carlo simulations which reveal the need to take into account both the radiation field and the detector material when performing the conversion of measured values to radiation protection quantities. It is shown that for low Z target material, most of the dose equivalent at aviation altitudes comes from neutrons originating from nuclear reactions, while in high Z targets most of the dose equivalent comes from photons, originating from electromagnetic reactions.

After the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP), the Nuclear Regulation Authority (NRA) has adopted measures based on radiation monitoring in residential areas, instead of making decisions based on predictive radioactive material diffusion to protect residents in emergency preparedness and response. Protective actions such as sheltering and evacuation based on the measured radiation levels have been defined in each municipality where a nuclear facility is locating, but the measures to be taken when radioactive materials arrive from a neighboring country have not been discussed. We employed historical data of environmental gamma-ray dose rate in 20 cities for more than 60 years, stored in the Environmental Radiation Database. In order to identify the abnormal signal from radiation emergency at neighboring country, we propose a new peak detection, detrended fluctuation analysis with the centered moving average, with real-time systematic analysis by checking the changes in radiation levels at multiple or all residential areas. Finally, we discuss a radiation monitoring strategy for taking protective actions for the local population.

Deep learning has been utilized to trace nuclear reactions in the CR-39 nuclear track detector. Etch pit images on front and back surfaces of the CR-39 detector were obtained sequentially by moving the objective lens of a microscope, and merged to one image. This image merging makes it possible to combine information on the displacement of the position of the etch pits produced by single particle traversals through a CR-39 layer in a single image, thereby making it easier to recognize corresponding nuclear fragmentation reactions. Object detection based on deep learning has been applied to the merged image to identify nuclear fragmentation events for measurement of the total charge changing cross-section based on the number of incident particles (N-in) and the number of particles that passed through target without any nuclear reaction (N-out). We verified the accuracy (correct answer rate) of algorithms for extracting the two patterns of etch pit in merged images which corresponds to N-in and N-out using the learning curves expressed as a function of the number of trainings. Accuracy of N-in and N-out were found to be 97.3 +/- 4.0% and 98.0 +/- 4.0%, respectively. These results show that the object detection algorithm based on the deep learning can be a strong tool for CR-39 etch pit analysis.

We developed a highly-selective technique to measure the energy loss and linear-energy-transfer (LET) spectra of energetic charged particles in high-resolution and over a large collection of particle-event types. Precise and wide-range spectral and tracking measurements were performed with a single semiconductor pixel detector. The quantum-counting sensitivity, high-granularity and per-pixel spectrometric response of the Timepix ASIC chip enable the detailed spectral-tracking registration of single charged particles across the detector semiconductor sensor. Both the deposited energy along the particle trajectory (energy loss) and the path length of the particle track across the semiconductor sensor are precisely measured for each particle. This allows for the determination of the particle LET in silicon in high accuracy and over a wide-range of energies, particle types and directions. The tracking and energy loss response together with the resolving power at the particle-event level make it possible to selectively provide LET distributions of the light and heavy charged particle components in mixed-radiation and omnidirectional fields. This technique applies to energetic (E > 10 MeV/u) charged particles generating tracks greater than the pixel size and incident at nonperpendicular direction (>20 degrees) to the sensor plane. The technique applies also to electrons of energy above few MeV as well as highly energetic and minimum-ionizing-particles (MIPs). We make use of existing and in part newly collected data at well-defined radiation fields with proton and light ion beam accelerators. Flexible measurements, ease of deployment and online response are possible by the use of compact readout electronics such as the miniaturized radiation camera MiniPix (size < 8 cm, weight < 50 g) operable by any PC. Results are given for protons and light ions (He, C) of selected energies above 10 MeV/u and directions (2 pi FoV). We include also electrons (20 MeV). Selective and detailed LET spectra are produced over a wide range (10(-1) to 102 keV/mu m) in silicon.

Aircraft crew are one of the groups of radiation workers which receive the highest annual exposure to ionizing radiation. Validation of computer codes used routinely for calculation of the exposure due to cosmic radiation and the observation of nonpredictable changes in the level of the exposure due to solar energetic particles, requires continuous measurements onboard aircraft. Appropriate calibration of suitable instruments is crucial, however, for the very complex atmospheric radiation field there is no single reference field covering all particles and energies involved. Further intercomparisons of measurements of different instruments under real flight conditions are therefore indispensable. In November 2017, the REFLECT (REsearch FLight of EURADOS and CRREAT) was carried out. With a payload comprising more than 20 different instruments, REFLECT represents the largest campaign of this type ever performed. The instruments flown included those already proven for routine dosimetry onboard aircraft such as the Liulin Si-diode spectrometer and tissue equivalent proportional counters, as well as newly developed detectors and instruments with the potential to be used for onboard aircraft measurements in the future. This flight enabled acquisition of dosimetric data under well-defined conditions onboard aircraft and comparison of new instruments with those routinely used. As expected, dosimeters routinely used for onboard aircraft dosimetry and for verification of calculated doses such as a tissue equivalent proportional counter or a silicon detector device like Liulin agreed reasonable with each other as well as with model calculations. Conventional neutron rem counters underestimated neutron ambient dose equivalent, while extended-range neutron rem counters provided results comparable to routinely used instruments. Although the responses of some instruments, not primarily intended for the use in a very complex mixed radiation field such as onboard aircraft, were as somehow expected to be different, the verification of their suitability was one of the objectives of the REFLECT. This campaign comprised a single short flight. For further testing of instruments, additional flights as well as comparison at appropriate reference fields are envisaged. The REFLECT provided valuable experience and feedback for validation of calculated aviation doses.

Terrestrial gamma and neutron flashes can result in considerable radiation exposure of aircraft crew and passengers in their close vicinity. Lightning impulse voltage generators imitate selected stages of natural lightning processes and can serve as a test environment for the development and calibration of detector systems for such short term radiation events. This work presents the results of measurements of absorbed dose using thermoluminescent dosimeters for 400 negative discharges at the lightning impulse voltage generator. The thermoluminescent dosimeter CaSO4:Dy and the combination of lithium-fluoride detectors MTS–6, MTS–7, and MTS–N were used to quantify the photon and neutron components of the radiation field. The detectors were placed in four positions near the generator spark gap. The results confirm the presence of thermal neutrons and photon radiation in two positions at the lightning impulse voltage generator.

The use of thermoplastic micro- and nanocomposites for space-related neutron shielding applications is examined. The materials of particular interest are high in hydrogen content such as polyethylene and polyimide resins, and additives that provide structural support and desirable mechanical properties such as boron nitride, boron carbide, boron nitride nanotubes, and carbon fiber. This chapter covers some of the topics relating to the selection of particular materials which provide benefits that exceed current industry standard aluminum alloys. Results from various studies regarding computational radiation modeling, mechanical testing, thermal stability analysis, and radiation exposure data are provided and analyzed as a whole. The overall analysis shows that composites made from high-density polyethylene and boron nitride provide superior radiation shielding at smaller amounts than required of aluminum and further study into the use of this material with carbon fiber in sandwich composites is of particular interest.

[N-13]Ammonia is commonly produced using O-16(p, alpha)N-13 reaction but one of the limiting factor of this reaction is the relatively small nuclear cross-section at proton energies of < 10 MeV. An alternative production method using C-13(p, n)N-13 reaction, which has a higher nuclear cross-section at low proton energies, is more suitable for a preclinical PET imaging facility equipped with a < 10 MeV cyclotron. Here, we report a novel method to produce [N-13]ammonia from [C-13]methanol for preclinical use on a 7.5 MeV cyclotron. A tantalum solution target (80 mu l) consisting of a havar window supplied by the cyclotron manufacturer for the production of [F-18]fluoride was used without any modifications. The final bombardment parameters were optimized as follow: [C-13]methanol concentration in target solution - 10%, bombardment time - 8 min, and beam current - 2.2 mu A. These parameters provided doses of [N-13]ammonia which were sufficient to conduct preclinical PET imaging studies in a mouse model of myocardial infarction. Under optimized conditions, the operational lifetime of the target was approximately 150 mu Amin. Radionuclide identity of the product as N-13 was confirmed by measuring the decay half-life and its radionuclide purity was confirmed by gamma-ray spectroscopic analysis. Gas chromatography revealed that the final [N-13]ammonia dose was not distinguishable from water, showing no traces of methanol. As expected, PET/CT imaging in healthy CD-1 mice indicated the accumulation of [N-13]ammonia in myocardial tissue; mice with myocardial infarction created by left ascending coronary ligation showed clear perfusion deficit in affected tissue. This work demonstrates the proof-of-concept of using C-13(p, n)N-13 reaction to produce [N-13]ammonia from [C-13]methanol with a < 10 MeV cyclotron, and its diagnostic application in imaging cardiac perfusion.

A variety of radiation detectors and instruments have been deployed to characterize the radiation environment in low and high Earth orbit, lunar orbit, Mars orbit and on the surface of Mars. Here we discuss the testing and calibration of these detectors using HIMAC ion beams.

The ICCHIBAN project was an international collaboration to intercalibrate and intercompare the response of the different detectors and instruments used for radiation dosimetry aboard manned spacecraft. The objectives of the ICCHIBAN project were: 1) to determine the response of space radiation instruments and dosimeters to heavy ions of charge and energy similar to that found in the galactic cosmic radiation (GCR) spectrum; 2) to compare the response and sensitivity of various space radiation monitoring instruments and aid in reconciling differences in measurements made by various radiation instruments during space flight; and 3) to establish and characterize a heavy ion “reference standard” against which space radiation instruments can be calibrated. ICCHIBAN experiments were carried out at a number of particle accelerator facilities, the vast majority, eight, using the HIMAC heavy ion accelerator at the National Institute for Radiological Sciences, Chiba, Japan. Benefits of the ICCHIBAN project included the identification and correction of problems in calibration and data interpretation of a number of active space radiation instruments, and the demonstration of the overall efficacy and reproducibility of passive radiation dosimeters, especially luminescence-based detectors such as TLD and OSLD used in conjunction with CR-39 PNTD.

In this study, we show that angular measurement of nuclear tracks produced in heavy ion interactions can be made with high precision using a CR-39 solid-state nuclear track detector. For this purpose, we have increased the position resolution of nuclear track (etch pit) analysis and the precission of thickness measurement of the CR-39 detector. The position resolution of the heavy ion track was verified to be 0.02 pm by the dedicated image analysis software package PitFit. The precision of the thickness measurement of the CR-39 detector was increased to 0.6 mu m by our new both sides imaging method of the CR-39 detector using the autofocus system of the microscope. As a consequence, the angular distributions of projectiles and fragments can be realized with a precision of 1.4 x 10(-2) degrees (2.5 x 10(-4) radian). As a demonstration, we applied the angular measurement technique to the diagnosis of heavy ion beam and the small Coulomb scattering angle measurement of interactions of C-12 + Al in energies below 100 MeV/nucleon. By this new imaging technique, event-by-event interaction of the projectiles in the CR-39 detector can be measured rapidly and can be applied to the measurement of the total charge-changing cross section, the decay mode, and the branching ratios of the projectile with higher angular precision.

Polyethylene is a hydrogen-rich polymer and has been used in making composite materials for radiation shielding. It has been shown that the radiation shielding properties of polyethylene are enhanced through the incorporation of multifunctional nanostructured materials into the matrix of the polymer. In this study, composites of boron nitride added to injection-molding grade high-density polyethylene (HDPE) were prepared and physically tested for their radiation shielding capabilities. Also, the mechanical properties of these composites were also investigated using the novel technique of AFM indentation. The goal is to create a composite material which exhibits advantageous properties in areas besides radiation shielding, i.e., structural or mechanical properties, which does not inhibit the shielding properties to provide multifunctionality which pure polyethylene materials lack.

The linear energy transfer (LET) spectrum, absorbed dose and dose equivalent from secondary particles of LET∞H2O ≥15 keV/μm deposited within the plateau of the Bragg curve in primary particle-induced nuclear target fragmentation reactions in tissue during proton and heavy ion radiotherapy were measured using CR-39 plastic nuclear track detectors and analyzed by means of atomic force microscopy. It was found that secondary target fragments contributed 20% to dose equivalent for primary protons (157 MeV), 13% for primary helium ions (145 MeV/n) and 4% for primary carbon ions (383 MeV/n), respectively. Little research has been done on the contribution from these particles to primary given dose. The smaller contribution measured for energetic carbon ion beams compared to proton beams can be considered an advantage of carbon ion radiotherapy over proton radiotherapy.