Radiation Damage Research Articles

Radiation damage and recovery of plastic scintillators under ultra-high dose rate 200 MeV electrons at CERN CLEAR facility.

The FLASH effect holds significant potential in improving radiotherapy treatment outcomes. Very high energy electrons (VHEEs) with energies in the range of 50-250 MeV can effectively target tumors deep in the body and can be accelerated to achieve ultra-high dose rates (UHDR), making them a promising modality for delivering FLASH radiotherapy in the clinic. However, apart from suitable VHEE sources, clinical translation requires accurate dosimetry, which is challenging due to the limitation of standard dosimeters under UHDR conditions. Water-equivalent and real-time plastic scintillation dosimeters (PSDs) may offer a viable solution. &#xD;Purpose & Methods: In this study, a 4-channel PSD, consisting of polystyrene-based BCF12 and Medscint proprietary scintillators, polyvinyltoluene (PVT)-based EJ-212 and a blank plastic fiber channel for Cherenkov subtraction was exposed to the 200 MeV VHEE UHDR beam at the CLEAR CERN facility. The Hyperscint RP200 platform was used to assess linearity to dose pulses of up to 90 Gy and dose rates up to 4.6×109Gy/s, and to investigate radiation damage and recovery after dose accumulation of 37.2 kGy. &#xD;Results: While blank fiber response was linear across the entire dose range studied, light output saturated above 45 Gy/pulse for scintillators. Despite radiation damage, linearity was preserved, though it resulted in a decrease of scintillator and blank fiber light output of <1.87 %/kGy and a shift in spectra towards longer wavelengths. Short-term recovery (<100h) of these changes was observed and depended on rest duration and accumulated dose. After long-term rest (<172 days), light output recovery was partial, with 6-22% of residual permanent damage remaining, while spectral recovery was complete. &#xD;Conclusions: We showed that PSDs are sensitive to radiation damage, but maintain dose linearity even after a total accumulated dose of 37.2 kGy, and exhibit significant response recovery. This work highlights the potential of PSDs for dosimetry in UHDR conditions.

Potential Antioxidant and Anti-inflammatory Effects of Astaxanthin Ionic Liquid Liposomes.

Astaxanthin is an antioxidant with extremely high antioxidant activity. However, the stability and solubility of free astaxanthin are poor. Therefore, we prepared astaxanthin-betaine (ASTA-Bet) ionic liquid liposomes through a combination of theoretical calculations and experimental research and studied their physicochemical properties and biological effects. This liposome has good stability and skin permeability. The cumulative permeability of the ASTA-Bet ionic liquid liposome is 22.95 times that of free astaxanthin and 2.41 times that of the ASTA-Bet ionic liquid. The particle size of astaxanthin liposomes was 117.2 nm, and the particle size did not change significantly after 28 days of storage, indicating good stability. Compared with free astaxanthin, the ASTA-Bet ionic liquid liposome has good antioxidant activity and can exert antioxidant and anti-inflammatory effects by regulating the TGF-β1/smad2/smad3 pathway damaged by ultraviolet radiation, which may contribute to the resistance to ultraviolet radiation damage. Therefore, it can be used as a raw material to develop cosmetics with antiaging and anti-inflammatory functions.

Spontaneous Nanocrystals/Amorphous MoS2 Film Induced by Fe+ Irradiation with Superior Irradiation Tolerance and Tribology Properties.

High-performance radiation-resistant lubricating materials (RRLMs) with nanostructures hold great promise for enhancing the irradiation tolerance because of their sinking effect of boundaries on defects. Despite recent advances, challenges remain in finding a nanostructure that exhibits both superior irradiation tolerance and excellent lubricant properties. Unlike traditional nanostructured composite materials that required complex predesign, herein, a MoS2 nanocrystals (NCs)/amorphous dual phase in subirradiation saturation (SIS) state was spontaneously formed during irradiation, exhibiting high irradiation resistance under the synergistic effect of "defect traps" by interfaces and edge dislocation. This nanocrystals (NCs)/amorphous dual phase where each has its own advantages exhibits a significant reduction in both friction coefficient and wear rate even under irradiation damage of 8 dpa, pushing the limit of irradiation performance for current solid lubricants. Furthermore, based on the molecular dynamics (MD) analysis, other factors influencing the intrinsic irradiation tolerance of MoS2, such as collision angles and S off-sites, have also been comprehensively investigated to clarify the damage mechanism of MoS2. Our findings offer advanced perspectives for the design of high-performance RRLMs, enabled by edge dislocations, S off sites, and crystal orientation, inspiring the fabrication of structural-functional integrated materials in extreme environment applications such as nuclear reactors.

High Radiation Resistance in the Binary W-Ta System Through Small V Additions: A New Paradigm for Nuclear Fusion Materials.

Refractory High-Entropy Alloys (RHEAs) are promising candidates for structural materials in nuclear fusion reactors, where W-based alloys are currently leading. Fusion materials must withstand extreme conditions, including i) severe radiation damage from energetic neutrons, ii) embrittlement due to H and He ion implantation, and iii) exposure to high temperatures and thermal gradients. Recent RHEAs, such as WTaCrV and WTaCrVHf, have shown superior radiation tolerance and microstructural stability compared to pure W, but their multi-element compositions complicate bulk fabrication and limit practical use. In this study, it is demonstrated that reducing alloying elements in RHEAs is feasible without compromising radiation tolerance. Herein, two Highly Concentrated Refractory Alloys (HCRAs) - W53Ta44V3 and W53Ta42V5 (at.%) -were synthesized and investigated. Wefound that small V additions significantly influence the radiation response of the binary W-Ta system. Experimental results, supported by ab-initio Monte Carlo simulations and machine-learning-driven molecular dynamics, reveal that minor variations in V content enhance Ta-V chemical short-range order (CSRO), improving radiation resistance in the W53Ta42V5 HCRA. By focusing on reducing chemical complexity and the number of alloying elements, the conventional high-entropy alloy paradigm is challenged, suggesting a new approach to designing simplified multi-component alloys with refractory properties for thermonuclear fusion applications.

Size-Dependent Ultrafast UV Photochemistry of Aliphatic Disulfides in Solution.

We have investigated the photochemistry of dimethyl disulfide (DMDS) and glutathione disulfide (GSSG) in solution upon ultraviolet (UV) excitation in comparison to L-cystine by femtosecond X-ray absorption spectroscopy at the sulfur K-edge. For these aliphatic disulfides, the very similar differential absorption spectra reveal unequivocally a pair of geminate thiyl radicals as the single primary reaction product with a formation time constant of about 100 fs. We find size-dependent majority yields for disulfide recombination with DMDS reforming ten-fold slower and at lower quantum yield than L-cystine while GSSG recombines even faster than L-cystine at a yield of nearly 80 % within 2 ps after excitation. We attribute the much lower recombination rates and yields of DMDS to larger product separation after homolytic S-S bond cleavage due to the smaller thiyl radical mass and correspondingly larger mutual acceleration. Furthermore, we observe the delayed formation of at least one additional reaction product of these disulfides that we attribute to perthiyl radicals. The ultrafast recombination of L-cystine and GSSG at majority yield in condensed phase suggests a dynamic S-S bond integrity which may be exploited in natural systems to mitigate UV radiation damage, and which could be of interest in materials design.

A compact C-band FLASH electron linear accelerator prototype for the VHEE SAFEST project

FLASH therapy, a novel cancer treatment technique, aims to control tumor growth, sparing the healthy tissue from radiation damage and thus increasing the therapeutic ratio. Translating FLASH therapy into clinical practice, especially for treating deep-seated tumors, necessitates achieving Very High-Energy Electron (VHEE) levels within the 50-250 MeV range. In 2022 Sapienza University, in collaboration with INFN, launched the SAFEST project, a compact C-band 100 MeV Ultra-High Dose Rate (UHRD) radiation source for the treatment of deep-seated tumors, which was partially funded by Italian PNRR (Next Generation EU). A C-band linac prototype at lower energy, with an electron pulse of 100 nC and repetition frequency &amp;lt;200 Hz, is being developed to test the key choices and technology of a VHEE machine. This paper provides insights into the design strategy of the prototype, discussing the optimization of the main RF and electron beam parameters. The expected dose profiles are also shown and discussed. The progress of this innovative linac represents a step forward in the realization of a C-band compact FLASH VHEE source for cancer treatment.

Niallia tiangongensis sp. nov., isolated from the China Space Station.

Understanding the characteristics of microbes during long-term space missions is essential for safeguarding the health of astronauts and maintaining the functionality of spacecraft. In this study, a Gram-positive, aerobic, spore-forming, rod-shaped strain JL1B1071T was isolated from the surface of hardware on the China Space Station. This strain belongs to the genus Niallia, with its closest relative being Niallia circulans ATCC 4513T. The genome of JL1B1071T is 5 166 230 bp in size, with a G+C content of 35.6 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between JL1B1071T and N. circulans ATCC 4513T are 83.3 and 27.5%, respectively, both below the recommended thresholds for species delineation. The major cellular fatty acids were anteiso-C15:0 and iso-C15:0. The major quinone was menaquinone-7 (MK-7). Notably, strain JL1B1071T demonstrates a unique ability to hydrolyse gelatin, suggesting that it can utilize gelatin as a substrate in nutrient-limited environments. Genomic analysis of JL1B1071T revealed two conserved signature indels in the GAF domain-containing protein and DNA ligase D protein, which are specific to the genus Niallia. Additionally, structural and functional differences in proteins BshB1 and SplA were identified, which may enhance biofilm formation, oxidative stress response and radiation damage repair, thereby aiding its survival in the space environment. Based on phenotypic, physiological and chemotaxonomic characteristics, as well as genome annotation, strain JL1B1071T was considered a novel species within the genus Niallia and is proposed to be named Niallia tiangongensis sp. nov. The type strain is JL1B1071T (=GDMCC 1.4642=KCTC 43715).

Extending the reach of single-particle cryoEM.

Molecular structure determination using electron cryomicroscopy (cryoEM) is poised in early 2025 to surpass X-ray crystallography as the most used method for experimentally determining new structures. But the technique has not reached the physical limits set by radiation damage and the signal-to-noise ratio in individual images of molecules. By examining these limits and comparing the number and resolution of structures determined versus molecular weight, we identify opportunities for extending the application of single-particle cryoEM. This will help guide technology development to continue the exponential growth of structural biology.

Advancements in primary radiation damage models and SRIM simulations: A review of radiation damage predictions

Advancements in primary radiation damage models and SRIM simulations: A review of radiation damage predictions

Influence of implantation and annealing temperatures on the irradiation damage in He2+ ion implanted 6H-SiC

Influence of implantation and annealing temperatures on the irradiation damage in He2+ ion implanted 6H-SiC

Molecular dynamics simulations of the evolution of primary radiation damage in Ti-6Ta alloy for spent nuclear fuel reprocessing

Molecular dynamics simulations of the evolution of primary radiation damage in Ti-6Ta alloy for spent nuclear fuel reprocessing

Simulation analysis of 35 MeV high-power electron accelerator driven white neutron source target.

Simulation analysis of 35 MeV high-power electron accelerator driven white neutron source target.

Experimental investigation of the impact of irradiation damages on the mechanical properties of tungsten

Experimental investigation of the impact of irradiation damages on the mechanical properties of tungsten

Surface activation via irradiation damage treatment using low-energy protons to enhance pulsed-current-assisted diffusion bonding of Ti–6Al–4V alloy

Surface activation via irradiation damage treatment using low-energy protons to enhance pulsed-current-assisted diffusion bonding of Ti–6Al–4V alloy

Quantitative assessment of Ni+ and He+ ion irradiation damage in a tungsten heavy alloy under the simulated nuclear fusion environment

A 90W-7Ni-3Fe (wt.%) tungsten heavy alloy has been sequentially Ni+ and He+ ion irradiated at 700 °C to simulate the high temperature irradiation environment of a fusion reactor interior. W/Ni–Fe-W dual-phase alloys have been proposed to serve as plasma facing materials and require detailed investigation of their behavior under fusion relevant conditions to assess their overall applicability. To evaluate material performance under five years of simulated fusion reactor service, microstructural characterization of the nanoscale defect distribution has been performed on both constituent phases, revealing peak swelling in the W phase of approximately 0.03%. The γ-phase (Ni–Fe-W) is found to swell approximately 0.68% under the same irradiation conditions, indicating significant cavity formation and growth. Additionally, a novel multi-projection imaging approach has been applied to determine the extent of damage segregation along the dual-phase W-to-γ interface and exposes that these interfaces act as sink sites for the accumulation of cavities. Interphase boundaries are noted to possess an 11.8% areal coverage of defects along the boundary plane, primarily on the γ-phase side of the boundary. The accumulation of cavities at these interphase boundaries is anticipated to adversely affect overall material toughness, and this work reveals a pressing need for mechanical property testing of irradiated W–Ni-Fe dual-phase alloys.

Instantaneous dose rate as a crucial factor in reducing mortality and normal tissue toxicities in murine total-body irradiation: a comparative study of dose rate combinations

PurposeThe ultra-high dose rate (UHDR) radiation shows promise in eradicating tumors while reducing normal tissue toxicities. However, the biological outcomes of UHDR are influenced by various factors, particularly the mean dose rate and instantaneous dose rate. Additionally, the UHDR response at large field sizes is lacking. This study aimed to explore the impact of different dose rate combinations on gastrointestinal biological outcomes following total-body irradiations (TBI) and to examine the involved molecular signaling pathways.MethodFemale C57BL6/J mice received 10 Gy TBI using three modes: ultra-high mean and ultra-high instantaneous dose rate irradiation (HH mode), low mean and ultra-high instantaneous dose rate irradiation (LH mode), and low mean and low instantaneous dose rate irradiation (LL mode). Mice were euthanized at 3 h and 48 h post irradiation to assess acute normal tissue damage and perform transcriptome sequencing. Furthermore, a subset of mice was monitored for 30 days to evaluate survival.ResultsWe found that when the instantaneous dose rate is sufficiently high (> 105 Gy/s), both ultra-high or low mean dose rate irradiation reduced mice mortality, myelosuppression, DNA damage, and cell apoptosis. The survival probabilities 30 days after 10 Gy TBI were 4/7, 4/6, and 0/6 in the HH, LH, and LL groups, respectively. Myelosuppression was lower at 3 h and 48 h post HH and LH irradiations than LL irradiation. The better regulated inflammatory response was evident at 48 h post HH and LH irradiation compared to LL irradiation. Additionally, DNA damages and cell apoptosis in the intestinal tissue were significantly reduced after HH and LH irradiations compared to LL irradiation. Transcriptome sequencing of intestinal tissues revealed that HH irradiation activated immune response pathways and suppressed mitochondrial related pathways compared to LL irradiation.ConclusionOur findings underscore the pivotal role of instantaneous dose rate in reducing radiation damages. When the instantaneous dose rate is sufficiently high (> 105 Gy/s), both ultra-high or low mean dose rate irradiation (HH and LH mode) reduced mice mortality, myelosuppression, DNA damage, and cell apoptosis. Understanding these dose rate effects and biological responses are crucial for optimizing radiotherapy strategies and exploring the potential benefits of UHDR irradiation.

Radiation-Hardened Position-Sensitive Photodetector Based on Undoped 4H-SiC.

Position-sensitive photodetectors (PSDs) have been widely used for seamless, high-resolution light tracking, but applications such as aerospace and prolonged field operations require stable performance in extreme environments. Conventional PSDs, typically based on the lateral photovoltaic effect of silicon or other semiconductor junctions, are prone to radiation damage and material degradation, limiting their reliability under harsh conditions. Silicon carbide (SiC), with its wide bandgap, high mobility, low defect density, and strong resistance to radiation damage, offers a promising alternative for developing robust detectors. In this work, we present a PSD based on undoped 4H-SiC, designed with a simple vertical structure that eliminates the need for complex multi-interface architectures. The device demonstrates excellent performance, including a light on-off ratio exceeding 103 under sub-milliwatt illumination, spatial resolution of ∼0.1 μm, and fast response times of ∼10 μs (rise) and ∼6.3 μs (fall). It also exhibits remarkable stability under γ-ray irradiation (300 krad) with minimal photocurrent variation, making it suitable for accurate position tracking in radiation-prone environments. This work highlights the potential of 4H-SiC-based PSDs for advanced sensing applications that demand both high performance and resilience in extreme environments.

Synthesis and Preclinical Evaluation of Novel 99mTc-Labeled FR-Targeting Agents with Satisfactory Imaging Contrast and Reduced Renal Uptake.

The folate receptor is overexpressed in a variety of epithelial-derived malignant cells. Several folate-based tracers have shown the ability to target FR, but excessive renal uptake is a general concern. To decrease renal uptake and achieve high target-to-nontarget ratios, two folate derivatives (DProFA and DAlaFA) were designed and synthesized. Eight complexes with high labeling yields and good in vitro stability were obtained by radiolabeling with technetium-99m and different coligands. The results of both in vitro cell and in vivo normal mice biodistribution studies demonstrated specific binding of eight complexes to the FR. Among them, [99mTc]Tc-DProFA-L1 exhibited lower off-target uptake and high tumor uptake in tumor-bearing mice, and significant inhibition in the biodistribution and SPECT/CT imaging study. The lower renal uptake of [99mTc]Tc-DProFA-L1 may prevent irradiation damage to the kidney. Consequently, [99mTc]Tc-DProFA-L1 is a highly promising candidate probe for the diagnosis of epithelial tumors in clinical nuclear medicine.

Radiation symptoms resemble laminopathies and the physical underlying cause may sit at the lamin A C-terminus

Ionizing radiation causes three divergent effects in the human body: On one side, tissue death (= deterministic effects) sets on, on the other side, mutations and cancer growth (= stochastic effects) can occur. In recent years, the additional phenomenon of accelerated aging has come to light. In the following, we argue that these seemingly contradictory radiation responses namely: (i) increased cancer growth, (ii) ablation of cancer tissue or (iii) deterministic senescence, share an underlying cause from damage at the lamin A C-terminus. In other words, besides the typically described genomic radiation impact, we propose an additional destabilization pathway via oxidation at the nuclear envelope. We propose five concrete hypotheses that draw a direct mechanistic model from radiation damage and cellular oxidative stress, to micronuclei and clinical symptoms. In conjunction with lamin B compensation, we might be able to explain why deterministic or stochastic responses dominate. If our model holds true, a novel target for radiotherapeutics and radiooncology arises, and a rationale to closer connect laminopathy and radioprotection research.Graphical

Reliability Improvement of High Mobility Oxide TFTs Based on Hydrogen-Resistant PEALD Al2O3 Gate Insulators Grown with N2O Plasma.

High quality aluminum oxide (Al2O3) dielectric films were fabricated based on plasma-enhanced atomic layer deposition (PEALD) and applied as gate insulators in high mobility oxide thin film transistors (TFTs). N2O plasma was used as the oxidizing reactant during the PEALD process, which resulted in the incorporation of nitrogen in the growing layers. The nitrogen content in Al2O3 could be adjusted by varying the N2O plasma power between 100 and 250 W. An optimum power of 200 W was observed, at which a 3% improvement in the hard breakdown and a 90% reduction in the trap density could be achieved, as compared with Al2O3 grown at an N2O plasma power of 100 W. However, as the power was increased up to 250 W, the film properties were compromised owing to the dominant plasma radiation damage. High mobility top gate oxide TFTs were next fabricated using indium-rich indium-gallium-zinc oxide (IGZO) as the active layer, and the PEALD grown Al2O3 films as the gate insulators. At an N2O plasma power of 200 W, a peak field effect mobility of 53.45 cm2/(V s) and a threshold voltage (Vth) of -0.03 V were achieved. During positive bias temperature stress (PBTS), the devices exhibited only slight negative Vth shifts of less than 0.18 V as the N2O plasma power was increased up to 200 W, which may be interpreted to be due to the improved hydrogen resistance of the Al2O3 film. The out-diffusion of hydrogen from the gate insulator is suppressed, and the retained hydrogen atoms are anticipated to diffuse into IGZO to generate free electrons during bias stress. This effect dominates the generally observed electron trapping phenomenon, which results in highly stable devices. To substantiate this hypothesis, the TFTs were annealed at 350 °C for 3 h in a hydrogen forming gas. The devices fabricated with Al2O3 at an N2O plasma power of 200 W exhibited changes of 0.28 cm2/(V s) in field effect mobility and 0.04 V in Vth after the anneal process. This is indicative of a suppressed hydrogen diffusion from the ambient into the active layer, thus demonstrating the hydrogen resistance of the Al2O3 dielectrics under consideration.