Radiation Damage Research Articles

CaF2 optical components are critical elements in DUV lithography systems, and their performance degradation directly impacts system reliability. The simultaneous thermal and photochemical effects of deep ultraviolet (DUV) nanosecond light source irradiation on optical elements' intricate component irradiation damage mechanisms, posing challenges for accelerated lifetime studies. Therefore, this study examines the combined accelerating impact of photothermal and photochemical effects on component damage by contrasting the damage evolution under different deep ultraviolet laser irradiation scenarios. The consistency observed between the absorption spectra and XRD characterization results indicates that photochemical effects dominate in the initial irradiation stage, manifested by the irradiation-induced generation of M centers and the development of tensile lattice strain. However, accelerated irradiation amplified the UV absorbance by about 104 compared to real-time irradiation. Contamination increased the RMS roughness by 10∼102 relative to non-accelerated samples, and the average UV absorbance rose by 19.93%. Therefore, the thermal effects of irradiation influence the photochemical processes and surface roughness of optical elements by promoting defect generation and aggregation, internal stress states, and contaminant reaction rates, respectively.

The Second Target Station (STS) at Oak Ridge National Laboratory’s Spallation Neutron Source is designed to become the world’s highest peak brightness source of cold neutrons. To design a complex radiation facility such as the STS in a timely manner, the latest radiation transport computational tools are necessary. In this work we discuss the application the new Attila4MC ® mesh generator and the new Attila4MC-CottonwoodTM variance reduction module, both developed by Silver Fir Software, Inc. The new tools were used to generate unstructured mesh geometry and coupled neutron-photon weight windows for the subsequent MCNP simulation of energy deposition, radiation damage, and prompt dose rate for several STS components with significantly increased efficiency.

The Second Target Station (STS) at the Oak Ridge National Laboratory Spallation Neutron Source (SNS) uses light water to cool the primary components inside the core vessel, including the target, proton beam window, moderators, beryllium reflectors, and other structures. As water circulates through the core vessel, it becomes radioactive due to spallation and transmutation reactions induced by high-energy protons, neutrons, and other particles. The activated coolant then flows through secondary components, such as pipes, tanks, and pumps, located outside of the core vessel. These secondary components require adequate shielding to ensure personnel safety and protect sensitive facility electronics from radiation damage. Unique challenges arise in modeling coolant activation in spallation systems because several key radionuclides originate in significant quantities from high-energy spallation reactions with oxygen. These processes are largely absent in fission and fusion reactors, where the maximum radiation energies are approximately two orders of magnitude lower. The goal of this paper is to demonstrate how to perform shielding analysis for the secondary components of water-cooling loops in spallation neutron facilities. It describes the method used during the original SNS design, which has also been adopted at the European Spallation Source (ESS). This “dilution method” assumes stagnant irradiation but dilutes the activities of the radioisotopes produced within the core vessel by the total loop volume to account for water circulation. A new method developed during the SNS Proton Power Upgrade (PPU) project is introduced. This “short- and long-lived (S&L) method” uses two activation calculations. The first calculation is tailored to long-lived radioisotopes whose half-lives are longer than loop circulation times. The second calculation focuses on radioisotopes that decay significantly between circulations. The two methods are compared by calculating radioisotope inventories, decay photon spectra, and dose rates in a concrete shield surrounding an infinite pipe. To validate both approaches, dose rates were also computed for one of the SNS coolant pipes and compared against facility measurements. The dilution method underestimates the measured dose by a factor of approximately 14, while the S&L method produces results within 20% of observed values. The S&L method is then applied to assess the shielding requirements of key secondary components of the water coolant loops at STS, including the delay tanks, hydrocyclone, and gas-liquid separator tanks. Using realistic STS operational design parameters, the required concrete wall thickness for the delay tank vault is estimated to range from 160 to 190 cm. These results provide design guidance for STS and align with scaled estimates based on PPU shielding analyses.

The scanning helium microscope (SHeM) is a new technology that uses a beam of neutral helium atoms to image surfaces non-destructively and with extreme surface sensitivity. Here, we present the application of the SHeM to image bacterial biofilms. We demonstrate that the SHeM uniquely and natively visualises the surface of the extracellular polymeric substance matrix in the absence of contrast agents and dyes and without inducing radiative damage.

This study investigates the effects of Ar ion irradiation on the mechanical properties and microstructure of SA508 Grade 3 Class 1 and Class 2 reactor pressure vessel steels. Three different fluence levels of Ar ion irradiation were applied to simulate accelerated irradiation damage conditions. Charpy impact and tensile tests conducted before and after irradiation showed no significant changes in bulk mechanical properties. Stopping and Range of Ions in Matter (SRIM) and Transport of Ions in Matter (TRIM) simulations revealed that Ar ion irradiation produces a shallow penetration depth of approximately 2.5 µm, highlighting the limitations of conventional macro-mechanical testing for evaluating irradiation effects in such a thin surface layer. To overcome this limitation, nano-indentation tests were performed, revealing a clear increase in indentation hardness after irradiation. Transmission electron microscopy (TEM) analysis using STEM–BF imaging confirmed a higher density of irradiation-induced defects in the irradiated specimens. The findings demonstrate that while macro-mechanical properties remain largely unaffected, micro-scale testing methods such as nano-indentation are essential for assessing irradiation-induced hardening in shallowly damaged layers, providing insight into the behavior of SA508 reactor pressure vessel steels under accelerated irradiation conditions.

Temperature effects on radiation damage in HCP-zirconium: A molecular dynamics study using a fine-tuned machine-learned potential

Influence of symmetric tilt grain boundaries and/or Cr-rich α′ precipitates on irradiation damage in Fe-Cr-Al alloys: A molecular dynamics investigation

Performance of newly constructed plastic scintillator barrel in the WASA-FRS experiments and evaluation of radiation damage effects on multi-pixel photon counter

Radiation damage of ultrafine grained and nanocrystalline 304 austenitic stainless steel subjected to heavy ion irradiation

Effect of Fe irradiation on the corrosion of 321 stainless steel at high-temperature CO2: Different oxidation responses of δ-ferrite and austenite to irradiation damage

Polymer-based composites show great potential as lightweight radiation shielding materials; however, a significant gap remains in understanding their performance stability under extreme high-energy radiation conditions. For this reason, the present study pioneers a systematic investigation into the dynamic evolution of polypropylene/lead oxide (PP/PbO) composite with heterogeneous network structure exposed to high-energy γ ray. Through multiscale characterisation spanning structure, surface, rheological behaviour, crystallinity, thermal stability, mechanical property, and shielding efficiency across incremental radiation doses, we reveal the fundamental role of heterogeneous network structure in irradiation damage mechanisms. The results indicate that although γ-ray irradiation indeed leads to varying degrees of degradation in various aspects of PP/PbO composite, the formation of a heterogeneous network structure mitigates the irradiation damage to a large extent, enabling the composite to exhibit superior tensile and impact strength compared to previously reported PP-based materials. More importantly, PP/PbO composite with a heterogeneous network structure retains a shielding efficiency of approximately 7.67% after high-energy ray exposure (120 kGy), which is 1.5 times higher than that of its unmodified counterpart (conventional polypropylne/lead oxide, CPP/PbO) at the same irradiation dose. Meanwhile, the half-value layer and tenth-value layer values of PP/PbO composite increased by less than 13.7% compared to the unirradiated state and are only 60% of those of CPP/PbO. The tensile strength of PP/PbO composite (120 kGy) decreases by only 11% after irradiation but still remains above 20 MPa. This work establishes comprehensive structure–property relationships that could facilitate the development of radiation-resistant polymer-based composites for extreme service conditions.

Advances of gas molecules against radiation damage.

Radiotherapy (RT) is a cornerstone in cancer treatment, but often causes radiation-induced injury. Accumulating evidence points to the gut microbiota in modulating immune functions and maintaining intestinal integrity to impact RT efficacy. This review examines the current understanding of intestinal flora and their metabolites within the context of RT. We outlined the current research applications in how microbiota-targeted strategies such as probiotics, prebiotics, dietary interventions, and faecal microbiota transplantation could restore microbial balance, reduce toxicity, and improve patient prognosis. Microbial byproducts such as short-chain fatty acids, bile acids and tryptophan exhibit protective effects against radiation damage, supporting immune modulation and enhancing tumour radiosensitivity. These microbial products underscore the potential of gut microbiota-targeted therapies as adjunctive treatments in RT, with implications for reducing toxicity and personalizing cancer care. All these strategies targeting gut microbiota and metabolites potentially aim to develop innovative therapies that boost RT effectiveness while minimizing side effects, and finally revolutionizing personalized cancer treatment. KEY POINTS: RT alters gut microbiota composition and contributes to intestinal injury and systemic toxicity. Gut microbiota regulate mucosal integrity, immune responses and therapeutic outcomes of RT. Microbial metabolites, including SCFAs, BAs and tryptophan derivatives, protect against radiation injury and enhance tumour radiosensitivity. Microbiota-targeted interventions (e.g. probiotics, prebiotics, dietary strategies, FMT) show promise for reducing RT-related toxicity and improving patient prognosis.

One of the most urgent and significant issues in modern medicine and veterinary science is the protection of humans and animals from radiation damage, as well as the development of effective and safe methods of nootropic therapy. The main goal of scientific research conducted in this area is to determine 154ways to protect living organisms from the harmful effects of ionizing radiation and to minimize its consequences. In the first stage of the study, an experiment was conducted under laboratory conditions using 30 laboratory mice. Hematological analysis showed that all blood parameters were within physiological norms, indicating no significant abnormalities in body systems at the initial stage of the experiment. In the second stage, the effectiveness of removing radionuclides from the bodies of rats using natural sorbents based on shungite and bentonite was evaluated. During this phase, the level of radionuclide elimination and the time of residual dose load formation in the gastrointestinal tract and critical organs were determined at 5, 15, 30, and 60 minutes. As a result, the group that received sorbents showed significantly lower accumulation of radiopharmaceutical substances: after 5 minutes –4.48%, after 15 minutes –2.0%, after 30 minutes –1.35%, and after 60 minutes –1.04%

High-energy (710 MeV) Bi ion track morphology in polycrystalline silicon nitride was investigated during post-irradiation annealing. Using both in-situ and ex-situ transmission electron microscopy, we monitored the recovery of crystallinity within initially amorphous ion track regions. In-situ annealing involved heating samples from room temperature to 1000 °C in 50 °C increments, each held for 10 s. We observed a steady decrease in both the size and number of tracks, with only a small number of residual crystalline defects remaining at 1000 °C. Ex-situ annealing experiments were conducted at 400 °C, 700 °C, and 1000 °C for durations of 10, 20, and 30 min. Complete restoration of the crystalline lattice occurred after 30 min at 700 °C and 20 min at 1000 °C. Due to inherent differences in geometry, heat flow, and stress conditions between thin lamella and bulk specimens, in-situ and ex-situ results cannot be compared. Molecular dynamics simulations further revealed that track shrinkage begins in cells within picoseconds, supporting the notion that recrystallization can start on very short timescales. Overall, these findings demonstrate that thermal recrystallization of damage induced by swift heavy ion irradiation in polycrystalline Si3N4 is possible. This study provides a foundation for future research aimed at better understanding radiation damage recovery in this material.

This study employs in situ transmission electron microscopy (TEM) to investigate the dynamic evolution of radiation-induced defects in gallium nitride (GaN) under high temperature (800 °C). The results demonstrate that defect cluster size increases progressively with irradiation dose (up to 2.48 displacements per atom, dpa), while cluster density exhibits a non-monotonic trend, peaking at intermediate doses (0.31–0.62 dpa) before declining due to coalescence of smaller clusters. Aberration-corrected scanning TEM reveals that irradiation generates dislocations, stacking faults, and cavities. Besides, N2 bubbles nucleate even at ultralow doses (0.02 dpa), driven by interstitial N aggregation and vacancy capture. Despite significant radiation damage, GaN maintains its crystalline structure without amorphization at high doses. Besides, there is negligible aggregation of defects around intrinsic dislocations—a behavior attributed to the high migration energy barriers of vacancies and interstitials in GaN. These findings elucidate the intrinsic radiation resistance mechanisms of GaN through atomic-level defect dynamics, providing critical guidance for designing next-generation radiation-tolerant power electronics and radiation detectors in extreme environments such as nuclear reactors and space applications.

Martin C. (Marty) Mihm made multiple, pivotal contributions over four decades of discovery, innovation, and development leading to the world-wide application of lasers in dermatology. This started with trying to understand how pulses of light could be tailored to affect microscopic "target" structures in skin where the light is absorbed. There were many surprises, often first observed by light or electron microscopy. A host of new capabilities ensued, including laser treatments for microvascular and vascular malformations, non-melanoma pigmented lesions, tattoo and hair removal, rehabilitation of scars, improvement of photoaged skin, and lipid-targeting lasers for reduction of fat and acne. Dr. Mihm extended himself directly to patients, especially children with vascular anomalies. He contributed to the discovery that GLUT1, a glucose transporter expressed on vascular endothelium, is a defining diagnostic for infantile hemangiomas. He established a multispecialty vascular-anomalies clinic at the Massachusetts General Hospital, and co-founded the Vietnam Vascular Anomalies Center (VVAC) in Ho Chi Minh City. In Vietnam, topical radioactive phosphorus (32P) is applied as a misguided treatment for infantile hemangiomas, leading to radiation damage in uncounted thousands of children. By teaching the use of beta-adrenergic drug treatment, the use of 32P has been greatly reduced. Dr. Mihm pioneered the concept of pulsed dye laser (PDL) in combination with angiogenic inhibitors to improve the clinical efficacy of port wine stain (PWS) treatment. Moreover, he made seminal contributions to our understanding of the pathogenesis and spectrum of phenotypes of PWS lesions. The legacy of Martin C. Mihm extends to the entire world.

The formation of various DNA base modifications is one of the significant consequences of the action of ionizing radiation on biological systems. These modifications can alter the conformation of damaged fragments and change their interaction with oncoming nucleotides during biosynthesis. In this work, the consequences of the formation of 8-oxo-guanine (OG) and 5-formyl-cytosine (fC) in the DNA structure are considered. The structural and genetic experimental data available in the literature for these modifications is analyzed in comparison to the MM and QM results obtained for the simple fragments of damaged DNA. The computations shed light on how the change in the interaction energy between subunits due to the radiation damage alters their biological function. The existence of OG nucleoside in both anti- and syn- base sugar orientations explains its high mutagenicity. The anti- conformation supports the formation of an OG pair with cytosine, resembling the canonical G:C pair with three hydrogen bonds (H-bonds), while the syn- conformation can form mispairs with purines, both outcomes having the energy and structural characteristics favorable for insertion into the duplex. The H-bonded pair of fC with guanine resembles that of an intact base, and the minor probability of formation of mispairs leads to marginal mutagenicity of fC.

Bismuth and Lead are commonly used for radiation shielding to mitigate risks such as radiation damage and cancer. However, these materials are costly and impractical for certain applications. This study aims to explore the attenuation properties of various elements and composites using Monte Carlo simulations to develop improved radiation shielding materials. GAMOS software was employed to simulate materials with thicknesses ranging from 0.1 to 2.0 mm and x-ray energies between 10 and 150 keV. Initial simulations focused on validating bismuth and lead by calculating their mass attenuation coefficients, which matched NIST (National Institute of Standards and Technology) values within a 2% margin of difference. After verification, the study simulated various shielding materials incorporating metals and rare earth elements. Among these, four composites with rare earth elements demonstrating the highest mass attenuation coefficients were selected. These composites exhibited superior absorption in the 50–80 keV energy range compared to bismuth and lead.

Purpose: To explore the efficacy and safety of 125I source implantation via a coaxial puncture in treating locally advanced pancreatic cancer (LAPC). Methods: A retrospective analysis was used to investigate the efficacy and safety of 40 patients with LAPC treated with radioactive 125I particles under CT guidance in the hospital. A treatment planning system was used to develop the preoperative plan, and the radioactive 125I particles were implanted using a coaxial puncture technique in the same plane to simulate a sector distribution system. CT scans were performed at postoperative months 2, 4, and 6 for follow-up treatment outcome assessment. Overall survival (OS) time and progression-free survival (PFS) were calculated, and factors affecting prognosis were assessed. Results: All patients completed the operation successfully. The overall response rate of treatment at 2, 4, and 6 months was 37.5%, 47.5%, and 50.0%. The median OS and PFS were 11.0 months (95% confidence interval [CI]: 9.14-12.86) and 9.0 months (95% CI: 7.45-10.55), respectively. The 6- and 12-month PFS rates were 85.0% (95% CI: 69.6%-93.0%) and 35.0% (95% CI: 20.8%-49.5%), respectively. The 12-month OS rates were 47.5% (95% CI: 20.2%-49.8%). The intraoperative complications related to the operation were local abdominal hemorrhage in 2 cases, subcutaneous soft tissue hematoma in 2 cases, and wrong puncture of the pancreatic duct in 1 case. The main side-effects were fever in 10 cases and decreased appetite in 3 cases in the recent postoperative period. Eighteen grade 0 cases and 3 cases of grade I acute radiation enteritis occurred. No acute radiation damage above grade II and late radiation damage was observed. Conclusions: Coaxial puncture 125I source implantation is a promising percutaneous minimally invasive technology that is safe and effective in treating LAPC.