Effects Of Alpha Particles Research Articles

Resistive wall mode and fishbone mode in ITER steady state scenario: roles of fusion-born alphas and plasma flow

Drift-kinetic effects of fusion-born alpha particles on the n= 1 (n is the toroidal mode number) resistive wall mode (RWM) is numerically investigated for a recent design of the ITER 10 MA steady state plasma scenario, utilizing a magneto-hydrodynamic (MHD)-kinetic hybrid toroidal model. While the fluid theory predicts unstable RWM as the normalized plasma pressure β N exceeds the no-wall Troyon limit and with the mode growth rate monotonically increasing with β N, inclusion of the drift-kinetic contribution of trapped alphas qualitatively modifies the behavior by stabilizing the mode at high β N. In fact, a complete stabilization of the n= 1 RWM up to the ideal-wall Troyon limit is found. On the other hand, another unstable branch—the alpha-driven n = 1 fishbone mode (FB)—is identified in the high-β N regime, with the mode frequency matching that of the toroidal precession frequency of trapped alphas. Fast plasma toroidal flow however helps mitigate the FB instability. Kinetic stabilization of the RWM and flow stabilization of the (alpha-triggered) FB result in an enhancement of β N from the design value of 3.22–3.52 for the ITER scenario considered, while still maintaining stable plasma operation against the aforementioned MHD instabilities.

Role of damaged mitochondrial transfer in alpha-particle generator 212Pb radiation-induced bystander effect.

Rationale: 212Pb, a promising in vivo alpha-particle generator of 212Bi, has aroused much interest as a therapeutic radionuclide. For the development of targeted alpha therapy (TAT), it is important to determine the contribution of targeted effects in irradiated cells, and also of non-targeted effects in non-irradiated bystander cells. Currently, the critical roles of mitochondrial transfer in cellular crosstalk have garnered significant attention. However, the specific involvement of damaged mitochondrial transfer in orchestrating this alpha-particle radiation-induced bystander effect (RIBE) needs to be further explored. Methods: A novel alpha-emitting radiopharmaceutical, 212Pb-hydrogel nanoparticles (HNPs), was synthesized and subsequently evaluated its theranostics effects. The impact of irradiated cell-conditioned media (ICCM), collected at different times post-212Bi irradiation, on bystander cancer cells regarding cell viability was also investigated. Additionally, damaged mitochondria were isolated and cultured with non-irradiated bystander cells to assess their role. Results: 212Pb-HNPs exhibited efficient therapeutic antitumor effects in vitro, including increased GSH depletion, ROS accumulation, and mitochondrial damage in irradiated tumor cells. In vivo studies demonstrated its imaging potential through SPECT/CT, and RNA sequencing results indicated activation of oxidative stress-related pathways in irradiated tumors. Additionally, ICCM influenced the viability of non-irradiated bystander cells, suggesting a radiation-induced bystander effect by the alpha-particle 212Bi. Interestingly, damaged mitochondria isolated from ICCM were observed to enter co-cultured non-irradiated bystander cells. Further experiments confirmed that the transfer of damaged mitochondria results in the death of non-irradiated bystander cells. Conclusion: The present study highlights the theranostic potential of the alpha-particle generator 212Pb and, more importantly, elucidates the role of damaged mitochondrial transfer in alpha-particle RIBE. These findings provide a novel theoretical mechanism for the antitumor effects of alpha-particles and expand the clinical application prospects of TAT.

Stopping power of high-density alpha-particle clusters in partially degenerated deuterium–tritium fuels

The state of burning plasma had been achieved in inertial confinement fusion (ICF), which was regarded as a great milestone for high-gain laser fusion energy. In the burning plasma, alpha particles incident on the cryogenic (warm dense) fuels cannot be simply regarded as single particles, and the new physics brought about by the density effects of alpha particles should be considered. In this work, the collective interaction between them has been considered, namely, the effect of the superposition of wake waves. The stopping power of alpha-particle clusters, i.e., the rate of energy loss per unit distance traveled has been calculated using both analytical and simulation approaches. In theory, we obtain the stopping power of alpha clusters in cryogenic (warm dense) fuel by the dielectric function method, which illustrates the importance of the effective interaction between particles. Simulation results using the LAPINS code show that the collective stopping power of the alpha cluster is indeed increased via coherent superposition of excitation fields (the excitation of high-amplitude wake waves). However, the comparison between simulation and theoretical results also illustrates a coherent–decoherent transition of the stopping power of the cluster. The initial conditions with various sizes and densities of the alpha clusters have been considered to verify the condition of decoherence transition. Our work provides a theoretical description of the transport properties of high-density alpha particles in warm dense cryogenic fuel and might give some theoretical guidance for the design of actual fusion processes.

Effect of Ultraviolet Radiation and Alpha-particles on Nuclear Track Detector CR-39

Effect of Ultraviolet Radiation and Alpha-particles on Nuclear Track Detector CR-39

Calculation of Radon Gas Concentration in the Buildings of College of Women Education - Tikrit University using the Nuclear Track Detector CR-39

This study analyses the radon gas content in (17) samples taken from buildings of the College of Women's Education - Tikrit University. Using a long-term measuring approach and a nuclear effect detector, the effects of radon's alpha particles were measured (CR-39). Radon concentrations were discovered to fluctuate, with the greatest levels being found in computer lab buildings (1).it reaching (72.7 Bq.m-3), while the lowest value was in a Department of Psychological Sciences if it reaches (15.8 Bq.m-3) compared to the radioactive background of (39.0 Bq.m-3) There is no risk to the College's workforce, including workers and students, and there was no exposure to excessive levels of radiation or environmental pollution. This provided the College with an advantage in that it was not subjected to harmful amounts of radiation or contamination.

Effects of alpha particles on the transport of helium ash driven by collisionless trapped electron mode turbulence

The effects of alpha (α) particles on the transport of helium ash driven by collisionless trapped electron mode (CTEM) turbulence are analytically studied using quasi-linear theory in tokamak deuterium (D) and tritium (T) plasmas. Under the parameters used in this work, the transport of helium ash is mainly determined by the diffusion due to very weak convection. It is found that the ratio between helium ash diffusivity and effective electron thermal conductivity (D He/χ eff) driven by CTEM turbulence, which is a proper normalized parameter for quantifying the efficiency of helium ash removal, is smaller than unity. This indicates the less efficient removal of helium ash through CTEM turbulence as compared with ion temperature gradient (ITG) turbulence in [Angioni et al 2009 Nucl. Fusion 49 055013]. However, the efficiency of helium ash removal is increased 55% by the presence of 3% α particles with their density gradient being equivalent to that of electrons, and this enhancement can be further strengthened by steeper profile of α particles. This is mainly because the enhancement of helium ash diffusivity by α particles is stronger than that of the effective electron thermal conductivity. Moreover, the higher fraction of T ions, higher temperature ratio between electrons and thermal ions as well as flatter electron density profile, the stronger enhancement of D He/χ eff, and α particles further strengthen the favorable effects of these parameters on the removal of helium ash.

A Study on Low Frequency Electromagnetic Cyclotron Waves in the Solar Wind

According to Wind observations between 2005 and 2015, this paper investigates the dependences of the occurrence of low frequency electromagnetic cyclotron waves (ECWs) on the plasma parameters, the solar cycle, and the orientations of alpha-proton drift velocity ( V d ) and the ambient magnetic field ( B ). The occurrence rates of ECWs with respect to six plasma parameters are calculated. Results show that the preferential conditions for generation of left-handed (LH) ECWs are higher proton temperature (T p ), higher proton velocity (V p ), lower proton density (N p ), stronger proton temperature anisotropy (T ⊥/T ∥), higher normalized alpha-proton drift velocity (V d /V A), and higher normalized alpha particle density (N α /N p ), where T ⊥ and T ∥ refer to proton temperatures perpendicular and parallel to B , and V A is the local Alfvén velocity. For right-handed (RH) ECWs, however, the dependences on these plasma parameters are not obvious. On the other hand, it is found that the occurrence rate of LH ECWs increases as the sunspot number decreases, and decreases as the sunspot number increases. Further investigation shows that the increased occurrence rate of LH ECWs is accompanied by an increase in the medians of V p , V d /V A, and N α /N p . For RH ECWs, the occurrence rate appears to be nearly unrelated to the sunspot number, suggesting a negligible correlation with the solar cycle. In addition, a modified angle is introduced to include the factors of orientation of B (anti-sunward or sunward) and angle between V d and B , simultaneously. It is found that the occurrence of LH ECWs has the strong preferential condition that V d is anti-sunward, while a different situation arises for RH ECWs. These results are discussed in the context of the temperature-anisotropy-driven instabilities with the effect of alpha particles.

Effects of alpha particles on the CTEM driven zonal flow in deuterium–tritium tokamak plasmas

The effects of fusion-born alpha (α) particles on zonal flow (ZF) driven by collisionless trapped electron mode (CTEM) turbulence are analytically investigated, using gyrokinetic and bounce kinetic theories in the deuterium–tritium (D–T) tokamak plasmas. It is found that ZF growth rate is increased by α particles because of the reduction of polarization shielding as well as enhancement of CTEM instability. The results of this paper are qualitatively consistent with the enhancement of the level of residual ZF by α particles in (Cho and Hahm 2019 Nucl. Fusion 59 066026). The parametric dependence of ZF growth rate is also analyzed. The increment of ZF growth rate is further enhanced by α particles with higher fraction and steeper density profile. Besides, the dependence of ZF growth rate on electron temperature T e could be changed qualitatively by the presence of α particles when T i = T e. Moreover, the difference of ZF growth rates in the presence of α particles with slowing down and equivalent Maxwellian distribution functions is very weak. These results could be very important for accurate prediction of the confinement in the future burning plasmas such as International Thermonuclear Experimental Reactor and China Fusion Engineering Test Reactor.

Alpha particles detection using P3HT conducting polymer-coated DAM-ADC

For radiation detection applications, Raman analysis, photoluminescence (PL), and UV–Vis spectroscopy are thoroughly studied using the DAM-ADC (diallyl maleate - allyl diglycol carbonate) detector coated with poly(3-hexylthiophene-2,5-diyl) (P3HT) conducting polymer. A thin Am-241 disk that emits alpha particles with an activity of 340 kBq was used to irradiate the surface of DAM-ADC detector. After irradiation with different fluencies of alpha particles, the spectroscopic analysis confirms that the effects of alpha particles on the DAM–ADC detector coated by P3HT conducting polymer are detectable in Raman spectra and PL spectral emission. Furthermore, the photoluminescence and UV–Vis responses of the DAM–ADC samples are influenced by the track density of the irradiated samples. For Raman, UV–vis, and PL analysis, the spectral peak heights and the area under the peaks show a correlation with the fluencies of alpha particles. For the irradiated samples, all the techniques displayed major spectral alterations, suggesting that they could be used to establish sensitive alpha particle detection methods. For both direct and indirect transitions, the optical band gap was found to decrease with increasing the alpha fluencies.

Characterization of a custom-made 241Am alpha-source for radiobiological studies

A compact in-house alpha particle source has been developed and fully characterized. The irradiation source is a large area, 25 cm2, 5.4 MeV average energy 241Am source, above which a Mylar dish containing a monolayer of target cells can be placed at defined positions. The source uniformity, flux, particle energy and dose rate were determined experimentally. The dose rate to the nucleus at the closest position was 1.57 Gy/min. Furthermore, a 3D printed collimator was tested and found to improve the uniformity of the energy spectra of particles reaching the target. For validation, prostate PC-3 cells were irradiated in our experimental setup with absorbed doses up to 2 Gy and for reference compared with cells irradiated with conventional X-rays with doses up to 8 Gy. The Relative Biological Effectiveness for alpha particles at 10% survival was 3.66± 0.40 agreeing with previously published data. Data presented here show the feasibility of utilising a low-cost alpha-irradiation source for accurate in vitro assays to better understand the radiobiological effects of high LET alpha particles.

The Effect of α-Particles on Structural, optical and Morphological Properties for Cadmium Selenide Thin Film

In this paper, the effect of alpha particles on cadmium selenide thin film properties was invistecated. (CdSe) thin films prepared on glass bases at 50°C and 70°C tempartures, and pH=9 using the chemical bath deposition method. The irradiation was performed on (CdSe) films use the alpha particles source Americium (Am-241) with activity of 50μCi and energy 5.3MeV for a period irradiation of 5 hours. The samples were characterized by using the XRD, FESEM and EDX techniques. The optical measurements have been obtained by using the UV-V spectrophotometer. The results showed that there are effects of alpha particles on the optical and structural properties of the films. It was found that the energy gap increases slightly after the CdSe thin film irradiated, the absorption coefficient (α) is increases with irradiation due to the increase in the energy gap. The structure of the CdSe films has been transformed slightly from the cube structure to the hexagonal structure. The grain size increases with irradiation where the relative density increases clearly. The shape of the CdSe thin film at 70°C is affected by irradiation more over than at 50°C.

Modeling bystander effects that cause growth delay of breast cancer xenografts in bone marrow of mice treated with radium-223

Rationale The role of radiation-induced bystander effects in cancer therapy with alpha-particle emitting radiopharmaceuticals remains unclear. With renewed interest in using alpha-particle emitters to sterilize disseminated tumor cells, micrometastases, and tumors, a better understanding of the direct effects of alpha particles and the contribution of the bystander responses they induce is needed to refine dosimetric models that help predict clinical benefit. Accordingly, this work models and quantifies the relative importance of direct effects (DE) and bystander effects (BE) in the growth delay of human breast cancer xenografts observed previously in the tibiae of mice treated with 223RaCl2. Methods A computational model of MDA-MB-231 and MCF-7 human breast cancer xenografts in the tibial bone marrow of mice administered 223RaCl2 was created. A Monte Carlo radiation transport simulation was performed to assess individual cell absorbed doses. The responses of the breast cancer cells to direct alpha particle irradiation and gamma irradiation were needed as input data for the model and were determined experimentally using a colony-forming assay and compared to the responses of preosteoblast MC3T3-E1 and osteocyte-like MLO-Y4 bone cells. Using these data, a scheme was devised to simulate the dynamic proliferation of the tumors in vivo, including DE and BE propagated from the irradiated cells. The parameters of the scheme were estimated semi-empirically to fit experimental tumor growth. Results A robust BE component, in addition to a much smaller DE component, was required to simulate the in vivo tumor proliferation. We also found that the relative biological effectiveness (RBE) for cell killing by alpha particle radiation was greater for the bone cells than the tumor cells. Conclusion This modeling study demonstrates that DE of radiation alone cannot explain experimental observations of 223RaCl2-induced growth delay of human breast cancer xenografts. Furthermore, while the mechanisms underlying BE remain unclear, the addition of a BE component to the model is necessary to provide an accurate prediction of the growth delay. More complex models are needed to further comprehend the extent and complexity of 223RaCl2-induced BE.

Comparative study of Single Crystal (SC)-Diamond and 4H-SiC bulk radiation detectors for room temperature alpha spectroscopy

In this work, the fabrication, electrical characterization and alpha spectral characterization of single-crystal (SC) diamond bulk radiation detector have been carried out. The performance metrics of the SC-diamond bulk detector such as the leakage current density, charge collection efficiency, spectral resolution and polarization effects are studied and are compared with a bulk detector fabricated using High-Pure Semi-Insulating (HPSI) 4H-SiC. It is found that the SC-diamond detector exhibits lower leakage current density, higher μτ product, better spectral resolution and no polarization effects in comparison to the HPSI 4H-SiC detector. The time response analysis of the SC-diamond detector is carried out to study the effect of alpha particles on the operation of the SC-diamond detector. Accordingly, the stability of the SC-diamond detector is tested by evaluating the total counts versus real time and the performance of the diamond detector is found to be stable during the alpha-time spectroscopy. Hence, diamond bulk detectors using commercially available electronic grade diamond may be better suited for alpha particle spectroscopy compared to HPSI 4H-SiC of nearly equivalent thickness.

Isolation of the effects of alpha-related components from total effects of radium at low doses

Purpose Radium is the most common source of alpha radiation exposure to humans and non-human species in the environment but the dosimetry is complicated by the decay chain which involves gamma exposure due to radon daughters. This paper seeks to determine the separate contributions of alpha and gamma doses to the total dose and total direct and non-targeted effect in a fish and a human cell line. Materials and methods This study aimed to isolate the effect of alpha particles following exposure to low doses of radium in cells, and their progeny which received no further exposure. This was initially done by comparing the survival values of a human keratinocyte cell line (HaCaT) and an embryonic Chinook salmon cell line (CHSE-214) exposed to gamma radiation, from survival of the same cell lines exposed to mixed alpha and gamma radiation through exposure to Ra-226 and its decay products. A Monte Carlo simulation was later performed to determine the contributions of radium decay products including radon daughters. Results The human cell line showed increased radioresistance when exposed to low doses of alpha particles. In contrast the fish cell line, which demonstrated radioresistance to low dose gamma radiation, showed increased lethality when exposed to low doses of alpha particles. Significant and complex levels of non-targeted effects were induced in progeny of irradiated cells. The simulation showed that gamma and beta decay products did not contribute significant dose and the highest beta dose was below the threshold for inducing non-targeted effects. Conclusions The results confirm the need to consider the dose-response relationship when developing radiation weighting factors for low dose exposures, as well as the need to be aware of possible cell line and species differences.

Reliability of PERC Solar Cells under Alpha Irradiation: A Simulation-Based Study for Space Applications

The effects of alpha particles’ irradiation on the performance of simplified PERC silicon solar cells are studied through technology computer aided design (TCAD) simulations. The methodology adopted in this work incorporates the non-ionizing energy loss (NIEL) phenomenon to understand the radiation effects, which does not depend on extensive irradiation experimentations. Simulation results show that alpha particles in the range of ∼10 MeV and with fluence >1014 cm−2 lead to maximum performance degradation of the solar cell. Moreover, it is found that upon irradiating the solar cell with 1 MeV alpha particles, the output power reduces proportionally with increasing fluence due to the reduction of minority carrier lifetime in the base. On the other hand, the fill factor (FF) degrades by only <10% up to a fluence of ∼1013 cm−2, after which it decreases sharply. This trend reveals that the FF deteriorates significantly only when the irradiation process creates a Frenkel pair density that approaches the majority carrier density in the base. The methodology presented in this work opens new research avenues for potentially optimizing the solar cell design not only for better efficiency but also for improved reliability in radiation rich environments.

Особенности проявления модифицирующих свойств радиопротекторов при действии излучений разного качества на эукариотические клетки

Modification of the action of ionizing radiation by chemicals, used both to enhance its action and to weaken it’s known and is widely used in medical radiology. The article presents a comparative analysis of the modifying properties of three chemical radioprotectors (cysteamine, cysteine and cysteamine) when they are simultaneously act with to gama-rays, alpha-particles and ultraviolet radiation on yeast cells. The aim of the study was to compare the features of the manifestation of the properties of chemicals in relation to the protection of cells from UV-like damage when exposed to ionizing radiation or from damage caused by ultraviolet radiation. It was demonstrated that the cysteamine protects cells both from the damaging effects of gama-rays and from ultraviolet radiation, unlike cysteamine and cysteine, which protect cells exclusively from the effects of ionizing radiation. Moreover, cystamine does not change the effect of alpha-particles, which have a high ionization density of the substance, but practically do not cause excitation processes in biological objects. The obtained data indicate that cystamine realizes its protective properties against damage caused by ultraviolet radiation and UV-like damage resulting from the action of gama-rays due to the excitation of molecules or, more precisely, the ultraviolet component of Vavilov-Cherenkov luminescence accompanying the action of ionizing radiation.

Measuring Laser Beam Transmission through Exposed/Etched CN-85 Detectors

Cellulose Nitrate (CN-85) plastic detectors, with a thickness of 100 μm, were exposed to radiation by alpha particles. Then, the irradiated detectors were etched and treated with radiation by using He-Ne laser source. The influence of laser irradiation on the physical characterization of CN-85 track detectors has been investigated through track radii. In this study, the tracks’ number and track radii were calculated. The results showed that the track radii of laser-etched CN-85 detectors were reduced with increasing the etching time. Further, the track radii were changed due to the effects of alpha particles on the CN-85 detectors. This method is found to be a relatively inexpensive, easy, and effective tool for measuring the radiation dose.

A high-throughput alpha particle irradiation system for monitoring DNA damage repair, genome instability and screening in human cell and yeast model systems.

Ionizing radiation (IR) is environmentally prevalent and, depending on dose and linear energy transfer (LET), can elicit serious health effects by damaging DNA. Relative to low LET photon radiation (X-rays, gamma rays), higher LET particle radiation produces more disease causing, complex DNA damage that is substantially more challenging to resolve quickly or accurately. Despite the majority of human lifetime IR exposure involving long-term, repetitive, low doses of high LET alpha particles (e.g. radon gas inhalation), technological limitations to deliver alpha particles in the laboratory conveniently, repeatedly, over a prolonged period, in low doses and in an affordable, high-throughput manner have constrained DNA damage and repair research on this topic. To resolve this, we developed an inexpensive, high capacity, 96-well plate-compatible alpha particle irradiator capable of delivering adjustable, low mGy/s particle radiation doses in multiple model systems and on the benchtop of a standard laboratory. The system enables monitoring alpha particle effects on DNA damage repair and signalling, genome stability pathways, oxidative stress, cell cycle phase distribution, cell viability and clonogenic survival using numerous microscopy-based and physical techniques. Most importantly, this method is foundational for high-throughput genetic screening and small molecule testing in mammalian and yeast cells.

Assessment of Single-and Double-Strand Breaks in DNA Induced by Auger Electrons of Radioisotopes Used in Diagnostic and Therapeutic Applications.

Introduction:Most of the radionuclides that are used for diagnostic purposes emit Auger electrons and can thus cause damage to the DNA molecule on a nanometer scale. Therefore, the nanodosimetric calculation of these radioisotopes is necessary to achieve better understanding on their effects.Aim:The aim of this study was to calculate the mean number of DNA strand breaks (single-strand breaks and double-strand breaks) caused by direct and indirect effects for six widely used Auger electron-emitting diagnostic radioisotopes, including 123I, 125I, 99mTc, 67Ga, 201Tl, 111In and two therapeutic radioisotopes of 131I(beta + Auger + CK emitter) and 211At(alpha + Auger + CK emitter).Materials and Methods:Geant4-DNA simulation tool was used to evaluate the effects of Auger electrons, beta and alpha particles of these radioisotopes on DNA molecules. Two different DNA molecule geometric models were simulated and the results of these two models were compared with each other as well as with the results of previous studies.Results and Conclusion:The results showed that the geometric shape of the sugar-phosphate groups may have a significant effect on the number of single-strand breaks (SSBs) and double-strand breaks (DSBs) of the DNA molecule. Among the most widely used diagnostic radioisotopes, 201Tl and 125I, had the greatest impact on the number of SSBs and DSBs, respectively, while therapeutic radioisotope of 131I almost had no effect, therapeutic radioisotope of 211At had the moderate effect on the number of breaks in the DNA chain.

MEAN VALUE OF LET FOR ONCOGENIC EFFECTS OF RADON AND ITS PROGENY

The topic of the article is to define the average value of linear energy transfer (LET) for carcinogenic effects of radon progeny. The microdosimetric model of boundary specific energy is used. It follows that the effect at high LET should decrease approximately with the third power of LET. This is verified by the analysis of the relationship between radiation effects ratio and LET in published experiments with oncogenic transformation of mammalian cells irradiated with the monoenergetic alpha particles. If these cells are exposed with the radon irradiator, our analysis leads us to conclude that the oncogenic effect of radon progeny is comparable to that of alpha particles with a LET of 75keV/μm. It is about a quarter lower than the LET value, where the effect of the monoenergetic alpha particles reaches its maximum level. Some implications for lung cancer due to radon inhalation may also be carefully examined.