Alpha Particle Beam Research Articles

Excitation functions for [formula omitted]Ag(α,x) reactions with detailed covariance analysis

Natural silver targets were irradiated using an alpha particle beam to measure the activation cross sections of radioisotopes within the energy range of 23–40 MeV. The newly obtained cross section data, compared with previous experimental results, underline the importance of this work in the context of nuclear reactions and medical applications. Alpha particle induced reaction with natAg involved the production of radioisotopes such as 111In, 105Ag, 106mAg. In this study, we focused on calculating correlation matrices for the natAg(α,x) nuclear reactions. These matrices were generated by considering various interconnected variables, such as decay constants, particle number densities, γ-ray intensities and detector efficiencies for both monitor and sample nuclear reaction products.

Investigation of 209Bi (α,2n)211At reaction route for the production of α-emitter 211At

In this research, the calculations have been done for α-emitters of 211At, which is a promising isotope in cyclotrons for radiotherapy. The scope of the study is to investigate the production parameters of 211At, which can be produced in the cyclotron by bombarding bismuth with an alpha particle beam for the 209Bi(α,2n)211At reaction. The total activity, reaction yield, and production cross–sections of 209Bi(α,2n)211At reaction have been calculated by using diverse level density models of the TALYS 1.95 code. Furthermore, recommended data with 95% confidence limits have been obtained. Experimental data available in the literature based on EXFOR compilation are used to compare the findings. Consequently, the required beam energy has been found to be 28 MeV to produce 211At.

Activation cross section measurement of alpha-particle induced nuclear reactions on tantalum

Activation cross sections induced by 50 MeV alpha-particle beam on natural tantalum were measured at the AVF cyclotron of the Nishina Center of RIKEN. The well-established stacked target technique and activation method were applied followed by high-resolution gamma spectrometry to determine the reaction cross sections. The experiment aimed to determine activation cross sections for the longer-lived reaction product. Accordingly, activation cross sections were deduced for the formation of 181, 182m, 182g, 183, 184m, 184gRe and 178g, 182gTa.

On the Use of Accelerated Helium Ions for Radionuclide Production: are Beams of Alpha Particles Needed?

On the Use of Accelerated Helium Ions for Radionuclide Production: are Beams of Alpha Particles Needed?

Geant4-DNA simulation of human cancer cells irradiation with helium ion beams

Purpose:This study aimed to develop a computational environment for the accurate simulation of human cancer cell irradiation using Geant4-DNA. New cell geometrical models were developed and irradiated by alpha particle beams to induce DNA damage. The proposed approach may help further investigation of the benefits of external alpha irradiation therapy. Methods:The Geant4-DNA Monte Carlo (MC) toolkit allows the simulation of cancer cell geometries that can be combined with accurate modelling of physical, physicochemical and chemical stages of liquid water irradiation, including radiolytic processes. Geant4-DNA is used to calculate direct and non-direct DNA damage yields, such as single and double strand breaks, produced by the deposition of energy or by the interaction of DNA with free radicals. Results:In this study, the “molecularDNA” example application of Geant4-DNA was used to quantify early DNA damage in human cancer cells upon irradiation with alpha particle beams, as a function of linear energy transfer (LET). The MC simulation results are compared to experimental data, as well as previously published simulation data. The simulation results agree well with the experimental data on DSB yields in the lower LET range, while the experimental data on DSB yields are lower than the results obtained with the “molecularDNA” example in the higher LET range. Conclusion:This study explored and demonstrated the possibilities of the Geant4-DNA toolkit together with the “molecularDNA” example to simulate the helium beam irradiation of cancer cell lines, to quantify the early DNA damage, or even the following DNA damage response.

Separation of 71,72As from alpha-particle induced reaction on gallium oxide target using naturally occurring alkaloid caffeine

Abstract Gallium oxide target was irradiated with 46 MeV alpha-particle beam, which produced 71,72As and 67Ga radioisotopes in the matrix. Separation of radio-arsenics from the bulk gallium target was carried out by caffeine, a nature-resourced reagent, extracted from black tea leaves. 71,72As radionuclides were preferentially attached with caffeine and precipitated with caffeine in 2 M Na2SO4 solution as caffeine was insoluble in aqueous medium under this condition. With increase in weight of caffeine, extraction of 71,72As and bulk gallium significantly increased. Bulk Ga along with 67Ga remained in the supernatant. Geometry optimization of caffeine–metal complex was carried out by theoretical computational analysis. DFT calculation corroborated with the experimental findings where As3+ preferentially binds with caffeine in presence of gallium and arsenic. As evidenced by the short As–O and As–N distances, the high binding energies are a result of the metal ion’s strong binding to the carbonyl and nitrogen centres, whereas no such result could be obtained in case of bulk gallium.

Proton and alpha radiation-induced mutational profiles in human cells

Ionizing radiation is known to be DNA damaging and mutagenic, however less is known about which mutational footprints result from exposures of human cells to different types of radiation. We were interested in the mutagenic effects of particle radiation exposures on genomes of various human cell types, in order to gauge the genotoxic risks of galactic cosmic radiation, and of certain types of tumor radiotherapy. To this end, we exposed cultured cell lines from the human blood, breast and lung to fractionated proton and alpha particle (helium nuclei) beams at doses sufficient to considerably affect cell viability. Whole-genome sequencing revealed that mutation rates were not overall markedly increased upon proton and alpha exposures. However, there were modest changes in mutation spectra and distributions, such as the increases in clustered mutations and of certain types of indels and structural variants. The spectrum of mutagenic effects of particle beams may be cell-type and/or genetic background specific. Overall, the mutational effects of repeated exposures to proton and alpha radiation on human cells in culture appear subtle, however further work is warranted to understand effects of long-term exposures on various human tissues.

Development of Tracer Particles for Positron Emission Particle Tracking

Positron Emission Particle Tracking (PEPT) is a radioactive tracer-based approach to studying dynamic physical processes and multiphase flows. Short-lived positron-emitting isotopes are loaded onto suitable substrates used as tracer particle flow followers in physical and engineering-relevant systems. Coincident photons from electron-positron annihilation are detected using large arrays of pixelated scintillators, with the reconstructed photon trajectories collectively used to determine tracer particle dynamics. We have developed indirect radiochemical, and direct physical activation, techniques for producing tracer particles for such studies, and we report on the current state of the art with focus on the direct approach with high-energy alpha-particle beams. The 16O(α,x)18F reactions have been explored as viable candidates in producing the pure positron emitter 18F from natural 16O-bearing targets. Silicon dioxide (SiO2) glass spheres of diameters of 5 to 10 mm were irradiated in a 100-MeV alpha-particle beam of around 800-nA current for approximately 2 h. Radioisotope activation yields were characterized by half-life measurements and gamma-ray spectroscopy, with the highest yield being 18F (<2.5 mCi). Contaminants from other reaction channels were observed and characterized, including the positron emitter 43Sc and negative beta emitter 24Na, produced from alpha and neutron activation of contaminant species in the target material, respectively. The activation technique is shown to be a reasonable candidate to complement and enhance existing tracer particle production techniques for PEPT and other radiotracer-based studies.

A multi-MeV alpha particle source via proton-boron fusion driven by a 10-GW tabletop laser

Nuclear fusion between protons and boron-11 nuclei has undergone a revival of interest thanks to the rapid progress in pulsed laser technology. Potential applications of such reaction range from controlled nuclear fusion to radiobiology and cancer therapy. A laser-driven fusion approach consists in the interaction of high-power, high-intensity pulses with H- and B-rich targets. We report on an experiment exploiting proton-boron fusion in CN-BN targets to obtain high-energy alpha particle beams (up to 5 MeV) using a very compact approach and a tabletop laser system with a peak power of ~10 GW, which can operate at high-repetition rate (up to 1 kHz). The secondary resonance in the cross section of proton-boron fusion (~150 keV in the center-of-mass frame) is exploited using a laser-based approach. The generated alpha particles are characterized in terms of energy, flux, and angular distribution using solid-state nuclear-track detectors, demonstrating a flux of ~105 particles per second at 10 Hz, and ~106 per second at 1 kHz. Hydrodynamic and particle-in-cell numerical simulations support our experimental findings. Potential impact of our approach on future spread of ultra-compact, multi-MeV alpha particle sources driven by moderate intensity (1016-1017 W/cm2) laser pulses is anticipated.

Stopping Power of Matter for a Beam of Monoenergetic Alpha Particles

Stopping Power of Matter for a Beam of Monoenergetic Alpha Particles

On the Peculiarities of Studying Unbound Excited States of 4He Nucleus by α + 3H Interaction

Due to the alpha-particle beam interaction with tritium, the two-dimensional spectra of tt, t3He, and dd coincidences are obtained using the particle-decay spectroscopy from three-particle 3H(α,tt)p, 3H(α,t 3He)n, and 3H(α,td)d reactions (Eα = 67.2 MeV). Excitation energies and energy widths for seven excited 4He states, as well as the ratio of their different decay modes, namely t + p, n + 3He, and d + d, are obtained by using the Monte Carlo method.

Stopping Power of Matter for a Beam of Monoenergetic Alpha Particles

The results of using the statistics of multiple scattering to describe the dependence of the stopping power S of matter on the energy E0 of an alpha particle beam are presented. It is shown that the application of a new technique based on taking into account the dependence of the charge state of the beam ions on the ratio of the ion velocity to the minimum velocity of the substance electrons makes it possible to calculate S adequately to the experimental results in a wide range of particle energies E0.

Targetry for the in-beam activation of tracer particles for positron emission particle tracking

Positron emission particle tracking measures the trajectory of a single radioactively labelled tracer particle by coincident detection of emitted annihilation photons. The technique enables the non-invasive study of dense opaque flows, with the tracer acting as a small neutrally buoyant flow-follower. The University of Cape Town has established a PEPT facility at iThemba LABS, utilising tracer particles produced through radiochemical methods, and measured using adapted positron tomographs. An activation approach producing the positron emitter 18F inside glass target spheres of diameter between 5.0 and 10 mm using accelerated beams of alpha-particles has been explored. The reaction 16O(O, x)18F is used, exploiting the high concentration of natural oxygen and the correspondingly high cross-sections for 18F formation. A standard target holder for the batch production of radionuclides at iThemba LABS was modified, reducing the entrance window thickness, allowing ingress of circulating cooling water, and adapted for a primary tparticle beam of 100 MeV energy delivered by the separated sector cyclotron (SSC) of iThemba LABS. Two-hour bombardment at nominal beam current 0.8 eµA produced activities up to ~ 110 MBq (3 mCi), with over 95% of the activity being 18F.

Measurement of the insensitive surface layer thickness of a PIN photodiode based on alpha-particle spectrometry

In this work, the insensitive layer thickness of a PIN photodiode (SFH206K - Osram) has been measured by varying the incident angle of a collimated monoenergetic alpha particle beam. This technique is based on the fact that, except for the intrinsic uncertainties of the emission and straggling of alpha particles, their trajectories at different incident angles are distinct, with smaller ones corresponding to the incidence perpendicular to the detector surface. The result obtained (711 ± 23) nm, less than 1% of the intrinsic layer thickness, besides validating the employed method, demonstrates that the diode herein investigated is suitable for high resolution charged particle spectrometry.

Cross section measurement of alpha-particle-induced reactions on natSb

Cross sections of alpha-particle induced reactions were determined on antimony targets using alpha-particle irradiation with a primary energy of 50 MeV. The standard stacked target technique, activation method and offline gamma-ray spectrometry were applied for determination of the reaction cross sections. Thin Sb targets prepared by vacuum evaporation onto Kapton backings were activated. Ti foils were inserted into the stack for monitoring the alpha-particle beam parameters and energy loss of the particles in the target by using the natTi(α,x)51Cr monitor reaction. Reaction cross sections for formation of 121,123,124,125,126I, 121m,g,123m,125mTe and 118m,120m,122gSb were determined and compared to the available literature data and theoretical estimation of the cross sections from the TENDL-2019 data library.

Quantifying nanodiamonds biodistribution in whole cells with correlative iono-nanoscopy

Correlative imaging and quantification of intracellular nanoparticles with the underlying ultrastructure is crucial for understanding cell-nanoparticle interactions in biological research. However, correlative nanoscale imaging of whole cells still remains a daunting challenge. Here, we report a straightforward nanoscopic approach for whole-cell correlative imaging, by simultaneous ionoluminescence and ultrastructure mapping implemented with a highly focused beam of alpha particles. We demonstrate that fluorescent nanodiamonds exhibit fast, ultrabright and stable emission upon excitation by alpha particles. Thus, by using fluorescent nanodiamonds as imaging probes, our approach enables quantification and correlative localization of single nanodiamonds within a whole cell at sub-30 nm resolution. As an application example, we show that our approach, together with Monte Carlo simulations and radiobiological experiments, can be employed to provide unique insights into the mechanisms of nanodiamond radiosensitization at the single whole-cell level. These findings may benefit clinical studies of radio-enhancement effects by nanoparticles in charged-particle cancer therapy.

Stability analysis of Alfvén eigenmodes in China Fusion Engineering Test Reactor fully non-inductive and hybrid mode scenarios

In this paper, NOVA/NOVA-K codes are used to investigate the stability of Alfvén eigenmodes (AEs) in the China Fusion Engineering Test Reactor (CFETR). Firstly, the stability of AEs excited by energetic alpha particles is investigated. For the fully non-inductive scenario, it is found that all AEs are stable, and the least stable toroidal mode number is However, for the hybrid mode scenario, it is found that many AEs are unstable, and the least stable toroidal mode numbers are Secondly, the effect of energetic alpha-particle parameters and beam ions on AE stability is also presented. The threshold of the least stable AE is about less than the value of alpha-particle beta (). The result demonstrates that the AEs excited by alpha particles are weakly unstable. The effect of the beam ions on AE stability is found to be very weak in CFETR.

Monte Carlo Modeling of DNA Lesions and Chromosomal Aberrations Induced by Mixed Beams of Alpha Particles and X-Rays

Prediction of health risks associated with exposure to mixed beams of high and low LET (linear energy transfer) ionizing radiation is based on the assumption that the biological effect caused by them equals the sum of effects resulting from the action of individual beam components. Experimental studies have been published indicating that the cellular effects in cells exposed to mixed radiations are higher than calculated based on the assumption of additivity. The present work contains a comparative analysis of published results on chromosomal aberrations in human peripheral blood lymphocytes exposed to mixed beams of alpha particles and X-rays with computer simulations using the PARTRAC program based on Monte Carlo methods. PARTRAC was used to calculate the levels of DNA single-strand breaks (SSB) and double-strand breaks (DSB - both complex and simple) and of chromosomal aberrations. The levels and SSB and DSB were found to be additive. A synergistic effect was obtained at the level of chromosomal aberrations, being in good agreement with the experimental results. This result demonstrates that the synergistic action of mixed beams results from processing of SSB and DSB, and not from their initial frequencies. The level of synergy was dependent on the composition of the mixed beam, with highest level at a 50:50 ratio of alpha particles and X-rays.

Study on the Dose Enhancement of Gold Nanoparticles When Exposed to Clinical Electron, Proton, and Alpha Particle Beams by Means of Geant4.

Background:Various factors effecting deposited energy and dose enhancement ratio (DER) in the simplified model of cell caused by the interaction of a cluster of gold nanoparticles (GNPs) with electron beams were assessed, and the results were compared with other sources through Geant4 Monte Carlo simulation toolkit.Method:The effect of added GNPs on the DNA strand breaks level, irradiated to electron, proton, and alpha beams, is assessed.Results:Presence of GNPs in the cell makes DER value more pronounced for low-energy photons rather than electron beam. Moreover, the results of DER values did not show any significant increase in absorbed dose in the presence of GNP for proton and alpha beam. Moreover, the results of DNA break with GNPs for proton and alpha beam were negligible. It is demonstrated that as the sizes of the GNPs increase, the DER is enlarged until a certain size for 40 keV photons, while there is no striking change for 50 keV electron beam when the size of the GNPs changes. The results indicate that although energy deposited in the cell for electron beam is more than low-energy photon, DER values are low compared to photon.Conclusion:Larger GNPs do not show any preference over smaller ones when irradiated through electron beams. It is proved that GNPs do not significantly increase single-strand breaks (SSBs) and double-strand breaks during electron irradiation, while there exists a direct relationship between SSB and energy.

A new waveform analysis technique to extract good energy and position resolution from a dual-axis duo-lateral position-sensitive detector

The dual-axis duo-lateral position-sensitive silicon detector was developed to detect charged particles with high quality position and energy resolution. When these detectors were used with conventional signal processing electronics, an empirically determined correction was used to improve energy resolution. In this work, the waveforms from the detector after preamplification are studied in detail to investigate position information contained in the waveforms. A 7.22 MeV/nucleon alpha particle beam was impinged directly on a masked dual-axis duo-lateral detector. Data obtained using a 228Th alpha particle source was also used. By studying the waveform characteristics that give rise to the position-dependent distortions, a new summed trigger analysis method has been developed to significantly improve linearity in position reconstruction without sacrificing energy resolution.