Alpha Particles Research Articles

Mass Stopping Power and Range of Alpha Particles in Biological Human Body (Water and Eye Lens Tissue)

Mass Stopping Power and Range of Alpha Particles in Biological Human Body (Water and Eye Lens Tissue)

Mortality from Diseases of the Circulatory System in Europe and the Mediterranean Connected with Space Energetic Alpha Particles?

In the present work, a dangerous phenomenon for mankind is described, increasing the mortality from the most deadly diseases on the planet – circulatory system diseases, in particular, the deadly ones of ischemic heart diseases. In the joint analysis of data from satellites in orbit around the Earth and from the health statistics sources EUROSTAT, it became clear that, by some mechanism, streams of positively charged solar particles with high energy entering the Earth's orbit increase mortality from circulatory system diseases. The annual increase is by an average of 5% to 15% in a zone of maximum risk in the Northern Hemisphere, parallel to the equator and bounded by the parallels of 30° and 50° north latitude. The dates are given when the risk of a vascular accident is maximum depending on the latitude of the place in the Europe and Mediterranean area. During the day, the risk of a vascular accident is maximum around local noon. In this regard, it is perhaps not a coincidence that in the Mediterranean region, a midday break is practiced indoors ("siesta").

Stopping Power of Alpha Particles in Some Human Body Tissues Using Density Functional Theory

In this research, the stopping power, range, and stop time of alpha particle (He+2) in lung, bladder, intestine, and ovary human tissues are calculated using density functional theory and Beth's relativistic equation in range of alpha particle energy (0.01-1000 MeV). The experimental data of alpha particles extracted from SRIM-2013 program was used for the same human tissues applied in the MATLAB-2021 program, The Mean ionization potential of studied tissues is calculated using Gaussian 09W program. A good agreement has been found between our calculations for stopping power, range, and stopping time of alpha particle in studied human body tissues and SRIM-2013 program calculations

Intrinsic background of EJ-309 liquid scintillator detectors

In deep-underground experiments, intrinsic detector background can exceed the external one, limiting the detection sensitivity. Intrinsic background in liquid scintillator neutron detectors consists of α particles emitted from radioactive impurities in the detector housing (and possibly in the liquid). We present the results of long background measurements of 12 EJ-309 liquid organic scintillators detectors in the deep-underground Gran Sasso National Laboratory of the Italian Institute of Nuclear Physics. These detectors are a part of the detection array for the SHADES ERC project that aims to measure the very low cross section (down to picobarn) of the astrophysically important reaction 22Ne(α,n)25Mg. With an exposure of ∼35 days we identify an actinide concentration in the detector housing of 8.4(1.8)sta(1.4)sys×10−2ppm and 1.62(0.57)sta(0.03)sys×10−1ppm of 238U and 232Th, resulting in 64 α particle counts per hour. The half-life of 214Po was also determined as 163.7(11)μs.

Boron Neutron Capture Therapy: Microdosimetry at Different Boron Concentrations

This paper explores the role of microdosimetry in boron neutron capture therapy (BNCT), a cancer treatment involving the selective accumulation of boron-containing compounds in cancer cells, followed by neutron irradiation. Neutron interactions with 10B induces a nuclear reaction, releasing densely ionizing particles, specifically alpha particles and recoiling lithium-7 nuclei. These particles deposit their energy within a small tissue volume, potentially targeting cancer cells while sparing healthy tissue. The microscopic energy distribution, subject to significant fluctuations due to the short particle range, influences treatment efficacy. Microdosimetry, by studying this distribution, plays a crucial role in optimizing BNCT treatment planning. The methodology employs paired tissue equivalent proportional counters (TEPCs), one with cathode walls enriched with boron and the other without. Precise assessment of boron concentration is essential, as well as the ability to extrapolate results to the actual 10B concentration within the treatment region. The effective 10B concentrations within four boronated TEPCs, containing 10, 25, 70, and 100 ppm of 10B, have been determined. Results show variations of less than 3% from nominal values. Additionally, dose enhancement due to BNC interactions was measured and found to be proportional to the 10B concentration, with a proportionality factor of 7.7 × 10−3 per ppm of boron. Based on these findings, a robust procedure is presented for assessing the impact of BNCT in the treatment region, considering potential variations in boron content relative to the TEPC used.

Radiation Shielding Features of Glass Fiber Reinforced Cast Polyamide Using Phy-X/PSD and SRIM Software

The utilization of various materials for their nuclear radiation shielding properties has been the subject of a growing number of research and development projects. In this study, the radiation shielding characteristics of E-glass fiber reinforced cast polyamide were evaluated. E-glass is a form of glass fiber frequently utilized as a reinforcement in various composite materials to provide more durability, stiffness, and strength. Samples S1-S7 were defined according to various compositions of E-glass fiber contents (SiO2, Al2O3, B2O3, MgO, CaO, Na2O and K2O) and cast polyamide (C12H22N2O2). Within the energy range 0.015-15 MeV, the shielding parameters: Linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half and tenth value layers (HVL, TVL), mean free path (mfp), effective atomic number (Zeff), atomic and electronic cross sections (ACS, ECS), fast neutron removal cross-section (FNRCS) and exposure buildup factor (EBF) were analyzed. E-glass fiber reinforced cast polyamide S7 (70% glass fiber content) exhibited higher values of LAC, MAC and Zeff and lower values of HVL, TVL, and mfp proving it to be a better radiation shielding material among the samples. An abrupt reduction in values of Zeff was discerned within the photoelectric absorption-dominant region, contrasted with a stable trend within the Compton scattering-dominant region, and a marginal elevation was noted in the pair production region. The maximum and minimum values of FNRCS were observed for samples S1 (10% glass fiber content) and S5 (50% glass fiber content) respectively. Hence, S1 would be the most effective material in fast neutron shielding. At 35 mfp penetration depth, the minimum EBF values belonged to S7 in lower and intermediate regions (0.015-3 MeV) whereas S1 showed the minimum values at higher energy regions (4-15 MeV). Furthermore, the mass stopping power (MSP) and projected range (PR) of the samples for alpha and proton particles were determined using SRIM-2008 codes. S7 exhibited better shielding features for alpha and proton particles with lower values of mass stopping power and projected range. The reinforcement of glass fiber in the cast polyamide has been noticed to have a significant impact on the shielding performance of polymer composites.

Microbial consortium and impact of industrial mining on the Natural High Background Radiation Area (NHBRA), India – Characteristic role of primordial radionuclides in influencing the community structure and extremophiles pattern

The present investigation is the first of its kind which aims to study the characteristics of microbial consortium inhabiting one of the natural high background radiation areas of the world, Chavara Coast in Kerala, India. The composition of the microbial community and their structural changes were evaluated under the natural circumstances with exorbitant presence of radionuclides in the sediments and after the radionuclide's recession due to mining effects. For this purpose, the concentration of radionuclides, heavy metals, net radioactivity estimation via gross alpha and beta emitters and other physiochemical characteristics were assessed in the sediments throughout the estuarine stretch. According to the results, the radionuclides had a significant effect in shaping the community structure and composition, as confirmed by the bacterial heterogeneity achieved between the samples. The results indicate that high radioactivity in the background environment reduced the abundance and growth of normal microbial fauna and favoured only the growth of certain extremophiles belonging to families of Piscirickettsiacea, Rhodobacteriacea and Thermodesulfovibrionaceae, which were able to tolerate and adapt towards the ionizing radiation present in the environment. In contrast, communities from Comamondacea, Sphingomonadacea, Moraxellacea and Erythrobacteracea were present in the sediments collected from industrial outlet, reinforcing the potent role of radionuclides in governing the community pattern of microbes present in the natural environment. The study confirms the presence of these novel and unidentified bacterial communities and further opens the possibility of utilizing their usefulness in future prospects.

Alpha particle spectrometry in fluorescent nuclear track detectors with an automatic 3D track reanalysis algorithm

The main obstacle to applying aluminum oxide doped with carbon and magnesium (Al2O3:C,Mg)-based fluorescent nuclear track detectors (FNTDs) in radionuclide therapy with alpha emitters is that it has not been known how to achieve an accurate and in situ dose assessment for in vitro cellular experiments. In this study, we developed an automatic 3D track reanalysis algorithm (ATRA) to analyze the alpha energy spectra in FNTDs. The algorithm provides an excellent track identification rate and an excellent track linking rate (0.961) without significant variations in various track densities. The algorithm also achieves a reliable track detection rate exceeding 0.927 for track densities at the level of in situ measurement, and it successfully measures the alpha energy spectra for obtaining the absorbed dose. We also confirmed that the track overlap clearly interferes with accurate track reconstruction for track densities beyond 1.5 × 106 tracks cm−2. We provided a correction equation that can be used to obtain the actual alpha tracks for high track densities; the equation may also correct estimations of absorbed doses due to alpha particles.

Therapeutic efficacy of an alpha-particle emitter labeled anti-GD2 humanized antibody against osteosarcoma-a proof of concept study.

Current treatments for osteosarcoma (OS) have a poor prognosis, particularly for patients with metastasis and recurrence, underscoring an urgent need for new targeted therapies to improve survival. Targeted alpha-particle therapy selectively delivers cytotoxic payloads to tumors with radiolabeled molecules that recognize tumor-associated antigens. We have recently demonstrated the potential of an FDA approved, humanized anti-GD2 antibody, hu3F8, as a targeted delivery vector for radiopharmaceutical imaging of OS. The current study aims to advance this system for alpha-particle therapy of OS. The hu3F8 antibody was radiolabeled with actinium-225, and the safety and therapeutic efficacy of the [225Ac]Ac-DOTA-hu3F8 were evaluated in both orthotopic murine xenografts of OS and spontaneously occurring OS in canines. Significant antitumor activity was proven in both cases, leading to improved overall survival. In the murine xenograft's case, tumor growth was delayed by 16-18days compared to the untreated cohort as demonstrated by bioluminescence imaging. The results were further validated with magnetic resonance imaging at 33days after treatment, and microcomputed tomography and planar microradiography post-mortem. Histological evaluations revealed radiation-induced renal toxicity, manifested as epithelial cell karyomegaly and suggestive polyploidy in the kidneys, suggesting rapid recovery of renal function after radiation damage. Treatment of the two canine patients delayed the progression of metastatic spread, with an overall survival time of 211 and 437days and survival beyond documented metastasis of 111 and 84days, respectively. This study highlights the potential of hu3F8-based alpha-particle therapy as a promising treatment strategy for OS.

Investigation of the Influence of Infrared Illumination on the Pulse Shapes of Output Signals of CdZnTe Detectors.

The spectrometric characteristics of CdZnTe detectors are largely determined by the nonuniformity of the material and the influence of the negative polarization effects associated with the formation of space charges in the sensitive volume of the detector. They change the electric field distribution in the detector and affect the efficiency of the charge carrier collection. An analysis of the waveforms of the output pulses was used to investigate the uniformity of the charge collection and electric field distribution in the detectors when irradiated by the alpha particles. The influence of infrared (IR) illumination on these parameters was evaluated. IR illumination had no positive effect on the planar detector but greatly improved the charge collection in quasi-hemispherical detectors in the peripheral (corner) regions. The output pulse amplitude increased, and the rise time notably decreased. Polarization that occurred predominantly in the corner regions at low temperatures (from -30 °C to -20 °C) was eliminated using IR illumination.

Modeling Alpha Particle-Induced Radioluminescence Using Geant4

"Optical detection of alpha particle emitters in the environment by air radioluminescence is a new technology that enables sensing a radiological threat at safe distances, without putting personnel at risk or contaminating equipment. Radiolumi- nescence detection systems need to be fine-tuned to efficiently capture a substantial number of photons while minimizing the contribution from ambient ultraviolet light. The accurate simulation of radioluminescence, in conjunction with ray tracing, facili- tates the design and optimization of such detection systems. In this work, an application within the Geant4 framework has been developed to simulate radioluminescence pho- tons emitted in the vicinity of accelerated alpha particles and at the surface of alpha ra- dioactive samples. The application relies on existing scintillation physics implemented in Geant4 classes such as G4OpticalPhysics and G4Scintillation, which are used to simulate radioluminescence photons as scintillations produced during the passage of alpha particles through air. The application computes the ultraviolet image of alpha particles accelerated at energies of 5.1 MeV and 8.3 MeV, as well as an extended alpha source, M. Luchkov et al., Nucl. Instrum. Meth. Phys. Res. A 1047, 167895 (2023) [1]. The application enables optimization of experimental setups for various scenarios, such as radiological emergency management, radiological crime scene investigations, or decommissioning of nuclear facilities, thus minimizing the use of costly resources and exposure to radiation."

Quantum-mechanical four-body versus semi-classical three-body theories for double charge exchange in collisions of fast alpha particles with helium targets

AbstractWithin the two-channel distorted wave second-order perturbative theoretical formalism, we study capture of both electrons from helium-like targets by heavy nuclei as projectiles at intermediate and high impact energies. The emphasis is on the four-body single-double scattering (SDS-4B) method and the three-body continuum distorted wave impact parameter method (CDW-3B-IPM). The SDS-4B method deals with the full quantum-mechanical correlative dynamics of all the four interactively participating particles (two electrons, two nuclei). The CDW-3B-IPM is a semi-classical three-body independent particle model (one electron, two nuclei), using a combinatorial calculus to describe double capture by a product of two uncorrelated probabilities, integrated over impact parameters. Both theories share a common feature in having altogether two electronic full Coulomb continuum wave functions. One such function is centered on the projectile nucleus in the entrance channel, whereas the other is centered on the target nucleus in the exit channel. These two methods satisfy the correct initial and final Coulomb boundary conditions in the asymptotic region of scattering, at infinitely large inter-particle separations. Yet, it is presently demonstrated that most of the available experimental data on total cross sections for the double capture from helium by alpha particles distinctly favor the SDS-4B method. This is especially true at intermediate energies. Such energies are critically important in versatile applications under the general umbrella of ion transport in matter, including thermonuclear fusion (plasma physics) and ion therapy (medicine).

The low-LET radiation contribution to the tumor dose in diffusing alpha-emitters radiation therapy.

Diffusing alpha-emitters Radiation Therapy ("Alpha DaRT") is a new technique that enables the use of alpha particles for the treatment of solid tumors. Alpha DaRT employs interstitial sources carrying a few Ci of Ra below their surface, designed to release a chain of short-lived atoms (progeny of Ra) which emit alpha particles, along with beta, Auger, and conversion electrons, x- and gamma rays. These atoms diffuse around the source and create-primarily through their alpha decays-a lethal high-dose region measuring a few millimeters indiameter. While previous studies focused on the dose from the alpha emissions alone, this work addresses the electron and photon dose contributed by the diffusing atoms and by the atoms remaining on the source surface, for both a single Alpha DaRT source and multi-source lattices. This allows to evaluate the low-LET contribution to the tumor dose and tumor cell survival, and demonstrate the sparing of surrounding healthytissue. The low-LET dose is calculated using the EGSnrc and FLUKA Monte Carlo (MC) codes. We compare the results of a simple line-source approximation with no diffusion to those of a full simulation, which implements a realistic source geometry and the spread of diffusing atoms. We consider two opposite scenarios: one with low diffusion and high Pb leakage, and the other with high diffusion and low leakage. The low-LET dose in source lattices is calculated by superposition of single-source contributions. Its effect on cell survival is estimated with the linear quadratic model in the limit of low doserate. For sources carrying 3 Ci/cm Ra arranged in a hexagonal lattice with 4mm spacing, the minimal low-LET dose between sources is Gy for the two test cases and is dominated by the beta contribution. The low-LET dose drops below 5Gy mm away from the outermost source in the lattice with an effective maximal dose rate of Gy/h. The accuracy of the line-source/no-diffusion approximation is for the total low-LET dose over clinically relevant distances (2-4mm). The low-LET dose reduces tumor cell survival by a factor of . The low-LET dose in Alpha DaRT can be modeled by conventional MC techniques with appropriate leakage corrections to the source activity. For 3 Ci/cm Ra sources, the contribution of the low-LET dose can reduce cell survival inside the tumor by up to two orders of magnitude. The low-LET dose to surrounding healthy tissue is negligible. Increasing source activities by a factor of 5 can bring the low-LET dose itself to therapeutic levels, in addition to the high-LET dose contributed by alpha particles, leading to a "self-boosted" Alpha DaRT configuration, and potentially allowing to increase the latticespacing.

Floating Block Method for Quantum MonteCarlo Simulations.

Quantum MonteCarlo simulations are powerful and versatile tools for the quantum many-body problem. In addition to the usual calculations of energies and eigenstate observables, quantum MonteCarlo simulations can in principle be used to build fast and accurate many-body emulators using eigenvector continuation or design time-dependent Hamiltonians for adiabatic quantum computing. These new applications require something that is missing from the published literature, an efficient quantum MonteCarlo scheme for computing the inner product of ground state eigenvectors corresponding to different Hamiltonians. In this work, we introduce an algorithm called the floating block method, which solves the problem by performing Euclidean time evolution with two different Hamiltonians and interleaving the corresponding time blocks. We use the floating block method and nuclear lattice simulations to build eigenvector continuation emulators for energies of ^{4}He, ^{8}Be, ^{12}C, and ^{16}O nuclei over a range of local and nonlocal interaction couplings. From the emulator data, we identify the quantum phase transition line from a Bose gas of alpha particles to a nuclear liquid.

Numerical Modeling of the Interaction of Dark Atoms with Nuclei to Solve the Problem of Direct Dark Matter Search

The puzzle of the direct dark matter search can be resolved by examining the concept of «dark atoms», which consist of hypothetical stable lepton-like particles with a charge of −2n, where n is any natural number, bound to n nuclei of primordial helium. These «dark atoms», known as «XHe» (X-helium) atoms, remain undiscovered in experiments due to their neutral atom-like states. In this model, the positive results of the DAMA/NaI and DAMA/LIBRA experiments could be explained by the annual modulation of radiative capture of XHe atoms engaging in low-energy bound states with sodium nuclei. This specific phenomenon does not occur under the conditions of other underground experiments. The proposed solution to this puzzle involves establishing the existence of a low-energy bound state of «dark atoms» and nuclei while also considering the self-consistent influence of nuclear attraction and Coulomb repulsion. Resolving this complex issue, which has remained unsolved for the past 17 years, necessitates a systematic approach. To tackle this problem, numerical modeling is employed to uncover the fundamental processes behind the interaction of «dark atoms» with nuclei. To comprehend the essence of XHe’s interaction with baryonic matter nuclei, a classical model is employed wherein quantum physics and nuclear size effects are progressively incorporated. A numerical model describing the interaction between XHe «dark atoms» and nuclei is developed through the continuous inclusion of realistic features of quantum mechanics in the initial classical three-body problem involving the X-particle, the helium nucleus, and the target nucleus. This approach yields a comprehensive numerical model that encompasses nuclear attraction and electromagnetic interaction between the «dark atom» and nuclei. Finally, this model aids in supporting the interpretation of the results obtained from direct underground dark matter experiments through the lens of the «dark atom» hypothesis.

10255-BOT-5 EXOSOMAL MIRNAS RELEASED FROM GLIOBLASTOMA CELLS AFTER BNCT TARGET CELL PROLIFERATION AND SURVIVAL SIGNALS

Abstract Boron neutron capture therapy (BNCT) is a tumor -selective particle radiation therapy. In BNCT, p-boronophenyl alanine, which is actively taken up by tumor cells through LAT1 transporter, a member of the system L family of heterodimeric, sodium-independent, amino acid transporters, is administrated to patients, and thermal or epithermal neutron is irradiated to tumor tissue of the patients. Nuclear capture and fission reactions between boron-10 and thermal neutron occurred only in tumor cells produce high- linear energy transfer (LET) alpha particles and recoiling lithium-7 (7Li). These high LET particles have very short pathlength (5-9 μmeter), and kill boron-10 containing tumor cells sparing adjacent normal tissue cells. BNCT was applied to malignant glioma, the most devastating tumor and has prolonged the survival of malignant glioma patients. In this study, we comprehensively investigated the micro RNAs (miRNAs) in exosomes derived from BNCT-treated glioblastoma U87 MG cells using microarray. Comparing with non-treated cells, more than 300 up-regulated miRNAs or 100 down-regulated miRNAs were detected in BNCT-treated cells. From the results of the prediction analysis of the target genes which interact with the miRNAs, the pathway analysis was performed. We found significantly associated pathways, such as Focal adhesion-PI3K-Akt-mTOR, Ras, MAPK, etc. miRNAs in exosomes released from BNCT-treated glioblastoma cells may suppress such essential pathways for cell proliferation and survival.

Stark Broadening of N VI Spectral Lines

Stark broadening parameters, line widths and shifts, for 15 N VI multiplets are calculated using semiclassical perturbation theory for temperatures from 50,000 K to 2,000,000 K, and perturber density of 1016 cm−3. As perturbers have been taken electrons, protons and He III ions (alpha particles), which are of interest particularly for white dwarfs. Moreover, B III, B IV, B V and B VI ions have been taken as well, due to their significance for proton-boron fusion investigations. An example of the importance of Stark broadening in comparison with thermal Doppler broadening in atmospheres of spectral class DO white dwarfs is also presented. The obtained results are of interest particularly for white dwarf atmospheres modelling and analysis and synthesis of their spectra as well as for laser driven plasma in proton-boron fusion investigations.

Simulation of ionization charge carrier cascade time and density for a new radiation detection method based on modulation of optical properties.

In time-of-flight PET, image quality and accuracy can be enhanced by improving the annihilation photon pair coincidence time resolution, which is the variation in the arrival time difference between the two annihilation photons emitted from each positron decay in the patient. Recent studies suggest direct detection of ionization tracks and their resulting modulation of optical properties, instead of scintillation, can improve the CTR significantly, potentially down to less than 10 ps CTR. However, the arrival times of the 511keV photons are not predictable, leading to challenges in the spatiotemporal localization characterization of the induced charge carriers in the detector crystal. To establish an optimized experimental setup for measuring ionization induced modulation of optical properties, it is critical to develop a versatile simulation algorithm that can handle multiple detector material properties and time-resolved charge carrier dynamics. We expanded our previous algorithm and simulated ionization tracks, cascade time and induced charge carrier density over time in different materials. For designing a proof-of-concept experiment, we simulated ultrafast electrons and free-electron x-ray photons for timing characterization along with alpha and beta particles for higher spatial localization. With 3 MeV ultrafast electrons, by reducing detector crystal thickness, we can effectively reduce the ionization cascade time to 0.79ps and deposited energy to 198.5keV, which is on the order of the desired 511keV energy. Alpha source simulations produced a cascade time of 2.45ps and charge carrier density of 6.39×1020cm-3 . Compared to the previous results obtained from 511keV photon-induced ionization track simulations, the cascade time displayed similar characteristics, while the charge density was found to be higher. These findings suggest that alpha sources have the potential to generate a stronger ionization-induced signal using the modulation of optical properties as the detection mechanism. This work provides a guideline to understand, design and optimize an experimental platform that is highly sensitive and temporally precise enough to detect single 511keV photon interactions with a goal to advance CTR for ToF-PET.

Comprehensive investigation on physical, structural, mechanical and nuclear shielding features against X/gamma-rays, neutron, proton and alpha particles of various binary alloys

In this study, four alloys composed of highly pure elements (lead, zinc, tin and bismuth), named Pb–Zn50, Pb–Sn50, Sn–Zn50 and Sn–Bi50 were prepared by rapid solidification process (RSP) using melt-spun technique. The structural, mechanical properties (elastic and plastic deformations), and microhardness have been investigated and analyzed using X-ray diffraction, tensile test machine, and vickers microhardness respectively. According to results, the yield strength, ultimate tensile strength (UTS), toughness, and Vickers hardness (Hv) were improved due to the advantages of rapid solidification technology including elimination of grain boundary segregation, improvement in alloy homogeneity, refinement of grain size, formation of novel metastable crystalline, rises in the equilibrium solid solubility's of solute elements and reduction in the degree of order. This can be ascribed to reinforcement of Zn and Bi particles, refined β-Sn, Zn and Bi grains that could obstruct the dislocation slipping. In addition, the shielding performance of these alloys for gamma radiation were examined and analyzed utilizing WinXCom software over energy range 0.015–15 MeV. The alloys under study found to be good shielding materials against γ-ray relative to common shielding materials and newly studied materials. The results indicate that the Sn–Bi50 alloy has the highest values of μm, Zeff and Zeq ranging from 0.039 to 81.3 cm2/g, 60.41–73.83, and 64.02–70.793 respectively. While it has the smallest values of HVL (ranging from 8.73E-4 to 1.86 cm) which means that it is the best choice as a γ-ray shielding material. In aspects of neutron attenuation characteristics, the results also indicate that the Pb–Zn50 alloy has the highest value of ΣR (0.133 cm−1) amongst all other alloys, frequently used neutron shielding materials, and recently studied materials. Furthermore, proton (H+1) and alpha particles (He+2) projected range (PR) and mass stopping power (MSP) values have been calculated. It can be concluded that Zn–Pb alloy among the examined samples is superior in terms of shielding against proton and alpha particles. This paper provides a comprehensive examination of the use of lead and the development of new safety lead-free shielding materials in many applications including nuclear medicine.

Electronic cross section, stopping power and energy-loss straggling of metals for swift protons, alpha particles and electrons

Understanding and quantifying the electronic inelastic interactions of swift ions and electrons in metals is fundamental for many applications of charged particle beams. A common theoretical approach is moreover desirable for the case of both types of projectiles, as large numbers of secondary electrons arise as the result of ion interaction with metals. The electronic cross section, stopping power and energy-loss straggling resulting from the interaction of swift protons, alpha particles and electrons when moving through the metals aluminum, iron, copper, molybdenum, platinum and gold, are calculated theoretically for a wide energy range of the projectiles. The model is based on the dielectric formalism, which realistically accounts for the excitation spectrum of each metal through the Mermin Energy-Loss Function–Generalized Oscillator Strength (MELF-GOS) methodology. The impact of the complexity of the excitation spectrum of each metal (encompassing interband transitions and collective excitations), as well as the different sources of (sometimes conflicting) optical data is analysed in detail. Specific interactions are considered for each projectile, such as electron capture/loss and electron cloud polarisation for ions, and indistinguishability, exchange and low-energy corrections for electrons. An estimate of possible contributions of surface excitations to the interaction probabilities of low energy electrons is given. Comparison of our results with a large collection of available experimental data shows good agreement. As a practical and useful outcome of the work, we provide analytical expressions fitting all our calculated quantities, which can be applied for simulation or comparison purposes.