Alpha Particle Energy Research Articles

Calculation of alpha particle single-event spectra using a neural network.

A neural network was trained to accurately predict the entire single-event specific energy spectra for use in alpha-particle microdosimetry calculations. The network consisted of 4 inputs and 21 outputs and was trained on data calculated using Monte Carlo simulation where input parameters originated both from previously published data as well as randomly generated parameters that fell within a target range. The 4 inputs consisted of the source-target configuration (consisting of both cells in suspension and in tissue-like geometries), alpha particle energy (3.97-8.78 MeV), nuclei radius (2-10 μm), and cell radius (2.5-20 μm). The 21 output values consisted of the maximum specific energy (zmax), and 20 values of the single-event spectra, which were expressed as fractional values of zmax. The neural network consisted of two hidden layers with 10 and 26 nodes, respectively, with the loss function characterized as the mean square error (MSE) between the actual and predicted values for zmax and the spectral outputs. For the final network, the root mean square error (RMSE) values of zmax for training, validation and testing were 1.57 x10-2, 1.51 x 10-2 and 1.35 x 10-2, respectively. Similarly, the RMSE values of the spectral outputs were 0.201, 0.175 and 0.199, respectively. The correlation coefficient, R2, was > 0.98 between actual and predicted values from the neural network. In summary, the network was able to accurately reproduce alpha-particle single-event spectra for a wide range of source-target geometries.

Fabrication of a cell irradiation technique by alpha-particles using allyl diglycol carbonate (ADC) detector and micro-capillary tubes.

To study the impact of micro-alpha irradiation collimator with a specific design to irradiate specific normal or up-normal cells using capillary tubes and nuclear track detector type CR-39. The in vitro experimental study was conducted at radiobiology Lab, of the Physics department, Salahaddin University, Erbil, Iraq from February to April 2022. Several alpha irradiation collimators were calibrated using allyl diglycol carbonate to fabricate a suitable blood cell irradiation technique. Time of irradiation and alpha particle energy were calibrated. Healthy blood samples of Albino rats and cancer blood samples were used to assess the applicability of the fabricated cell irradiation technique. The Rats were divided into intervention and control groups. Data was analysed using SPSS software version 28. Of the 15 healthy, male Albino rats having a mean weight of 230±12g each, there were 12(80%) in the intervention group and 3(20%) in the control group. Microcapillary tubes with suitable diameters had high stability for deposition of a sufficient density of alpha particles on the surface of allyl diglycol carbonate and blood samples. The optimum time of irradiation that had a significant (p<0.05) effect was 20 sec corresponding to alpha energy 4.5MeV. Low irradiation time had significant impact of alpha particles on the average percentage of lymphocyte and neutrophil cells.

Properties of charge recombination in liquid argon

Liquid argon is an excellent medium for detecting particles, given its yields and transport properties of light and charge. The technology of liquid argon time projection chambers has reached its full maturity after four decades of continuous developments and is, or will be, used in world class experiments for neutrino and dark matter searches. The collection of ionization charge in these detectors allows to perform a complete tridimensional reconstruction of the tracks of charged particles, calorimetric measurements, particle identification. This work proposes an innovative approach to the problem of charge recombination in liquid argon which moves from a microscopic model and is applied to the cases of low energy electrons, alpha particles, and nuclear recoils. It takes inspiration and expands the recombination models commonly used by the liquid argon community. The model is able to describe precisely several sets of experimental data available in the literature, over wide ranges of electric field strengths and kinetic energies and can be easily extended to other particles. Published by the American Physical Society 2024

Single Event Effects in 3.3 kV 4H-SiC MOSFETs due to MeV Ion Impact

In this work, MeV alpha particles generated from an accelerator are used to study single event breakdown (SEB) in 4H-SiC MOSFET samples, rated at 3.3 kV. The samples are exposed to bursts of alpha particles under reverse bias conditions to investigate the SEB sensitivity to ion energy and reverse bias. The energies of alpha particles are chosen to reach different depths in the drift region of the MOSFET devices, and also to penetrate the whole drift region. Forward and reverse characteristics are measured after each exposure, as long as no failures occur, to ensure that the device performance is maintained. The measurements show that no significant effects are observed on the drain-source leakage current, while minor effects on gate behavior can be seen as a function of accumulated fluence. Furthermore, SEB can only be triggered with a reverse bias larger than, or equal to 3 kV. A standard MOSFET cell with a similar rated voltage is also simulated in Sentaurus TCAD to study these effects, using two different models for the incident ion-induced ionization: the Alpha Particle and the Heavy Ion model. Simulations show that the Alpha Particle model cannot induce any device failures even with a 3.5 kV reverse bias, while it is possible to trigger a failure by the Heavy Ion model, where the ionization can be selected. Carrier plasma and internal electric field distributions of the two models are plotted and compared, showing that device failures triggered by a heavy ion are related to the hole injection at epi-substrate interface, in which linear energy transfer (LET) of the particle plays an important role.

Alpha particle detection based on low leakage and high-barrier vertical PtOx/β-Ga2O3 Schottky barrier diode

High-performance radiation detectors are essential in many sectors spanning medical diagnostics, nuclear control, and particle physics. Ultrawide bandgap semiconductor materials have become one of the most promising candidates due to their excellent performance. Here, based on β-Ga2O3, a Schottky diode-type alpha particle detector was demonstrated. In order to reduce the reverse leakage current of the large-area device, the metal-oxide electrode PtOx was introduced to form high-barrier contacts (1.83 eV) with Ga2O3. The device exhibits a low leakage current density of 63 pA/cm2 at −100 V and apparent energy spectra of 241Am generated alpha particles with an energy of 5.486 MeV at various reverse voltages from −40 to −120 V. The charge collection efficiency (CCE) and energy resolution of the device (at −120 V) are 31.7% and 15.3%, respectively. Meanwhile, the mechanism of interaction between alpha particles and β-Ga2O3 was analyzed, and a 45° oblique incidence was adopted to increase the deposited energy of alpha particles in the depletion region. Furthermore, the differences between actual CCE and theoretical CCE are investigated as guidance for further improving detector performance. This work reveals the great potential and good prospects of Ga2O3 as an economical, efficient, and radiation-resistant ionizing radiation detector.

Ammonia borane-based targets for new developments in laser-driven proton boron fusion

Nuclear fusion reactions involving protons and boron-11 nuclei are sparking increasing interest thanks to advancements in high-intensity, short-pulse laser technology. This type of reaction holds potential for a wide array of applications, from controlled nuclear fusion to radiobiology and cancer therapy. In line with this motivation, solid ammonia borane samples were developed as target material for proton-boron (pB) nuclear fusion. Following synthesis and shaping, these samples were tested for the first time in a laser-plasma pB fusion experiment. An investigation campaign focusing on surface chemical/physical analysis was carried out to characterize such samples in terms of composition of B and H, precursors of the pB fusion nuclear reaction, thus having a key impact on the yield of the generated nuclear products, i.e., alpha particles. A follow-up experiment used an 8 J, 800 fs laser pulse with an intensity of 2 × 1019 W cm−2 to irradiate the targets, generating ∼ 108 alpha particles per steradian. The alpha particle energy range (2–6 MeV) and normalized yield per laser energy of up to (6 × 107 J/sr) are comparable with the best previous alpha particle yields found in literature. These results pave the way for a yet unexplored category of pB fusion targets.

Radiation effects on multi-channel Forksheet-FET and Nanosheet-FET considering the bottom dielectric isolation scheme

This study analyzes the single-event transient (SET) characteristics of alpha particles on multi-channel Forksheet-FET and Nanosheet-FET at the device and circuit levels through 3D TCAD simulations. The study investigates the differences in SET responses based on the energy and incident position of incoming alpha particles, considering the structural variances between Forksheet-FET and Nanosheet-FET, as well as the presence or absence of bottom dielectric isolation (BDI) in the fabrication process. Specifically, the introduction of BDI is observed to significantly suppress the voltage drop caused by ‘unintended' current, as it can block the substantial electron-hole pairs (EHP) generated by injected alpha particles in the bulk substrate from reaching the FET terminals. Furthermore, it was confirmed that the size of abnormal current decreases as the energy of the injected alpha particle increases. Additionally, evaluating the response to SET based on the fundamental logic circuit, the CMOS inverter, revealed relatively small abnormal voltage drops for both Forksheet and Nanosheet when BDI was applied, confirming high immunity to radiation effects. Moreover, it can be observed that the application of BDI enhances reliability from a memory perspective by effectively suppressing voltage flips in the SRAM's cross-coupled latch circuit.

High count rate alpha particle spectroscopy by a digital optical camera: A comparison study on edge detection algorithms

Alpha particle spectroscopy is highly significant in technologies related to radioactivity, particularly in radiation safety and the study of natural radioactivity. On the other hand, tools capable of identifying and determining the energies of alpha particles are of great interest. Among these tools, Commercial Off-The-Shelf (COTS) instruments, which can be used for alpha particle detection, have gained significant importance due to their ease of use and low cost. In this study, alpha particle spectroscopy of a Ra-226 source has been performed using a commercial digital camera based-on a CMOS sensor. In order to determine energy spectrum of alpha particles emitted from the source, the performance of various edge detection algorithms was examined. An algorithm based-on local pixel changes was introduced and implemented. By comparing the run times of the algorithms, it was shown that the algorithm proposed in this article exhibited the shortest run-time. Additionally, a method for rejecting pile-up events to correct their destructive effects on the alpha particle energy spectrum was introduced and implemented.

Research on Detection Efficiency of Imaging Plates for Alpha Particles Using Two Types of Imaging Plate.

Imaging plates can measure isotopes with alpha decay (such as radon and its progeny, americium, and so on). However, the detection efficiency of imaging plates is affected by alpha particle energy, types of imaging plates, and the overlapping effect. In this study, simulations were performed to analyze the relationship between detection efficiency and these three influence factors. The research findings suggest that BAS-TR and BAS-MS are well-suited for the detection of alpha particles with energy levels below 6.83 MeV and above, respectively. The track overlap effect correction method proposed in this study is applicable to both BAS-TR and BAS-MS image plates. The measurement results of radon progeny demonstrate that the correction method enhances the detection efficiency from 0.203 to 0.288. This study presents a valuable approach for selecting the appropriate image plate and correcting the track overlap effect in the measurement of alpha radioactive material concentration and other related information.

Low energy alpha particles dose mapping with a combination of CR-39 detector and a high resolution flatbed scanner

The potential of a combination of the well-known CR-39 detector and a high-resolution flatbed scanner for low energy alpha particles dose mapping is investigated. The CR-39 detectors were irradiated with perpendicular incident 4 MeV alpha particles of doses 0.009, 0.018, 0.033, 0.051, 0.067, 0.134, and 0.164 Gy, thereafter, etched in 6.25 N NaOH at 70 °C. The CR-39 detectors were scanned with Canon CanScan 9000F Mark II of spatial resolution of 9600 dpi and color depth of 48 bit. The measurements reveal that the pixel values for different color channels are correlated linearly with 4 MeV alpha particles dose at the etching times of 2 h, 3 h, and 4 h. For blue channel, the maximum sensitivity was −53178 ± 1463 pixel value/Gy at etching time of 4 h, compared to −15290 ± 2004 pixel value/Gy, and −42255 ± 840 pixel value/Gy at 2 h and 3 h respectively, the negative sign indicates the pixel values decrease as the 4 MeV alpha particles dose increases. While for etching times, 5 h and 6 h, the pixel values decrease exponentially as the 4 MeV alpha particles dose increases. For prolonged etching time, the pixel values are non-monotonic function of alpha particles dose. The optical density was evaluated as a function of etching time (removal thickness) of CR-39 irradiated with different doses. For 0.009 Gy, and 0.018 Gy doses of alpha particles, the optical density is linearly correlated with the etching time; for other doses, the optical density is not a monotonic function of the etching time. These new findings pave the way to use the combination of the CR-39 detector and high-resolution flatbed scanner for dose mapping of alpha particles and heavy ions over large-scale areas, applying etching conditions for each particle type and corresponding energy, that produce maximum sensitivity and linearity.

Heavy ions and alpha particles irradiation impact on III-V broken-gap gate-all-around TFET

This report deals with the impact of radiation on III-V and Si gate-all-around tunnel field effect transistors (GAA TFET). The highly energetic particles (HEPs) such as heavy ions and alpha particles are allowed to strike the device at several locations along the channel to determine the sensitive location of the device. Once the sensitive location is determined, then the device is irradiated to different energies of heavy ions and alpha particles. Further, to get a proximate match as a practically exposed device, the device has been irradiated to several incident angles. Before analyzing the device's behaviour, the models used for the analysis are calibrated with the transfer characteristics of an experimentally published report on III-V GAA TFET. Thereafter, analysis of charge collection, transient current, hole generation in the channel, and different incident angles are analyzed. Finally, it is concluded that III-V GAA TFET shows better immunity towards different incident angles under a radiation environment when compared to Si GAA TFET.

A novel method for efficiently measuring the non-proportionality of scintillators between light output and alpha particle energies from 1.8 MeV to 5.2 MeV

It is known that scintillators exhibit non-proportional behavior between light output and the energy of gamma photons or beta particles. However, the non-proportionality between light output in scintillators and the energy of alpha particles has not been extensively measured, likely due to the challenges associated with preparing alpha particles with varying energies. To address this issue, we propose a novel method to modulate the energy of alpha particles using an americium-241 (Am-241) source covered with different numbers of Mylar films. By irradiating various scintillators, including GAGG, GGAG, YAP(Ce), and plastic scintillator, with alpha particles of different energies, we measured and evaluated the non-proportional response of these scintillators. We then compared the measured response as a function of incident energy to a simulation, which assumes a proportional response to evaluate the non-proportionality. For all the scintillators tested, non-proportionality was observed; the light output per MeV at 1.8 MeV ranged from 0.60 to 0.81 of the values observed at 5.2 MeV. The non-proportional response was largest for plastic scintillator (0.60) and smallest for GAGG (0.81). We conclude that the proposed method could be an efficient means of measuring the non-proportionality of scintillators between light output and alpha particle energies

Analysis of 238U, 232Th, 222Rn and 220Rn contents in medical drugs, petroleum products and petrol/gas-oil exhaust fumes by using CR-39 and LR-115 type II nuclear track detectors – Experimental and new Monte Carlo simulation approaches

Petroleum products and medical drugs have been studied in order to determine 238U, 232Th, 222Rn, 220Rn and their progenies contents in them using mean absolute detection efficiency based Solid State Nuclear Track Detectors (SSNTDs) experimental method. In the present paper, a Monte Carlo code based theoretical approach has been also developed to determine mean absolute detection efficiencies of SSNTDs; this theoretical approach has been combined with experimental one for deriving levels of natural radioactivity inside different materials studied. The dependence of CR-39 and LR-115 type II mean absolute detection efficiencies on initial alpha particle energy, removed thickness of SSNTDs and SSNTDs areas for different natural materials studied has been highlighted as well. The mean absolute detection efficiency depends clearly on the initial alpha particle energy and the removed layer while it does depend neither on the detector surface nor on the nature of the material being studied. The results obtained using the present method and those obtained by mean critical angle based SSNTD technique and isotope dilution mass spectroscopy (IDMS) are in good agreement with each other: our method has less relative uncertainties, which do not exceed 4%, than the other methods, whose the relative uncertainties exceed 9% and 7%, respectively.

Development of contamination detection system combined with various remote devices

The detection of alpha and beta contamination locations is important for decontaminating nuclear facilities. In the high radiation dose rate environment at the decommissioning sites, the contamination measurement by the workers is not effective. Thus, we developed a remote automatic contamination measurement system using a new scintillator-based detector. A 50 mmφ × 100-μm-thick YAlO3(Ce)(YAP:Ce) scintillator was coupled with a flat panel-type multianode photomultiplier tube. The detector was installed downwards at the bottom of a robot. It has an energy measurement capability, and the energy measurement could discriminate the alpha particles from the beta and 222Rn alpha particles. With the energy information, alpha and beta particles could be identified and mapped simultaneously. In addition, a slow-moving robot could be used to obtain statistically sufficient counts in a single run measurement, allowing the evaluation of surface contamination density using only alpha particles. The remote automatic contamination measurement system will be useful in visualizing the contamination distribution in environments that are inaccessible to workers.

Range and light output measurements of trajectory images in a GAGG plate with different alpha particle energies

An imaging method that utilizes a scintillator plate combined with a magnifying unit and a cooled electron multiplying charge-coupled device (EM-CCD) camera shows promise for obtaining high-resolution trajectory images. However, it is not yet clear whether the ranges of the trajectory images change with the energy of the alpha particles. Additionally, it remains unclear whether the intensity of the trajectory images is affected by the energy of the alpha particles. To address these questions in our trajectory imaging research, we conducted experiments to capture trajectory images of alpha particles with varying energy levels. To generate alpha particles with different energies, we modulated the energy using an americium-241 (Am-241) source covered with varying numbers of Mylar films. With this alpha source and imaging system, we successfully captured trajectory images with different alpha particle energies and were able to assess the ranges and intensities of these trajectories at various energy levels. The estimated ranges from the measured images with different alpha particle energies closely matched the results obtained through simulations. However, it's worth noting that the light output, as evaluated for the measured trajectory images, was slightly lower than the simulated results at lower energy levels probably due to the non-proportionality of the GAGG plate with respect to alpha particle energies.

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

Source efficiency of alpha-emitters applied to the skin surface.

Skin surface contamination by alpha-emitters is in itself not hazardous, but it would cause significant internal exposure in the case of injured skin as well as misjudgment in direct in vivo measurements (e.g. lung counting). The present study determined the source efficiency of alpha-emitters (241Am) applied to swine skin samples by analysing the observed alpha-particle energy spectra using advanced alpha-spectrometric simulation. Based on our results, the source efficiency was determined to be 0.365 (alpha-particle s-1 per Bq) on average (c.f. 0.5 in the case of no self-absorption in the source). The decrease in source efficiency would be attributed primarily to the radionuclide entering hair follicles or deep wrinkles. The degradation of the measured spectra from the skin samples indicates the penetration of some radionuclides into the upper layers of the stratum corneum. Although this study was limited to results obtained from swine skin samples, it suggests that irregularities in the skin surface may affect direct alpha measurements.

The probability of escape of the products of charged particles resulting from thermonuclear fusion of advanced fuels in the hotspot

Establishing fuel ignition conditions depends on the stability of hotspot ignition. Excessive energy escape from the plasma leads to its cooling and shutdown. In this research, the escape probability of charged particles due to the p/11B fuel fusion has been investigated. First, the contribution of p/11B fuel plasma electrons in the Alpha particle energy loss based on the Krokhin and Rozanov (KR) model and then the auxiliary contribution of plasma ions in the Alpha particle energy loss produced in the hotspot of p/11B fuel, based on Li–Petrasso (LP) calculations were analyzed numerically. By calculating the escape fraction of Alpha particles, it has been shown that the contribution of the stopping power of the electrons of the plasma is dominant at both 70 and 170 keV temperatures, which are the starting temperature of the p/11B fuel reaction and the proper ignition temperature, respectively. By increasing the density of p/11B fuel from 300 to 400 g/cc, it can be seen that at a temperature of 70 keV, the penetration depth of Alpha particles decreases from 1200 to 900 μm based on the KR model. It has also been shown that by reducing the number density ratio of boron to protons from 0.3 to 0.2 and 0.1, due to the reduction of the coupling of electrons and ions, which leads to the reduction of collisions with Alpha particles, the stopping length of Alpha particles increases.

Monte Carlo simulations of charged particle transport in plasmas: A fast single-scattering model

When simulating a charged particle trajectory in plasmas with Monte Carlo methods, the traditional single-scattering model is accurate but computationally expensive. The traditional multiple-scattering model reduces the computation cost but assumes an exponential distribution of the scattering angle, which overestimates the cumulative scattering angle. In this paper, we develop a new Monte Carlo method for the charged particle transport simulations. The scattering angle is naturally sampled from a modified screened Rutherford scattering cross section, in which a greatly amplified minimum deflection angle is used. With this model, the simulations give the same scattering angle distribution with the single-scattering model but only take a comparable computation cost with the multiple-scattering model when the small scattering angle and Markovian approximations can be fulfilled. This model would be especially useful for the study of inertial-confinement-fusion, which is sensitive to the alpha-particle energy deposition.

Experimental determination of alpha particle etchable track lengths in thermally treated CR-39 detectors demonstrates the existence of significant chemical changes

In the present work, a clear-cut determination of alpha particle track length in poly allyl diglycole carbonate (PADC) polymer-based nuclear track detectors NTDs (called CR-39) has been performed. We have applied the Over-Etched Track Diameter (OETD) method to determine the alpha particle etchable lengths in both non-thermally treated (pristine) and thermally treated CR-39 detectors. The diameters of etched alpha tracks in pristine and thermally treated CR-39 detectors have been measured as a function of etching time at different heating temperatures and times, using a 241Am radioactive source with alpha particles of specific energy of 5 MeV. This is the first-time etchable lengths of alpha particles have been determined in thermally treated CR-39 detectors. The results of the OETD method for the etchable lengths of alpha particles in non-thermally treated CR-39 detectors are in an excellent agreement with the previously published data and with the calculated lengths. On the contrary, the etchable lengths determined for thermally treated detectors are smaller than expected track lengths, the higher the heating times and temperatures. These results are discussed in the light of our understanding of the effects of thermal treatment in the polymer material that makes up CR-39.