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PurposeTo evaluate the accuracy of relative stopping power and spatial resolution of images reconstructed with simulated helium CT (HeCT) in comparison to proton CT (pCT).MethodsA Monte Carlo (MC) study with the TOPAS tool was performed to compare the accuracy of relative stopping power (RSP) reconstruction and spatial resolution of low-fluence HeCT to pCT, both using 200 MeV/u particles. An ideal setup consisting of a flat beam source and a totally absorbing energy-range detector was implemented to estimate the theoretically best achievable RSP accuracy for the calibration and reconstruction methods currently used for pCT. The phantoms imaged included a cylindrical water phantom with inserts of different materials, sizes, and positions, a Catphan phantom with a module containing high-contrast line pairs (CTP528) and a module with cylindrical inserts of different RSP (CTP404), as well as a voxelized 10-year-old female phantom. Dose to the cylindrical water phantom was also calculated. The RSP accuracy was studied for all phantoms except the CTP528 module. The latter was used for the estimation of the spatial resolution, evaluated as the modulation transfer function (MTF) at 10%.ResultsAn overall error under 0.5% was achieved for HeCT for the water phantoms with the different inserts, in all cases better than that for pCT, in some cases by a factor 3. The inserts in the CTP404 module were reconstructed with an average RSP accuracy of 0.3% for HeCT and 0.2% for pCT. Anatomic structures (brain, bones, air cavities, etc.) in the digitized head phantom were well recognizable and no artifacts were visible with both HeCT and pCT. The three main tissue materials (soft tissue, brain, and cranium) were well identifiable in the reconstructed RSP-volume distribution with both imaging modalities. Using 360 projection angles, the spatial resolution was 4 lp/cm for HeCT and 3 lp/cm for pCT. Generally, spatial resolution increased with the number of projection angles and was always higher for HeCT than for pCT for the same number of projections. When HeCT and pCT scan were performed to deliver the same dose in the phantom, the resolution for HeCT was higher than pCT.ConclusionMC simulations were used to compare HeCT and pCT image reconstruction. HeCT images had similar or better RSP accuracy and higher spatial resolution compared to pCT. Further investigation of the potential of helium ion imaging is warranted.

An analytical solution to the equation for the distribution of the flux density of reflected light ions over the path length and energy losses in the target is obtained. It is based on the solution of boundary problems for the transport equation using the invariant imbedding method in the small-angle approximation. In the case of proton reflection from copper and tungsten targets, the analytical results are compared with computer-simulation data obtained using the OKSANA program, as well as with experimental data. The possibility of verifying the stopping power of the target material based on the created methodology is noted. [ABSTRACT FROM AUTHOR]

The Monte Carlo (MC) method is a computer simulation that is widely used in different disciplines including physics, biology, biophysics, medical imaging, biomedical engineering, etc. In addition, MC method is often used to simulate the interaction of radiation with cells, tissues, and the environment. In the present study, mass attenuation coefficient, stopping power, and penetrating distance calculations were performed for cell membranes having an approximately 60-100Å thickness. These calculations have been done for lipid bilayer structure of cell membrane via MC techniques employing two of the most known computer-aided calculation and simulation software which are MC methods such as SRIM-2013 (The Stopping and Range of Ions in Matter) and MCNPv6 (Monte Carlo N-Particle) with XCOM software. Stopping power and penetrating distance calculations were obtained using SRIM-2013. Also, both XCOM software and MCNPv6 simulation code were used to obtain photon interaction parameters within the energy range of 0.01 – 10000keV. Obtained all results from different codes have been visualized by graphing for evaluation. [ABSTRACT FROM AUTHOR]

Fast ignition (FI) by the laser-accelerated ion beams is an advanced possible remedy to produce high energy in inertial confinement fusion. Low-divergence high-power beams can now be produced due to new technological advances in laser–plasma accelerators. Using the Deira-4 simulation code, conditions optimal for the ignition of deuterium–tritium (D-T) pellets by the aluminium heavy ion beam were investigated in this work. The results show that an aluminium ignitor beam with 1.4 GeV energy can provide hot-spot optimal ignition conditions. [ABSTRACT FROM AUTHOR]

The Time-dependent density functional theory was used to calculate stopping power of one and two layers of Hexagonal Boron Nitride (h-BN) with different stacking sequences. The simulation results revealed that stopping power is influenced by collision parameters and electron density, while proton charge state has little effect on stopping power. Additionally, charge transfer and force of protons in h-BN materials were analyzed in detail under different stacking sequences. The calculation results show that although the force on the projectile mainly comes from the target atoms, the limited interaction time allows the projectile to primarily dissipate energy through electron excitation. The influence of the variations in electronic structure due to different stacking structures on the stopping power was investigated. The research results indicate that the dislocation stacking in h-BN, which slightly increases the energy loss, is mainly attributed to the changes in electron density and the role of the impact parameter. This asymmetric stacking structure may have a more pronounced shielding effect on particles. Despite the slight variations in band structures due to different stacking configurations of h-BN, the bandgap widths are roughly consistent, which leads to protons displaying similar energy transfer properties as they pass through bilayer h-BN with varying stackings.&#xD., (© 2025 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Fluorine 18-deoxyglucose is often used in Positron Emission Tomography devices. Positron Emission Tomography imaging is one of the useful tools which is used for cancer detection and its management. Positron Emission Tomography growth is limited due to problems that depend on the production of Fluorine-18. Imaging results are strongly depending on the information of nuclear reaction cross-section data. This study is presented to calculate different quantities such as stopping power, CSDA range, and simulated and distributed absorbed dose of Fluorine-18 in water. In order to access these goals, we use Geant4/Gate7 simulation and the theoretical Bethe-Bloch model. The results of this simulation and the theoretical model presented are in good agreement with each other. The important point of this paper is the presentation of a theoretical approach in order to the production of Fluorine-18 using protons generated through the main D(d;p) Tand side 3He(d;p)4He nuclear fusion reaction in which uses Helium-3 is catalyzed.

Tungsten (W) plays a crucial role in the lifetime of the plasma-facing components of DEMO. In order to avoid oxidation, W-based alloys have been studied as alternatives to W. In this work, the Monte Carlo SRIM-2013 simulation program was used to calculate the nuclear stopping power, electronic stopping power, amount of target vacancies, displacements, replacement collisions, and total target damage of W, W-Cr-Si, W-Cr-Ti, and W-Cr-Y by hydrogen and helium ion bombardment. It is found that W is resistant to vacancies, atomic displacement, and total damage compared to W-based alloys. [ABSTRACT FROM AUTHOR]

A precise relative stopping power map of the patient is crucial for accurate particle therapy. Charged particle imaging determines the stopping power either tomographically - particle computed tomography (pCT) - or by combining prior knowledge from particle radiography (pRad) and x-ray CT. Generally, multiple Coulomb scattering limits the spatial resolution. Compared to protons, heavier particles scatter less due to their lower charge/mass ratio. A theoretical framework to predict the most likely trajectory of particles in matter was developed for light ions up to carbon and was found to be the most accurate for helium comparing for fixed initial velocity. To further investigate the potential of helium in particle imaging, helium computed tomography (HeCT) and radiography (HeRad) were studied at the Heidelberg Ion-Beam Therapy Centre (HIT) using a prototype pCT detector system registering individual particles, originally developed by the U.S. pCT collaboration. Several phantoms were investigated: modules of the Catphan QA phantom for analysis of spatial resolution and achievable stopping power accuracy, a paediatric head phantom (CIRS) and a custommade phantom comprised of animal meat enclosed in a 2 % agarose mixture representing human tissue. The pCT images were reconstructed applying the CARP iterative reconstruction algorithm. The MTF10% was investigated using a sharp edge gradient technique. HeRad provides a spatial resolution above that of protons (MTF1010%=6.07 lp/cm for HeRad versus MTF10%=3.35 lp/cm for proton radiography). For HeCT, the spatial resolution was limited by the number of projections acquired (90 projections for a full scan). The RSP accuracy for all inserts of the Catphan CTP404 module was found to be 2.5% or better and is subject to further optimisation. In conclusion, helium imaging appears to offer higher spatial resolution compared to proton imaging. In future studies, the advantage of helium imaging compared to other imaging modalities in clinical applications will be further explored.

PurposeProton computed tomography (pCT) is a promising imaging technique to substitute or at least complement x-ray CT for more accurate proton therapy treatment planning as it allows calculating directly proton relative stopping power from proton energy loss measurements. A proton CT scanner with a silicon-based particle tracking system and a five-stage scintillating energy detector has been completed. In parallel a modular software platform was developed to characterize the performance of the proposed pCT.MethodThe modular pCT software platform consists of (1) a Geant4-based simulation modeling the Loma Linda proton therapy beam line and the prototype proton CT scanner, (2) water equivalent path length (WEPL) calibration of the scintillating energy detector, and (3) image reconstruction algorithm for the reconstruction of the relative stopping power (RSP) of the scanned object. In this work, each component of the modular pCT software platform is described and validated with respect to experimental data and benchmarked against theoretical predictions. In particular, the RSP reconstruction was validated with both experimental scans, water column measurements, and theoretical calculations.ResultsThe results show that the pCT software platform accurately reproduces the performance of the existing prototype pCT scanner with a RSP agreement between experimental and simulated values to better than 1.5%.ConclusionsThe validated platform is a versatile tool for clinical proton CT performance and application studies in a virtual setting. The platform is flexible and can be modified to simulate not yet existing versions of pCT scanners and higher proton energies than those currently clinically available.

Objective: We introduce a new treatment verification technique to estimate the primary particle’s stopping power from prompt gamma timing measurements in proton therapy.Approach: The starting point is the Spatio-temporal Emission Recostruction technique, which provides the time-depth distribution of the emitted prompt photons with a multiple Prompt-Gamma Timing detector setup based on Lanthanum Bromide crystals. A dedicated formalism based on an analytical approximation of the stopping power is developed to obtain the desired information. Its performance is evaluated in a proof of concept configuration via Monte Carlo simulations of monochromatic proton beams impinging on a homogeneous PMMA phantom.Main Results: Results indicate stopping power estimations as good as 3.8% with respect to NIST values, and range estimations within 0.3 cm (standard deviation), when considering 250 ps FWHM timing resolution.Significance: The current study shows, for the first time, the feasibility of evaluating the stopping power of primary beams with a technique that can be performed in-vivo, opening up new possibilities in the field of treatment verification and therapy optimization.

Ionizing radiation has many negative effects on human health. These include eye and skin disorders and DNA damage inside cells. To eliminate or reduce these destructive effects of radiation, economical, low-corrosion, effective shielding materials with high absorption properties are needed. In this study, zinc-iron-based metal matrix composite materials with various proportions of boron nitride were produced on steel substrates. The structural and surface properties of the materials were examined with XRD and SEM images, respectively. These structures were irradiated with radioactive Am-241, Sr-90, Na-22, and Co-60 sources for their radiation shielding properties. Then, the absorption ratios in the samples were investigated according to the reinforced ceramic amounts in their content. In addition to the experiment, the stopping power and range values of the samples were calculated to check the reliability of the results. ZnFe alloys and composites are based on the dominant peaks of the heta (ƞ) phase of zinc. The amount of boron nitride added to the electrolyte significantly affected the crystal structure, while the incorporation of boron nitride into the zinc-iron matrix impressed the average grain size of the coating. The microstrain and dislocation densities of the film first decreased to 15 g/L and then increased depending on the ion diameter. The BN doping made the porous surface smooth, crack-free, and compact. It was found that the absorption rates for radiation increased as the amount of boron nitride in the samples increased. According to the rising amount of boron nitride, the absorption percentages are between 1.88 and 6.19% for alpha particles, 0.78–3.06% for electrons, 0.77–6.56% for positrons, and 0.61–6.34% for gamma photons. When the stopping power and range values were averaged, the amount of boron nitride increased directly and inversely with the stopping power and range values, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

• TYtool: a software application useful for optimization and maximizing radionuclide production without exceeding the power limits of the target material or holder. • Provides fast computer aided calculations of optimal target thicknesses, particle energies and beam currents based on user input of particle energy, current range, and power limit of target and or holder. • Facilitates graphical representation of many basic plots such as cross section, mass stopping power, activity output, projected range and it is useful for many different particles, reactions and radionuclides. A software application useful for optimization and maximizing radionuclide production without exceeding the power limits of the target material or holder has been developed. The software (TYtool) can be used for target optimization including yield calculations vs time, thickness, and incident energy, W/mm through the target, and automated target thickness optimization with the Makkonen-Craig & Helariutta − or the novel Yield/Wapproach. TYtool also facilitates graphical representation of many basic plots such as cross section, mass stopping power, activity output, projected range and it is useful for many different particles, reactions, radionuclides via the default cross section data base or the import function for cross section and mass stopping power. The software is available for free at: https://gitlab.com/NM_Karolinska_Solna/TYtool. [ABSTRACT FROM AUTHOR]

One of the ways to use a focused ion beam in lithographic processes to create nanostructures is through the exposure of special sensitive materials, i.e., resists. As a result of exposure, the solubility of such a material increases ("positive" resist) or, conversely, decreases ("negative" resist). Subsequent selective irradiation and development of the resist make it possible to create a predetermined pattern on the substrate. This work is aimed at developing the theoretical foundations for this ion lithography method. A practically important case of stopping heavy ions in an organic resist, the average atomic mass of which is much less than the mass of the incident ion, is considered. Expressions for the "energy" and transport lengths of ions are obtained. The calculations are carried out assuming a power-law interaction potential. The "energy" length characterizes the depth of penetration of ions into the material, and the transport length is related to beam expansion due to scattering. Therefore, these lengths are the main characteristics of the zone in which the ion-beam energy is absorbed. [ABSTRACT FROM AUTHOR]

Fluorine 18-deoxyglucose (18FDG) is often used in Positron Emission Tomography (PET). PET imaging is one of the useful tool which is used to cancer detection and management. PET growth is limited due to problems that depend on the production of Fluorine-18.Imaging results are strongly dependent on the information of nuclear reaction cross section data. This study is done to calculate the stopping power, RCSDA, simulated and distributed absorbed dose of F-18, in water. In order to access these goals, we use the Geant4/Gate simulation and the Bethe-Bloch theory model. The results of this simulation and this theory model are in good agreement with each other .The main point of this paper is the presentation of a theoretical approach to the production of Fluorine-18 by using protons production through the main nuclear fusion reaction and the side fusion reaction uses helium-3 as a catalyzed.

Purpose: Dual-energy computed tomography (DECT) has been used to derive relative stopping power (RSP) maps by obtaining the energy dependence of photon interactions. The DECT-derived RSP maps could potentially be compromised by image noise levels and the severity of artifacts when using physics-based mapping techniques. This work presents a noise-robust learning-based method to predict RSP maps from DECT for proton radiation therapy. Materials and Methods: The proposed method uses a residual attention cycle-consistent generative adversarial network to bring DECT-to-RSP mapping close to a 1-to-1 mapping by introducing an inverse RSP-to-DECT mapping. To evaluate the proposed method, we retrospectively investigated 20 head-and-neck cancer patients with DECT scans in proton radiation therapy simulation. Ground truth RSP values were assigned by calculation based on chemical compositions and acted as learning targets in the training process for DECT datasets; they were evaluated against results from the proposed method using a leave-one-out cross-validation strategy. Results: The predicted RSP maps showed an average normalized mean square error of 2.83% across the whole body volume and an average mean error less than 3% in all volumes of interest. With additional simulated noise added in DECT datasets, the proposed method still maintained a comparable performance, while the physics-based stoichiometric method suffered degraded inaccuracy from increased noise level. The average differences from ground truth in dose volume histogram metrics for clinical target volumes were less than 0.2 Gy for D95% and Dmax with no statistical significance. Maximum difference in dose volume histogram metrics of organs at risk was around 1 Gy on average. Conclusion: These results strongly indicate the high accuracy of RSP maps predicted by our machine-learning–based method and show its potential feasibility for proton treatment planning and dose calculation.

The electronic stopping power of Zn for energetic protons is studied by using a nonequilibrium approach based on real-time time-dependent density-functional theory combined with molecular dynamics simulations. We calculated the electronic stopping power of protons traveling along two channeling trajectories depending on the impact parameter and off-channeling trajectories, and revealed the mechanism for d -electron excitation. In the low-velocity range, we reproduced not only the velocity proportionality of the stopping power of Zn for protons, but also the smooth transition between two velocity proportionality regimes, which is ascribed to the gradually increasing efficiency for d -electron excitation. The off-channeling electronic stopping power is in a good agreement with experimental data in the low and middle-velocity regimes. Our results showed that the contribution of d -electron excitation to the electronic stopping is remarkable in the high-velocity regime. [ABSTRACT FROM AUTHOR]

The mean energy loss per path length, also known as stopping force, is a key quantity that characterizes the interaction of cluster ions with matter. If the internuclear distance in a cluster approaches the interaction range for events, substantial energy transfer is involved. The aim of this theoretical research is to evaluate the electronic stopping power in free electron gas of hetero nuclear dicluster (He-H) by using a semi classical partial-wave scattering method based on the induced density approach (IDA) model. For ion electron scattering, the transport cross section is used to calculate the energy loss. This method yields a nonperturbative exemplification of energy loss, bridging the difference among classical and quantal representations. The results show the relation of the three kinds of stopping power in (a.u) (cluster stopping power, self-stopping power and correlated stopping power) of hetero nuclear di-cluster ions (He-H) with velocity at different atomic di-cluster distances ( r12)( 0,1.5,3.5,4.5) for different densities(n=1022, 1023, 1024 cm-3 ) and different temperatures(T=10, 20, 40 eV). It was found that Bragg’s peak of stopping power is directly proportional to density and temperature and inversely with atomic di-cluster distance (r12 ). In literature, there is no information about stopping of hetero di-cluster ions in plasma, therefore, the first time present results needs more attention. The equations in present work were programmed in fortran-90 for numerical calculations. [ABSTRACT FROM AUTHOR]

Recently, it was demonstrated that ions impacting a correlated finite graphene‐type honeycomb cluster can excite strong nonequilibrium states. In particular, this can lead to an enhanced population of bound pairs of electrons with opposite spin—doublons—where the doublon number can be increased further via multiple ion impacts. These predictions were made based on nonequilibrium Green functions (NEGF) simulations allowing for a time‐dependent non‐perturbative study of the energy loss of charged particles penetrating a strongly correlated system. Herein, these simulations are extended to larger clusters and longer simulation times, utilizing the recently developed G1–G2 scheme, which allows for a dramatic speedup of NEGF simulations. Furthermore, the dependence of the energy and doublon number on the time interval between ion impacts and on the impact point is investigated. [ABSTRACT FROM AUTHOR]

This paper is to investigate stopping power of α-particles in air at various pressure of 0 to 1 bar, using a surface barrier silicon detector. The energy loss has been obtained at a different distance from 0 to 10 cm. It was found that the energy of the passed α-particles has been decreased in a small vacuum chamber with increasing pressure. It is also studied that the amount of α-particles reaching the detector follows a decreasing behavior as the distance increases. The result of stopping power was compared with ICRU and SRIM result. Experimental, ICRU and SRIM results for stopping power are closely in good agreement. [ABSTRACT FROM AUTHOR]

Objective. The integration of proton beamlines with x-ray imaging/irradiation platforms has opened up possibilities for image-guided Bragg peak irradiations in small animals. Such irradiations allow selective targeting of normal tissue substructures and tumours. However, their small size and location pose challenges in designing experiments. This work presents a simulation framework useful for optimizing beamlines, imaging protocols, and design of animal experiments. The usage of the framework is demonstrated, mainly focusing on the imaging part. Approach. The fastCAT toolkit was modified with Monte Carlo (MC)-calculated primary and scatter data of a small animal imager for the simulation of micro-CT scans. The simulated CT of a mini-calibration phantom from fastCAT was validated against a full MC TOPAS CT simulation. A realistic beam model of a preclinical proton facility was obtained from beam transport simulations to create irradiation plans in matRad. Simulated CT images of a digital mouse phantom were generated using single-energy CT (SECT) and dual-energy CT (DECT) protocols and their accuracy in proton stopping power ratio (SPR) estimation and their impact on calculated proton dose distributions in a mouse were evaluated. Main results. The CT numbers from fastCAT agree within 11 HU with TOPAS except for materials at the centre of the phantom. Discrepancies for central inserts are caused by beam hardening issues. The root mean square deviation in the SPR for the best SECT (90 kV/Cu) and DECT (50 kV/Al-90 kV/Al) protocols are 3.7% and 1.0%, respectively. Dose distributions calculated for SECT and DECT datasets revealed range shifts <0.1 mm, gamma pass rates (3%/0.1 mm) greater than 99%, and no substantial dosimetric differences for all structures. The outcomes suggest that SECT is sufficient for proton treatment planning in animals. Significance. The framework is a useful tool for the development of an optimized experimental configuration without using animals and beam time., (Creative Commons Attribution license.)

Pretreatment computed tomography (CT) imaging is an essential component of the particle therapy treatment planning chain. Treatment planning and optimization with charged particles require accurate and precise estimations of ion beam range in tissues, characterized by the stopping power ratio (SPR). Reduction of range uncertainties arising from conventional CT‐number‐to‐SPR conversion based on single‐energy CT (SECT) imaging is of importance for improving clinical practice. Here, the application of a novel imaging and computational methodology using dual‐layer spectral CT (DLCT) was performed toward refining patient‐specific SPR estimates. A workflow for DLCT‐based treatment planning was devised to evaluate SPR prediction for proton, helium, and carbon ion beam therapy planning in the brain. DLCT‐ and SECT‐based SPR predictions were compared in homogeneous and heterogeneous anatomical regions. This study included eight patients scanned for diagnostic purposes with a DLCT scanner. For each patient, four different treatment plans were created, simulating tumors in different parts of the brain. For homogeneous anatomical regions, mean SPR differences of about 1% between the DLCT‐ and SECT‐based approaches were found. In plans of heterogeneous anatomies, relative (absolute) proton range shifts of 0.6% (0.4 mm) in the mean and up to 4.4% (2.1 mm) at the distal fall‐off were observed. In the investigated cohort, 12% of the evaluated organs‐at‐risk (OARs) presented differences in mean or maximum dose of more than 0.5 Gy (RBE) and up to 6.8 Gy (RBE) over the entire treatment. Range shifts and dose differences in OARs between DLCT and SECT in helium and carbon ion treatment plans were similar to protons. In the majority of investigated cases (75th percentile), SECT‐ and DLCT‐based range estimations were within 0.6 mm. Nonetheless, the magnitude of patient‐specific range deviations between SECT and DLCT was clinically relevant in heterogeneous anatomical sites, suggesting further study in larger, more diverse cohorts. Results indicate that patients with brain tumors may benefit from DLCT‐based treatment planning. [ABSTRACT FROM AUTHOR]

The interaction of a heavy-ion beam with matter is a fundamental problem of plasma physics and high-energy density in matter physics. The paper presents the results of experimental studies of energy losses of Fe+2 ions with an energy of 100 keV/u in a hydrogen plasma. The experimental data of plasma free electron stopping power are compared with theoretical models. [ABSTRACT FROM AUTHOR]

In the current study, 10PbO-xSrO-(90-x)B2O3 (x is between 20 and 45 mol% with a step of 5 mol%) glasses with SrO inserted in various proportions were surveyed in terms of nuclear shielding qualities. Gamma- ray shielding features of the glasses encoded BPS1-BPS6 were investigated in the energy range of 0.015–15 MeV. The mass attenuation coefficients (MAC) of BPS glasses were composed via GEANT4 simulation codes and the accuracy of the outcomes was checked by WinXCOM software. The MAC values of BPS1 and BPS6 glasses were obtained between 14.934–0.024 g/cm2 and 19.047–0.029 g/cm2 in the energy range of 0.015–15 MeV. Further, other essential parameters, MFP, Zeff, Zeq, EABF, and EBF were derived from the MAC values for the same energies. It was noted that the MFP values of the BPS6 glass are higher than some commercial glasses and ordinary concrete at chosen energy intervals. According to the results achieved, EBF, EABF, and MFP values decline as the percentage of SrO in the BPS glasses increases. The highest Zeff was achieved by BPS6 (with 45% SrO), while the lowest Zeff was obtained by BPS1 (with 20% SrO). Finally, fast neutron removal cross-sections (ΣR), Mass Stopping Power (MSP), and Projected Range (PR) values were computed to investigate the fast neutron, proton and alpha shielding properties of SrO added BPS glasses. It is seen that the ΣR values of BPS glasses vary in the range of 0.126 cm−1–0.117 cm−1. The addition of SrO in the glass leads to reduce the ranges of charged and uncharged particles. According to the outcomes achieved, BPS6 glass with 45% SrO additives can be regarded as an effective radiation shield used in many technological disciplines. [ABSTRACT FROM AUTHOR]

We investigate the charge-state effects on charge transfer of helium ions in gold nanosheet using the time-dependent density functional theory non-adiabatically coupled to the molecular dynamics. In order to characterize and extract the charge-state information of incident particles inside the nanosheet, we develop two novel computational methods. It is found that the charge transfer behavior of He ion in gold nanosheet is sensitive to its charge state at the time of incident. Analysis of these results allows us to gain new insights in the interaction between He ions and gold nanosheet. This work validates the ability of current methodology in dealing with ion collisions in materials.

Based on the kinetic theory, improved T -matrix models for the continuous-slowing-down and the linear-energy-transfer stopping powers are established at the same level, where multiple scattering effects and the related transverse deflection are accounted for consistently and systematically. The degree of deflection characterizing the extent of transverse deflection is defined by means of the ratio of these two stopping powers. Calculations for the energy deposition and deflection of α particles in hot dense deuterium–tritium (DT) plasmas and also in hot dense DT plasmas mixed with carbon (C) impurities are performed. Multiple scattering effects and the resulting transverse deflection are demonstrated to have a significant influence on the stopping power of α particles, in particular, in mixtures containing different ions with large mass and charge asymmetry. It is shown that for DT plasma mixed with $5\%$ C impurities, the range and penetration depth of the α particle are shortened by about $21\%$ and $27\%$ , respectively. Our models are found to be appropriate for the evaluation of stopping powers not only in weakly coupled plasmas but also in moderately degenerate and correlated plasmas. These results manifest that multiple scattering effects and the induced transverse deflection need to be taken into account in modeling the transport of α particles in hot dense plasmas relevant to inertial confinement fusion.

The energy loss of heavy ions in thin Mylar and nickel foils was measured accurately using fission fragments from 239 P u (n t h , f) , mass and energy separated by the Lohengrin separator at ILL. The detection setup, placed at the focal plane of the Lohengrin separator enabled to measure precisely the kinetic energy difference of selected fragments after passing through the sample. From these data, the stopping powers in Mylar and nickel layers were extracted and compared to calculations. Whereas large deviations are observed with SRIM-2013 for Mylar, fairly good agreements are obtained with the semi-empirical approach of Knyazheva et al. (2006) and the calculations contained within the DPASS database. In nickel, SRIM-2013 and Knyazheva model are in agreement with our data within about 10%, while large deviations are observed with DPASS. We used our data to provide updated parameters for the Knyazheva model and rescale DPASS database for nickel and Mylar. [ABSTRACT FROM AUTHOR]

We recently adapted the Auxiliary DFT framework as implemented in deMon2k to the simulation of time-dependent problems via the Runge and Gross equations. Our implementation of the so-called Real-Time-Time-Dependent ADFT (RT-TD-ADFT) fully benefits from the algorithms available in deMon2k to carry out variational density fitting, notably the MINRES algorithm recently proposed for self-consistent-field calculations. We test here MINRES for the first time in the context of RT-TD-ADFT. We report extensive benchmarks calculations to assess the reliability of the ADFT framework. These encompass the construction of absorption spectra in the gas phase and in solvent, the calculation of electronic stopping power curves, the irradiation of zeolites by swift ions and the investigation of charge migrations with attosecond time resolution. All our results are very encouraging. We show that even small auxiliary basis sets are sufficient to obtain results almost undisguisable from those obtained with large and flexible auxiliary bases. Overall, we establish the reliability of RT-TD-ADFT to simulate electronics dynamics in large or very large molecular systems. [ABSTRACT FROM AUTHOR]

A major contributing factor to proton range uncertainty is the conversion of computed tomography (CT) Hounsfield Units (HU) to proton relative stopping power (RSP). This uncertainty is elevated with implanted devices, such as silicone breast implants when computed with single energy CT (SECT). In recent years, manufacturers have introduced implants with variations in gel cohesivity. Deriving the RSP for these implants from dual‐energy CT (DECT) can result in a marked reduction of the error associated with SECT. In this study, we investigate the validity of DECT calibration of HU to RSP on silicone breast implants of varying cohesivity levels. A DECT capable scanner was calibrated using the stoichiometric method of Bourque et al for SECT and DECT using a tissue substitute phantom. Three silicone breast implants of increasing gel cohesivity were measured in a proton beam of clinical energy to determine ground‐truth RSP and water equivalent thickness (WET). These were compared to SECT‐derived RSP at three CT spectrum energies and DECT with two energy pairs (80/140 kVp and 100/140 kVp) as obtained from scans with and without an anthropomorphic phantom. The RSP derived from parameters estimates from CT vendor‐specific software (syngo.via) was compared. The WET estimates from SECT deviated from MLIC ground truth approximately +11%–19%, which would result in overpenetration if used clinically. Both the Bourque calibration and syngo.via WET estimates from DECT yielded error ≤0.5% from ground truth; no significant difference was found between models of varying gel cohesivity levels. WET estimates without the anthropomorphic phantom were significantly different than ground truth for the Bourque calibration. From these results, gel cohesivity had no effect on proton RSP. User‐generated DECT calibration can yield comparably accurate RSP estimates for silicone breast implants to vendor software methods. However, care must be taken to account for beam hardening effects. [ABSTRACT FROM AUTHOR]

This work investigates the electronic stopping power for protons of a tungsten plasma at various electron densities and temperatures. The study employs a dielectric formalism to model the stopping power due to free and bound electrons, considering relativistic and non-relativistic effects. The bound electron stopping power is modeled using the shellwise local plasma approximation (SLPA) introduced by Montanari and Miraglia. The ionization state of the plasma is also examined, revealing its impact on the bound electron contribution. We compare our results with the T-Matrix approach and the Li–Petrasso model for free electrons in combination with SLPA calculations for the bound electron ones. Results demonstrate the significance of bound electron stopping power, particularly for plasma with high- Z ions. This investigation contributes valuable insights into plasma physics and fusion energy research, providing essential data for future experiments and simulations. [ABSTRACT FROM AUTHOR]

A universal gain theory of the multiplying layer in electron bombardment complementary metal oxide semiconductor imaging device based on elastic and inelastic scattering is investigated by using Monte Carlo simulation method. The influence of the incident electron energy, the doping concentration in the P-type substrate layer, the radiation flux and the passivation layer thickness on the charge collection efficiency and the gain of the multiplying layer are analyzed theoretically. The results show that the gain in the case of the universal electron stopping power (SP) is lower than that in the case of the Bethe SP, which is more consistent with the actual device gain performance. In addition, increasing the incident electron energy, reducing the passivation layer thickness and irradiation flux, and decreasing the doping concentration are beneficial ways to increase the charge collection efficiency and gain of the electron multiplying layer. [ABSTRACT FROM AUTHOR]

• w -Values are a source of uncertainty in reference dosimetry for hadrontherapy. • MDM-Ion is a Monte Carlo code developed for swift ions transport in liquid water. • w -Values shown to be independent of both particle charge and energy. • Electronic excitation and Auger electron emission strongly affect the results. • w -Values in liquid water should be used as a benchmark for microdosimetry. To develop a particle transport code to compute w -values and stopping power of swift ions in liquid water and gases of interest for reference dosimetry in hadrontherapy. To analyze the relevance of inelastic and post-collisional processes considered. The Monte Carlo code MDM was extended to the case of swift ion impact on liquid water (MDM-Ion). Relativistic corrections in the inelastic cross sections and the post-collisional Auger emission were considered. The effects of introducing different electronic excitation cross sections were also studied. The stopping power of swift ions on liquid water, calculated with MDM-Ion, are in excellent agreement with recommended data. The w- values show a strong dependence on the electronic excitation cross sections and on the Auger electron emission. Comparisons with other Monte Carlo codes show the relevance of both the processes considered and of the cross sections employed. W and w -values for swift electron, proton, and carbon ions calculated with the MDM and MDM-Ion codes are in very close agreement with each other and with the 20.8 eV experimental value. We found that w -values in liquid water are independent of ion charge and energy, as assumed in reference dosimetry for hadrontherapy from sparse experimental results for electron and ion impact on gases. Excitation cross sections and Auger emission included in Monte Carlo codes are critical in w -values calculations. The computation of this physical parameter should be used as a benchmark for micro-dosimetry investigations, to assess the reliability of the cross sections employed. [ABSTRACT FROM AUTHOR]

Fluorine 18-deoxyglucose (18FDG) is often used in Positron Emission Tomography (PET). PET imaging is one of the valuable tools used for cancer detection and management. PET growth is limited due to problems that depend on the production of Fluorine-18. Imaging results are strongly dependent on the information of nuclear reaction cross-section data. This study calculates the stopping power, RCSDA, and the simulated and distributed absorbed dose of F-18, in water. We use the Geant4/Gate simulation and the Bethe-Bloch theory model to access these goals. The results of this simulation and this theory model agree with each other. The main point of this paper is the presentation of a theoretical approach to the production of Fluorine-18 by using protons production through the main nuclear fusion reaction D(d,p)T and the side fusion reaction ³He(d,p)4 He uses helium-3 as a catalyzed. [ABSTRACT FROM AUTHOR]

Electronic stopping cross section of tungsten for light ions was experimentally measured in a wide energy interval (20 to 6000 keV for protons and 50 to 9000 keV for helium) in backscattering and transmission geometries. The measurements were carried out in three laboratories (Austria, Germany and Sweden) using five different set-ups, the stopping data deduced from different data sets showed excellent agreement amongst each other, with total uncertainty varying within 1.5–3.8% for protons and 2.2–5.5% for helium, averaged over the respective energy range of each data set. The final data is compared to available data and to widely adopted semi-empirical and theoretical approaches, and found to be in good agreement with most adopted models at energies around and above the stopping maximum. Most importantly, our results extend the energy regime towards lower energies, and are thus of high technological relevance, e.g., in fusion research. At these low energies, our findings also revealed that tungsten – featured with fully and partially occupied f- and d-subshells, respectively – can be modeled as an electron gas for the energy loss process. [ABSTRACT FROM AUTHOR]

In this work we investigate the energy-loss straggling of low and medium energy protons on available simple materials (C, Al, Si, Ni, Cu, Zn, Ge, Se, Pd, Ag, Sb, Pt, Au, Pb) and demonstrate that the well-known Yang-O'Connor-Wang empirical formula for the energy-loss straggling of protons in matter has a clear physical interpretation. This formula predicts, on empirical grounds, energy-loss straggling values for protons that exceed the values of traditional straggling formulas (e.g., by Lindhard and Chu) at energies around 0.3 MeV/amu by a factor of 2–3. This excess is correlated to the bunching effect, which comes from the inhomogeneity feature of the electron density. Although this effect is specific to each element and can be calculated using e.g. the CasP and PASS programs, a single formula correlates better with overall experimental values. The Yang-O'Connor-Wang formula was refined accounting for subsequent experimental data. [ABSTRACT FROM AUTHOR]