Energy Loss Of Protons Research Articles

Nonadditivity effects during the passage of protons through multilayer targets

A theoretical approach is proposed for describing the effect of the number and sequence of surface layers of different compositions on the distribution of radiation defects over the depth of the screened material. It is shown that the energy losses of fast protons penetrating through the tungsten-carbon media depend not only on the thickness and chemical composition of the media but also on the sequence and the number of the layers. Results of calculations using GEANT4 and SRIM programs agree well with each other and show that proton loses a larger amount of energy during the passage through the bilayer W/C target than through the C/W one. An increase in the number of layers leads to a decrease in the influence of the target structure on the distribution of the absorbed energy. This effect is explained by the difference in the stopping powers of neighboring layers.

Estimation and analysis of the influence of ionizing radiation on the operation of nanosatellite onboard radio electronic equipment

The paper presents the results of a calculation aimed to study the influence of ionizing, bremsstrahlung radiation on the operation of a nanosatellite obtained during the implementation of the project 0777-2020-0018 in 2020. A comparative analysis of the results of calculating the specific ionization and radiation energy losses of protons (from 0.1 to 400 MeV) and electrons (from 0.04 to 7 MeV), as well as their path lengths in aluminum according to the formulas of various authors and the database of materials of the National Institute of Standards and Technologies is presented. Based on the analysis results, the annual dose in the aluminum structure of the SamSat ION nanosatellite in a circular sun-synchronous orbit (SSO) is calculated. All calculations are based on the data of the energy spectra of protons and electrons of the SSO given in the Information system Spenvis of the European Space Agency. The results of calculating the integral fluxes in aluminum under the action of protons and electrons of a circular SSO for different thicknesses are obtained, and the fraction of passed particles is shown in the approximation of a single-layer stack. The radiation resistance of the electronic elements ISL70321SEH, ISL73321SEH and Virtex-4QV, Virtex-5QV included in the SamSat ION avionics and its ability to operate during a year was assessed.

Computer-based modeling of radiation defect parameters in materials irradiated with charged particles

The paper considers a new approach to approximation expressions for integral sections of interaction and for approximation coefficients included in expressions for cascade-probability functions (CPF), spectra of primary knocked-on atoms (PNA) and the concentration of radiation defects in materials irradiated with charged particles, namely electrons, protons, alpha particles and ions. The obtained approximations made it possible to design the mathematical models of cascade-probability functions taking into account energy losses for electrons, protons, alpha particles and ions. The integral sections of interaction, penetration depths were calculated, the approximation expressions were chosen, and the approximation coefficients for the above particles were found. Recurrence ratios were derived to obtain CPF. The choice of an approximation expression and finding of approximation coefficients was compared with the earlier process using different software packages. It is apparent that that the use of modern algorithms considerably simplifies this process.

Оценка и анализ радиационной стойкости радиоэлектронных элементов на кремниевой основе бортовой аппаратуры наноспутника при воздействии ионизирующего излучения солнечно-синхронной орбиты.

The paper presents the results of a calculation to study the influence of ionizing, bremsstrahlung radiation on the functioning of a nanosatellite. A comparative analysis of the results of calculating the specific ionization and radiation energy losses of protons (from 0.1 to 400 MeV) and electrons (from 0.04 to 7 MeV), as well as their path lengths in aluminum according to the formulas of various authors and the database of materials of the National Institute of Standards and Technologies is presented. Based on the analysis results, the annual dose in the aluminum structure of the SamSat-ION nanosatellite in a circular sun-synchronous orbit (SSO) is calculated. All calculations are based on the data of the energy spectra of protons and electrons of the SSO given in the "Information system Spenvis of the European Space Agency". The results of calculating the integral fluxes in aluminum under the action of protons and electrons of a circular SSO for different thicknesses are obtained, and the fraction of passed particles is shown in the approximation of a single-layer stack. Estimation of the radiation resistance of the electronic elements ISL70321SEH, ISL73321SEH and Virtex - 4QV, Virtex -5QV included in the SamSat - ION in the approximation of a double-layer stack was made for various thickness of Si and its ability to operate during the year.

First-principles study of semicore electron excitation in the electronic energy loss of ZnO for protons

The electronic stopping power of zinc oxide for protons is presented over a wide range of velocities by using real-time time-dependent density functional theory. We calculated the electronic stopping power of energetic protons for both channeling and off-channeling trajectories, and revealed the microcosmic mechanism of semicore $3d$-electron excitation in ZnO. In the low-energy regime, the stopping power obtained from channeling geometry is in a quantitative agreement with the measured data, which reproduced not only the experimental threshold velocity of the stopping power, but also the deviation from velocity-proportional electronic stopping power which is considered to be caused by excitation of the tightly bound $3d$ electrons. In the high-energy regime, we examined the impact parameter dependence of semicore $3d$-electron excitation of ZnO, and showed that the stopping power obtained from off-channeling geometry greatly improves the simulation results in comparison with the channeling results. We also demonstrated that the electronic energy loss of protons is not only related to the number of electrons excited, but also associated with the energy distribution of excited electrons and holes after collisions.

Collision dynamics of cytosine under proton irradiation

In the framework of the time-dependent density-functional theory, applied to valence electrons, coupled non-adiabatically to molecular dynamics of ions, the collision dynamics of cytosine impacted by proton is studied. We especially focus on the effect of the collision orientations on the damage of cytosine by choosing two collision orientations taking the oxygen atom on the double bond CO as the collision site with the incident energy of proton ranging from 150 eV to 1000 eV. First, two collision dynamical processes are explored by analyzing the molecular ionization, the ionic position and the kinetic energy, the energy loss of proton and the electronic density evolution. The results show that the damage process of cytosine induced by proton impact is mainly the capture of electrons by proton, the departments of ions and groups as well as the opening of ring. It is found that the orientation has little effect on the loss of the kinetic energy of proton, which is about 21.5[Formula: see text] of the incident energy of proton. Although the scattering angle [Formula: see text] has a polynomial relationship with [Formula: see text] in both cases, it is greatly affected by the orientation. When [Formula: see text] eV, the scattering angle of proton colliding with O along the [Formula: see text]-axis is greater than that of proton colliding with O along the [Formula: see text]-axis. The orientation also has a great effect on the mass distribution of the fragments and the fragmentation route. When proton moves along the [Formula: see text]-axis, the fragmentation route is that O leaves the cytosine and the rest keeps on vibration, while products are not only related to the incident kinetic energy, but also show diversity when proton moves along the [Formula: see text]-axis.

Proton Energy Loss in GaN

The proton energy loss in GaN in an energy range between 0 and 65 MeV is investigated. The energy of protons generated by a cyclotron at about 65 MeV is varied by inserting an energy‐absorbing medium of varying thickness. The precise modeling of the GaN Schottky diode response as a function of the absorbing medium thickness allows us to demonstrate that the energy absorption loss in GaN precisely follows the Bethe theory. In addition, the region of the detector contributing to its response to a proton beam, which is of prime importance for proton detector optimization, can be identified.

Designing of active plasma lens for focusing laser-plasma-accelerated pulsed proton beams

Active plasma lenses (APLs) have been proved as an effective device for focusing charged particles. In this paper, we have theoretically studied the feasibility of using a discharged-capillary based high gradient APL to focus laser accelerated pulsed proton beams. We specify equations of motion of proton beams in both straight and curved discharge-capillary APLs, on which the regulation law of a specific APL focusing and tuning protons can be calculated. Then, we summarize several constraints of APLs. Confirmed by a 2D PIC simulation, we find that with a proper plasma state, the proton energy loss, the transverse current distribution, and the Z-pinch effect do not significantly affect the beam transport, while the passive plasma lens (PPL) effect can promote the APL focusing within an acceptable extent. The regime of working parameters, including the plasma density ${n}_{0}$, the discharge current $I$, the length $L$ and the radius $R$ of APLs are given for different aimed proton energy. The results show that APL, whose parameters can be adjusted flexibly, is suitable for focusing and transporting proton beams with energy of 1--100 MeV. It is expected to build a beam-line based on plasma with centimeter length scale for pulsed proton beams. Such compact beam-line can have significant impact on various applications.

The Charge State of Protons with 90 and 100 keV Energies Decelerated in Hydrogen Plasma

Energy loss of protons with 90 and 100 keV energies penetrating through a hydrogen plasma target has been measured, where the electron density of the plasma is about 1016 cm−3 and the electron temperature is about 1-2 eV. It is found that the energy loss of protons in the plasma is obviously larger than that in cold gas and the experimental results based on the Bethe model calculations can be demonstrated by the variation of effective charge of protons in the hydrogen plasma. The effective charge remains 1 for 100 keV protons, while the value for 90 keV protons decreases to be about 0.92. Moreover, two empirical formulae are employed to extract the effective charge.

Erratum: Excitation effect of d electrons on the electronic energy loss of energetic protons colliding with a Zn atom [Phys. Rev. A 101 , 062705 (2020)

Erratum: Excitation effect of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>d</mml:mi></mml:math> electrons on the electronic energy loss of energetic protons colliding with a Zn atom [Phys. Rev. A <b>101</b> , 062705 (2020)

Molière maximum likelihood proton path estimation approximated by cubic Bézier curve for scatter corrected proton CT reconstruction

A maximum likelihood approach to the problem of calculating the proton paths inside the scanned object in proton computed tomography is presented. Molière theory is used for the first time to derive a physical model that describes proton multiple Coulomb scattering, avoiding the need for the Gaussian approximation currently used. To enable this, the proposed method approximates proton paths with cubic Bézier curves and subsequently maximizes the path likelihood through parametric optimization, based on the Molière model. Results from the Highland formula-based Gaussian approximation are also presented for comparison. The simplex method is utilized for optimisation. The scattering properties of the material(s) of the scanned object are taken into account by appropriately calculating the scattering parameters from the stopping power map that is calculated/updated at every iteration of the algebraic reconstruction process. Proton track length constraint imposed by the proton energy loss is accounted for. The method is also applied in the case that no exit angle data are measured. Geant4 Monte Carlo simulations were performed for model validation. Our results show that use of Molière probability density function for modelling the multiple Coulomb scattering presents a modest 2% accuracy improvement over the Gaussian approximation and most-likely-path method. Simulations of voxelized phantom showed no essential benefit from the inclusion of the material information into the optimization, while path optimization with energy constraint slightly increased path resolution in a bone/water interface phantom. Method error was found to depend on energy, proton track-length within the medium, and proportion of data filtering.

Excitation effect of d electrons on the electronic energy loss of energetic protons colliding with a Zn atom

By using a nonequilibrium approach based on real-time time-dependent density-functional theory combined with molecular dynamics simulations, the effects of $d$-electron excitation on the electronic energy loss of energetic protons colliding with atomic zinc target are studied. The results show that the semicore electrons play a crucial role in the electronic energy loss in an extended energy range. In the low-energy regime, the electronic energy loss displays the threshold effect before it is proportional to velocity, which is explained by the quantization of the energy levels of zinc atom, and the charge transfer contributes greatly to the electronic energy loss, especially at 0.1 a.u. In addition, due to the electron resonance excitation, the number of excited electrons and charge transfer is significantly increased at the velocity thresholds for electron excitation. In the high-energy regime, the electronic energy loss is greatly enhanced as the the impact parameter decreases, which is ascribed to the excitation of $3d$ electrons. We also calculated the stopping cross section for energetic protons colliding with atomic zinc, which is in a good agreement with the experimental values in both low- and high-velocity regimes.

Stopping Power and Partial Stopping Power Effective Charge in The Plasma

The energy losses of ions moving in an electron gas can be studied through the stopping power of the medium. A large number of calculations of the stopping power of ions and electrons in plasmas have been carried out using the random phase approximation (RPA) in the dielectric formalism, for low and high energies. Then we calculated the partial stopping power effective charge (PSPEC) from the energy loss of an incident proton, Ar-ion, and He-ion in target plasma. The Brandt-Kitagawa (BK) model is used to describe the projectile charge fraction (q) and calculate the stopping power and PSPEC, which depends on temperature and electron density ρ(k) of the plasma. This is a topic of relevance to understanding the beam-target interaction in the contexts of particle driven fusion. The presented study is formulated in terms of classical dielectric functions. The programming language Fortran - 90 was used for a required calculation. In the present work, three systems of plasma (Z-pinch, Tokamak, ICF) for different temperatures and densities were covered. Additionally, a comparison has been done with the previous work of plasma.

A mathematical expression for depth-light curves of therapeutic proton beams in a quenching scintillator.

Recently, there has been increasing interest in the development of scintillator-based detectors for the measurement of depth-dose curves of therapeutic proton beams (Beaulieu and Beddar [2016], Phys Med Biol., 61:R305-R343). These detectors allow the measurement of single beam parameters such as the proton range or the reconstruction of the full three-dimensional dose distribution. Thus, scintillation detectors could play an important role in beam quality assurance, online beam monitoring, and proton imaging. However, the light output of the scintillator as a function of dose deposition is subject to quenching effects due to the high-specific energy loss of incident protons, particularly in the Bragg peak. The aim of this work is to develop a model that describes the percent depth-light curve in a quenching scintillator and allow the extraction of information about the beam range and the strength of the quenching. A mathematical expression of a depth-light curve, derived from a combination of Birks' law (Birks [1951], Proc Phys Soc A., 64:874) and Bortfeld's Bragg curve (Bortfeld [1997], Med Phys., 24:2024-2033) that is termed a "quenched Bragg" curve, is presented. The model is validated against simulation and measurement. A fit of the quenched Bragg model to simulated depth-light curves in a polystyrene-based scintillator shows good agreement between the two, with a maximum deviation of 2.5% at the Bragg peak. The differences are larger behind the Bragg peak and in the dose build-up region. In the same simulation, the difference between the reconstructed range and the reference proton range is found to be always smaller than 0.16mm. The comparison with measured data shows that the fitted beam range agrees with the reference range within their respective uncertainties. The quenched Bragg model is, therefore, an accurate tool for the range measurement from quenched depth-dose curves. Moreover, it allows the reconstruction of the beam energy spread, the particle fluence, and the magnitude of the quenching effect from a measured depth-light curve.

Disparate Energy Scaling of Trajectory-Dependent Electronic Excitations for Slow Protons and He Ions.

We have simultaneously measured angular distributions and electronic energy loss of helium ions and protons directly transmitted through self-supporting, single-crystalline silicon foils. We have compared the energy loss along channeled and random trajectories for incident ion energies between 50 and 200keV. For all studied cases the energy loss in channeling geometry is found lower than in random geometry. In the case of protons, this difference increases with initial ion energy. This behavior can be explained by the increasing contribution of excitations of core electrons, which are more likely to happen at small impact parameters accessible only in random geometry. For helium ions we observe a reverse trend-a decrease of the difference between channeled and random energy loss for increasing ion energy. Because of the inefficiency of core-electron excitations even at small impact parameters at such low energies, another mechanism has to be the cause for the observed difference. We provide evidence that the observation originates from reionization events induced by close collisions of helium ions occurring only along random trajectories.

Measurement of differential cross sections for Single Diffractive Dissociation in [formula omitted] pp collisions using the ATLAS detector

Preliminary LHC results on proton-tagged measurements of Single Diffractive Dissociation (pp → pX) are presented from ATLAS using s=8 TeV data. The central ATLAS detector is used to reconstruct the dissociative X system, and the forward spectrometer ALFA is used to tag the intact proton. Differential cross sections are measured as a function of ξ, the fractional energy loss of the intact proton; |t|, the squared four-momentum exchanged and Δη, the observable rapidity gap. The unfolded t differential cross section is consistent with an exponential dependence dσ/dt ∝ eBt with a slope parameter B = 7.60 ± 0.32 GeV−2. The unfolded ξ differential cross section is interpreted in the framework of Regge phenomenology to extract a Pomeron intercept of α(0) = 1.07 ± 0.09.

Theoretical investigations of collision dynamics of cytosine by low-energy (150–1000 eV) proton impact**Project supported by the National Natural Science Foundation of China (Grant Nos. 11905160 and 11635003) and the Natural Science Foundation of Jiangsu Province of China (Grant No. BK20160199).

Using a real-space real-time implementation of time-dependent density functional theory coupled to molecular dynamics (TDDFT-MD) nonadiabatically, we theoretically study both static properties and collision process of cytosine by 150–1000 eV proton impact in the microscopic way. The calculated ground state of cytosine accords well with experiments. It is found that proton is scattered in any case in the present study. The bond break of cytosine occurs when the energy loss of proton is larger than 22 eV and the main dissociation pathway of cytosine is the breaks of C1N2 and N8H10. In the range of 150 eV ≤ Ek ≤ 360 eV, when the incident energy of proton increases, the excitation becomes more violent even though the interaction time is shortened. While in the range of 360 eV < Ek ≤ 1000 eV, the excitation becomes less violent as the incident energy of proton increases, indicating that the interaction time dominates mainly. We also show two typical collision reaction channels by analyzing the molecular ionization, the electronic density evolution, the energy loss of proton, the vibration frequency and the scattering pattern detailedly. The result shows that the loss of electrons can decrease the bond lengths of C3N8 and C5N6 while increase the bond lengths of C4H11, C5H12 and C4C5 after the collision. Furthermore, it is found that the peak of the scattering angle shows a little redshift when compared to that of the loss of kinetic energy of proton.

A Method of Determining Channeling Parameters in Backscattering Geometry

The energy loss of channeled protons in silicon has been measured in the past in the transmission geometry and was found to be approximately half of the normal loss, thus confirming the equipartition rule. Other measurements however, concerning different crystals (e.g. Ge), deviated from this theory. In the backscattering geometry, the most successful corresponding attempts combined RBS with the nuclear resonance phenomenon. Nevertheless, they involved ether considerable additions to the standard goniometer setup commonly used, or tedious Monte-Carlo calculations, thus limiting their applicability. ïïi the present work, a method for the determination of the energy loss and dechanneling probabilities of axially channeled protons in silicon [100], in the energy range Ep = 1.7-2.6 MeV, is presented. It is carried out in situ, using the same experimental setup and beam properties (size, divergence) with the ones present in the actual analysis of a sample. The results obtained are in good agreement with already existing values in literature.

Electrical responses of a carbon nanotube thin-film transistor to MeV proton irradiation in air

ABSTRACTWe used protons with incident energy of 3.30 MeV to irradiate a carbon nanotube thin-film transistor (CNTTFT) to study its electrical response in air environment. The drain current (ID) was monitored by applying a constant gate voltage (VGS) to the CNTTFT; proton irradiation was turned on and off at a beam intensity of 50,000 cps. ID increased at a negative VGS of −20 V and decreased at a positive VGS of + 10 V during proton irradiation. For both VGS values, ID began to recover after proton irradiation. According to the calculations for the energy loss of protons, the incident protons deposited their energy on the CNTTFT. Micro-Raman analysis revealed that no structural change in the CNT was caused by the incident protons. The reversible electrical responses of the CNTTFT to proton irradiation should be applicable to the detection and dosimetry of MeV incident protons in air.

Proton-dynamic therapy following photosensitiser activation by accelerated protons demonstrated through fluorescence and singlet oxygen production

We demonstrate excitation of photosensitisers (PSs) by accelerated protons to produce fluorescence and singlet oxygen. Their fluorescence follows a pattern similar to the proton energy loss in matter, while proton-derived fluorescence spectra match the photon-induced spectra. PSs excited in dry gelatin exhibit enhanced phosphorescence, suggesting an efficient PSs triplet state population. Singlet oxygen measurements, both optically at ~1270 nm and through the photoproduct of protoporphyrin IX (PpIX), demonstrate cytotoxic singlet oxygen generation by proton excitation. The singlet oxygen-specific scavenger 1,4-diazabicyclo[2.2.2]octane (DABCO) abrogates the photoproduct formation under proton excitation, but cannot countermand the overall loss of PpIX fluorescence. Furthermore, in two cell lines, M059K and T98G, we observe differential cell death upon the addition of the PS cercosporin, while in U87 cells we see no effect at any proton irradiation dose. Our results pave the way for a novel treatment combining proton therapy and “proton-dynamic therapy” for more efficient tumour eradication.