Proton Cross Sections Research Articles

Formation of medical radioisotope 111In in photonuclear reactions

The possibility of photonuclear production of 111In radioisotope has been investigated. The enriched target 112Sn was irradiated at the linear electron accelerator LUE-75 of A. Alikhanian National Science Laboratory (Yerevan, Armenia) at the bremsstrahlung endpoint energy Eγmax = 55 MeV. The cross section per equivalent quantum for reactions 112Sn(γ,x)111In, 112Sn(γ,n)111Sn, 112Sn(γ,2n)110Sn, 112Sn(γ,3n)109Sn,112 Sn(γ,pn)110mIn, 112Sn(γ,pn)110g110In, 112Sn(γ,p2n)109In have been measured via the method of activation and off-line γ-ray spectrometric technique. The cross section per equivalent quantum of the 111In in photonuclear reaction was compared with its cross section in proton induced reaction on cadmium targets and other possible 111In production routes. It is shown that the photonuclear method can be used for the production of 111In.

Nuclear elastic scattering of protons below 250 MeV in FLUKA v4-4.0 and its role in single-event-upset production in electronics

FLUKA is among the general-purpose codes for the Monte Carlo simulation of radiation transport that are routinely employed to estimate the production of single-event-upsets (SEUs) in commercial static random access memories (SRAMs) exposed to radiation. Earlier studies concerning the production of SEUs in commercial SRAMs under proton irradiation revealed very good agreement between experimental measurements and FLUKA estimates of the SEU production cross section for proton energies above 20-30 MeV. However, at lower proton energies, where the cross section for SEU production in such low-critical-charge components increases drastically, a FLUKA underestimation of up to two orders of magnitude was observed. Preliminary analyses indicated that this underestimation was in great measure due to the lack of nuclear elastic scattering of protons below 10 MeV in FLUKA up to version 4-3.4. To overcome this limitation, a new model for the nuclear elastic scattering of protons has been developed, combining partial-wave analyses and experimental angular distributions. This newly developed model has been included in FLUKA v4-4.0, and leads to an order-of-magnitude improvement in the agreement between FLUKA and experimental cross sections for the production of SEUs in SRAMs under proton irradiation in the 1–10 MeV energy domain.

Results on elastic cross sections in proton–proton collisions at [formula omitted] GeV with the STAR detector at RHIC

We report results on an elastic cross section measurement in proton–proton collisions at a center-of-mass energy s=510 GeV, obtained with the Roman Pot setup of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The elastic differential cross section is measured in the four-momentum transfer squared range 0.23≤−t≤0.67 GeV2. This is the only measurement of the proton-proton elastic cross section in this t range for collision energies above the Intersecting Storage Rings (ISR) and below the Large Hadron Collider (LHC) colliders. We find that a constant slope B does not fit the data in the aforementioned t range, and we obtain a much better fit using a second-order polynomial for B(t). This is the first measurement below the LHC energies for which the non-constant behavior B(t) is observed. The t dependence of B is also determined using six subintervals of t in the STAR measured t range, and is in good agreement with the phenomenological models. The measured elastic differential cross section dσ/dt agrees well with the results obtained at s=540 GeV for proton–antiproton collisions by the UA4 experiment. We also determine that the integrated elastic cross section within the STAR t-range is σelfid=462.1±0.9(stat.)±1.1(syst.)±11.6(scale)μb.

Comparison of Proton and Gamma Irradiation on Single-Photon Avalanche Diodes

In this paper, the effects of proton and gamma irradiation on reach-through single-photon avalanche diodes (SPADs) are investigated. The I–V characteristics, gain and spectral response of SPAD devices under proton and gamma irradiation were measured at different proton energies and irradiation bias conditions. Comparison experiments of proton and gamma irradiation were performed in the radiation environment of geosynchronous transfer orbit (GTO) with two different radiation shielding designs at the same total ionizing dose (TID). The results show that after 30 MeV and 60 MeV proton irradiation, the leakage current and gain increase, while the spectral response decreases slightly. The leakage current degradation is more severe under the “ON”-bias condition compared to the “OFF”-bias condition, and it is more sensitive to the displacement radiation damage caused by protons compared to gamma rays under the same TID. Further analysis reveals that the non-elastic and elastic cross-section of protons in silicon is 1.05 × 105 times greater than that of gamma rays. This results in SPAD devices being more sensitive to displacement radiation damage than ionizing radiation damage. Under the designed shielding conditions, the leakage current, gain and spectral response parameters of SPADs do not show significant performance degradation in the orbit.

Activation cross sections of proton induced nuclear reactions on tungsten: Special regard to the formation of 186Re

Cross-sections for the production of 181,182m,g,183,184g,186gRe radioisotopes from proton bombardment of natural tungsten have been measured using the stacked foil activation technique for proton energies up to 14.7 MeV. The results were analyzed and compared with the reported experimental data, and the theoretical excitation functions as calculated by the EMPIRE 3.2.3 and TALYS 1.9 codes. Several attempts have been made to reproduce the experimental excitation functions by different EMPIRE input parameters, and a reasonable agreement was attained. While measuring the activity of radionuclide 181Re, the intensity of the emitted 360-keV γ-photon was estimated at around 10 %, about half of the value reported in various databases. The integral yield of the investigated radioisotopes has been calculated, and a particular interest in the 186gRe therapeutic radionuclide was discussed.

Calculation of radiation damage of key components of China Spallation Neutron Source II target station

China Spallation Neutron Source (CSNS) I project passed the national acceptance in 2018, and current beam power has reached 140 kW. In order to further improve the output neutron strength of the target station moderator, a 500 kW power upgrade plan has been proposed for CSNS II. The target station is an important part of the spallation neutron source. In the target station, a large number of neutrons are produced by the spallation reaction between high energy protons and the target, these neutrons are moderated by the moderator and become neutrons for neutron scattering experiments. During operation, the target and other key components such as the target container, the moderator reflector container, and the proton beam window are irradiated by high-flux and high-energy particles for a long time, which will result in serious radiation damage. It is important to assess the accumulated radiation damage during operation to determine the service life of each component. At present, the physical quantities used to evaluate the radiation damage degree of materials include displacement per atom (DPA), H and He production. In this work, the displacement damage cross sections of protons and neutrons and the H, He production cross sections for W, SS316 and Al-6061 materials are obtained by using PHITS. The effects of the Norgett-Robinson-Torrens (NRT) model and athermal recombination corrected (ARC) model on the calculation of displacement damage are analyzed. The results show that the cross section calculated based on ARC model is lower than that based on NRT model, because the NRT model does not take into account the resetting of the atoms before reaching thermodynamic equilibrium. On this basis, DPA, H and He production of the key components of the target station operating for 5000 h at a power of 500 kW are calculated by combining the baseline model of the second phase target station of the spallation neutron source in China. The results show that the yields of NRT-dpa, ARC-dpa, H and He produced by irradiation are 8.01 dpa/y (in this paper, 1 y = 2500 MW·h), 2.39 dpa/y, 5110 appm/y and 884 appm/y, respectively. The radiation damage values of the target vessel are 5.34 dpa/y, 1.92 dpa/y, 2180 appm/y and 334 appm/y, respectively. The radiation damage values of the moderators and reflectors are 3.78 dpa/y, 1.77 dpa/y, 124 appm/y, and 36.7 appm/y. The radiation damage values of the proton beam window are 0.35 dpa/y, 0.19 dpa/y, 962 appm/y, and 216 appm/y. Subsequently, the life of each component is estimated by analyzing the radiation damage. These results are very important for analyzing the radiation damage of these parts, and constructing reasonable maintenance programs.

Semi-empirical parameterization of HI/p L-shell X-ray production cross section ratios in Bi for Heavy Ion PIXE

Quantitative analysis of materials from Heavy Ion PIXE spectra remains impeded by the lack of reliable X-ray production cross section (XPCS) data. Although efforts at experimental Heavy Ion induced XPCS measurements still continue, Multiple Ionisation (MI) effects, which are not fully described by theory, render simulations of heavy ion PIXE data unreliable for large Z1/Z2 collisions, especially at low energies. This is also exacerbated by the random selection of projectile-target combinations for measured and reported experimental data available to validate theory. This study explored heavy ion induced X-ray production cross section deviations from those induced by protons at the same ion velocity. This enabled evaluations of the degree to which cross sections are enhanced through MI effects, with the aim of predicting XPCS due to heavy ion impact. The evaluation was carried out through the scaling of experimental heavy ion to theoretical proton cross section ratios (R), which were then used for the interpolation of XPCS in the same target element for ‘missing’ projectiles within the range of evaluation. Here we present measurements of heavy ion induced total L-shell XPCS in Bi, carried out to determine HI/p MI induced deviations due to C, F, Cl and Ti projectiles at an ion velocity range of (0.2–1.0) MeV/nucleon.

Dosimetric effects of inserted non-radioactive elements in a tumor area in proton therapy

Introduction: Various prompt gamma (PG) ray-based techniques have been proposed to monitor the proton range during treatment, but the poor PG statistics produced entangle their clinical application. Recently, we developed a Monte Carlo (MC) simulation model for the enhancement of PG production based on the nuclear cross section of protons with the material transversed, via inserting the non-radioactive elements 19F, 17O, and 127I in a hypothetical tumor area. This work aimed to study the dose distribution changes caused by the addition of specific % weight fractions of PG enhancers in a water medium using MC simulations.Methods: Our MC model was created using the TOPAS MC package and retaining identical geometries, mixture compositions, and incident proton energies (75, 100, and 200 MeV, respectively) previously tested for the PG statistics enhancement. The total dose deposition in water and in mixture compositions that have been found to maximally increase the PG production was scored and evaluated based on the important dosimetric metrics R90, Bragg peak (BP) width, and full width at half maximum (FWHM). Furthermore, the spatial correlation of PG emissions relative to BPs was also studied and compared on the basis of the BP decrease at R90.Results and Discussion: There is no significant change in total dose deposition except for 127I. However, dose curve shifts in R90 toward shallower depth, followed by steeper BP and reduced FWHM, were observed in all cases. The percentage changes vary with incident proton energies and mixture compositions. The addition of the stable elements had no effect on the PG spatial emission. The dosimetric study reveals that the addition of the tested stable elements did not change the dose distribution and did not alter the dose deposited by secondary particles. Since their addition increases the electron density of the medium, the shift of BP to shallower depths is linked with the mixture composition changes. Furthermore, a steeper BP value is observed that could be beneficial for OAR avoidance. Since this theoretical study of using 19F, 17O, and 127I as PG enhancers is promising from a dosimetric point of view, experimental studies are necessary to determine their clinical application feasibility.

Elastic proton–neutron and antiproton–neutron scattering in holographic QCD

The total and differential cross sections of the elastic proton–neutron and antiproton–neutron scattering are studied in a holographic QCD model, focusing on the Regge regime. Taking into account the Pomeron and Reggeon exchange, which are described by the Reggeized spin-2 glueball and vector meson propagator respectively, those cross sections are obtained. It is presented that the currently available experimental data of the total cross sections can be well described within the model. Once a single adjustable parameter is determined with the total cross section data, the differential cross sections can be calculated without any additional parameters. Although the available differential cross section data are limited, it is found that our predictions are consistent with those.

Direction-sensitive dark matter search with 3D-vector-type tracking in NEWAGE

Abstract NEWAGE is a direction-sensitive dark matter search experiment with a 3D tracking detector based on a gaseous micro time projection chamber. A direction-sensitive dark matter search was carried out at Kamioka Observatory with a total live time of 318.0 days resulting in an exposure of 3.18 kg·days. A new gamma-ray rejection and a head–tail determination analysis were implemented for this work. No significant non-isotropic signal from the directional analysis was found and a 90% confidence level upper limit on a spin-dependent weakly interactive massive particle (WIMP)–proton cross section of 25.7 pb for a WIMP mass of 150 GeV/c2 was derived. This analysis marks the most stringent upper limit in the direction-sensitive dark matter searches.

Studying differential cross section for elastic proton scattering by a tensor model

Previous studies have shown the reliability of the Bayesian Gaussian CANDECOMP/PARAFAC tensor decomposition (BGCP) algorithm in predicting the independent fission yields and evaluating global uncertainty of the data. This work proposes to apply the BGCP algorithm for the purpose of predicting and evaluating the differential cross section for elastic proton scattering. The tensor model is developed by training with the experimental data of elastic proton scattering from the EXFOR database. The Root Mean Square Error is used to evaluate the experimental data and search for potential errors and omissions in EXFOR, in order to identify outlying data of 98Mo, 100Mo, 144Sm and 209Bi. After the revision for the outlying data in EXFOR, the reproduced values for 144Sm are compared with the remaining controversial entries. Besides, the predicted data for 9C are compared with the published data not available in EXFOR. The results demonstrate that the tensor model can make reasonable predictions and has a role to play in evaluating the quality of elastic proton scattering data. The tensor model may become a powerful tool for nuclear data evaluation in EXFOR.

Determination of matter radius and neutron-skin thickness of 60,62,64Ni from reaction cross section of proton scattering on 60,62,64Ni targets

Background:In our previous work, we determined matter radii rm(exp) and neutron-skin thickness rskin(exp) from reaction cross sections σR(exp) of proton scattering on 208Pb, 58Ni, 40,48Ca, 12C targets, using the chiral (Kyushu) g-matrix folding model with the densities calculated with Gogny-D1S-HFB (D1S-GHFB) with angular momentum projection (AMP). The resultant rskin(exp) agree with the PREX2 and CREX values. As for 58Ni, our value is consistent with one determined from the differential cross section for 58Ni＋4He scattering. As for p＋60,62,64N scattering, σR(exp) are available as a function of incident energies Ein, where Ein=22.8∼65.5MeV for 60Ni, Ein=40,60.8MeV for 62Ni, Ein=40,60.8MeV for 64Ni. PurposeOur aim is to determine matter radii rm(exp) for 60,62,64Ni from the σR(exp). Method:Our method is the Kyushu g-matrix folding model with the densities scaled from D1S-GHFB ＋ AMP densities, Results:Our skin values are rskin(exp)=0.076±0.019,0.106±0.192,0.162±0.176 fm, and rm(exp)=3.759±0.011,3.811±0.107,3.864±0.101 fm for 60,62,64Ni, respectively.

Preequilibrium cluster emission in massive transfer reactions near the Coulomb barrier energy

Within the framework of the dinuclear system model, the preequilibrium emission of neutron, proton, deuteron, triton, $^{3}\mathrm{He}$, $\ensuremath{\alpha}$, $^{6}\mathrm{Li}$, $^{7}\mathrm{Li}$, $^{8}\mathrm{Be}$, and $^{9}\mathrm{Be}$ in the transfer reactions of $^{12}\mathrm{C}$ $+$ $^{209}\mathrm{Bi}$, $^{40,48}\mathrm{Ca}+^{238}\mathrm{U}$, $^{238}\mathrm{U}+^{238}\mathrm{U}$, and $^{238}\mathrm{U}+^{248}\mathrm{Cm}$ has been systematically investigated. The production rate, kinetic energy spectra, and emission angular distribution are calculated. It is found that the preequilibrium emission mechanism is associated with the reaction system and beam energy. The preequilibrium cross sections of proton, deuteron, triton, and alpha are comparable in magnitude. The reaction with $^{40}\mathrm{Ca}$ is favorable for the cluster emission in comparison with $^{48}\mathrm{Ca}$ on $^{238}\mathrm{U}$ at the near barrier energy. A broad angular distribution of the preequilibrium cluster is found in the heavy systems $^{238}\mathrm{U}+^{238}\mathrm{U}$ and $^{238}\mathrm{U}+^{248}\mathrm{Cm}$. The method is also possible for the weakly bound nuclei induced reactions. Future experiments are discussed for the preequilibrium cluster measurements.

Using Track Structure Theory to Predict Proton and Heavy-Ion Cross Sections

Using Track Structure Theory to Predict Proton and Heavy-Ion Cross Sections

Proton Direct Ionization Upsets at Tens of MeV

Experimental mono-energetic proton single-event upset (SEU) cross-sections of a 65 nm low core-voltage static random access memory (SRAM) were found to be exceptionally high not only at low energies (< 3 MeV), but also at energies > 3 MeV and extending up to tens of MeV. The SEU cross-section from 20 MeV protons exceed the 200 MeV proton SEU cross-section by almost a factor of 3. Similarly, mono-energetic neutron cross-sections at 14 MeV are about a factor of 3 lower than the 20 MeV proton cross-section. Thanks to Monte-Carlo (MC) simulations it was determined that this strong enhancement is due to the proton direct ionization process as opposed to the elastic and inelastic scattering processes that dominate the SEU response above 3 MeV in other SRAMs. As shown by means of a detailed energy deposition scoring analysis, however, this does not appear to be caused by the critical charge of the SRAM being lower than the charge resulting from the average proton ionization through the linear energy transfer (LET). On the other hand, this is caused by high-energy δ-rays (> 1 keV) that can deposit their full kinetic energy within the sensitive volume (SV) of a cell despite their range being theoretically much longer than the characteristic size of the SV. Multiple scattering events are responsible for increasing the trajectory path of the δ-rays within the sensitive volume, resulting in a 6 fold increase in the probability of upset with respect to the sole electron ionization.

Time-Dependent Density-Functional Theory for Determining the Electron-Capture Cross Section for Protons Impacting on Atoms and Molecules.

The use of the Time-Dependent Density-Functional Theory (TDDFT) has increased in the atomic collision field. Calculating the electron-capture cross section (ECCS) for protons is an important question in hadrontherapy and plasma physics, among other areas. In previous studies, it was shown that the approach based on the Local Density Approximation (LDA) fails in the 1-50 keV region, requiring the use of the Optimized Effective Potential (OEP) method. In this work, the ECCS values for 1-50 keV protons impacting on isolated hydrogen, carbon, nitrogen, oxygen, and nitrogenous atoms were determined using the TDDFT. It is shown that adding the Self Interaction Correction to the LDA (LDA-Sic) allows obtaining results close to those provided by the OEP and experiments, with the advantage that the LDA-Sic consumes less computational time. In addition, it was demonstrated that it is imperative to include the spin correction for the specific helium and oxygen cases, in order to get good results for the ECCS using the TDDFT. Theoretical results obtained in this work show excellent agreement with experimental values.

A systematic analysis of deuteron breakup

Inclusive breakup cross sections for deuterons incident on a wide range of nuclei at different incident energies are studied. In our analysis, we use the post-form distorted-wave-Born approximation (DWBA) to calculate the elastic and nonelastic breakup cross sections. We also calculate exciton and statistical compound-nucleus model cross sections to account for pre-equilibrium and equilibrium emissions. The calculations are performed using the code EMPIRE and are compared to the available experimental data. The comparisons of the integrated cross sections reveal a generally good agreement between the calculations and the data. However, systematic discrepancies are observed between the calculated double differential neutron and proton cross sections and the data, especially for heavier targets. Possible reasons for the disagreements between the theoretical predictions and the experimental data are discussed.

Neutron skin thickness of 116,118,120,122,124Sn determined from reaction cross sections of proton scattering

Background:The cross sections of the isovector spin-dipole resonances (SDR) in the Sb isotopes have been measured. Within the model used, the neutron-skin thicknesses rskin(exp) deduced 0.12±0.06 fm for 116Sn, 0.13±0.06 fm for 118Sn, 0.18±0.07 fm for 120Sn, 0.22±0.07 fm for 122Sn, 0.19±0.07 fm for 124Sn. We tested the chiral (Kyushu) g-matrix folding model for 12C+12C scattering, and found that the Kyushu g-matrix folding model is reliable for reaction cross sections σR in 30˜<Ein˜<100MeV and 250˜<Ein˜<400MeV. We determine neutron skin thickness rskin(exp), using measured σR of 4He+116,120,224Sn scattering. The results are rskin(exp)=0.242±0.140 fm for 116Sn, rskin(exp)=0.377±0.140 fm for 120Sn, rskin(exp)=0.180±0.142 fm for 124Sn. The σR are available for proton scattering on 116,118,120,122,124Sn with high accuracy of 2∼3% as a function of incident energy Ein. Purpose:Our aim is to determine rskin(exp) for 116,118,120,122,124Sn with small errors by using the Kyushu g-matrix folding model. Methods:Our model is the Kyushu g-matrix folding model with the densities scaled from the D1S-GHFB+AMP neutron density, where D1S-GHFB+AMP stands for Gogny-D1S HFB (D1S-GHFB) with the angular momentum projection (AMP). Results:The proton radii of D1S-GHFB+AMP agree with those calculated with the isotope shift method based on the electron scattering. We then scale the D1S-GHFB+AMP neutron densities so as to reproduce the σR(exp). In 30˜<Ein˜<65MeV, we determine rskin(exp) from measured σR. The values are rskin(exp)=0.118±0.021 fm for 116Sn, 0.112±0.021 fm for 118Sn, 0.124±0.021 fm for 120Sn, 0.156±0.022 fm for 124Sn. As for 122Sn, the skin value in 30˜<Ein˜<50MeV is 0.122±0.024 fm. Conclusions:Our results are consistent with the previous values.

The Atacama Cosmology Telescope: limits on dark matter-baryon interactions from DR4 power spectra

Diverse astrophysical observations suggest the existence of cold dark matter that interacts only gravitationally with radiation and ordinary baryonic matter. Any nonzero coupling between dark matter and baryons would provide a significant step towards understanding the particle nature of dark matter. Measurements of the cosmic microwave background (CMB) provide constraints on such a coupling that complement laboratory searches. In this work we place upper limits on a variety of models for dark matter elastic scattering with protons and electrons by combining large-scale CMB data from the Planck satellite with small-scale information from Atacama Cosmology Telescope (ACT) DR4 data. In the case of velocity-independent scattering, we obtain bounds on the interaction cross section for protons that are 40% tighter than previous constraints from the CMB anisotropy. For some models with velocity-dependent scattering we find best-fitting cross sections with a 2σ deviation from zero, but these scattering models are not statistically preferred over ΛCDM in terms of model selection.

Cross section measurements of low-energy charged particle induced reactions using moderated neutron counter arrays

A high-and-flat efficiency moderated neutron detection array of 3He counters has been recently developed for photoneutron cross section measurements at the future ELI-NP gamma-ray beam source. We have designed a three rings geometry of 31 counters with a ˜37% efficiency flat within 5% in the 10 keV to 5 MeV neutron energy interval. A commissioning experiment was performed using proton beams delivered by the 9 MV Tandem accelerator of IFIN-HH. We measured the neutron production cross sections for proton induced reactions on nat Cu and 27Al. The (p, xn) reactions on nat Cu were investigated in the 4.5 MeV to 14 MeV proton energy range with 250 keV steps, using pulsed and continuous proton beams. The low energy measurements below 10 MeV served to validate the detection efficiency calibration against well-known natCu(p, n) cross sections. The 27Al(p, n) reaction was investigated in the 5.8 MeV to 6.75 MeV energy range with 5 keV steps. Preliminary cross section results are here compared with preceding data.