Proton-induced Reactions Research Articles

Activation cross sections of proton-induced reactions on natural platinum up to 30 MeV

Activation cross sections of proton-induced reactions on natural platinum were measured. The stacked-foil activation technique and high-resolution gamma-ray spectrometry were used. The production cross sections of 198, 196, 196m2, 195, 194, 193, 192, 191Au, 191Pt, and 192, 190Ir were determined up to 30 MeV. The experimental results were compared with previous experimental data and theoretical calculations in the TENDL-2019 library.

Cross sections and calculated yields of some radionuclides of yttrium, strontium and rubidium formed in proton-induced reactions on enriched strontium-86: possibility of production of 85gSr, 83Rb and 82mRb in no-carrier-added form

Abstract Cross sections of the 86Sr(p,3n)84mY, 86Sr(p,αn)82mRb, and 86Sr(p,x)85gSr reactions were measured from their respective thresholds up to 16.2 MeV and from 23.0 to 44.1 MeV at FZJ, and from 14.3 to 24.5 MeV at LBNL, using 96.4% enriched 86SrCO3 as target material. Thin targets prepared by sedimentation were irradiated with protons in a stacked-form, and the induced radioactivity was measured by high-resolution γ-ray spectrometry. Nuclear model calculations based on the code TALYS reproduced our experimental cross section data well. From the excitation functions, the integral yields of the above three radionuclides were calculated. The yield of 85gSr via the natSr(n,γ) process was also measured using the TRIGA Mark-II reactor at AERE, Savar. A comparison of the reactor and cyclotron production of carrier-added 85gSr is given. The production possibilities of the three investigated radionuclides in no-carrier-added forms at a 30 MeV cyclotron via new routes are discussed.

17.9 MeV’lik Enerjide (p,α) Tesir Kesiti Verileri üzerine Sistematik Bir İnceleme

Nuclear cross section data are needed in various applications such as radiation therapy, astrophysics, radioisotope production, fusion and fission. The systematics play a very important role in determining cross sections on neutron- and proton-induced reactions at incoming energies of which there are no experimental values. So, empirical systematics have been extensively used at present in the studies on cross section calculations. In this paper, we proposed empirical cross section formulas considering Q–value dependence on (p,α) reactions at proton energy of 17.9 MeV. The present formulas including Coulomb and odd-even effects are based on the statistical theory. In addition, these formulas are a modification to the Levkovskii’s original asymmetry parameter formulas for neutron induced reactions and the Tel et al.’s empirical formulas for proton reactions. Fitting parameters of formulas were determined by least-squares fitting to experimental excitation function data. It is seen that new empirical formulas give good fits with (p,α) experimental cross section values in the literature at 17.9 MeV.

The SINQ gas-jet facility as a source for radionuclides from neutron-induced fission of 235U

The Swiss Spallation Neutron Source SINQ of the Paul Scherrer Institute provides neutrons via proton-induced spallation reactions in a lead target. Produced neutrons are thermalized and impinge on 235U-targets, enclosed in a three-part chamber assembly, which is located in the inner wall of the SINQ shielding. The thermal-neutron-induced fission products can be readily transported from this chamber assembly to a radiochemical laboratory using the gas-jet technique either with a pure carrier gas or with an aerosol-particle-loaded carrier gas. In the past, mainly radioisotopes of the elements Se, Br, Rb, and Kr were retrieved and used for gas-phase chemistry experiments. Here, we present first experiments after the commissioning of the SINQ gas-jet facility as a source of recoverable, non-volatile and volatile, carrier-free fission products for general radiochemical studies and other applications.

Measurement of nuclide production cross sections for proton-induced reactions on [formula omitted]Ni and [formula omitted]Zr at 0.4, 1.3, 2.2, and 3.0 GeV

Nuclide production cross sections for proton-induced reactions on natNi and natZr at incident energies of 0.4, 1.3, 2.2, and 3.0 GeV were measured by the activation method at Japan Proton Accelerator Research Complex (J-PARC). In total, 24 and 43 residual nuclides were measured for the natNi and natZr targets, respectively. Among them, the cross sections of the following reactions were measured for the first time: natZr(p,x)28Mg, natZr(p,x)42K, natZr(p,x)43K, natZr(p,x)44gSc, natZr(p,x)55Co, natZr(p,x)69mZn, and natZr(p,x)93Y reactions. To examine the prediction capabilities, the measured data were compared with the spallation reaction models in PHITS (INCL4.6, Bertini, and JAM as intranuclear cascade models, and GEM as an evaporation model), INCL++/ABLA07, semi-empirical calculation code SPACS, and the JENDL/HE-2007 library. From the evaluation introducing the mean square deviation factor, the best reproducibility was exhibited by the JENDL/HE-2007 library for natNi and INCL++/ABLA07 for natZr.

Bayesian evaluation of residual production cross sections in proton-induced nuclear spallation reactions

Residual production cross sections in spallation reactions are key data for nuclear physics and related applications. Spallation reactions are very complex due to the wide range of incident energies and abundant fragments involved. Therefore, it is challenging to obtain accurate and complete energy-dependent residual cross sections. With the guidance of a simplified EPAX formula (sEPAX), the Bayesian neural network (BNN) technique is applied to form a new machine learning model (BNN + sEPAX) for predicting fragment cross sections in proton-induced nuclear spallation reactions. Three types of sample dataset for measured residual production cross sections in proton-induced nuclear spallation reactions are made, i.e. D1 consists of isotopic cross sections in reactions below 1 GeV/u, D2 consists of fragments excitation functions of reactions up to 2.6 GeV/u, and D3 is a hybrid of D1 and D2. With the constructed BNN and BNN + sEPAX models, the isotopic and mass cross section distributions are compared for the 356 MeV/u 40Ca + p and 1 GeV/u 136Xe + p reactions, and fragment excitation functions in 40Ca + p, 56Fe + p, 138Ba + p and 197Au + p reactions. It is found that the BNN model needs sufficient information to achieve good extrapolations, while the BNN + sEPAX model performs better extrapolations based on less information due to the physical guidance of the sEPAX formulas. It is suggested that the BNN + sEPAX model provides a new approach to predict the energy-dependent residual production cross sections produced in proton-induced nuclear spallation reactions of incident energies from tens of MeV/u up to several GeV/u.

Hyperon physics at HADES as a fair phase-0 experiment

The HADES experiment investigates the nuclear matter and the properties of baryonic resonances. As part of the FAIR Phase-0 program, HADES is being upgraded to enable a wide range of experiments, including investigating electromagnetic decays of hyperons produced in proton-induced reactions. Feasibility studies show that the newly installed forward detectors are crucial for hyperon reconstruction. The detector upgrade and feasibility studies in preparation for the upcoming beamtimes are presented.

Production of high-energyγrays in proton- andα-induced reactions

The high-energy $\ensuremath{\gamma}$ rays have been measured in proton and $\ensuremath{\alpha}$-induced reactions on medium mass target nuclei $^{115}\mathrm{In}$ and $^{112}\mathrm{Sn}$, respectively. Theoretical analyses of the spectra have been performed within the Hauser-Feshbach statistical model and the Akkermans-Gruppelaar exciton model formalisms. It is observed that the proton-induced reaction has significant contribution from the direct-semidirect capture in the region ${E}_{\ensuremath{\gamma}} \ensuremath{\approx}10--20$ MeV. The $^{4}\mathrm{He}$-ion-induced reaction could be described reasonably well by the results of the statistical model calculations. A reduced level density parameter, as compared to that used for the proton-induced reaction, was required to explain the high-energy $\ensuremath{\gamma}$-ray spectrum in the $^{4}\mathrm{He}$-ion-induced reaction.

Excitation functions of proton-induced reactions on natW target for rhenium isotope production

The proton-induced reaction cross-sections on natural tungsten within the proton energy range of 12.50 ± 0.79 MeV to 44.08 ± 0.33 MeV are determined by using the stacked-foil activation method and offline γ-ray spectrometry at the MC50 cyclotron of the Korea Institute of Radiological and Medical Science. The proton beam intensity is determined by using the natCu(p,xn)62Zn and natCu(p,xn)65Zn monitor reactions. The residual nuclide activities are measured using an HPGe γ-ray detector. The experimental results in this work contains 63 individual measured points for seven identified nuclides 181;182m,g;183;184m,g;186Re via the natW(p,xn) reactions. In addition, the thick target yields are determined for the 181;182m,g;183;184m,g;186Re products produced from the natW(p,xn) reactions. The present data are compared with literature data and the theoretical predictions from the TALYS-1.9 code and the TENDL-2019 library.

Excitation functions of proton-induced nuclear reactions on ^{86}Sr, with particular emphasis on the formation of isomeric states in ^{86}Y and ^{85}Y

Cross sections of proton-induced nuclear reactions on enriched ^{mathrm {86}}Sr target were measured by the activation technique up to proton energies of 44 MeV. The isomeric cross-section ratios for ^{mathrm {86m,g}}Y and ^{mathrm {85m,g}}Y as a function of projectile energy were deduced from their measured data. The present experimental data for the nuclear reaction products, namely ^{mathrm {86m}}Y, ^{mathrm {86g+xm}}Y, ^{mathrm {85m}}Y, ^{mathrm {85g}}Y, ^{mathrm {84}}Rb and ^{mathrm {83}}Rb were compared with the results of nuclear model calculations using the code TALYS, which combines the statistical, precompound, and direct interactions. In general, the experimental cross-section data as well as the isomeric cross-section ratios are reproduced well by the model calculations, provided the input model parameters are properly chosen and the level structure of the product nucleus is thoughtfully considered. The quality of the agreement between experimental data and model calculations was numerically quantified. For products formed via emission of a light complex particle as well as multi-nucleons (e.g., alpha and 2p2n), the contribution of the latter process starts increasing when its energy threshold is crossed.

Excitation functions of natNi(p, x) reactions in the energy range of 75–100 MeV

Stacked-foil activation technique and high-resolution gamma spectrometry were used to investigate new excitation functions of proton-induced nuclear reactions on natNi targets in the energy range of 75–100 MeV. The stack foils were irradiated with 100 MeV protons at the separated-sector cyclotron of the Institute of Modern Physics, Chinese Academy of Sciences, China. The proton intensity for each nickel foil was determined using the natNi(p, x)57Ni monitor reaction. The cross-sections of the natNi(p, x)56Ni, 55,57,58Co, and 54Mn reactions were calculated and compared with the existing literature data presented in the Experimental Nuclear Reaction Data (EXFOR). Furthermore, evaluated nuclear data of the PADF-2007, ENDF/B-VIII.0, and JENDL-4.0/HE libraries as well as theoretical calculations of the TALYS code were used. Overall, our experimental data agree with the majority of the literature data. The results of TALYS code as well as the ENDF/B-VIII.0 and JENDL-4.0/HE libraries could reproduce most of the experimental trend, whereas the results of PADF-2007 library could not do so. The new experimental results provide cross-sections for proton-induced natNi reactions in the energy range of 75–100 MeV and could serve as a technical assistance for radionuclide production and radiation safety practices.

A first glimpse at the shell structure beyond 54Ca: Spectroscopy of 55K, 55Ca, and 57Ca

States in the N=35 and 37 isotopes 55,57Ca have been populated by direct proton-induced nucleon removal reactions from 56,58Sc and 56Ca beams at the RIBF. In addition, the (p,2p) quasi-free single-proton removal reaction from 56Ca was studied. Excited states in 55K, 55Ca, and 57Ca were established for the first time via in-beam γ-ray spectroscopy. Results for the proton and neutron removal reactions from 56Ca to states in 55K and 55Ca for the level energies, excited state lifetimes, and exclusive cross sections agree well with state-of-the-art theoretical calculations using different approaches. The observation of a short-lived state in 57Ca suggests a transition in the calcium isotopic chain from single-particle dominated states at N=35 to collective excitations at N=37.

Improvement of nuclear reaction modeling for the production of 47Sc on natural vanadium targets for medical applications

The proton-induced reaction on natural vanadium targets is studied for the production of the innovative theranostic radionuclide 47Sc as well as of its contaminants, mainly 46Sc. The theoretical excitation functions are calculated using the nuclear reaction code TALYS and are compared with the most recent experimental data. A better agreement between the theoretical curves and the data is achieved with an optimization of the nuclear level density parameters. The obtained improvements represent a useful and important result for accurate evaluations of yields and purities which are needed quantities for subsequent dosimetric studies, in view of the radiopharmaceutical applications of 47Sc. The optimization procedure is explained and shown for 47Sc and 46Sc, and also a comparison among the theoretical and experimental cumulatives is given (for the main contaminant) in addition to an estimation of the production yields for two irradiation conditions for both nuclides.

Measurement and modeling of proton-induced reactions on arsenic from 35 to 200 MeV

$^{72}$As is a promising positron emitter for diagnostic imaging that can be employed locally using a $^{72}$Se generator. However, current reaction pathways to $^{72}$Se have insufficient nuclear data for efficient production using regional 100-200 MeV high-intensity proton accelerators. In order to address this deficiency, stacked-target irradiations were performed at LBNL, LANL, and BNL to measure the production of the $^{72}$Se/$^{72}$As PET generator system via $^{75}$As(p,x) between 35 and 200 MeV. This work provides the most well-characterized excitation function for $^{75}$As(p,4n)$^{72}$Se starting from threshold. Additional focus was given to report the first measurements of $^{75}$As(p,x)$^{68}$Ge and bolster an already robust production capability for the highly valuable $^{68}$Ge/$^{68}$Ga PET generator. Thick target yield comparisons with prior established formation routes to both generators are made. In total, high-energy proton-induced cross sections are reported for 55 measured residual products from $^{75}$As, Cu, and Ti targets, where the latter two materials were present as monitor foils. These results were compared with literature data as well as the default theoretical calculations of the nuclear model codes TALYS, CoH, EMPIRE, and ALICE. Reaction modeling at these energies is typically unsatisfactory due to few prior published data and many interacting physics models. Therefore, a detailed assessment of the TALYS code was performed with simultaneous parameter adjustments applied according to a standardized procedure. Particular attention was paid to the formulation of the two-component exciton model in the transition between the compound and pre-equilibrium regions, with a linked investigation of level density models for nuclei off of stability and their impact on modeling predictive power.

Collisions of Nucleons with Atoms: Calculated Cross Sections and Monte Carlo Simulation

After a summary description of the theory of elastic collisions of nucleons with atoms, we present the calculation of a generic database of differential and integrated cross sections for the simulation of multiple elastic collisions of protons and neutrons with kinetic energies larger than 100 keV. The relativistic plane-wave Born approximation, with binding and Coulomb-deflection corrections, has been used to calculate a database of proton-impact ionization of K-shell and L-, M-, and N-subshells of neutral atoms These databases cover the whole energy range of interest for all the elements in the periodic system, from hydrogen to einsteinium (Z = 1–99); they are provided as part of the penh distribution package. The Monte Carlo code system penh for the simulation of coupled electron-photon-proton transport is extended to account for the effect of the transport of neutrons (released in proton-induced nuclear reactions) in calculations of dose distributions from proton beams. A simplified description of neutron transport, in which neutron-induced nuclear reactions are described as a fractionally absorbing process, is shown to give simulated depth-dose distributions in good agreement with those generated by the Geant4 code. The proton-impact ionization database, combined with the description of atomic relaxation data and electron transport in penelope, allows the simulation of proton-induced x-ray emission spectra from targets with complex geometries.

Measurement of nuclide production cross sections for proton-induced reactions on Mn and Co at 1.3, 2.2, and 3.0 GeV

Nuclide production cross sections for proton-induced reactions on Mn and Co at incident energies of 1.3, 2.2, and 3.0 GeV were measured by the activation method at the Japan Proton Accelerator Research Complex (J-PARC). In total, 143 production cross sections of reaction products with half-lives ranging from 1.8 h to 2.6 yr were obtained. Among them, the cross sections of 55Mn(p,x)38S, 55Mn(p,x)41Ar, and 59Co(p,x)38S reactions were measured for the first time. The stable proton beam and well-established beam profile-motoring system contributed to the reduction of the systematic uncertainties to typically less than 5%, which was better than those of the previous data (typically ∼10%). To examine the prediction capabilities of spallation reaction models and evaluated nuclear data library, the measured data were compared with the spallation reaction models in PHITS (INCL4.6, Bertini, and JAM as intranuclear cascade models, and GEM as an evaporation model), INCL++/ABLA07, and the JENDL/HE-2007 library. The comparison of the mean square deviation factors indicated that both INCL4.6/GEM and JENDL/HE-2007 showed better agreement with the measured data than the others.

Benchmark study of particle and heavy-ion transport code system using shielding integral benchmark archive and database for accelerator-shielding experiments

ABSTRACT To validate the accuracy of the general-purpose Monte Carlo Particle and Heavy-Ion Transport code System (PHITS), a benchmark study of the recent version (version 3.24) of PHITS has been conducted using neutron-shielding experiments listed in the Shielding Integral Benchmark Archive and Database (SINBAD). Five neutron sources were selected, which are generated from (1) 43- and 68-MeV proton-induced reaction on a thin lithium target, (2) 52-MeV proton-induced reaction on a thick graphite target, (3) 590-MeV proton-induced reaction on a thick lead target, (4) 500-MeV proton-induced reaction on a thick tungsten target, and (5) 800-MeV proton-induced reaction on a thick tantalum target. For all these cases, overall agreements between the experimental and calculated results were satisfactory to simulate neutron- and proton-induced reactions up to 200 MeV when using the Japanese evaluated nuclear data library JENDL-4.0/HE; however, using default settings in the code system made discrepancies between the results in neutron production and scatterings in shielding materials with energies lower than 100 MeV. The present study revealed that it is preferable to use JENDL-4.0/HE in the PHITS calculation.

Activation cross sections of proton-induced reactions on praseodymium up to 30 MeV

Activation cross sections of proton-induced reactions on 141Pr were measured. Stacked foil activation technique and γ-ray spectrometry were adopted to derive the cross sections. The production cross sections of 141,140,139mNd, and 139Ce were determined up to 30 MeV. The physical yield of 140Nd was deduced using the measured cross sections of the 141Pr(p,2n)140Nd reaction. The physical yields of the proton- and deuteron-induced reactions on 141Pr and 3He-induced reaction on natCe for 140Nd production were compared.

Production cross-section measurements of proton-induced reactions on natural tantalum in the 0.3 GeV–1.7 GeV energy range

This work reports the production cross-section data for seventy-one radionuclides produced by 0.3 GeV–1.7 GeV protons impinging on thin tantalum targets. For that purpose, activation experiments were performed using the COSY synchrotron at FZ Jülich utilizing the stacked-foils technique and γ-ray spectrometry with high-purity germanium detectors. The Al-27(p,x)Na-24 reaction has been used as monitor reaction. All experimental data have been systematically compared with the existing literature. The excitation functions of Te-116, I-123, Dy-153 and Er-158 are reported for the first time.

The activation cross section measurements of proton-induced reactions on Li and Ta in the energy region 12.5–34 MeV

The experimental data on cross sections are necessary to clarify existing ideas on the mechanisms of nuclear reactions and for testing of nuclear models. Proton-induced reaction on 7Li serves as a source of quasi-monoenergetic neutrons which are widely used in the measurement of cross sections for neutron induced reactions. Tantalum plays an important role in technology and nuclear facilities mainly for its low induced activity (screens, degraders). In order to investigate the important nuclides, we have carried out the irradiation experiments with the variable-energy cyclotron U-120M of the NPI CAS Řež. The cross section of the reaction 7Li(p,n)7Be(ground state+0.43 MeV) and the cross sections of the nuclides 180,178mTa, 178W and 175Hf from reactions on natural tantalum were investigated, of which 181Ta(p,n)180gTa for the first time. The stacked-foil technique was utilized. The comparison of new results with prior data and predictions of evaluations is discussed.