Isotopic Cross Sections Research Articles

Production Cross Sections of Residual Nuclides from 93Zr + p at 27 MeV/Nucleon

Abstract Nuclear transmutation emerges as a promising approach for reprocessing high-level waste, specifically treating long-lived nuclides like 93Zr from spent fuel. It is essential to accumulate reaction data for these nuclei to advance this prominent treatment and to build a comprehensive understanding of reaction mechanisms. In this study, the residual production cross sections resulting from proton-induced reactions on 93Zr were measured at 27 MeV/nucleon in inverse kinematics. At the RI Beam Factory (RIBF) the OEDO beamline was used to deduce production cross sections for isotopes, 91 − 93Nb, 91, 92Zr, and 88, 89Y. Comparing the results from this study and prior research with calculated excitation functions, a moderate agreement is found with theoretical predictions derived from TALYS and CCONE. The measured cross sections offer valuable insights for future considerations in nuclear-waste treatment facilities. This is particularly relevant for facilities exploring innovative methods, such as accelerator-driven systems.

Actinium isotope cross sections for 226Ra(p,xn) reactions measured at low energies

Cross sections for production of the medical isotope 225Ac by the 226Ra(p,2n) reaction have not previously been measured in fine steps over the relevant energy region, and no measurements are presently available in the literature for the actinium contaminant isotopes created by the adjacent 226Ra(p,n)226Ac and 226Ra(p,3n)224Ac reactions. We report thin-target cross-section measurements for production of 224Ac and 225Ac by protons of 15.1–16.8 MeV incident on radium. An upper limit for the 226Ac cross section is also reported.

Xenon photonuclear cross sections for the production of 123I radionuclide

A simple reliable theoretical model for the calculation of total photo-absorption cross sections by atomic nuclei has been presented and applied it to get the relevant data needed for the evaluation of the production rate of 123I radionuclide isotope. Since experimental measurements are not available, the model calculation represents the only source of information. The present results, based on an accurate model of nuclear structure, are in very good agreement with the observed photoabsorption cross sections of Te isotopes, which provide reliable cross sections for the neighboring Xe nuclei, where the usual simple estimates are clearly discordant.

Short-range correlations in dynamical intranuclear cascade models for describing nucleon knockout reactions

Spallation and fragmentation reactions at incident energies above the Fermi momentum are considered to be the main mechanism for the production of neutron-rich nuclei at worldwide nuclear physics facilities, such as RIBF, FRIB, and GSI-FAIR. Although it is widely known that dynamical reaction models give a rather good prediction of cross sections for nuclear residues produced in spallation and fragmentation reactions, these reaction models fail in the description of peripheral collisions involving short-range nucleon-nucleon correlations (SRCs). Here, we present state-of-the-art dynamical reaction calculations based on the intranuclear cascade approach to describe spallation and fragmentation reactions. The new version of our dynamical model, including SRCs, successfully describes isotopic cross sections of neutron-rich nuclear residues and inclusive single-neutron and single-proton knockout cross sections for various stable and exotic nuclei. Finally, the results show that the systematic strong dependency of the single-knockout cross section reduction factor on the neutron-proton separation energy asymmetry parameter (ΔS) obtained by Tostevin and Gade disappears when SRCs are taken into account.

A new empirical formula for calculation of (n,3n) cross sections of heavy mass nuclei in the energy region 22–27.5 MeV

In this paper we want to study (n,3n) reactions using an empirical formula derived on the basis of the statistical model considering reaction Q-value dependence. This formula was obtained by taking into account the exponential dependence on asymmetry parameter (N−Z)/A for neutron-induced reactions in Levkovskii's empirical formula. In addition, the present formula depends also on incident energy En, reaction Q-value and symmetry term (N−Z)2/A. Herein, a new analysis of experimental data of (n,3n) reactions in the energy region 22–27.5 MeV was carried out for quick estimation of cross sections of the heavy mass isotopes of odd Z-even N nuclides in the region of A = 151 to 209. We observed a good agreement of the experimental cross section data with the calculations performed using the present empirical formula.

First simultaneous evaluation of fission probabilities and neutron-induced cross sections for the Pu fissile isotopes

Surrogate reactions are a powerful tool to access neutron-induced reaction cross sections of short-lived nuclei. However, to infer neutron-induced reaction cross sections from measured deexcitation probabilities requires a consistent and rigorous theoretical framework describing both charged-particle and neutron-induced reactions. This work presents the first practical application of the new approach developed in O. Bouland, Phys. Rev. C 100, 064611 (2019) to Pu fissile isotopes, 237,238,240,242,244Pu*. Average neutron-induced reaction cross sections and deexcitation probabilities measured in surrogate reactions are simultaneously analyzed with an efficient Monte Carlo R-matrix-extended theory algorithm using a unique set of nuclear-structure parameters to describe both observables. Fission probabilities allow one to estimate fission-barrier heights, not otherwise accessible in fissile isotopes. The theoretical framework is here extended to model 'giant' resonance structures observed in the fission probabilities of some nuclides. A careful study of the impact of the uncertainties on nuclear parameters and on the populated compound system angular distribution has been carried out. This study raises questions on the normalization of some fission probabilities measured in the 70's in (t,p) reactions, that could not have been pointed out without the use of the here-presented complex technique. This finding is especially important for the peculiar 240Pu* system. In addition, our study reveals for the 237Pu* compound system a 10 to 30% too high value of the only-performed low-energy neutron-induced fission cross section measurement (Gerasimov et al., JINR-E–3-97-213 (1997)) and, subsequently of the evaluated fission cross section below 50 keV for the 236Pu.

Measurements of the Reaction Cross Sections of Neutron-rich Sn Isotopes at the R\(^3\)B Setup

Measurements of the Reaction Cross Sections of Neutron-rich Sn Isotopes at the R\(^3\)B Setup

Inductively coupled plasma optical emission spectroscopic determination of trace rare earth elements in highly refractory gadolinium zirconate (Gd2Zr2O7).

Gadolinium zirconate (Gd2Zr2O7) belongs to the category of burnable absorber (BA) material in nuclear reactors. The high neutron-absorption cross sections of Gd isotopes (155Gd and 157Gd) implement negative reactivity in the reactor core to control the excess reactivity of the fuel at the beginning of the fission cycle. The presence of other rare earth elements, which can come from the starting material and/or may be taken up during the synthesis steps, will affect the negative reactivity calculation. Thus the chemical quality assurance of Gd2Zr2O7 concerning the other trace rare earth impurities is indispensable. Here in this work, we decided to quantify thirteen trace rare earth elements in Gd2Zr2O7 by inductively coupled plasma optical emission spectroscopy (ICP-OES). One of the matrix elements viz., zirconium was separated via precipitation using d,l-mandelic acid. The trace rare earths were determined in the presence of gadolinium matrix in solution. It was found that all thirteen rare earth elements can be quantified in the range of 0.25 to 2.5 mg L-1 in the presence of 516 mg L-1 of Gd with a relative standard deviation of 1-3%. This corresponds to the determination of a minimum of 0.25 mg analyte per g of Gd2Zr2O7. The method detection limits of all thirteen rare earth elements range between 0.01 and 0.075 mg g-1. The proposed methodology was validated by analyzing synthetic standards and real samples with spike addition.

Measurement of flux distribution of an AmBe neutron source and estimation of two group integral capture cross-sections

Neutron capture cross sections of elements are of utmost importance in reactor physics, dosimetry applications and stellar nucleosynthesis studies. Manipal Centre for Natural Sciences (MCNS) possesses a 16Ci AmBe neutron source, which is housed inside a concrete structure. The neutrons undergo multiple scattering events in the concrete structure and surrounding materials; therefore, the neutron flux profile is unique to this source and structural material, which differs from the standard ISO spectrum. Using this AmBe source, experiments are being conducted to understand the neutron energy distribution in two groups to measure capture cross sections of various isotopes. In the present work, gold has been used as a flux monitor, and the indium cross-section has been measured in two groups. These foils (Gold and Indium) are irradiated with and without cadmium cover to understand the neutron spectra in two spectral regions as cadmium cutoffs neutrons of energy below 0.5 eV. Irradiated samples were counted in High-Pure Germanium (HPGe) detector, and the γ-spectra obtained were used to get the epi‑cadmium (0.5 eV and above) to total ratio of ⟨σ(E)ϕ(E)⟩. The neutron flux is estimated in two groups corresponding to thermal (thermal energy neutron extended up to 0.5 eV) and epi‑cadmium regions, and also the flux-weighted capture cross sections of 115In are determined.

Empirical formula for (n, f) reaction cross sections of Uranium isotopes at 1–20 MeV neutrons

This article describes how to calculate neutron-induced fission reaction cross sections using a proposed empirical formula and the EMPIRE 3.2.3 and TALYS 1.95 computer codes for Uranium isotopes up to the third fission plateau. In this study, the excitation functions of 232U (n, f), 233U (n, f), 234U (n, f), 235U (n, f), 236U (n, f), 237U (n, f) and 238U (n, f) nuclear reactions were calculated at 1–20 MeV neutron energies. The results were contrasted to measured values from the Experimental Nuclear Reaction Data (EXFOR) as well as the evaluated data from Evaluated Nuclear Data File (ENDF) such as (EAF-2010, JEFF-3.3, ENDF/B-VIII.0 and TENDL-2019). Overall, the calculated, experimental, and evaluated fission cross-sections are in concordance.

Study of6,8He+p elastic scattering using the BHF formalism with three-body forces

In the present work, we have analyzed the elastic scattering data of6He+p at 25.6, 38.6, 40.9, and 71 MeV/A and8He+p at 15.6, 25.6, 32.5, 66, and 72 MeV/A, using the microscopic local optical potential calculated within the framework of the Brueckner–Hartree–Fock (BHF) formalism. The calculation requires mainly two inputs: (1) the nucleon–nucleon (NN) interaction and (2) the nucleon distributions in target nuclei. In the present work, realistic internucleon (NN) potential from Argonne v18 (AV18) and the Urbana IX (UVIX) model of three-body forces with several nucleon density distributions are used for generating the nucleon–nucleus optical potential. We have used the exact method for calculating both the direct and the exchange parts of the spin–orbit potential. We confirm the earlier results that the spin–orbit potential for these neutron-rich nuclei is diffused and extended. Our results show that the different density distributions reproduce rather well the experimental differential cross sections for both isotopes, while the phenomenological density with a two-neutron halo gives satisfactory results for6He-p analyzing power data. None of the densities used for8He can reproduce the experimentally analyzed power data. Our analysis reveals that the calculated microscopic optical potentials, with and without three-body forces using the BHF approach, provide satisfactory agreement with the elastic scattering data for6,8He+p.

Neutron capture cross-section measurement by mass spectrometry for Pb-204 irradiated in JRR-3

ABSTRACT Reliable neutron capture cross sections of lead isotopes are necessary for the development of lead or lead-bismuth cooled fast reactors. Although 204Pb has the smallest natural abundance in stable Pb isotopes, its neutron capture cross-section data are important because a long-lived radionuclide 205Pb (T1/2 = 17.3 million years) is produced by a neutron capture reaction on 204Pb. This study applied a mass spectrometry method to measure the neutron capture cross section of 204Pb. An enriched 204Pb sample was irradiated for 24 days with a neutron flux on the order of 1013 n/cm2/sec at the Japan Research Reactor-3. The irradiated 204Pb sample was analyzed by thermal ionization mass spectrometry to obtain the isotopic ratio between 205Pb and 204Pb. Consequently, the thermal-neutron capture cross-section of 204Pb was found to be 0.536 ± 0.030 barns.

Prediction of synthesis cross sections of new moscovium isotopes in fusion-evaporation reactions

Prediction of synthesis cross sections of new moscovium isotopes in fusion-evaporation reactions

Farklı seviye yoğunluk modelleri kullanılarak reaksiyon eşik değerinden 20 MeV’e kadar Paladyum izotoplarının (n,2n), (n,p) ve (n,) tesir kesitlerinin hesaplanması

Bu çalışmada, Paladyum izotoplarının (102,104,106,108,110Pd) (n,2n), (n,p) ve (n,) reaksiyon tesir kesitleri Empire-3.2.3 (Malta) istatistiksel model kodu kullanılarak reaksiyon eşik değerinden 20 MeV’e kadar nötron enerjilerinde hesaplanmıştır. Hesaplamalar, dört farklı nükleer seviye yoğunluğu modeli (Genelleştirilmiş Süper Akışkan modeli, Gelişmiş Genelleştirilmiş Süper Akışkan modeli, Gilbert-Cameron modeli ve Hartree-Fock-Bogoliubov mikroskobik modeli) kullanılarak yapılmıştır. Hesaplardan elde edilen sonuçlar, EXFOR kütüphanesinde bulunan deneysel verilerle ve ENDF kütüphanesinden alınan ENDF/B-VIII.0 (USA,2018), TENDL-2019 (TALYS, 2019) ve JENDL-5 (Japan,2021) değerlendirilmiş verilerle karşılaştırılmıştır. 14.5 MeV civarında deneysel ve değerlendirilmiş verilerle karşılaştırıldığında, sonuçlar genel olarak tutarlı bir uyum göstermektedir.

Isotopic production cross sections in proton-16O and proton-12C interactions for energies from 10 MeV/u to 100 GeV/u

Proton interactions with16O or 12C nuclei are frequent nuclear interaction leading to secondary radiation in tissues for space radiationandcancer therapy with protons or ion beams. The fragmentation of these ionsby protons produces a large number of heavy ion (A > 4) target or projectile fragments often with high ionization density. Here we develop an analytical model of energy dependent proton-16O and proton-12C cross sections for isotopic nuclei production. Using experimental data and a 2nd order optical modelan accurate formula for the absorption cross section from <10 MeV/u to >10 GeV/u is obtained. The energy dependence of theelemental and isotopiccross sections is modeled as multiplicities scaled toabsorption cross section with average isotopic fractions estimated from experimental data. We show that this approach results in accurateanalytic formulae for isotopic fragmentation cross sections over the full energy range in hadron therapy and space radiation protection studies.

Analysis of Neutron-Induced Fission Cross Sections of Pb Isotopes near the Closed Neutron Shell

Analysis of Neutron-Induced Fission Cross Sections of Pb Isotopes near the Closed Neutron Shell

Production of neutron-deficient nuclei around N = 126 by proton-induced spallation* *Supported by the Open Project of Guangxi Key Laboratory of Nuclear Physics and Nuclear Technology (NLK2020-02), the National Natural Science Foundation of China (11875328, 12075327) and the Fundamental Research Funds for the Central Universities, Sun Yat-Sen University (22qntd1801)

Many isotopes of Np, Pu, Am, and Cm around the N = 126 shell still have not been produced in the laboratory. This study aims to investigate the cross sections and yields of the neutron-deficient nuclei of Np, Pu, Am, and Cm produced in the proton-induced spallations of transuranium elements. The isospin-dependent quantum molecular dynamics (IQMD) model is applied to study the dynamical process of reaction, and the subsequent decay process is simulated by the GEMINI++ model. The IQMD-GEMINI++ model is applied to calculate the cross section, kinetic energy, and angular distribution of the isotopic productions around N = 126. The Lindhand, Scharff, and Schiott theory is applied to calculate the energy loss of different heavy nuclei in the target material. A comparison between the data and the calculations shows that the IQMD-GEMINI++ model can reproduce the production cross sections of the neutron-deficient nuclei in spallation within approximately 1.5 orders of magnitude. The maximum cross section of the undiscovered isotopes of Np, Pu, Am, and Cm is about 10−5 mb, while the kinetic energies of the productions are all less than 16 MeV. The angular distribution shows that the emission direction of production is mostly at a backward angle. The range of production in the target is within the range of 10−7 to 10−5 cm. This range is the effective target thickness for the online identification of undiscovered isotopes. Based on the effective thickness of the target and assuming an intensity of 120 μA for the proton beam, the yields of the undiscovered neutron-deficient nuclei are calculated. Productions of the undiscovered isotopes of Np, Pu, Am, and Cm by the proton-induced spallations of transuranium elements are feasible. However, experimental techniques for online identification of neutron-deficient nuclei produced in proton-induced spallation should be developed.

Development and validation of operational reactor physics code “ORPAC” for research reactors at Trombay

An interactive code system ORPAC has been developed to perform calculations related to operational reactor physics jobs of research reactors. The code is aimed at providing a handy tool for radioactivity estimation, safety analysis related with isotope irradiations and post irradiation handling, xenon transients, etc. Initially the code was developed to cater the operational needs for Dhruva and hitherto operating CIRUS reactor. With the commissioning of 2 MW Apsara-U reactor, it was necessary to enhance its features for extending its support for the newly commissioned reactor. The code ORPAC is upgraded to solve generalized Bateman equations for neutron transmutation reactions e.g. (n, γ), (n,p), (n,α), (n,2n), etc. The code is designed to provide users to select cross-section data library from drop down list for appropriate spectrum of irradiation position in the concerned reactor. Spectrum averaged cross-section library has been generated using PREPRO-19 and ENDF/B-VIII library for Apsara-U and Dhruva reactors. 69- group structure from WIMSD is used to generate effective one-group cross section of isotopes using neutron spectrum of given irradiation position. Estimation of xenon transients, reactivity load of isotope samples, nuclear heating, dose rate, and shielding thickness of lead cask for transportation of radioisotope has also been included through different modules. This software can be used for any research reactor by incorporating its neutron spectrum and corresponding one-group cross-section library. It has improved and generalized methodology, updated data library, increased usage options, inclusion of more facilities and better graphical user interface as compared to its predecessor. In this paper, radioactivity in fuel as well as target materials for radioisotope production are discussed in detail and validated with measurements and standard code ORIGEN.

Production of unknown neutron-rich isotopes with Z=99–102 in multinucleon transfer reactions near the Coulomb barrier

Multinucleon transfer reactions provide a possible access to the synthesis of new neutron-rich isotopes. Within the theoretical framework of a hybrid model combining the dinuclear system model and the GRAZING model together, the transfer reaction is investigated in $^{86}\mathrm{Kr}+^{248}\mathrm{Cm}$. In this work, it is found that the hybrid model can reproduce experimental transfer cross sections well. After the verification of the hybrid model, the transfer reactions $^{112,124,132}\mathrm{Sn}+^{249}\mathrm{Cf}$ are investigated by the influence of charge equilibration on the production cross sections of the exotic nuclei. The neutron-deficient projectile $^{112}\mathrm{Sn}$ shows advantages of producing neutron-deficient nuclei, while $^{124,132}\mathrm{Sn}$ are favorable to produce neutron-rich nuclei. In order to obtain available production cross sections of the unknown neutron-rich isotopes with $Z=99\text{\ensuremath{-}}102$, the dependence of cross sections on incident energy in the reaction $^{132}\mathrm{Sn}+^{249}\mathrm{Cf}$ is also investigated. It is found that the reaction $^{132}\mathrm{Sn}+^{249}\mathrm{Cf}$ at 510 MeV is a potential candidate to produce unknown neutron-rich isotopes of trans-target.

Production of neutron-rich heavy nuclei around $$N = 162$$ in multinucleon transfer reactions

Within the framework of the dinuclear system model, the production mechanism of neutron-rich heavy nuclei around \(N = 162\) has been investigated systematically. The isotopic yields in the multinucleon transfer reaction of \(^{238}\)U + \(^{248}\)Cm are analyzed and compared with the available experimental data at GSI. Systematics on the production of superheavy nuclei via the collisions of \(^{238}\)U on actinide nuclides \(^{252,254}\)Cf, \(^{254}\)Es and \(^{257}\)Fm is investigated thoroughly. It is found that the shell effect is of importance in the formation of neutron-rich nuclei around \(N~=~162\) owing to the enhancement of fission barrier and neutron separation energy. The fragments in the multinucleon transfer reactions manifest the broad isotopic distribution and are dependent on the beam energy. The polar angles of the fragments tend to the forward emission with increasing the beam energy. The production cross sections of new isotopes are estimated and the heavier targets are available for the neutron-rich superheavy nucleus formation. The optimal reaction system and beam energy are proposed for the future experimental measurements.