EXFOR Database Research Articles

Measurement of neutron induced 86Sr(n, 2n)85Sr reaction cross sections at different neutron energies

The cross-sections for 86Sr (n, 2n)85Sr reaction are measured at neutron energies 19.44 ± 1.02 MeV and 16.81 ± 0.85 MeV wherein there is scarcity of data. The standard neutron activation analysis technique and offline gamma ray spectroscopy have been employed for measurement and analysis of the data. The results are compared with experimental data available in EXFOR database, JEFF-3.3, JENDL-4.0, TENDL-2017 and ENDF/B-VIII.0 evaluated data. The theoretical prediction was incorporated using nuclear modular codes TALYS 1.8 and EMPIRE 3.2.2. A detailed comparative study of experimental results with the theoretical models and various major evaluations has been presented.

Analysis of neutron induced (n,γ) and (n,2n) reactions on 232Th from reaction threshold to 20 MeV

Excitation functions for 232Th(n,γ) and 232Th(n,2n) reactions from reaction threshold to 20 MeV were calculated using TALYS-1.9 nuclear code by invoking suitable options for the level densities, optical model potentials, pre-equilibrium effects and γ-ray strength functions. In earlier studies, theoretical plots for 232Th(n,γ) and 232Th(n,2n) reaction cross-sections were obtained by using EMPIRE 3.2 and TALYS 1.9 codes with default parameters, however none of the reported plots could match with the corresponding experimental cross-sections reported in EXFOR data particularly between 14-20 MeV. The results of the present study reveal that by using a combination of specific input parameters in TALYS 1.9 code, the theoretical evaluation of the cross sections favour a higher pre-equilibrium rate for the harder spectrum. Moreover the estimated cross-sections match fairly well with the corresponding experimental data (EXFOR database) as well as with the evaluated data files (ENDF/VII.0, JENDL-4.0). The results of the present study are important for the validation of nuclear model approaches with increased predictive power for (n,xn) cross-sections and particularly for the application of thorium based fuel in Accelerator-Driven Sub-critical System.

A new developed semi-empirical formula for the (α,p) reaction cross-section at 19±1 MeV

The aim of this study is to obtain a new semi-empirical formula for [Formula: see text] reactions concerning the possible usage areas of this reaction type, where the fusion reactor studies could be pointed as one of them. The formula development studies have been performed by considering the existing semi-empirical formula modification studies in the literature where an absence of [Formula: see text] reaction has been realized. The suitable experimental data, existing on the EXFOR database, have been used to generate the [Formula: see text] reaction cross-section systematics in the energy range of 19 [Formula: see text]1 MeV. Also, statistical analyses have been performed and the correlation coefficients [Formula: see text] generated by fit parameters have been given.

Measurements of 60Ni(p,n)60Cu reaction cross-sections and covariance analysis of the uncertainty

The cross sections of the 60Ni(p,n)60Cu reaction from threshold energy to ~ 20 MeV have been measured by employing stack foil activation technique and off-line γ-ray spectrometry. The uncertainties for the reaction cross sections have been estimated by applying covariance analysis and least square method. The measured cross-sections are found to be in agreement with most of the literature data available in EXFOR database. The excitation function of the 60Ni(p,n)60Cu reaction was also theoretically calculated by using the TALYS-1.9 code. The excitation functions of 60Ni(p,n)60Cu reaction from TALYS-1.9 and TENDL-2017 follow a similar trend as of the experimental data of present work and literature but are little higher around the peak cross-section region.

311. Preliminary results of the production of Ga-68 with biomedical cyclotron by liquid target

Purpose The aim of this work was to evaluate the feasibility of production of 68Ga via the 68Zn(p,n)68Ga reaction by proton irradiation of enriched zinc nitrate solution using a biomedical cyclotron, an alternative method to the current production through the 68Ge/68Ga generators. Methods The target material was prepared by dissolving metallic 68Zn (enrichment of 99.26%) in HNO3 6 N and then diluting it with HNO3 0.2 N to obtain a 1.7 M solution of 68Zn(NO3)2 [1] . Using the cross-section data (EXFOR database) and the proton stopping power (SRIM software), the 68Ga saturation yield and its impurities were estimated. Irradiation tests were performed using the GE PETtrace cyclotron, located at our Institution. A liquid target was used, with a 25 μm foil of Havar® and a 250 μm foil of Niobium, employed to obtain proper selection of entrance beam energy, to degrade the energy of the beam to 12 MeV in order to minimize the production of 67Ga through the 68Zn(p,2n)67Ga reaction. The modification of the target also allowed us to improve resistance of the foil to acidity of the target material. Irradiations were carried out for 32 ± 1 min at 47 ± 2 μA. The product’s activity was measured using an activity meter calibrated with a standard of 68Ge traceable to NIST, while radionuclidic purity was evaluated by using gamma-ray spectrometry with an HPGe detector. Results The gamma-spectra of the irradiated samples showed the presence of different isotopes of Ga, Cu and Co, as predicted by the theoretical estimates. Radionuclidic purity is within the limits of EU Pharmacopeia up to 3 h after end of bombardment. Separation and recovery up to a yield of 90 ± 9% was obtained. Conclusions In summary, although optimizations and further advances are necessary, the results obtained are very promising and demonstrate the feasibility to produce sufficient activity of 68Ga in cyclotron as a competitive alternative to the 68Ge/68Ga generators.

Calculations of Double-Differential Neutron and Proton Emission Cross Sections on 19F at 14.2-MeV Incident Neutron Energy

In the present paper, the double-differential cross sections (d2σ/dΩde) of emission spectra for the 19F(n, xn) and 19F(n, xp) structural fusion materials (contained in FLiBe) were calculated by using the Hybrid Monte-Carlo Simulation at 14.2-MeV incident neutron energy in emission angles ranging from 30◦ to 150◦. Theoretical model calculations were carried out by using ALICE-2011, EMPIRE, and TALYS computer codes. Theoretically calculated results of the double-differential cross section for neutron and proton emission are presented and compared with the existing experimental data taken from the international nuclear reaction EXFOR database.

201Tl production through light charged-particle induced reactions on Tl and Hg isotopes: theoretical and simulation approaches

Investigation of the significant 201Tl diagnostic radionuclide production via protons and deuterons induced reactions by using the 203Tl, 201Hg and 202Hg isotope targets is the main goal of this study. The effect of three phenomenological and microscopic level density models utilizing the TALYS-1.8 code along with TENDL-2017 data were applied to excitation functions evaluations. Furthermore, simulation code was used for the above production processes. Subsequently the prediction of the production yield in each reaction was done. Finally, the comparison between EXFOR database experimental data and the theoretical and simulation-based calculations was implemented.

A study on the excitation functions of 60,62Ni(α,n), 60,61Ni(α,2n), 58,64Ni(α,p), natNi(α,x) reactions

The prediction of nuclear cross-section data is crucial, especially in the absence of experimental data or in the difficulty of these experimental data. Nickel (Ni) is an important material in fusion and fission reactor technologies, the production of radionuclides in nuclear medicine, and many other fields. In this study, the excitation functions for 60,62Ni(α,n), 60,61Ni(α,2n), 58,64Ni(α,p), and natNi(α,x) reactions have been investigated by using pre-equilibrium reaction models. The calculations of the excitation functions for the reactions are used with the geometry-dependent hybrid model in ALICE/ASH code and the two-component exciton model in TALYS 1.8 code. The obtained results are compared to each other, and the experimental data are taken from the EXFOR database.

Atomistic model of xenon gas bubble re-solution rate due to thermal spike in uranium oxide

Atomistic simulations are performed to study the response of Xe gas bubbles in UO2 to ionizing fission products through the thermal spike approximation. A portion of the total electronic stopping power (Se) is taken as the thermal spike energy through a ratio variable ζ. The thermal spike energy causes extreme melting within the fission track cylindrical region. Molecular dynamics is employed to quantify the probability of a Xe gas atom to be re-solved (re-dissolved) back into the UO2 matrix. Subsequently, a re-solution model is developed and parametrized as a function of bubble radius (R), off-centered distance (r), and thermal spike energy (ζSe). The off-centered distance measures the shift of the thermal spike axis from the bubble center. To evaluate the re-solution model, independent fission product yield of U-235 fission due to thermal neutrons (0.0253 eV), taken from the JEFF-3.3 database, is used. The kinetic energy of the fission products is taken from the EXFOR database. Subsequently, the decay of Se over distance for each fission product is simulated. Finally, the evaluated re-solution rate (re-solution probability per second) is presented as a function of bubble radius for a range of ζ.

Excitation functions of proton-induced reactions on natFe and natZr targets for the production of cobalt and niobium isotopes

Excitation functions of proton-induced reactions for the natural iron and zirconium targets were measured from their respective threshold energies to 22 and 20 MeV. The conventional stacked foil technique was used in combination with the off-line $\gamma$ -ray spectroscopy at the BARC-TIFR Pelletron facility, Mumbai. The computer code SRIM 2013 was used to calculate the energy degradation along the stack and the proton beam intensity was measured via the natCu(p,x)62Zn monitor reaction. The measured excitation functions were then compared with the literature data available in EXFOR database as well as with the theoretical values from the TALYS-1.8 code and the TENDL-2017 data library. The shapes of the excitation function for all the reactions were reproduced well by TALYS-1.8. In terms of absolute values, for some reactions the data are in good agreement with both the literature data and TALYS-1.8 whereas, for others there is a slight deviation either from the literature data or from the theoretical values of TALYS-1.8 and TENDL-2017.

Activation Measurements of Cross Sections for Ground and Isomeric States Production in Neutron Threshold Reactions on Y and Au

The paper describes cross-section measurements consisting of neutron activation using a 7Li(p,n) quasi mono-energetic neutron source and gamma-ray spectrometry performed at the Nuclear Physics Institute of the Czech Academy of Sciences in Řež, Czech Republic. The analysis of the excitation functions of neutron-induced threshold reactions for the energy range from 17 up to 34 MeV is presented. The cross sections for the population of both ground and isomeric states were measured in yttrium and gold. A comprehensive comparison of the measured cross sections with earlier experimental data from the EXFOR database, TALYS calculations, and evaluated nuclear data libraries is presented.

Overview and evaluation of different nuclear level density models for the 123I radionuclide production

The 123I radionuclide (T1/2 = 13.22 h, β+ = 100%) is one of the most potent gamma emitters for nuclear medicine. In this study, the cyclotron production of this radionuclide via different nuclear reactions namely, the 121Sb(α,2n), 122Te(d,n), 123Te(p,n), 124Te(p,2n), 124Xe(p,2n), 127I(p,5n) and 127I(d,6n) were investigated. The effect of the various phenomenological nuclear level density models such as Fermi gas model (FGM), Back-shifted Fermi gas model (BSFGM), Generalized superfluid model (GSM) and Enhanced generalized superfluid model (EGSM) moreover, the three microscopic level density models were evaluated for predicting of cross sections and production yield predictions. The SRIM code was used to obtain the target thickness. The 123I excitation function of reactions were calculated by using of the TALYS-1.8, EMPIRE-3.2 nuclear codes and with data which taken from TENDL-2015 database, and finally the theoretical calculations were compared with reported experimental measurements in which taken from EXFOR database.

Photon Induced Reaction Cross-Section Calculations of Several Structural Fusion Materials

In this paper; photo-neutron cross-sections have been computed for 27Al, 28,29Si, 52Cr, 54,56Fe isotopes by using nuclear reaction codes TALYS 1.6 and EMPIRE 3.1 with different level density models. Constant Temperature Fermi Gas, Back Shifted Fermi Gas and Generalized Superfluid Models have been employed from TALYS 1.6 whereas Generalized Super Fluid Model was the only model employed from EMPIRE 3.1 reaction codes. Obtained results have been analyzed with experimental values taken from the EXFOR database.

The cross section calculation of 112Sn(α,γ)116Te reaction with different nuclear models at the astrophysical energy range

The theoretical cross section calculations for the astrophysical p process are needed because most of the related reactions are technically very difficult to be measured in the laboratory. Even if the reaction was measured, most of the measured reactions have been carried out at the higher energy range from the astrophysical energies. Therefore, almost all cross sections needed for p process simulation have to be theoretically calculated or extrapolated to the astrophysical energies. \(^{112}\hbox {Sn}(\alpha ,\gamma )^{116}\hbox {Te}\) is an important reaction for the p process nucleosynthesis. The theoretical cross section of \(^{112}\hbox {Sn}(\alpha ,\gamma )^{116}\hbox {Te}\) reaction was investigated for different global optical model potentials, level density, and strength function models at the astrophysically interested energies. Astrophysical S factors were calculated and compared with experimental data available in the EXFOR database. The calculation with the optical model potential of the dispersive model by Demetriou et al., and the back-shifted Fermi gas level density model and Brink-Axel Lorentzian strength function model best served to reproduce experimental results at an astrophysically relevant energy region. The reaction rates were calculated with these model parameters at the p process temperature and compared with the current version of the reaction rate library Reaclib and Starlib.

Calculations of Cross-Sections and Astrophysical S-factors for the (α,n) Reactions of Some Structural Fusion Materials

Structural material selection in design of fusion reactors is very crucial. These structural materials should satisfy the hard conditions such as high thermo-mechanical stresses, high heat loads and severe radiation damage without compromising on safety considerations. The materials such as titanium, vanadium and chromium are used in the construction of fusion reactors. Therefore, it is important to examine these materials. Obtained results from the nuclear reactions using structural materials can be used for developing of these structural materials. For this reason, in this study cross sections of the 46Ti(α,n) 49Cr, 50Cr(α,n) 53Fe and 51V(α,n) 54Mn reactions have been calculated at 2–20 MeV energy range. In these theoretical calculations, the TALYS 1.8 and NON-SMOKER codes were used. Also, the astrophysical S-factors which describe the possibility of reaction in low energies were calculated. Results of our calculations were checked to the experimental data obtained from EXFOR database.

Theoretical estimation of 64Cu production with neutrons emitted during 18F production with a 30 MeV medical cyclotron

PurposeThis work presents the theoretical estimation of a combined production of 18F and 64Cu isotopes for PET applications. 64Cu production is induced in a secondary target by neutrons emitted during a routine 18F production with a 30MeV cyclotron: protons are used to produce 18F by means of the 18O(p,n)18F reaction on a [18O]-H2O target (primary target) and the emitted neutrons are used to produce 64Cu by means of the 64Zn(n,p)64Cu reaction on enriched zinc target (secondary target). MethodsMonte Carlo simulations were carried out using Monte Carlo N Particle eXtended (MCNPX) code to evaluate flux and energy spectra of neutrons produced in the primary (Be+[18O]-H2O) target by protons and the attenuation of neutron flux in the secondary target. 64Cu yield was estimated using an analytical approach based on both TENDL-2015 data library and experimental data selected from EXFOR database. ResultsTheoretical evaluations indicate that about 3.8 MBq/μA of 64Cu can be obtained as a secondary, ‘side’ production with a 30MeV cyclotron, for 2h of irradiation of a proper designed zinc target. Irradiating for 2h with a proton current of 120 μA, a yield of about 457 MBq is expected. Moreover, the most relevant contaminants result to be 63,65Zn, which can be chemically separated from 64Cu contrarily to what happens with proton irradiation of an enriched 64Ni target, which provides 64Cu mixed to other copper isotopes as contaminants. ConclusionsThe theoretical study discussed in this paper evaluates the potential of the combined production of 18F and 64Cu for medical purposes, irradiating a properly designed target with 30MeV protons. Interesting yields of 64Cu are obtainable and the estimation of contaminants in the irradiated zinc target is discussed.

Evaluated cross-sections of 55Co radionuclide, a non-standard positron emitter for clinical applications

Production cross-sections of Cobalt-55 (T1/2=17.53h, Eβ+mean= 570keV, Iβ+total= 76%), a non-standard positron emitter have been evaluated in the energy range of 40MeV down to the threshold energy of the 56Fe(p,2n)55Co nuclear reaction due to its significance as a potential PET imaging agent in medical applications. Experimental cross-sections of 55Co radionuclide that lies within the scope of this work were collected from the EXFOR database, and renormalized using the latest agreed values of decay data and monitor cross-sections. Simultaneous Evaluation on KALMAN (SOK) code combined with least-squares method was applied to the corrected cross-sections to obtain evaluated cross-sections together with the covariance information. Knowledge of the underlying uncertainties in evaluated nuclear data, i.e., covariances are useful to improve the accuracy of nuclear data.

Verification of the databases EXFOR and ENDF

The objective of this work is for the verification of large experimental (EXFOR) and evaluated nuclear reaction databases (JEFF, ENDF, JENDL, TENDL…). The work is applied to neutron reactions in EXFOR data, including threshold reactions, isomeric transitions, angular distributions and data in the resonance region of both isotopes and natural elements. Finally, a comparison of the resonance integrals compiled in EXFOR database with those derived from the evaluated libraries is also performed.

Cross-sections of residual nuclei from deuteron irradiation of thin thorium target at energy 7 GeV

The residual nuclei yields are of great importance for the estimation of basic radiation-technology characteristics (like a total target activity, production of long-lived nuclides etc.) of accelerator driven systems planned for transmutation of spent nuclear fuel and for a design of radioisotopes production facilities. Experimental data are also essential for validation of nuclear codes describing various stages of a spallation reaction. Therefore, the main aim of this work is to add new experimental data in energy region of relativistic deuterons, as similar data are missing in nuclear databases. The sample made of thin natural thorium foil was irradiated at JINR Nuclotron accelerator with a deuteron beam of the total kinetic energy 7 GeV. Integral number of deuterons was determined with the use of aluminum activation detectors. Products of deuteron induced spallation reaction were qualified and quantified by means of gamma-ray spectroscopy method. Several important spectroscopic corrections were applied to obtain results of high accuracy. Experimental cumulative and independent cross-sections were determined for more than 80 isotopes including meta-stable isomers. The total uncertainty of results rarely exceeded 9%. Experimental results were compared with MCNP6.1 Monte-Carlo code predictions. Generally, experimental and calculated cross-sections are in a reasonably good agreement, with the exception of a few light isotopes in a fragmentation region, where the calculations are highly under-estimated. Measured data will be useful for future development of high-energy nuclear codes. After completion, final data will be added into the EXFOR database.

Study of concrete activation with IFMIF-like neutron irradiation: Status of EAF and TENDL neutron activation cross-sections

The aim of this paper is to check the performance of last versions of EAF and TENDL libraries (EAF2007, EAF2010, and TENDL2014) in the prediction of concrete activation under the neutron irradiation environment expected in IFMIF, an accelerator-based neutron source conceived for fusion materials testing. For this purpose Activity and dose rate responses of three types of concrete (ITER-Bioshield kind, barite and magnetite concretes) have been studied. For these quantities, dominant nuclides and production pathways have been determined and, then, a qualitative analysis of the relevant activation cross-sections involved has been performed by comparing data from mentioned libraries with experimental data from EXFOR database. Concrete activation studies have been carried out with IFMIF-like neutron irradiation conditions using the ACAB code and EAF and TENDL libraries. The cooling times assessed are related to safety and maintenance operations, specifically 1 hour, 1 day and 12 days. Final conclusions are focused on the recommendations for the activation library to be used among those analyzed and cross-section data to be improved.