Nuclear Model Code Research Articles

Measurement of deuteron-induced nuclear reactions cross-sections on 197Au and on natCu focused on the theranostic 197m,gHg

Theranostic 197m,gHg of high specific activity may be produced by proton or deuteron activation of gold. The particle choice affects the isomeric ratio. In order to compare both projectiles, we re-measured cross-sections of the nuclear reactions 197Au(d,x)197mHg, 197gHg, 198mAu, 198gAu, 196m2Au, 196m1+gAu in the energy range of 8.3–19.7 MeV having employed usual stacked-foil method. The obtained values were compared with previously measured data and with prediction of the TALYS nuclear reaction model code adopted from the TENDL-2017 library. Experimental data were used for calculation of the thick target yields. The yields for the isomeric pair 197m,gHg were confronted with those for recently re-measured proton-induced reactions. We also provide a new data set for the reaction natCu(d,x)63Zn.

Activation cross sections of alpha particle-induced reactions on natural hafnium up to 50 MeV

As an alternative production route for the medically interesting 178mTa isotope production cross sections of alpha particle induced nuclear reaction of the natHf(α,x)178W–178mTa process was investigated. Activation method, stacked target technique, and high resolution off-line γ-ray spectrometry were applied. Excitation functions of the natHf(α,x)178W reaction and of several other side reactions were determined up to 51 MeV. Activation cross section data were determined for the following reactions: natHf(α,x)176,177,178W, natHf(α,x)175,176,177,178g,180g,182g,183Ta, and natHf(α,x)173,175,179m2,180m,181Hf. The measured experimental data were compared with the results of earlier experimental data and the results of TALYS nuclear reaction model code calculation tabulated in the TENDL-2017 data library. Experimental data are presented for the first time in the 40–50 MeV energy region. Thick target yields were calculated for elemental hafnium target using the fitted experimental cross section data.

JENDL/ImPACT-2018: a new nuclear data library for innovative studies on transmutation of long-lived fission products

ABSTRACT A new nuclear data library, JENDL/ImPACT-2018, was developed for an innovative study on the transmutation of long-lived fission products. Nuclear reaction cross-sections were newly evaluated for incident neutrons and protons up to 200 MeV for 163 nuclides focusing on long-lived nuclei such as 79Se, 93Zr, 107Pd and 135Cs, adopting some parts of JENDL-4.0. Our challenge was an evaluation of cross-sections for a number of unstable nuclei over a wide energy range where the experimental data were very scarce. We estimated cross-sections based on a nuclear model code CCONE by incorporating an advanced knowledge on the nuclear structure theory and a model-parameterization based on new experimental cross-sections measured by the inverse kinematics. Through comparisons with available experimental data on the stable isotopes, it is found that the present data give better agreements with them than those in the existing libraries. In a neutronics simulation by the PHITS code, we also found that the largest impact of the present library was seen on the estimated amount of isotope productions.

Measurement of cross-sections of proton-induced nuclear reactions on 197Au focused on the production of the theranostic pair 197m,gHg

We measured cross-sections of the nuclear reactions 197Au(p,x)197mHg, 197gHg, 195mHg, 195gHg, 196m2Au, 196m1+gAu, 194m+gAu in the energy range of 6.4–35.3 MeV having used stacked-foil technique with high purity gold foils. The results were compared with previously published data and with prediction of the TALYS nuclear reaction model code adopted from the TENDL-2017 library. Thick target yields were deduced from the measured data. Production of the theranostic isomeric pair 197m,gHg is thoroughly discussed.

Excitation function of the [formula omitted] reactions within the energy range of 10-22 MeV

The production cross-sections of the V48, S47c, S46c, and S44mc residues were measured in the proton induced Tnati reactions using the stack foil activation technique followed by the off-line γ−ray spectrometry. The present work was carried out at 14UD BARC-TIFR Pelletron accelerator, Mumbai, India. The proton beam of 22 MeV was used for the irradiation of the samples and was degraded along the stack of target foils using aluminum (Al) degraders. The measured cross-section data were compared with the existing literature data available in EXFOR data library. The results were also compared with the theoretical values from the TALYS-1.9 and the ALICE-2014 nuclear model codes using the suitable input level density models. The pre-equilibrium contribution has also been estimated for the populated reaction residues in the present work. The present work offers a comparison between the two theoretical model codes using a similar input level density model. The reaction product S44mc also has some practical medical applications in nuclear medicine.

Measurement of the 58Ni(n, p)58Co and 58Ni(n, 2n)57Ni reaction cross-sections for fast neutron energies up to 18 MeV

The 58Ni(n, p) and 58Ni(n, 2n) reaction cross-sections were measured from threshold to 18MeV neutron energies using the activation and off-line $\gamma$ -ray spectroscopic technique. The quasi-monoenergetic neutron beam was generated using the 7Li(p, n) reaction. The results from the present work were compared with those of the literature and with the evaluated data from different libraries, like ENDF-B/VII.1, JENDL-4.0, CENDL-3.1, and JEFF-3.3. Nuclear model codes, like TALYS-1.9 and EMPIRE-3.2.3-Malta, were also used for a better description of the present work and literature data. The uncertainties in the measured cross-section were evaluated using the covariance analysis. The present experimental results were found to be in good agreement with those of the literature and with the evaluated data. The nuclear model code TALYS-1.9 was found successful in reproducing the experimental data for both reactions. However, the EMPIRE-3.2.3-Malta model code was found to be able to reproduce only the trend of the 58Ni(n, p) reaction excitation function. The present work provides a better insight on the comparison of both nuclear model codes. The present work is also essential for the production cross-section and the dose rate estimation of the medical isotope 58Co.

Theoretical cross-sectional calculation of some structural fusion material on (n, α)-induced reactions

27Al, 51V, 52Cr, 55Mn, 56Fe and 58Ni nuclei are some structural fusion substances. The neutron incident energy around 14–15 MeV is adequate to excite the nucleus for the reactions such as (n, p), (n, d), (n, 2n), (n, t), and (n, α). For fusion reactor technology, the reaction cross-sectional data have a critical importance in fusion reactors and development. Neutron irradiation produces considerable modifications in the mechanical and physical properties of each of the structural fusion material systems raising feasibility questions and design limitations. In this paper, for some structural fusion materials (n, α) reactions such as 52Cr(n, α)49Ti, 51V(n, α)48Si, 27Al(n, α)24Na, 58Ni(n, α)55Fe, 56Fe(n, α)53Cr and 55Mn(n, α)52V were done up to 40 MeV incident neutron energy. In the calculations, the equilibrium and pre-equilibrium impacts have been used. Calculations have been carried out with TALYS 1.9 and EMPIRE 3.2 (Malta) nuclear model codes. Results from performed calculations have been compared with the experimental nuclear reaction data, ENDF/B-VII.b4, JENDL-4.0 and JEFF-3.2 evaluated data.

Neutron capture cross-sections for 159Tb isotope in the energy range of 5 to 17 MeV

The neutron capture cross-sections have been measured for the 159Tb(n, γ)160Tb reaction at the spectrum average peak neutron energies of 5.08 ± 0.165, 12.47 ± 0.825, and 16.63 ± 0.95 MeV respectively. The experiment has been carried out using the standard neutron activation technique and off-line γ-ray spectrometry. The present measurement has been done for the energies where very few measured results are available in the data library. The results have been compared with ENDF/B-VII.1 and JENDL-4.0 data libraries. The present results have also been supported by theoretical predictions of nuclear model code TALYS 1.9. Detailed covariance analysis was carried out to find the uncertainty and the correlations among the measured cross-sections.

Activation cross section and isomeric cross section ratio for the 76Ge(n,2n)75m,gGe process

.We measured neutron-induced reaction cross sections for the 76Ge(n,2n)75m,gGe reactions and their isomeric cross section ratios sigma_{m}/sigma_{g} at three neutron energies between 13 and 15MeV by an activation and off-line gamma-ray spectrometric technique using the K-400 Neutron Generator at the Chinese Academy of Engineering Physics (CAEP). Ge samples and Nb monitor foils were activated together to determine the reaction cross section and the incident neutron flux. The monoenergetic neutron beams were formed via the 3H(d,n)4He reaction. The pure cross section of the ground state was derived from the absolute cross section of the metastable state and the residual nuclear decay analysis. The cross sections were also calculated using the nuclear model code TALYS-1.8 with different level density options at neutron energies varying from the reaction threshold to 20MeV. Results are discussed and compared with the corresponding literature data.

Activation cross section and isomeric cross-section ratio for the 151Eu(n,2n)150m,gEu process

The cross sections of 151Eu(n,2n)150m,gEu reactions and their isomeric cross section ratios σm/σt have been measured experimentally. Cross sections are measured, relative to a reference 93Nb(n,2n)92mNb reaction cross section, by means of the activation technique at three neutron energies 13.5, 14.1, and 14.8 MeV. Monoenergetic neutron beams were formed via the 3H(d,n)4He reaction and both Eu2O3 samples and Nb monitor foils were activated together to determine the reaction cross section and the incident neutron flux. The activities induced in the reaction products were measured using high−resolution gamma ray spectroscopy. Cross sections were also evaluated theoretically using the numerical nuclear model code, TALYS-1.8 with different level density options at neutron energies varying from the reaction threshold to 20 MeV. Results are discussed and compared with the corresponding literature.

Potential sources of uncertainties in nuclear reaction modeling

Nowadays, reliance on nuclear models to interpolate or extrapolate between experimental data points is very common, for nuclear data evaluation. It is also well known that the knowledge of nuclear reaction mechanisms is at best approximate, and that their modeling relies on many parameters which do not have a precise physical meaning outside of their specific implementations in nuclear model codes: they carry both specific physical information, and effective information that is related to the deficiencies of the model itself. Therefore, to improve the uncertainties associated with evaluated nuclear data, the models themselves must be refined so that their parameters can be rigorously derived from theory. Examples of such a process will be given for a wide sample of models like: detailed theory of compound nucleus decay through multiple nucleon or gamma emission, or refinements to the width fluctuation factor of the Hauser-Feshbach model. All these examples will illustrate the reduction in the effective components of nuclear model parameters, through the reduced dynamics of parameter adjustment needed to account for experimental data. The significant progress, recently achieved for the non-fission channels, also highlights the difficult path ahead to improve our quantitative understanding of fission in a similar way: by relying on microscopic theory.

Investigation of (n, p), (n, 2n) reaction cross sections for Sn isotopes for fusion reactor applications

The compound Nb3Sn possess superconductivity at suitable temperatures, therefore, it is best suited to be used in the toroidal coils of superconducting magnets which holds the fusion plasma and confine it inside the reactor core. The neutron induced reaction cross-sections are required from threshold to 20MeV for different isotopes of Tin (Sn). Since limited data is available for the reactions with the Sn isotopes. Therefore, we have optimized the (n, p) and (n, 2n) reaction cross-sections for all possible Sn isotopes from threshold to 20MeV with modified input parameters in the nuclear reaction modular codes EMPIRE-3.2.2 and TALYS-1.8. These codes account for the major nuclear reaction mechanisms, including direct, pre-equilibrium, and compound nucleus contributions. The present results from 116Sn(n,p)116mIn, 117Sn(n,p)117In, 117Sn(n,p)117mIn, 118Sn(n,2n)117mSn,120Sn(n,2n)119mSn and 124Sn(n,2n)123mSn reactions calculated with nuclear modular codes: TALYS – 1.8, EMPIRE – 3.2.2 were compared with EXFOR data, systematics proposed by several authors and with the existing evaluated nuclear data library ENDF/B-VII.1, as well. The results from the present study can be used for the future development of ITER devices as well as to upgrade the nuclear model codes.

Nuclear model analysis of excitation functions of α-particle induced reactions on In and Cd up to 60 MeV with relevance to the production of high specific activity 117mSn

Excitation functions were calculated for the α-particle induced reactions 115In(α,x)117mSn, 114Cd(α,n)117mSn, 116Cd(α,3n)117mSn and natCd(α,x)117mSn to analyse the production of the medically important 117mSn (T½ = 13.6 d). For calculations three nuclear model codes (i.e. TALYS, EMPIRE and ALICE-IPPE) were used and the results were compared with the available experimental data. For the most important reaction, 116Cd(α,3n)117mSn, evaluated data are presented. The yield and radionuclidic purity of 117mSn from each reaction are discussed.

Measurement of activation cross sections for quasi-monoenergetic neutron induced reactions of 89Y

The neutron induced cross sections of the 89Y(n,2n)88Y, 89Y(n,3n)87Y and 89Y(n,4n)86Y reactions were measured in the neutron energy range of 15.2 to 37.2 MeV by using an activation and off-line $\gamma$ -ray spectrometric technique. The quasi-monoenergetic neutrons used for the above reactions are based on a 9Be(p,n) reaction. Simulations of the neutron spectra from the Be target were done using the MCNPX 2.6.0 program. Theoretical calculations were performed for the 89Y(n,2n)88Y, 89Y(n,3n)87Y and 89Y(n,4n)86Y reaction cross sections using nuclear model code Talys 1.8. The measured and calculated cross sections were compared with the literature data given in EXFOR and the TENDL-2015 data libraries. The present data of the 89Y(n,xn) reaction were also compared with the similar data of the 89Y( $\gamma$ ,xn) reaction to examine the effect of the entrance channel parameters as well as the role of projectiles and ejectiles.

Activation Cross Section and Isomeric Cross-Section Ratio for the (n,2n) Reaction on 113,115In

Cross sections of the 113In(n,2n)112m,gIn and 115In(n,2n)114m,gIn reactions and their isomeric cross-section ratios σm/σg have been measured by means of the activation technique at three neutron energies in the range 13 to 15 MeV. Indium samples and niobium monitor foils were activated together to determine the reaction cross section and the incident neutron flux. The monoenergetic neutron beam was produced via the 3H(d,n)4He reaction at the Pd-300 Neutron Generator of the Chinese Academy of Engineering Physics. The activities induced in the reaction products were measured using high-resolution gamma-ray spectroscopy. The pure cross section of the ground state was derived from the absolute cross section of the metastable state and the residual nuclear decay analysis. Cross sections were also evaluated theoretically using the numerical nuclear model code TALYS-1.8 with different level density options at neutron energies varying from the reaction threshold to 20 MeV. Results are discussed and compared with the corresponding literature.

Excitation function of alpha-particle-induced reactions on natNi from threshold to 44 MeV

Excitation functions of the natNi( $\alpha$ ,x)62,63,65Zn, natNi( $\alpha$ ,x)56,57Ni and natNi( $\alpha$ ,x)56,57,58m+gCo reactions were measured from the respective thresholds to 44MeV using the stacked-foil activation technique. The tests for the beam characterization are described. The radioactivity was measured using HPGe $\gamma$ -ray detectors. Theoretical calculations on $\alpha$ -particles-induced reactions on natNi were performed using the nuclear model code TALYS-1.8. A few results are new, the others strengthen the database. Our experimental data were compared with results of nuclear model calculations and described the reaction mechanism.

Activation cross section and isomeric cross-section ratio for the (n,2n) reaction on 132,134Ba

Abstract Cross sections of the 132Ba(n,2n)131m,gBa and 134Ba(n,2n)133m,gBa reactions and their isomeric cross section ratios σm/σg have been measured by means of the activation technique at three neutron energies in the range 13−15 MeV. BaCO3 samples and Nb monitor foils were activated together to determine the reaction cross section and the incident neutron flux. The quasimonoenergetic neutrons beam were produced via the 3H(d,n)4He reaction at the Pd-300 Neutron Generator of the Chinese Academy of Engineering Physics (CAEP). The activities induced in the reaction products were measured using high−resolution γ ray spectroscopy. The pure cross section of the ground-state was derived from the absolute cross section of the metastable state and the residual nuclear decay analysis. Cross sections were also evaluated theoretically using the numerical nuclear model code, TALYS-1.8 with different level density options at neutron energies varying from the reaction threshold to 20 MeV. Results are discussed and compared with the corresponding literature.

Excitation functions of alpha particles induced nuclear reactions on natural titanium in the energy range of 10.4–50.2 MeV

We studied the excitation functions of residual radionuclide productions from α particles bombardment on natural titanium in the energy range of 10.4–50.2MeV. A well-established stacked-foil activation technique combined with HPGe γ-ray spectrometry was used to measure the excitation functions for the 51,49,48Cr, 48V, 43K, and 43,44m,44g,46g+m,47,48Sc radionuclides. The thick target yields for all assessed radionuclides were also calculated. The obtained experimental data were compared with the earlier experimental ones and also with the evaluated data in the TENDL-2015 library. A reasonable agreement was found between this work and some of the previous ones, while a partial agreement was found with the evaluated data. The present results would further enrich the experimental database and facilitate the understanding of existing discrepancies among the previous measurements. The results would also help to enhance the prediction capability of the nuclear reaction model codes.

(n, p) Reaction Cross Sections Calculations of Some Stellar Iron Group Fusion Materials

The excitation functions for (n, p) reactions from reaction threshold to 24 MeV on some important iron (Fe) group target elements (20 ≤ Z ≤ 28) for astrophysical (n, p) reactions such as Si, Ca, Sc, Ti, Cr, Fe, Co and Ni were calculated using TALYS-1.0 nuclear model code. The new calculations on the excitation functions of 28Si(n, p)28Al, 29Si(n, p)29Al, 42Ca(n, p)42K, 45Sc(n, p)45Ca, 46Ti(n, p)46Sc, 53Cr(n, p)53V, 54Fe(n, p)54Mn, 57Fe(n, p)57Mn, 59Co(n, p)59Fe, 58Ni(n, p)58Co and 60Ni(n, p)60Co reactions have been carried out up to 24 MeV incident neutron energy. In these calculations, the compound nucleus and pre-equilibrium reaction mechanism studied extensively. According to these calculations, we assume that these model calculations can be applied to some heavy elements, ejected into interstellar medium by dramatic supernova events.

Evaluation of neutron total and capture cross sections on99Tc in the unresolved resonance region

Long-lived fission product Technetium-99 is one of the most important radioisotopes for nuclear transmutation. The reliable nuclear data are indispensable for a wide energy range up to a few MeV, in order to develop environmental load reducing technology. The statistical analyses of resolved resonances were performed by using the truncated Porter-Thomas distribution, coupled-channels optical model, nuclear level density model and Bayes' theorem on conditional probability. The total and capture cross sections were calculated by a nuclear reaction model code CCONE. The resulting cross sections have statistical consistency between the resolved and unresolved resonance regions. The evaluated capture data reproduce those recently measured at ANNRI of J-PARC/MLF above resolved resonance region up to 800 keV.