Theoretical Excitation Functions Research Articles

Cross sections for 14 MeV neutron interaction with lutetium isotopes and their theoretical excitation functions* *Supported by the Natural Science Foundation of Henan (232300420130) and National Natural Science Foundation of China (11575090)

The cross-sections for the 175Lu(n,p)175Yb, 175Lu(n,α)172Tm, 176Lu(n,α)173Tm, 175Lu(n,2n)174mLu, and 175Lu(n,2n)174gLu reactions at 13.57, 14.03 14.62, and 14.86 MeV neutron energies were measured using an activation technique. The theoretical excitation functions of these reactions were calculated using the Talys-1.95 code. The reaction cross-section data experimentally obtained were analyzed and compared with experimental data reported in the literature, data from five major evaluated nuclear data libraries of IAEA, and theoretical values based on Talys-1.95. The data obtained at some neutron energies agree with some of the data reported in the literature and theoretical values based on Talys-1.95. The consistency of the theoretical curves of excitation functions based on Talys-1.95 with the data obtained in this study and those reported in the literature is higher than that of the evaluation curves of excitation functions for the 175Lu(n,p)175Yb, 175Lu(n,α)172 Tm, and 176Lu(n,α)173Tm reactions. This study is helpful because it provides new evaluated reaction cross-section data on lutetium (which is a fusion reactor material), improves the quality of neutron-induced reaction cross section data libraries, and advances the research on related applications.

Fusion Dynamics of 27Al + 74Ge Nuclear Reaction

The experimental data for the nuclear fusion of 27Al with 74Ge are examined within the context of symmetric-asymmetric Gaussian barrier distribution (SAGBD) model in sub-barrier domain. For bombarding energies smaller than the Coulomb barrier, predictions owing to simple Wong formula are found to be much smaller with reference to experimental outcomes. On other side, the SAGBD method is used, wherein impacts of inherent channels as a result of its multidimensional aspect of quantum mechanical tunneling arises because of weighted Gaussian function, to get desired outcomes. Larger fusion enhancement appears at lower energy region, which signifies the effective participation of inherent channels originated due to structure of participants. In present approach, the impacts of various inherent channels are cumulatively determined by calculating values of channel couplings parameter (λ) & VCBRED . Present calculations due to the SAGBD method suggests that the theoretical fusion excitation functions for 27Al + 74Ge reaction are in close resemblance with experimental findings around the nominal barrier.

Measurement of the (n, 2n) reaction cross-sections of iodine and cesium induced by D-T neutrons with covariance analysis* *Supported by the Key Laboratory of Nuclear Data Foundation (JCKY2022201C151), and the National Natural Science Foundation of China (11975113).

The cross-sections of the 127I (n, 2n) 126I and 133Cs (n, 2n) 132Cs reactions at neutron energies of 13.83 ± 0.05, 14.33 ± 0.10, and 14.79 ± 0.10 MeV were measured relative to the 93Nb (n, 2n) 92mNb reaction using the activation technique in combination with off-line γ-ray spectrometry. A neutron beam was generated from the T (d, n) 4He reaction using the K-400 neutron generator at the China Academy of Engineering Physics. Considering the correlations between different attributes, detailed uncertainty propagation was performed using covariance analysis, and the cross-sections were reported with their uncertainties and correlation matrix. The uncertainty of the measurement cross-sections ranged from 4.84 to 5.90%, which is lower than previous experimental data. Furthermore, the theoretical excitation functions of the 127I (n, 2n) 126I and 133Cs (n, 2n) 132Cs reactions were calculated using the TALYS-1.95 and EMPIRE-3.2.3 codes. Then, the experimentally determined cross-sections were analyzed by comparing them with literature data available in the EXFOR database and evaluated nuclear data in the ENDF/B-VIII.0, JEFF-3.3, JENDL-5, BROND-3.1, CENDL-3.2, and TENDL-2021 databases. Compared with the values previously reported in the 13.8-14.8 MeV energy region, the precision of the results obtained in this study was greatly improved. The current experimental results with thorough uncertainties and covariance information are critical for verifying the reliability of the theoretical model and improving the quality of the nuclear database.

γ-ray emission in proton-induced nuclear reactions on [formula omitted]C and Mylar targets over the incident energy range, Ep = 30 – 200 MeV. Astrophysical implications

We have measured the γ-ray line production cross sections in proton-induced nuclear reactions on various target nuclei (12C, 16O, 24Mg, 28Si, 56Fe) of chemical elements abundant in astrophysical sites (solar flares, the interstellar medium, cosmic compact objects) over the incident energy range of Ep = 30 – 200 MeV. We carried out experimental campaigns in joint collaboration at the K = 200 separated sector cyclotron of iThemba LABS using a high-energy resolution, high-efficiency detection array composed of 8 Compton-suppressed clover detectors comprising 32 HP-Ge crystals for recording the γ-ray energy spectra. In the current paper, we focus on γ-ray de-excitation lines produced in proton irradiations of natC and Mylar targets, in particular, on the prominent 4.439 and 6.129 MeV lines of 12C and 16O which are among the strongest lines emitted in solar flares and in interactions of low-energy cosmic rays (LECRs) with the gas and dust of the inner galaxy. We report new γ-ray production experimental cross section data for ten nuclear γ-ray lines that we compare to previous low-energy data sets from the literature, to the predictions of the TALYS code of nuclear reactions and to a semi-empirical compilation. In the first approach, performing calculations with default input parameters of TALYS we observed substantial deviations between the predicted cross sections and experimental data. Then, using modified optical model potential (OMP) and nuclear level deformation parameters as input data we generated theoretical excitation functions for the above two main lines fully consistent with experimental data. In contrast, the experimental data sets for the other eight analyzed lines from the two proton-irradiated targets exhibit significant deviations with the predicted cross section values. We also report line-shape experimental data for the line complex observed at Eγ = 4.44 MeV in irradiations of the two targets. Finally, we emphasize the astrophysical implications of our results.

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.

New results on proton-induced reactions on vanadium for Sc47 production and the impact of level densities on theoretical cross sections

New data for the ${}^{\text{nat}}\mathrm{V}(p,x)$ reactions have been measured in the range 26--70 MeV, with production of the nuclides $^{47}\mathrm{Sc}, ^{43}\mathrm{Sc}, {}^{44m}\mathrm{Sc}, {}^{44g}\mathrm{Sc}, ^{46}\mathrm{Sc}, ^{48}\mathrm{Sc}, ^{42}\mathrm{K}, ^{43}\mathrm{K}, ^{48}\mathrm{V}, ^{48}\mathrm{Cr}, ^{49}\mathrm{Cr}$, and $^{51}\mathrm{Cr}$. The focus is on the production of $^{47}\mathrm{Sc}$, a ${\ensuremath{\beta}}^{\ensuremath{-}}$ emitter suitable for innovative radiotheranostic applications in nuclear medicine. The measured cross sections for this radionuclide and its contaminants are compared with the theoretical excitation functions calculated with the talys code. In view of novel radiopharmaceutical applications, it is essential to accurately describe these cross sections for the evaluation of yields, purities, and dose releases. Hence, we optimize the level-density parameters of the microscopic models in the talys code to obtain the best possible descriptions of the new data. We consider different irradiation conditions to estimate the production yields from the cross sections determined in this paper.

Activation cross-section and isomeric cross-section ratio for the 122Te(n,2n)121m,gTe process

Measurements of the cross-section for the 122Te(n,2n)121mTe and 122Te(n,2n)121gTe reactions and their ratio within the energy range of 13  –5 MeV have been carried out using the method of activation and off-line γ-ray spectrometry. The fast-moving neutrons were produced via the 3H(d,n)4He reaction on a K-400 neutron generator. Natural high-purity Te powder was used as the target material. The value of pure ground-state cross-section σg was obtained. Theoretical excitation functions were also calculated by means of the nuclear-reaction codes TALYS-1.95 with six level densities, at neutron energies varying from the reaction threshold to 20 MeV. The results were also discussed and compared with some of the corresponding values found in the literature.

Excitation functions of proton induced reactions of some radioisotopes used in medicine

AbstractThe main purpose of this study is the investigation of a cross section of proton induced nuclear reactions. The excitation functions of the reactions:56Fe(p,2n)55Co58Fe(p,2n)57Co,111Cd(p,2n)110In,112Cd(p,2n)111In,125Te(p,2n)124I,126Te(p,2n)125I,68Zn(p,2n)67Gawere investigated. These reactions were studied as the resulting radioisotopes are used in medical applications. Theoretical excitation functions have been calculated with TALYS 1.6 nuclear reaction simulation code. The calculated excitation functions are compared with the experimental data.

Cross section of (n,2n) reaction on the low-abundance isotopes 156,158Dy at 13.5 and 14.8 MeV

Activation cross-sections for the 156Dy(n,2n)155Dy and 158Dy(n,2n)157m+gDy reactions with low-abundance target isotopes (156Dy:0.056 %, 158Dy:0.095 %) were measured by means of the activation technique and a coaxial HPGe γ-ray detector at 13.5 and 14.8 MeV. Theoretical excitation functions were calculated using the nuclear-reaction codes EMPIRE-3.2 Malta and TALYS-1.6 with default parameters, at neutron energies varying from the reaction threshold to 20 MeV. The results were discussed and compared with some corresponding values found in the literature, with the evaluation data in ENDF/B-VII.1, JENDF-4.0, and JEFF-3.2 libraries, and with the estimates obtained from a published empirical formula based on the statistical model.

Determination of the cross section for (n,p) reaction with producing short-lived nuclei on the 162,163Dy isotopes at 13.5 and 14.8 MeV

Abstract Activation cross-sections for the 162 Dy(n,p) 162 Tb and 163 Dy(n,p) 163 Tb reactions have been measured by means of the activation technique and a coaxial HPGe γ-ray detector at 13.5 and 14.8 MeV. The fast neutrons were produced via the 3 H( d , n ) 4 He reaction on Pd-300 neutron generator. The natural high-purity Dy 2 O 3 powder was used as target material. Theoretical excitation functions were calculated using the nuclear-reaction codes EMPIRE-3.2 Malta and TALYS-1.6 with default parameters, at neutron energies varying from the reaction threshold to 20 MeV. The results were also discussed and compared with some corresponding values found in the literature, with the comprehensive evaluation data in ENDF/B-VII.1 and JENDF-4.0 libraries, and with the estimates obtained from a published empirical formula based on the statistical model with Q -value dependence and odd–even effects taken into consideration.

Cross section measurement of the 159Tb(n, γ)Tb160 nuclear reaction

Abstract The cross section of the 159Tb(n, γ)Tb160 reaction was measured in four mono-energetic neutron fields of energy 3.7, 4.3, 5.4, and 6.85 MeV, respectively, with the activation technique applied to metal discs of natural composition. To ensure an acceptable precision of the results all major sources of uncertainties were taken into account. Calculations of detector efficiency, incident neutron spectrum and correction factors were performed with the Monte Carlo code (MCNPX), whereas theoretical excitation functions were calculated with the TALYS-1.2 code and compared to the experimental cross section values. This paper presents both measurements and calculation leading to the cross section values.

Nucleon flow in the process of evolution from dinucleus to mononucleus investigated with a dynamic model

Nucleon flow in the process of evolution from dinucleus to mononucleus is studied by means of the coupled Langevin equations in the three-dimensional collective space of the radial, neck, and asymmetry degrees of freedom for the systems ${}^{48}\mathrm{Ca}+{}^{238}\mathrm{U}$ and ${}^{58}\mathrm{Fe}+{}^{248}\mathrm{Cm}$. For a comparison, the dynamic evolution of the neck is also investigated with the Langevin equations in the two-dimensional collective space of the radial and neck for these two reaction systems. The results show that nucleon flow is strongly damped in the stage of the dinuclear system due to the large dissipation associated with the mass asymmetry degree of freedom. The evaporation residue (ER) cross sections for the ${}^{48}\mathrm{Ca}+{}^{238}\mathrm{U}$ and ${}^{58}\mathrm{Fe}+{}^{248}\mathrm{Cm}$ reactions are evaluated by means of the modified fusion-by-diffusion (FBD) model, in which the injection distance distributions in the asymmetric fission valley obtained from the dynamic calculations are integrated. The theoretical excitation functions of the ${}^{48}\mathrm{Ca}+{}^{238}\mathrm{U}$ reaction are in good agreement with the experimental data. For the ${}^{58}\mathrm{Fe}+{}^{248}\mathrm{Cm}$ reaction, the maximum ER cross sections in 3$n$- and 4$n$-evaporation channels calculated with the three-dimensional Langevin equations are, respectively, $0.008$ and $0.020$ fb. We have demonstrated that the effect of drift and diffusion towards a more symmetric configuration on the ER cross sections is counterbalanced by that of diffusion towards a more asymmetric one. The ER excitation functions calculated with the two approaches are similar, which means that the impact of the nucleon flow during the process of neck evolution on the formation probability of superheavy nuclei is small in the framework of the dynamic model. In this sense, the frozen approximation of mass asymmetry in the FBD model should be reasonable in the hot fusion reactions.

Feasibility study of production of radioactive carbon black or carbon nanotubes in cyclotron facilities for nanobioscience applications

A feasibility study regarding the production of radioactive carbon black and nanotubes has been performed by proton beam irradiation. Experimental and theoretical excitation functions of the nuclear reaction natC(p,x)7Be in the proton energy range 24–38MeV are reported, with an acceptable agreement. We have demonstrated that sufficient activities of 7Be radioisotope can be produced in carbon black and nanotube that would facilitate studies of their possible impact on human and environment.

Experimental study of excitation functions for the deuteron induced reactions 64Zn(d,2p) 64Cu and 64Zn(d,αn) 61Cu using the stacked-foil technique

There is considerable, and growing, interest in the 64Cu radioisotope for application in Nuclear Medicine for PET imaging and targeted radiotherapy of tumours. We are investigating the cyclotron production of this isotope by way of deuteron bombardment of enriched 64Zn target material. In this study, experimental excitation functions for both the 64Zn(d,2p) 64Cu and 64Zn(d,αn) 61Cu reactions up to 18.2 MeV deuteron energy have been measured using the stacked-foil technique. The deuteron energies in the various foils were calculated with the SRIM 2003 code and γ-ray spectrometry was used to measure the activities of the various radioisotopes produced. Monitor foils were used to determine the deuteron beam current on the target stack. Theoretical excitation functions, calculated both with the Empire II code and with an updated version of the Alice code, were compared with the experimental results and a reasonable agreement was found. The experimental work was performed at the MC40 Cyclotron at the European Commission's Joint Research Centre at Ispra, Italy.

Measurements of isomeric cross sections for (n,2n) reaction on 140Ce, 142Nd and 144Sm isotopes around 14 MeV

In this study, activation cross sections were measured for the 140Ce(n,2n) 139mCe, 142Nd(n,2n) 141mNd and 144Sm(n,2n) 143mSm reactions at six different neutron energies from 13.5 and 14.8 MeV. The fast neutrons were produced via the 3H(d,n) 4He reaction on SAMES T-400 neutron generator. The cyclic activation technique was used. Induced γ activities were measured by a high-resolution γ-ray spectrometer with a high-purity germanium (HpGe) detector. Corrections were made for the effects of γ-ray attenuation, dead-time and fluctuation of neutron flux. For these reactions, statistical model calculations for which the pre-equilibrium emission effects are taken into consideration were also performed between 13.6 and 14.8 MeV energy range. Theoretical excitation functions and experimental results were plotted together with previous works.

Experimental and theoretical excitation functions for [formula omitted] reactions

The excitation functions for protons incident on nat Br were measured from threshold up to 100 MeV by means of the stacked-foil technique. Where applicable, the measured cross-section values are compared with previously published values. Theoretical cross-sections were also calculated by means of the computer code ALICE (IPPE) for comparison purposes.

Excitation Functions of Rhenium Isotopes on the natW(d, xn) Reactions and Production of No-carrier-added 186Re

Experimental cross sections for the reactions 186W(d, 2n)186Re, natW(d, xn)181-184Re and 186W(d, p)187W are measured up to 34 MeV using the stacked target method. The values obtained are compared with cross sections calculated using the ALICE code. The experimental and theoretical excitation functions are in reasonable agreement except for the l86W(d, p)187W reaction.

Simulation of the interaction of galactic cosmic‐ray protons with meteoroids: On the production of radionuclides in thick gabbro and iron targets irradiated isotropically with 1.6 GeV protons

Abstract— Thick spherical targets made of gabbro (R = 25 cm) and of steel (R = 10 cm) were irradiated isotropically with 1.6 GeV protons at the Saturne synchrotron at Laboratoire National Saturne (LNS)/CEN Saclay in order to simulate the interaction in space of galactic cosmic‐ray (GCR) protons with stony and iron meteoroids. Proton fluences of 1.32 × 1014 cm−2 and 2.45 × 1014 cm−2 were received by the gabbro and iron sphere, respectively, which corresponds to cosmic‐ray exposure ages of about 1.6 and 3.0 Ma. Both artificial meteoroids contained large numbers of high‐purity target foils of up to 28 elements at different depths. In these individual target foils, elementary production rates of radionuclides and rare gas isotopes were measured by x‐ and γ‐spectrometry, by low‐level counting, accelerator mass spectrometry (AMS), and by conventional rare gas mass spectrometry. Also samples of the gabbro itself were analyzed. Up to now, for each of the experiments, ∼500 target‐product combinations were investigated of which the results for radionuclides are presented here. The experimental production rates show a wide range of depth profiles reflecting the differences between low‐, medium‐, and high‐energy products. The influence of the stony and iron matrices on the production of secondary particles and on particle transport, in general, and consequently on the production rates is clearly exhibited by the phenomenology of the production rates as well as by a detailed theoretical analysis. Theoretical production rates were calculated in an a priori way by folding depth‐dependent spectra of primary and secondary protons and secondary neutrons calculated by Monte Carlo techniques with the excitation functions of the underlying nuclear reactions. Discrepancies of up to a factor of 2 between the experimental and a priori calculated depth profiles are attributed to the poor quality of the mostly theoretical neutron excitation functions. Improved neutron excitation functions were obtained by least‐squares deconvolution techniques from experimental thick‐target production rates of up to five thick‐target experiments in which isotropic irradiations were performed. A posteriori calculations using the adjusted neutron cross sections describe the measured depth profiles of all these simulation experiments within 9%. The thus validated model calculations provide a basis for reliable physical model calculations of the production rates of cosmogenic nuclides in stony and iron meteorites as well as in lunar samples and terrestrial materials.

Cross sections for the proton-induced production of krypton isotopes from Rb, Sr, Y, and Zr for energies up to 1600 MeV

The production by proton-induced reactions of stable and long-lived Kr-isotopes from Rb, Sr, Y, and Zr was investigated by using isotope dilution mass spectrometry of targets irradiated at PSI/CH, TSL/S and LNS/F. Cumulative cross sections were determined for energies between 81 and 1600 MeV, between 15.4 and 1600 MeV, and between 70 and 1600 MeV for the target element Rb, Sr, and Y, respectively. For Zr, three energies of 156, 569 and 1200 MeV were investigated. As a by-product, cross sections for the production of short-lived radionuclides from Rb are reported which were measured by γ-spectrometry prior to mass spectrometry. Flux determination and absolute calibration of cross sections was done by the reaction 27Al(p,3p3n) 22Na. The new experimental data are consistent with a large database established during recent years for describing the interactions of cosmic ray protons with matter. They provide a first complete basis for model calculations of cosmogenic krypton in stony meteoroids and planetary surfaces. For the target element Rb we report the first measurements at all. For Sr, only one earlier measurement existed. For Y, our data confirm earlier measurements up to 200 MeV and extend the data set up to 1600 MeV, while for Zr three new energy points complement and check the consistency of the new investigations with earlier work from Bordeaux. The new experimental data are compared with theoretical excitation functions calculated on an a priori basis using the hybrid model of preequilibrium reactions, an intranuclear cascade/evaporation model in form of the HET/KFA2 code and the semi-empirical systematics by Silberberg, Tsao and coworkers. The differences between theories and experiments demonstrate severe shortcomings of the predictive power of existing models and emphasize the importance of experimental determinations if high-quality data are required for applications.

Nuclear model calculations of activation cross sections for fusion reactor technology

Intense neutron fluxes within fusion reactors that are currently being designed will lead to the activation of structural components. To assess and minimize this radioactivity, nuclear cross sections are needed for neutrons with energies up to 20 MeV. We describe research performed for the International Atomic Energy Agency (IAEA) Coordinated Research Programme on activation cross sections for fusion reactor technology, which has selected certain high-priority reactions for both experimental and theoretical study. Using statistical model codes, we have investigated: (1) excitation function cross sections for radionuclide production in the reactions 94Mo(n,p) 95Nb, 109Ag(n,2n) 108mAg, 151Eu(n,2n) 150m Eu 153Eu(n 2n) 152g+m2 Eu, 159Tb(n,2n) 158Tb 187Re(n 2n) 186mRe 179Hf(n,2n) 178m2Hf, 193Ir(n,2n) 192m2Ir; and (2) the systematical dependence of isomeric ratios on isomer spin and incident-energy. Using our calculated results for the excitation functions, along with calculations by other groups, the theoretical excitation functions have been normalized to experimental values at 14.5 MeV to produce evaluated excitation functions. These evaluations can be used within radiation transport and nuclide inventory codes to design and assess the environmental impact of fusion reactors.