The calculation of neutron cross-sections from optical potentials

Preequilibrium models for 58Ni (n, xp) and 60Ni (n, xp) reactions in neutrons at 8, 9, 9.4, 11 and 14.8 MeV using the EMPIRE and TALYS codes

In this study, the calculations of proton emission spectra produced by ⁵⁸Ni (n, xp) and ⁶⁰Ni (n, xp) reactions are used in the framework of preequilibrium models with the EMPIRE and TALYS codes. Exciton Model predictions combined with the Kalbach angular distributions systematics, quantum-mechanical preequilibrium models (Multi-step Direct (MSD) theory and Multi-step Compound (MSC) processes) were used, and some necessary parameters have been investigated for our calculations. The comparison with experimental data shows clear improvement over the Exciton and quantum-mechanical preequilibrium models calculations.

Simple parametrization of (n,d) cross sections using Flerov and Talyzin's formula

This article aims at providing new cross section data from empirical formulas for the (n,d) reactions of which experimental measurements at 14-15 MeV energy are not available or limited. If the experimental data for a nuclear reaction at a given energy are scarce, theoretical calculations and also developing empirical formulas have a critical importance. Here, we propose a new empirical formula of (n,d) reactions for analysis of the relationship between the experimental data and the parameters of empirical formula. The present formula was obtained by using the non-elastic Flerov and Talyzin expression to calculate (n,d) cross sections at 14-15 MeV. Due to the good overall agreement with the measured cross sections, our empirical formula with polynomial fitting model including asymmetry parameter can be useful in planning new experiments of (n,d) reactions for energies around 14 MeV.

The New Physics in LILITA_N21: An Improved Description of the Reaction 190 MeV 40Ar + 27Al

In this paper, light charged particle emission in the evaporation residue channel for the 190 MeV 40Ar + 27Al reaction leading to 67Ga composite nuclei at Ex = 91 MeV and angular momentum up to 46 ℏ has been re-analyzed. The main goal was to study the decay of 67Ga on the basis of an extended set of observables in order to provide a description of the evaporative decay cascades using the multistep Monte Carlo approach. The proton and α-particle energy spectra along with their angular distributions and ratios of differential multiplicities have been considered. The measured observables were compared with statistical model calculations. Having used a single-step Monte Carlo approach and standard parameters decades ago, the model does not provide a good description of the full dataset. Only a subset of the data was reproduced by assuming emitting nuclei with very large deformed shapes in a previous work published in the late 1980s. In the reported analysis, better agreement has been observed. Using the new transmission coefficients from the Optical Model, the parameters of which have recently been derived, the multi-step approach and the introduction of a nuclear shape description based on the nuclear stratosphere allowed us to realize a significant improvement.

Global Microscopic Description of Nucleon-Nucleus Scattering with Quantified Uncertainties

We develop for the first time a microscopic global nucleon-nucleus optical potential with quantified uncertainties suitable for analyzing nuclear reaction experiments at next-generation rare-isotope beam facilities. Within the improved local density approximation and without any adjustable parameters, we begin by computing proton-nucleus and neutron-nucleus optical potentials from a set of five nuclear forces from chiral effective field theory for 1800 target nuclei in the mass range 12≤A≤242 for energies between 0  MeV<E≲150  MeV. We then parameterize a global optical potential for each chiral force that depends smoothly on the projectile energy as well as the target nucleus mass number and isospin asymmetry. Uncertainty bands for elastic scattering observables are generated from a full covariance analysis of the parameters entering in the description of our global optical potential and benchmarked against existing experimental data for stable target nuclei. Since our approach is purely microscopic, we anticipate a similar quality of the model for nucleon scattering on unstable isotopes.

The dark side of alpha-particle optical potential: Emission from excited nuclei

Further analysis of α-particle emission from similar nuclei excited in neutron- as well as low-energy proton-induced reactions is involved concerning a possible difference between the optical model potentials (OMPs) which describe either alpha-particle elastic scattering and induced reactions or alpha-emission from excited compound nuclei. The key role of the pickup direct interaction is finally proved even at incident energies below ~10 MeV, as well as being eventually at the origin of the above-mentioned OMPs difference.

Investigation of cross sections of reactions used in neutron activation analysis

In this study, neutron incident reaction cross sections for some target nuclei such as 24Mg, 27Al, 28Si, 56Fe, and 63Cu used in neutron activation analysis have been investigated. The new calculations on the excitation functions of 24Mg(n, p)24Na, 27Al(n, p)27Mg, 27Al(n, α)24Na, 28Si(n, p)28Al, 56Fe(n, p)56Mn, and 63Cu(n, 2n)62Cu reactions have been carried out for incident neutron energies up to 20 MeV. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the new geometry dependent hybrid model and the full exciton model. Equilibrium effects are calculated according to the Weisskopf–Ewing model. In the present work, reaction cross-sections have been calculated by using empirical formulas developed for energies of 14–15 MeV. The calculated results are discussed and compared with the experimental data taken from the EXFOR database.

Evaluation of excitation functions of proton, ³He- and α-particle induced reactions for production of the medically interesting positron-emitter bromine-76

Cross section data for production of the medically interesting radionuclide ⁷⁶Br (T(½)=16.2 h) via the proton induced reactions on ⁷⁶Se, ⁷⁷Se, ⁷⁸Se and ⁷⁹Br, and ³He- and α-particle induced reactions on ⁷⁵As were evaluated. The nuclear model codes STAPRE, EMPIRE and TALYS were used to check the consistency in the experimental data and a statistical procedure was applied to derive the recommended excitation functions. A comparison of various production routes of ⁷⁶Br (and of ⁷⁵Br) is presented.

Level studies of 93Mo via 93Nb(p, nγ)93Mo reaction and density of discrete levels in 93Mo

The excited states of 93Mo have been investigated via the 93Nb(P,n?)93Mo reaction with proton beam energies of 2.5-4.3 MeV. The parameters of the nuclear level density formula were determined from the extensive and complete level scheme of 93Mo. The Bethe formula for the back-shifted Fermi gas model and the constant temperature model are compared with experimental level densities.

Evaluation of excitation functions of proton and deuteron induced reactions on enriched tellurium isotopes with special relevance to the production of iodine-124

Cross-section data for the production of medically important radionuclide (124)I via five proton and deuteron induced reactions on enriched tellurium isotopes were evaluated. The nuclear model codes, STAPRE, EMPIRE and TALYS, were used for consistency checks of the experimental data. Recommended excitation functions were derived using a well-defined statistical procedure. Therefrom integral yields were calculated. The various production routes of (124)I were compared. Presently the (124)Te(p,n)(124)I reaction is the method of choice; however, the (125)Te(p,2n)(124)I reaction also appears to have great potential.

Charged particle induced reaction cross section data for production of the emerging medically important positron emitter64Cu: A comprehensive evaluation

The radionuclide64Cu (T1/2=12.7 h) is an important non-standard positron emitter, suitable for combining PET imaging and targeted therapy. Its production in no-carrier-added form is doneviacharged particle induced reactions, and considerable amount of cross section data are available in the literature. We evaluated seven reactions, namely64Ni(p,n)64Cu,64Ni(d, 2n)64Cu,68Zn(p, αn)64Cu,66Zn(p, 2n)64Cu,64Zn(d, 2p)64Cu,66Zn(p, α)64Cu andnatZn(d,x)64Cu. Data analysis was generally limited up to about 25 MeV and the consistency check of experimental data was carried out using the nuclear model codes STAPRE, EMPIRE and TALYS. In a few cases experimental data were available up to 100 MeV; the consistency check in the high energy region was done only using the code TALYS. A statistical procedure (supported by nuclear model calculations) was then used to fit the data. The derived recommended sets of data, together with 95% confidence limits, are reported. The integral yields calculated from those data are also given. A critical comparison of the various production routes of64Cu is presented. The64Ni(p,n)64Cu reaction, utilizing a highly enriched target, is the method of choice.

Activation cross sections for reactions induced by 14 MeV neutrons on natural tin and enriched112Sn targets with reference to111In productionviaradioisotope generator112Sn(n, 2n)111Sn →111In

We measured activation cross sectionsviaγ-ray spectroscopy using high-purity germanium detectors for 16 reactions induced by (14.4 ± 0.2) MeV neutrons on isotopes of tin. The cross sections are:

Two112Sn targets enriched to 62.5% and 84%, respectively, were used for these measurements in addition to the natural tin. The cross sections were compared with experimental data found in the literature, with published empirical formulae and with model calculations including also the pre-equilibrium contribution. For reactions which do not involve protons from below the closedZ= 50 shell, the agreement to the data is reasonable, it is somewhat weaker for the (n,p) reactions and still worse in the case of (n, α), where, however, the pre-equilibrium component is not described properly by the models included so far. The possibility of production of111Sn →111In generator system is considered.

Level studies of 73As via 73Ge(p, nγ)73As reaction and density of discrete levels in 73As

The excited states of 73As have been investigated via the 73Ge(p, n?)73As reaction with the proton beam energies from 2.5-4.3 MeV. The parameters of the nuclear level density formula have been determined from the extensive and complete level scheme for 73As. The Bethe formula for the back-shifted Fermi gas model and the constant temperature model are compared with the experimental level densities.

Measurements and nuclear model calculations on proton-induced reactions on 103Rh up to 40 MeV: evaluation of the excitation function of the 103Rh(p,n)103Pd reaction relevant to the production of the therapeutic radionuclide 103Pd

Excitation functions were measured by the stacked-foil technique for the reactions 103Rh(p,n)103Pd, 103Rh(p,3n)101Pd and 103Rh(p,4n)100Pd from their respective thresholds up to 39.6 MeV. The radioactivity of the activation products was determined by high-resolution X-ray and gamma-ray spectrometry. Statistical model calculations taking into account the precompound effects were performed for all reactions, and good agreement was found with our data. A critical evaluation of the existing and present data for the 103Rh(p,n)103Pd reaction was carried out. Recommended cross sections and integral yields for this reaction of key importance in the production of the widely used therapeutic radionuclide 103Pd are given.

Cross sections of (n,p), (n,alpha) and (n,2n) reactions on some isotopes of zirconium in the neutron energy range of 10-12 MeV and integral tests of differential cross section data using a 14 MeV d(Be) neutron spectrum

Cross sections were measured for the 90Zr(n,alpha)87mSr, 90Zr(n,2n)89m,gZr, 91Zr(n,p)91mY, 92Zr(n,p)92Y, 94Zr(n,alpha)91Sr and 96Zr(n,2n)95Zr reactions over the neutron energy range of 11.4 to 12.4 MeV and for the 94Zr(n,p)94Y reaction from 9.2 to 12.4 MeV. Nuclear model calculations were performed up to 16MeV. The statistical model incorporating precompound effects reproduces excitation functions of the three major threshold reactions, namely (n,p), (n,alpha) and (n,2n), quite well. Spectrum averaged cross sections were measured using a thick target Be(d,n) neutron field at Ed = 14 MeV. For the same neutron field averaged reaction cross sections were deduced using the excitation functions measured in this work as well as those given in the ENDF/B-VI, JEF-2, JENDL-3.2, BROND and ADL-3 data files. A comparison of the experimental and deduced integral data helped validating the differential data.

Calculations for the excitation functions of 3-26 MeV proton reactions on 66Zn, 67Zn and 68Zn

Calculation of excitation functions of 66Zn(p,n)66Ga, 66Zn(p,n + p)65Zn, 66Zn(p,2n)65Ga, 67Zn(p,2n)66Ga, 68Zn(p,n)68Ga, 68Zn(p,2n)67Ga natZn(p,xn)66Ga and natZn(p,xn)67Ga reactions has been carried out using the statistical and pre-equilibrium nuclear reaction models in the 3-26 MeV energy range. The calculational results are compared with the reported measurements and evaluations.

Calculations for the excitation functions of the 63Cu(p,n)63Zn, 63Cu(p, 2n)62Zn and 65Cu(p,n)65Zn reactions

Calculations for the excitation functions of 63Cu(p, n)63Zn, 63Cu(p, 2n)65Zn and 65Cu(p, n)65Zn reactions have been carried out in 3-30 MeV energy range using statistical and pre-equilibrium nuclear reaction models. The calculations have been compared with reported measurements and discussed.