Phenomenological Optical Model Potential Research Articles

Measurement of proton induced absolute production cross-section of 6.13, 6.92 and 7.12 MeV γ-rays from 16O(p,p ′γ )16O reaction

In this article, we report the absolute production cross-section of 6.13, 6.92 and 7.12 MeV γ-rays from the 16O(p,p ′γ )16O reaction for incident proton energy range of 8-16 MeV. Angular distributions of the three γ-rays have been measured for seven angles at 9 MeV proton energy. A detailed phenomenological optical model potential (OMP) was set up to analyse the cross-section data. The OMP parameters were optimised using elastic, polarization and total reaction data available in the literature for protons and neutrons. Low-lying states of 16O were coupled, the optical potential was deformed using deformation parameters, and several resonances were included in the calculations to account for the nuclear structure effects. The potentials so generated have been used to calculate the differential and total cross sections for both 16O(p,p ′ )16O and 16O(p,p ′γ )16O reactions. Our calculated cross-sections are in fairly good agreement with our measured data for 6.13, 6.92 and 7.12 MeV γ-rays. However, there still exist discrepancies in reproduction of the finer details of the cross sections. The comparisons of the calculations with the data bring forth the rather complex roles of channel couplings, resonances in the p+16O system and target deformation in the variation of the cross sections with projectile energy. The increased contribution of nuclear structure effects in light mass nuclei, leads to an apparent loss of predictive power of the theoretical calculation, as we approach the low-energy region of less than 10 MeV projectile energy.

Global phenomenological optical model potential for 14N-nucleus elastic scattering

In this paper, a set of global optical model potential parameters of [Formula: see text]N is obtained by fitting the experimental data of the elastic scattering angular distributions for the targets from [Formula: see text]Mg to [Formula: see text]Pb below 200 MeV. The global optical model potential parameters of [Formula: see text]N-nucleus reactions obtained are analyzed and used to describe the experimental data. It is found that the present form of the global optical model potential could reproduce the experimental data. Moreover, the elastic scattering angular distributions for the reactions of [Formula: see text]N inducing on some lighter targets and the elastic scattering observable quantity for the reactions involving [Formula: see text]N projectile are predicted using the obtained global optical model potential, and a reasonable description of the experimental data is obtained by comparing with the existing corresponding experimental data.

Angular zone of influence for fusion and direct reactions on elastic scattering of 6Li with 58Ni, 59Co, 64Ni, and 64Zn

Recently, a systematic study of fusion and elastic scattering data was performed for the 6Li + (58Ni, 59Co, 64Ni, 64Zn) systems. Appropriate polarization potentials satisfying the dispersion relation were extracted, which can be associated to fusion and direct reaction couplings, respectively. By examining the relative strengths of the corresponding absorptive parts, a semiclassical analysis can be carried out which gives an indication about the angular range where direct (fusion) reactions are more important in determining the elastic scattering angular distributions. The results of such an analysis are presented for all four systems. The developed method is useful to explore the sensitivity of the elastic scattering angular distributions to the radial details of the phenomenological optical model potential. An example is presented where large sensitivity to distances smaller than the Coulomb barrier radius is evident.

Microscopic optical potential for 7Li

A microscopic optical potential (MOP) for 7Li without free parameter is obtained by folding the MOPs of its internal nucleons with their density distributions. An isospin-dependent nucleon MOP based on the Skyrme nucleon–nucleon effective interaction is used as the nucleon optical potential. Cluster model is employed to construct the internal wave function of 7Li and derive the density distributions of the internal nucleons. The 7Li MOP is used to calculate the elastic-scattering angular distributions and reaction cross sections for target nuclei from 27Al to 208Pb at incident energies up to 450 MeV. The results are compared with experimental data and the calculated results by a global phenomenological optical model potential. Generally the MOP can reproduce the experimental data reasonably well, and in many cases it is comparable to the global phenomenological optical potential.

Applicability of 9Be global optical potential to description of 8,10,11B elastic scattering * * Supported by the National Natural Science Foundation of China (11405099 and 11575291). This work is also a part of IAEA Coordinated Research Projects (CRPs) on Recommended Input Parameter Library (RIPL) for Fission Cross Section Calculations (20464)

We achieved a set of 9Be global phenomenological optical model potentials by fitting a large experimental dataset of the elastic scattering observable for target mass numbers from 24 to 209. The obtained 9Be global optical model potential was applied to predict elastic-scattering angular distributions and total reaction cross-sections of 8,10,11B projectiles. The predictions are made by performing a detailed analysis comparing with the available experimental data. Furthermore, these elastic scattering observables are also predicted for some lighter targets outside of the given mass number range, and reasonable results are obtained. Possible physical explanations for the observed differences are also discussed.

Microscopic optical potentials for Li isotopes

The microscopic optical potentials for Li isotopes (A=6,7) without free parameter are obtained by folding the microscopic optical potentials of their internal nucleons with density distributions generated from corresponding internal wave functions of Li isotopes. An isospin-dependent nucleon microscopic optical potential based on the Skyrme nucleon-nucleon effective interaction is used as the nucleon optical potential. Shell model is employed to construct the internal wave functions of Li isotopes and derive their density distributions of internal nucleons. The Li microscopic optical potentials are used to calculate the elastic-scattering angular distributions and reaction cross sections. The results reproduce experimental data well and are comparable to those calculated by phenomenological optical model potentials in many cases.

Measurement of Ni58(p,p)Ni58 elastic scattering at low momentum transfer by using the HIRFL-CSR heavy-ion storage ring

The very first in-ring reaction experiment at the Cooler Storage Ring at the Heavy Ion Research Facility in Lanzhou (HIRFL-CSR), namely proton elastic scattering on stable $^{58}\mathrm{Ni}$ nuclei, is presented. The circulating $^{58}\mathrm{Ni}^{19+}$ ions with an energy of 95 MeV/u were interacting repeatedly with an internal hydrogen gas target in the experimental storage ring (CSRe). Low-energy proton recoils from the elastic collisions were measured with an ultra-high vacuum compatible silicon-strip detector. Deduced differential cross sections were normalized by measuring $k$-shell x rays from $^{58}\mathrm{Ni}^{19+}$ projectiles due to the $^{58}\mathrm{Ni}^{19+}\text{\ensuremath{-}}{\mathrm{H}}_{2}$ ionization collisions. Compared to the experimental cross sections, a good agreement has been achieved with the theoretical predictions in the measured region, which were obtained by using the global phenomenological optical model potentials. Our results enable new research opportunities for optical model potential studies on exotic nuclides by using the in-ring reaction setup at the HIRFL-CSR facility.

Study of (p,n) Reaction in a Wide Energy Range

In this paper, the quasi-elastic scattering (p, n) reactions are studied for a wide range of target nuclei 13C, 14C, 48Ca, 90Zr and 208Pb and different incident energies (35-160 MeV). The phenomenological Optical model potential and density independent approaches are used for these calculations in comparison with density dependent semi-microscopic approach. The density dependent parameters are modified to achieve the best calculations for many targets at different energy levels.

Applicability of 9Be global optical potential to reactions of 7,10,11,12Be * * Supported by the National Natural Science Foundation of China (11405099, 11575291), this work is also a part of IAEA Coordinated Research Projects (CRPs) on Recommended Input Parameter Library (RIPL) for Fission Cross Section Calculations (20464)

Elastic scattering angular distributions and total reaction cross-sections of 7,10,11,12Be projectiles are predicted by the systematic 9Be global phenomenological optical model potential for target mass numbers ranging from 24 to 209. These predictions provide a detailed analysis by their comparison with the available experimental data. Furthermore, these elastic scattering observables are also predicted for some targets out of the mass number range. The results are in reasonable agreement with the existing experimental data, and they are presented in this study.

Global phenomenological optical model potentials for 8,10,11B projectiles

Based on the obtained [Formula: see text] global optical model potential, the global phenomenological optical model potential for [Formula: see text] projectile is obtained by fitting the experimental data of [Formula: see text] elastic scattering angular distributions from [Formula: see text] to [Formula: see text] targets with incident energies below 100[Formula: see text]MeV. Using the found global optical model potential, the reaction cross-sections are predicted and compared with the available experimental data. Moreover, the elastic-scattering angular distributions and reaction cross-sections for isotopic chain [Formula: see text] projectiles are predicted by the [Formula: see text] global optical model potential at different incident energies. These results are also compared with the corresponding experimental data. The performance shows that the [Formula: see text] global phenomenological optical model potentials can give a satisfactory description for elastic scattering of these projectiles.

Li6 global phenomenological optical model potential

A systematic global phenomenological optical model potential for a $^{6}\mathrm{Li}$ projectile is established by studying the experimental data of elastic-scattering angular distributions and reaction cross sections from $^{24}\mathrm{Mg}$ to $^{209}\mathrm{Bi}$ below 250 MeV. Based on the obtained $^{6}\mathrm{Li}$ global phenomenological optical model potential, the extensive analysis of $^{6}\mathrm{Li}$ elastic scattering is performed for different targets by comparing with the corresponding experimental data. It is found that the results calculated using the global optical model potential are consistent with a large body of elastic-scattering data for the reactions involving $^{6}\mathrm{Li}$ incidence. Application of the global potential is performed to predict the elastic-scattering angular distributions and reaction cross sections for those targets outside of the mass range. The reasonable results are also obtained.

Global phenomenological optical model potential for the Li7 projectile nucleus

A new global phenomenological optical model potential for the $^{7}\mathrm{Li}$ projectile is derived from the available experimental data of elastic-scattering angular distributions and reaction cross sections from $^{27}\mathrm{Al}$ to $^{208}\mathrm{Pb}$ with incident energies below 200 MeV. It is based on a smooth, unique functional form for the energy dependence of the potential depths, and physically constrained geometry parameters. The elastic-scattering angular distributions and reaction cross sections for other targets are also predicted by the obtained $^{7}\mathrm{Li}$ global phenomenological optical model potential at different incident energies. These results are further compared with the corresponding experimental data. The performance shows that the $^{7}\mathrm{Li}$ global phenomenological optical model potential can give a satisfactory description for $^{7}\mathrm{Li}$ elastic scattering.

Global phenomenological optical model potential for Li8 projectile

Global phenomenological optical model potential for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Li</mml:mi><mml:mprescripts /><mml:none /><mml:mn>8</mml:mn></mml:mmultiscripts></mml:math> projectile

Global phenomenological and microscopic optical model potentials for alpha

The global phenomenological and microscopic optical model potentials for alpha with the incident energy up to 400 MeV are obtained. The global phenomenological optical model potential is extracted by simultaneously fitting the experimental data of total reaction cross sections and elastic scattering angular distributions in the mass range of target nuclei 20 ≤ A ≤ 209. The microscopic optical model potential is obtained by the Green function method through nuclear matter approximation and local density approximation based on the effective Skyrme nucleon-nucleon interaction. Both optical model potentials are used to calculate the reaction cross sections and elastic scattering angular distributions for the target nuclei in the mass range 12 ≤ A ≤ 209 at incident alpha energies up to 400 MeV. The calculated results are compared with the experimental data, and the calculated results by phenomenological and microscopic optical model potentials are also compared with each other.

Global 6He optical model potential

A set of global [Formula: see text]He phenomenological optical model potential (OMP) parameters with incident energies up to 250[Formula: see text]MeV is obtained. They are based on a smooth, unique functional form for the energy dependence of the potential depths, and on physically constrained geometry parameters. The available experimental data including the reaction cross-sections and elastic scattering angular distributions from target [Formula: see text]Li to [Formula: see text]Bi are used. The global OMP parameters obtained for [Formula: see text]He are analyzed and used to calculate the reaction for [Formula: see text]He projectile. It is found that the present form of the global OMP can reproduce the experimental data for [Formula: see text]He and [Formula: see text]He projectiles.

The effect of breakup of 6Li on elastic scattering and fusion with 28Si at near barrier energies

Elastic scattering angular distributions for 6Li+[Formula: see text]Si system were measured at [Formula: see text] and analyzed along with the existing data from the previous measurements in the energy range of [Formula: see text]. The measured cross-sections and the existing data, forming a set of angular distributions over a range of E/[Formula: see text], were analyzed using the phenomenological optical model potential (OMP). Three different sets of potential parameters were used. The energy dependence of the real and the imaginary potential strengths were, subsequently, extracted at the radius of sensitivity ([Formula: see text]) for the system. Continuum Discretized Coupled Channel (CDCC) calculation was performed to explore the contribution of projectile break-up (BU) on the observed energy dependence of the effective potential for elastic scattering of 6Li from [Formula: see text]Si. The energy variation of the strength of the real potential with continuum coupling was found to agree with the energy dependence of the same extracted from the (OMP) analysis at energies around the barrier. But the behavior of the imaginary strength appeared to be different. The calculated fusion cross-sections, including the effect of BU, clearly overestimated the measured fusion excitation function data in the below and near barrier energies but compared well with the data at higher energies.

Evaluation of neutron nuclear data on xenon isotopes

ABSTRACTNeutron nuclear data of Xe isotopes have been evaluated in the energy region, including the resolved resonance one, from 1 keV to 20 MeV by using the theoretical nuclear reaction models. The phenomenological optical model potential was employed to calculate the total cross section for natural Xe with the coupled-channels method. The cross sections for channels of capture, (n, 2n), (n, p) and (n, α) reactions were calculated and compared with available experimental results including recently measured data. The elastic scattering angular distributions and particle emission spectra were calculated, although there is no experimental information available. Reaction cross sections of evaluated libraries were considered for comparison with the calculated results. The presently calculated cross sections reproduce better the available experimental data.

Global optical model potential for alpha projectile

A new set of global phenomenological optical model potential (OMP) parameters for alpha projectile is obtained by simultaneously fitting the experimental data of reaction cross-sections and elastic scattering angular distributions in the mass range of target nuclei [Formula: see text] at incident energies below 386[Formula: see text]MeV. The total reaction cross-sections and elastic scattering angular distributions are calculated and compared with experimental data for different targets. A satisfactory agreement is presented between them.

Systematic nonlocal optical model potential for nucleons

Based on the Perey–Buck nonlocal optical model potential, F. Perey and B. Buck, Nucl. Phys. 32 (1962) 353, we obtain a new set of nonlocal optical model potential (NLOMP) parameters for proton and neutron scattering off nuclei. The experimental angular distributions of nucleon scattering off nuclei ranging from 27 Al to 208 Pb with incident energies around 10 MeV to 30 MeV are adopted in the fitting procedures. This NLOMP is energy independent. The chi-squares χ2 obtained in the fittings are comparable to those from the KD03 phenomenological local optical model potentials (OMP) A. Koning and J. Delaroche, Nucl. Phys. A 713 (2003) 231. Good agreement is found in comparisons between optical model calculations using this NLOMP and KD03 in their reproduction to the experimental angular distributions of elastic scattering cross-sections and analyzing powers.

Proton Spectroscopic Factors Deduced from Helium-3 Global Phenomenological and Microscopic Optical Model Potentials

Global phenomenological GDP08 and microscopic helium-3 optical model potentials have been recently derived. We evaluate these two potential sets by comparing the elastic scattering data of 25 MeV 3He on 16O, 18O, 19F, 23Na, 24Mg, 25Mg, 26Mg, 27Al, 28Si, 30Si, 31P, 32S, 34S, 35Cl, 37Cl, and 39K isotopes. Using the deuteron angular distributions calculated with the distorted wave Born approximation model, we extract the ground-state proton spectroscopic factors from (3He, d) reactions on the same set of nuclei. The extracted proton spectroscopic factors are compared with the large-basis shell-model calculations.