Dynamic Polarization Potential Research Articles

Deuteron breakup effects on the d + 12C, 15N, 16O, 24Mg, 32S, 58Ni, and 70Ge elastic scattering angular distributions

Motivated by the well-known n + p cluster structure of deuterons, which appears at breakup threshold energy of 2.225 MeV, the angular distributions (ADs) for elastically scattered deuterons from various targets, namely, 12C, 15N, 16O, 24Mg, 32S, 58Ni, and 70Ge at different energies, are investigated microscopically within the continuum discretized coupled channel (CDCC) method as well as an effective potential (Ueff), considered as the sum of cluster folding and dynamical polarization potentials. The Ueff potentials were employed successfully to reproduce the elastic ADs data for the considered systems in a wide range of energies. The investigation gives evidence for the applicability of the Ueff in describing the ADs data for many nuclear systems.

Detailed analysis of the 6Li breakup in the field of the 209Bi nucleus

Abstract At energies between 24 and 50 MeV, the angular distributions of 6Li + 209Bi elastic scattering are reanalyzed phenomenologically as well as microscopically. The performed analysis adds to previous studies and aims to further explore the cluster nature of the 6Li nucleus by examining the associated breakup effects on the elastic scattering channel, in addition to probing the consistency of the different implemented potentials in reproducing the considered data. The strong coupling to the breakup channel has a strong influence on elastic data and reproduces a repulsive dynamical polarization potential (DPP), which dramatically reduces the real potential strengths. Such an observed effect was simulated by introducing a semi-microscopic repulsive DPP as well as by applying the continuum discretized coupled channels (CDCC) method. The analysis was extended to check the effect of direct deuteron stripping 209Bi(6Li,d)211Po on the elastic 6Li + 209Bi channel.

Dynamics of 7Li breakup and its influence on elastic scattering: a study of 7Li + 144Sm system* *This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (AP19680284). A.A.Ibraheem express his appreciation to the Deanship of Scientific Research at King Khalid University, Saudi Arabia, for funding this work

The angular distributions of 7Li + 144Sm elastic scattering over the energy range of 21.6–52 MeV are reanalyzed utilizing various interaction potentials. The analysis aims to study the consistency of the implemented potentials in representing the considered data and investigate the cluster nature of the weakly bound 7Li projectile. This will aid in the better understanding the impacts of 7Li breakup on the elastic scattering channel. Strong coupling to the breakup channel has a substantial impact on the elastic data and reproduces a repulsive dynamical polarization potential, which drastically diminishes the real potential strength. This reported impact was simulated by introducing a semi-microscopic repulsive DPP and by implementing the method of continuum discretized coupled channels. The analysis was also extended to understand the impact of triton transfer on the elastic scattering data.

Threshold anomalies in 9Be + 12C

The extended optical model is used to simultaneously analyze the elastic scattering and fusion data for the weakly-bound system of 9Be + 12C in the low-energy region. Dynamic polarization potentials UF, UD, associated with fusion and direct couplings, respectively, are introduced. Corresponding fitting parameters leading to dispersive potentials are found, which provide good simultaneous descriptions of elastic and fusion data. The energy-dependent behavior of the polarization potentials establishes a striking difference with respect to that observed for weakly bound projectiles, including 9Be, on medium- and heavy-mass targets. Contrary to similar analyses made on weakly-bound systems, the real part of UD is found to be attractive in the present case. The observed behavior is discussed.

Analysis of α + 16O elastic scattering in the semi-microscopical dispersive optical model

We study the elastic scattering cross sections of the α +16O system at 49.5, 69.5, and 80.7 MeV using the optical potentials calculated in the framework of the semi-microscopical dispersive optical model. In this model, the optical potential contains an energy-independent part calculated in the double folding model with a realistic effective nucleon-nucleon interaction, as well as an energy-dependent dynamic polarization potential, the parameters of which are adjusted to the data. The parameters of the real and imaginary parts of the dynamic polarization potential are connected by the dispersion relations.

New microscopic analysis for 15N(d,p)16N neutron transfer reaction at 15 MeV

Inspired by the prevalent [Formula: see text] cluster structure of deuterons, which appears at an excitation energy of 2.225[Formula: see text]MeV, the recently measured angular distributions (ADs) for [Formula: see text]N([Formula: see text],[Formula: see text]N and [Formula: see text]N([Formula: see text],[Formula: see text]N systems at an energy of 15[Formula: see text]MeV X. Y. Li et al., [Phys. Rev. C 106, (2022) 025807] are microscopically analyzed using the continuum discretized coupled channel (CDCC) method. The extracted [Formula: see text] potential, considered as the coherent sum of cluster folding and dynamical polarization potentials, both derived from the CDCC computations, was then employed to investigate the [Formula: see text]N([Formula: see text],[Formula: see text]N neutron transfer reaction leading to the (2−, 0.0[Formula: see text]MeV), (0−, 0.12[Formula: see text]MeV), (3−, 0.298[Formula: see text]MeV), and (1−, 0.397[Formula: see text]MeV) [Formula: see text]N states. Since extracting reliable information on spectroscopic factors (SFs) is highly dependent on the interaction potential, the extracted [Formula: see text] was employed to get such information. The investigation gives evidence for the applicability of the [Formula: see text] in describing the elastic scattering and the neutron transfer ADs data. The extracted SFs for the [Formula: see text]N states under consideration are consistent with those that have been reported before.

Reaction channel contributions to the triton + Pb208 optical potential

Background: Well-established coupled channel and coupled reaction channel (CRC) processes make contributions to elastic scattering that are not included in standard folding models of the optical model potential (OMP). Such contributions have been established for $^{3}\mathrm{He}$ interacting with $^{208}\mathrm{Pb}$ but the corresponding contributions for $^{3}\mathrm{H}$ are expected to be different, particularly for pickup coupling.Purpose: To establish and characterize the contribution to the interaction potential between $^{3}\mathrm{H}$ and $^{208}\mathrm{Pb}$ that is generated by coupling to proton pickup (outgoing $^{4}\mathrm{He}$) channels; also to study the contribution of collective states and identify effects of dynamical nonlocality due to these couplings.Methods: CRC calculations, including coupling to collective states, will provide the elastic channel $S$-matrix ${S}_{lj}$ resulting from the included processes. Inversion of ${S}_{lj}$ will produce the local potential that yields, in a single channel calculation, the elastic scattering observables from the coupled channel calculation. Subtracting the bare potential from the inverted CRC potential yields a local and $l$-independent representation of the dynamical polarization potential (DPP). From the DPPs due to a range of combinations of channel couplings, the influence of dynamically generated nonlocality can be identified.Results: Coupling to $^{4}\mathrm{He}$ channels makes a smaller contribution to the $^{3}\mathrm{H}$ interaction than it does for incident $^{3}\mathrm{He}$. On the other hand coupling to inelastic channels makes a greater contribution than it does for $^{3}\mathrm{He}$. The nonadditivity of the DPPs implies their dynamical nonlocality.Conclusions: The DPPs established here challenge the notion that folding models, in particular local density models, provide a satisfactory description of elastic scattering of $^{3}\mathrm{H}$ from nuclei. Coupling to proton pickup channels induces dynamical nonlocality in the $^{3}\mathrm{H}$ OMP with implications for direct reactions involving $^{3}\mathrm{H}$. Departures from a smooth radial form for the $^{3}\mathrm{H}$ OMP should be apparent in high quality fits to suitable elastic scattering data. Future theories of the interaction of $^{3}\mathrm{H}$ with nuclei should include some representation of outgoing $^{4}\mathrm{He}$.

Analysis of 6Li+16O system using different theoretical methods

In this paper, we report on the [Formula: see text] system to which the crystal model (CM), the coupled reaction channel method (CRC), and continuum discretized coupled channel (CDCC) method were applied in addition to the distorted waves-Born approximation (DWBA), which was also applied to the [Formula: see text] system. Also, CM is folded with inelastic scattering. The analysis of the experimental data was performed simply with elastic and inelastic scattering in a first step. Then transfers have been studied like pp, nn, dd, [Formula: see text] and [Formula: see text]B using the CRC method. The CRC method was used to study many suggested combinations of transfers with elastic scattering. The analyses were performed for 6Li elastically scattered from [Formula: see text]O in the energy range of 13–50[Formula: see text]MeV. The cluster structure of [Formula: see text] has been examined during the CDCC method in addition to the breakup of the weakly bound structure of the same nucleus. A dynamic polarization potential (DPP) was used at [Formula: see text][Formula: see text]MeV. A comparison between different models was performed. A general agreement was found between the experimental data and the proposed theoretical methods.

Comparing the Corrosion Resistance of 5083 Al and Al2O33D/5083 Al Composite in a Chloride Environment.

In this study, an Al2O33D/5083 Al composite was fabricated by infiltrating a molten 5083 Al alloy into a three-dimensional alumina reticulated porosity ceramics skeleton preform (Al2O33D) using a pressureless infiltration method. The corrosion resistance of 5083 Al alloy and Al2O33D/5083 Al in NaCl solution were compared via electrochemical impedance spectroscopy (EIS), dynamic polarization potential (PDP), and neutral salt spray (NSS) tests. The microstructure of the two materials were investigated by 3D X-ray microscope and scanning electron microscopy aiming at understanding the corrosion mechanisms. Results show that an Al2O33D/5083 Al composite consists of interpenetrating structure of 3D-continuous matrices of continuous networks 5083 Al alloy and Al2O33D phase. A large area of strong interfaces of 5083 Al and Al2O33D exist in the Al2O33D/5083 Al composite. The corrosion development process can be divided into the initial period, the development period, and the stability period. Al2O33D used as reinforcement in Al2O33D/5083 Al composite improves the corrosion resistance of Al2O33D/5083 Al composite via electrochemistry tests. Thus, the corrosion resistance of Al2O33D/5083 Al is higher than that of 5083 Al alloy. The NSS test results indicate that the corrosion resistance of Al2O33D/5083 Al was lower than that of 5083 Al alloy during the initial period, higher than that of 5083 Al alloy during the development period, and there was no obvious difference in corrosion resistance during the stability period. It is considered that the elements in 5083 Al alloy infiltrated into the Al2O33D/5083 Al composite are segregated, and the uniform distribution of the segregated elements leads to galvanic corrosion during the corrosion initial period. The perfect combination of interfaces of Al2O33D and the 5083 Al alloy matrix promotes excellent corrosion resistance during the stability period.

Reaction channel contributions to the proton +Pb208 optical potential at 40 MeV

Background: Reaction channel coupling substantially modifies the real and imaginary nucleon-nucleus interactions for nuclei of $Z=20$ or less in ways that cannot be represented as uniform renormalizations of folding model potentials. For such nuclei coupling to inelastic channels also contributes. This raises the question of the effect of these couplings for heavier target nuclei.Purpose: To establish and characterize the contribution to the proton-nucleus interaction generated by coupling to neutron pickup (outgoing deuteron) channels for 40 MeV protons on the heavy closed shell nucleus $^{208}\mathrm{Pb}$. To identify and evaluate the consequent dynamical non-locality.Methods: Coupled reaction channel (CRC) calculations provide the elastic channel $S$-matrix ${S}_{lj}$ due to the included processes. Inversion of ${S}_{lj}$ will produce the local potential that would yield, in a single channel calculation, the elastic scattering observables from the CRC calculation. Subtracting the bare potential of the CRC calculations gives a local and $l$-independent representation of the dynamical polarization potential (DPP). From the DPPs due to various combinations of channel couplings, the influence of dynamically generated nonlocality can be identified.Results: Coupling to deuteron channels generates a repulsive component for the real potential and an absorptive component for the imaginary term. The radial shapes of both terms were modified in ways that could not be represented by uniform renormalization; the rms radius of the real part was substantially altered. Evidence of the dynamical nonlocality of the DPP due to pickup is provided by the nonadditivity of contributions of different couplings and other effects. For the doubly closed shell $^{208}\mathrm{Pb}$ coupling to low-lying (nongiant) collective states has a very small effect on elastic scattering, making a negligible contribution compared with pickup, and was not included.Conclusions: The DPPs established here strongly challenge the notion that folding models, in particular local density models, provide a satisfactory description of elastic scattering of protons from heavy nuclei. Coupling to neutron pickup channels induces dynamical nonlocality in the proton optical model potential with implications for direct reactions.

Calculation of Coulomb breakup cross sections using a new Coulomb dynamical polarization potential

A new method for calculating the Coulomb breakup of unstable neutron-rich isotopes at high energies is presented. The calculations employ the eikonal approximation and use a new Coulomb dynamical polarization potential (CDPP), calculated by solving the Schr\"odinger equation for the entire motion of the exotic projectile as a two-body cluster structure using the adiabatic approximation and incorporating excitations to the continuum. Calculations for some exotic isotopes are compared with Coulomb dissociation cross section data and found to be in good agreement.

Extensive investigation of the 6Li + 27Al and 6He + 27Al systems using different models

In this paper, the angular distributions (ADs) for 6Li + 27Al and 6He + 27Al elastic scattering in the energy range of 7–88 MeV and 9.5–13.4 MeV, respectively, are reanalyzed utilizing various phenomenological and microscopic potentials. The purpose of this work is to investigate the cluster nature of the weakly stable 6Li and the two-neutron halo 6He projectiles to check the associated breakup effects on the scattering data and to examine the consistency of the results obtained across different implemented potentials. A novel semi-microscopic dynamical polarization potential is applied to the 6Li + 27Al system to simulate the coupling effects on the breakup channel. The ADs for the 6He + 27Al system are described using the continuum discretized coupled channels (CDCC) method, which considers the coupling to the resonant (2+, 1.8 MeV) state and twelve continuum bins belonging to L = 0, 1, and 2 states as per the adopted model for truncation and discretization of the continuum.

Comparing the effects of nonlocal sources on the neutron-nucleus elastic scattering process

The wave function of a nonlocal potential is reduced or enhanced in the nuclear interior where the potential acts. This is known as the Perey effect. We use the Perey damping factor to demonstrate that the phenomenological Perey-Buck and the velocity-dependent nonlocal potentials simulate sources of nonlocality. We compare their effectiveness in simulating nonlocal effects by comparing their corresponding Perey damping factors. The importance of the nonlocality arising from the dynamic polarization potential is also estimated by determining the corresponding damping factors. To calculate the needed wave functions corresponding to the local and nonlocal potentials, we determine the parameters of each considered potential by fitting the experimental angular distributions for neutron scattering off nuclei from 6Li to 208Pb for various energies in the range 9 - 35 MeV. Our results show that the nonlocality simulated by each of the three potentials is energy and angular momentum dependent. The effect of the nonlocality simulated by the velocity-dependent potential increases with increasing mass number and, for a given target, becomes more important for higher partial waves. The Perey-Buck potential simulates a nonlocality that is more important for light nuclei. Finally, the nonlocality arising from the dynamic polarization potential increases when more inelastic channels are coupled to the ground state, and becomes more important with increasing energy.

The role of dynamic absorption and polarization potentials in relativistic excitation of xenon

The role of dynamic absorption and polarization potentials in relativistic excitation of xenon

Break-up effect of the weakly bound 6Li nuclei scattered by 208Pb target

Using different potentials based on phenomenological, semi microscopic, and microscopic models, we investigated the reaction dynamics induced by the weakly bound 6Li ions on a heavy mass target 208Pb at sixteen energy sets ranging from 25 MeV to 210 MeV. The 6Li cluster nature and its dissociation into a core (α-particle) and a valence particle (deuteron) orbiting this core was taken into consideration using the cluster folding model (CFM). The new version of Sao Paulo potential (SPP2) is also used to investigate 6Li+208Pb data. In order to reproduce the experimental data, the strength of real part of potential created using SPP and CFM should be reduced by ~ 49 % and 62 %, respectively. The data could be well reproduced using non-renormalized real cluster folding potential, if an additional dynamical polarization potential (DPP) of repulsive real surface form is introduced. The observed reduction in the strength of the real double folded and cluster folding potentials is due to the break-up effect of 6Li.

Superior corrosion and wear resistance of AZ91D Mg alloy via electrodeposited SiO2–Ni-based composite coating

Improving the poor corrosion resistance and high wear defects of AZ91D Mg alloy by electroplating coating could be of importance to enhance its industrial applications. In this paper, we propose a method for constructing micro-nano structures by electrodeposition of SiO2–Ni-based composite coatings on AZ91D Mg alloy. Meanwhile, we systematically compared the effects of different SiO2 doping amounts on the properties of SiO2–Ni-based coating. The AFM and SEM results showed that as-prepared composite coating with 10 g/L SiO2 doping had relatively largest roughness and the most micro-nano structures. By the analysis of XRD, the grain size of SiO2–Ni-based composite coating was lower than the pure nickel coating. Mechanical and tribological results showed that the SiO2–Ni-based composite coating with 10 g/L SiO2 doping could exhibit the maximum micro-hardness, minimum friction coefficient and lowest specific wear rate. It exhibited excellent wear resistance than that of other coating. In addition, dynamic polarization potential and electrochemical impedance spectroscopy (EIS) tests analysis presented that composite coating could have excellent corrosion resistance compared to pure Ni coating. Consequently, AZ91D Mg alloy could achieve superior corrosion and wear resistance via electrodeposited SiO2–Ni-based composite coating, indicating it has a widely potential in the industrial applications.

Reanalysis of 6Li+90Zr angular distributions using different nuclear potentials

The experimental angular distributions for 6Li elastically scattered from a 90Zr target in the energy range 14.89–240 MeV are theoretically reanalyzed using phenomenological and semi-microscopic potentials. The phenomenon of the break-up threshold anomaly (BTA) is well represented in the various used potentials. In analyzing nuclear systems induced by weakly bound projectiles such as 6Li, the well-known reduction in the strength of the real part of potential generated based on double folding (DF) and cluster folding (CF) models is also observed. The Sao Paulo potential (SPP) is used to perform double folding calculations. In order to fit the data fairly, a reduction of ∼ 42% and 45% in the strength of the microscopic real part of potential constructed using SPP and CFM, respectively, is found to be required. By including an additional dynamical polarization potential, the data are also reproduced without renormalizing the real cluster folding potential.

Coulomb breakup reaction of loosely bound F17 with dynamic polarization potentials

We investigate the elastic scattering, inelastic scattering, breakup reaction, and total fusion reactions of the $^{17}\mathrm{F}+^{208}\mathrm{Pb}$ system using an optical model approach by including the dynamical polarization potential. In particular, we focus on the breakup reaction channels, whose effects on other reactions have been argued to be small. By exploiting two different potentials composed of a surface-type Woods-Saxon potential, which were obtained by a fitting analysis, and a Love-type optical potential, the breakup reaction cross sections are explained with other elastic and quasielastic scattering cross sections. For the breakup reaction at ${E}_{\text{lab}}=170$ MeV in the forward angle region, where only exclusive reaction data are known, inclusive breakup reaction data are deduced from available theoretical and experimental $E1$ strength values. We discuss the breakup reaction effects on the other nuclear reactions related to the $^{17}\mathrm{F}$ projectile in detail.

Simultaneous analysis of elastic scattering and fusion in He6+Zn64 : A transition in direct reaction mechanisms, striking threshold anomalies, and halo effects

Using the extended optical model, a simultaneous analysis is carried out of elastic scattering and fusion reactions induced by the neutron halo $^{6}\mathrm{He}$ projectile on a $^{64}\mathrm{Zn}$ target. Dynamic polarization potentials ${U}_{F}$, ${U}_{D}$ are introduced which can be associated to fusion and direct couplings, respectively. Appropriate fitting parameters leading to dispersive potentials are found which provide a good simultaneous description of the data. An unexpected local maximum is uncovered in the energy dependence of the total reaction cross sections, indicating a transition in the involved direct reaction processes, and a possible underlying mechanism is discussed. ${U}_{F}$ is found to follow the normal threshold anomaly but with an unusually large threshold energy. ${U}_{D}$, on the other hand, exhibits a breakup threshold anomaly, but with a strikingly high value of the peak energy, which can be associated to the above-mentioned transition. The results also are discussed within the context of possible halo effects.

Reaction channel contributions to proton scattering at 65 MeV

Background: Well-established coupled channel (CC) and coupled reaction channel (CRC) processes make contributions to elastic scattering that are absent from local density folding models.Purpose: To establish and characterize the contribution to the proton optical model potential (OMP) made by the coupling to neutron pickup channels, in particular the proton OMP for 65 MeV protons on $^{48}\mathrm{Ca}$ and $^{40}\mathrm{Ca}$. Also to relate this contribution to results for ${}^{40}\mathrm{Ca}$ at lower energies; to investigate the dynamical nonlocality of this contribution; to characterize the effect on the OMP of breakup of the deuteron.Methods: CRC calculations of neutron pickup and CC calculations of collective states, provide the elastic channel $S$ matrix ${S}_{lj}$. Inversion of ${S}_{lj}$ produces a local potential that yields, in a single channel calculation, the elastic scattering observables from the CC/CRC calculation. Subtracting the bare potential yields a local and $l$-independent representation of the dynamical polarization potential, DPP. From the DPPs due to a selection of channel couplings the influence of dynamically generated nonlocality can be identified. The effect of coupling to the deuteron breakup continuum is also identified.Results: For $^{40}\mathrm{Ca}$, coupling to pickup channels has an effect on observables somewhat weaker than that at 30 MeV, and much less than for pickup coupling for $^{48}\mathrm{Ca}$. The DPPs have similar general properties in each case, but are much larger in magnitude for $^{48}\mathrm{Ca}$. Subsequent breakup of the deuteron makes a large contribution to the DPP, and hence to the OMP. The formal DPPs due to pickup coupling exhibit dynamical nonlocality.Conclusions: The DPPs challenge local density folding models for elastic scattering. The breakup of the deuteron must henceforth be included in calculations of the DPP due to neutron pickup in proton scattering. Pickup coupling effects are still substantial at 65 MeV. No smoothly varying global OMP could fit proton elastic scattering from both ${}^{40}\mathrm{Ca}$ and ${}^{48}\mathrm{Ca}$.