Semi-microscopic Analysis Research Articles

Microscopic and Semi-Microscopic Analysis of the Deuterons Elastically Scattered by Light Nuclei

Microscopic and Semi-Microscopic Analysis of the Deuterons Elastically Scattered by Light Nuclei

APPLICATION OF THE NEW B3Y-FETAL POTENTIAL IN THE SEMI-MICROSCOPIC ANALYSIS OF THE SCATTERING OF ACCELERATED 6LI - LITHIUM AND 16O - OXYGEN NUCLEI FROM THE 12C - CARBON NUCLEUS

The phenomenological and semi-microscopic values of the potentials found in the angular distribution of scattering of ions 6Li -lithium, 16О -oxygen from the target nucleus 12C-carbon accelerated at low energies are determined.The experimental data of elastic scattering were analyzed based on the optical model and the doublefolding model.Based on the folding model, the density-dependent new Fetal potential of Yukawa 3 terms of effective nucleon-nucleon interactions was first used. The density-dependent Fetal, Paris, Reid microfolding potentials were constructed in the doublefolding model as a real part of the optical potential. The efficacy of the new Fetal micropotential at laboratory energies of 28 MeV and 30 Mev for the 16О+12С nuclear system was studied in comparison with the Reid, Paris variants. The efficacy of the new Fetal potential at laboratory energies of 12.3 MeV and 20 MeV for the 6Li+12Csystem has been studied in comparison with Reid and Paris potentials. The relative errors of phenomenological theoretical analysis and experimental cross-sections were determined in the range of 1.1 -3.0. As a result of semimicroscopic analysis, the coefficients of renormalization of folding potentials in the range Nr=0.8-1.0 were determined. The data obtained will be used in various fundamental research, in particular in future thermonuclear installations and nuclear astrophysics

INVESTIGATION OF THEENERGY DEPENDENCE OF THE INTERACTION POTENTIALS OF THE 16O+12С NUCLEAR SYSTEM WITH A SEMI-MICROSCOPIC METHOD

The study of the collision of heavy ions with light nuclei at low energy is important in nuclear physics, thermonuclear energy,and astrophysics. The high-precision values of the nuclear system described at an energy close to the Coulomb barrier are used to control the synthesis of light nuclei inside thermosynthesis. For cross sections of reactions of light nuclei on the sun, plasma,and stars, we can use the parameters we have set. The article presents a microscopic approach to describing the process of nuclear-nuclear interaction.In the phenomenological approach, which determines empirical values based on comparison with experimental data, it is possible to find many sets of parameters with potentials that characterize the cross-section well. But the question arises which of them are real.Therefore, it is necessary to additionally describe microscopic potentials. For the same reason, a semi-microscopic analysis was carried out, which describes the imaginary part of the nuclear potential on the basis of an optical model, and the real part on a double-folding model.The folding potential is constructed depending on the effective nucleon-nucleon interaction based on the matrix element of two nucleons and the density of the nucleon distribution.As a result of the analysis, differential cross sections and optimal parameters were determined that well characterize the experimental cross sections of the 16О+12C nuclear system at energies ELab=20, 24, 36 MeV. The coefficients of normalization of differential cross sections, described on the basis of real microfolding potentials, were determined in the range N=0.85-1.0.

Cluster folding optical potential analysis for 6Li+28Si elastic scattering

Available experimental angular distribution data for 6Li+28Si elastic scattering in the energy range 16 – 318 MeV are re-analyzed phenomenologically on the basis of optical model using Woods-Saxon (WS) potentials for both real and imaginary parts, while the semi microscopic analysis was performed on the basis of cluster folding potential. Cluster folding potential was generated based on the appreciable cluster structure and breakup of 6Li into a deuteron orbiting a core of α-particle. Although several data sets in a wide range of energies are subjected to investigation, the theoretical calculations using the different concerned potentials are fairly reproduced the experimental data in the whole energy range. The extracted real and imaginary volume integrals and reaction cross sections values are compared to the previously reported ones and they found to be in a good agreement

Semimicroscopic analysis of Li6+Si28 elastic scattering at 76 to 318 MeV

Semimicroscopic analysis of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>Li</mml:mi><mml:mprescripts /><mml:none /><mml:mn>6</mml:mn></mml:mmultiscripts><mml:mo>+</mml:mo><mml:mmultiscripts><mml:mi>Si</mml:mi><mml:mprescripts /><mml:none /><mml:mn>28</mml:mn></mml:mmultiscripts></mml:mrow></mml:math> elastic scattering at 76 to 318 MeV

Low-lying12C continuum states in three-αmodel

The electromagnetic monopole (E 0) transition of the 12 C nucleus, the 0+ ground state to three α -particles (3α ) continuum states, is calculated by applying the Faddeev three-body formalism in coordinate space accommodating the long range Coulomb potential between α particles. Results show that there are two 0+ states, 12 C(03 + ) and 12 C(04 + ) states at excitation energies around 10 MeV, which is consistent with results of recent semi-microscopic calculations and analysis of α-12 C inelastic scattering.

An efficient method to predict the heat transfer performance of a louver fin radiator in an automotive power system

A numerical method to efficiently predict heat transfer phenomena of a louver fin radiator was presented — multi-scale semimicroscopic heat exchange (SHE) method. This method consists of microscopic analysis and semimicroscopic analysis. To predict heat transfer characteristics of a louver fin element, the microscopic analysis employs modeling of the detailed geometry of a fin element. Numerical models for the heat transfer rate and flow friction derived from the microscopic analysis are then used for simulations of the full radiator model in semimicroscopic analysis. In the semimicroscopic analysis, conjugate heat transfer is analyzed for the domain with the radiator whose louver fin area is replaced by a porous media. The results with the proposed method show a good agreement with the experimental data. The proposed method can be used to predict flow and heat transfer characteristics of a realistic louver fin radiator with a reduced cost and sufficient accuracy.

Semimicroscopic Dispersive Analysis of Nuclear-Nuclear Collisions on the Basis of Folding Potential

A semimicroscopic analysis of a set of experimental data of elastic α + 12C scattering was performed at several laboratory energies. The Woods-Saxon parameters were adjusted to obtain the best χ2 fit to the scattering data. The energy systematics of the positions of Airy minima was constructed, and it was shown that their positions depend linearly on the inverse center of mass energy. The parameters of the model potential have been determined unambiguously. It has been shown that the energy dependence of the volume integrals satisfies the dispersion relation and agrees well with the results obtained within a phenomenological analysis. Also, it has been shown that the found positions of the Airy minima satisfy the rule of the quadratical dependence of the position of the Airy minima on the reduced mass of the colliding nuclei.

Analyzing Power in Elastic Scattering of Polarized Protons from Neutron-rich Helium Isotopes

The vector analyzing power has been measured for the elastic scattering of neutron-rich 6He from polarized protons at 71 MeV/nucleon. Two approaches based on local one-body potentials were applied to investigate the spin-orbit interaction between a proton and a 6He nucleus. An optical model analysis revealed that the spin-orbit potential for 6He is characterized by a shallow and long-ranged shape compared with the global systematics of stable nuclei. A semi-microscopic analysis with a α + n + n cluster folding model suggests that the inclusion of realistic interaction between a proton and the α core is important in describing the p-6He elastic scattering.

Phenomenological and semi-microscopic analysis for 16O and 12C elastically scattering on the nucleus of 16O and 12C at Energies near the Coulomb barrier

The nuclear burning process proceeds from the conservation of the most abundant element hydrogen to helium, then from helium to carbon and oxygen, and then from these to heavier elements. Some of the key reactions for the carbon and oxygen burning stages of the nucleosynthesis are 12C+12C and 16O+16O leading to all possible final states. This paper contains the experimental measurements of 12C+12C and 16O+16O angular distributions performed at the cyclotron DC-60 in Astana, Kazakhstan. The extracted beam of 16O and 12C was accelerated up to two energies 1.75 and 1.5 MeV/n and then directed to an Al2O3 target of thickness 20 μg/cm2 and a carbon self-supporting target of thickness 17.4 μg/cm2. The angular distribution calculations were performed using both the phenomenological optical potential (SPI-GENOA) code and the double folding potential (FRESCO) code.

Analyzing power in elastic scattering of6He from a polarized proton target at 71 MeV/nucleon

The vector analyzing power has been measured for the elastic scattering of neutron-rich 6He from polarized protons at 71 MeV/nucleon making use of a newly constructed solid polarized proton target operated in a low magnetic field and at high temperature. Two approaches based on local one-body potentials were applied to investigate the spin-orbit interaction between a proton and a 6He nucleus. An optical model analysis revealed that the spin-orbit potential for 6He is characterized by a shallow and long-ranged shape compared with the global systematics of stable nuclei. A semimicroscopic analysis with a alpha+n+n cluster folding model suggests that the interaction between a proton and the alpha core is essentially important in describing the p+6He elastic scattering. The data are also compared with fully microscopic analyses using non-local optical potentials based on nucleon-nucleon g-matrices.

Phenomenological and Semi-microscopic Analysis for Elastic Scattering of Protons on 6,7Li

Phenomenological and Semi-microscopic Analysis for Elastic Scattering of Protons on 6,7Li

α-particles optical potential for medium and heavy-mass nuclei around the Coulomb barrier

Recent high-precision measurements of�-particle elastic scattering and (�,x) reaction cross sections has motivated the extension of a previous semi-microscopic analysis for the mass-region 50<A<120 and energies from 13 to 50 MeV to heavy nuclei up to 209Bi. The regional optical model potential for low-energy �-particles which has thus been obtained entirely on the basis of elastic-scattering data a nalysis, for the nuclei within the above-mentioned mass and energy ranges, is involved within the (�,), (�,n) and (�,p) reaction cross sections analysis at incident energies below the Coulomb barrier. The statistical-mo del parameters used for the cross section calculations were established by analyzing various independent experimental data for the involved nuclei, making possible the focus on the uncertainties of �-particle OMP. An optical potential which describe equally well both the low energy elastic-scattering and induced-reaction data of �-particles has finally been obtained for medium and heavy mass nuclei.

Complementary optical-potential analysis of [formula omitted]-particle elastic scattering and induced reactions at low energies

A previously derived semi-microscopic analysis based on the Double Folding Model, for α -particle elastic scattering on A ∼ 100 nuclei at energies below 32 MeV, is extended to medium mass A ∼ 50 – 120 nuclei and energies from ∼13 to 50 MeV. The energy-dependent phenomenological imaginary part for this semi-microscopic optical model potential was obtained including the dispersive correction to the microscopic real potential, and used within a concurrent phenomenological analysis of the same data basis. A regional parameter set for low-energy α -particles entirely based on elastic scattering data analysis was also obtained for nuclei within the above mentioned mass and energy ranges. Then, an ultimate assessment of ( α , γ ) , ( α , n ) , and ( α , p ) reaction cross sections considered target nuclei from 45Sc to 118Sn and incident energies below ∼12 MeV. The former diffuseness of the real part of optical potential as well as the surface imaginary potential depth have been found to be responsible for the actual difficulties in the description of these data, and modified in order to obtain an optical potential which describes equally well both the low-energy elastic scattering and induced reaction data for α -particles.

Dispersive semimicroscopic analysis of nuclear-nuclear collisions on the basis of a corrected folding-model potential

A procedure for correcting the energy dependence determined for the mean-field component of the optical potential on the basis of the double-folding model with allowance for exchange effects in the approximation of single-nucleon exchange knockout is used to calculate the mean field and to analyze data on elastic scattering within the dispersive semimicroscopic optical-potential model. The results of an analysis of all data (including those that were obtained quite recently) on 16O + 12C and 16O + 14C interactions at energies of up to 100 MeV per nucleon are presented. The energy dependence of the resulting potentials agrees well with that which was obtained previously within the phenomenological approach. A systematics of the positions of Airy minima in angular distributions versus the reduced mass in the range from 2 to 8 amu is constructed.

On temperature dependence of the optical potential for alpha-particles at low energies

Within the double folding formalism of the α-nucleus optical potential, used previously for a semi-microscopic analysis of the α-particle elastic scattering on A ∼ 100 nuclei at energies below 32 MeV, effects due to changes of the nuclear density at a finite temperature are considered. Parameterizations of the double-folding (DF) real potential as well as of a regional phenomenological potential have been used in the study of the ( n , α ) reaction cross sections for the target nuclei 92,95,98,100Mo. Taking into account the microscopic DF potentials based on nuclear density distributions, we are able to fully describe the excitation functions of the ( n , α ) reactions. It is shown that the temperature dependence of the nuclear density distribution function can be an important aspect that has to be included in statistical model calculations even for a nuclear temperature smaller than 2 MeV.

Optical model potentials for α-particles scattering around the Coulomb barrier on A∼100 nuclei

The double-folding formalism of the α-nucleus optical potential is used and appropriate effective nucleon–nucleon ( NN) interaction and α-particle density distribution at low energies are obtained by analysis of the α– α elastic-scattering at energies below 35 MeV. Next a semi-microscopic analysis based on the Double Folding Model (DFM) for the α-particle elastic scattering on A∼100 nuclei at energies below 32 MeV has been carried out. The energy-dependent phenomenological imaginary part for this semi-microscopic optical model potential (OMP) was obtained, making use also of the dispersive correction to the microscopic real potential. This imaginary potential has then been introduced within a complete phenomenological analysis of the same data basis. A regional parameter set of the phenomenological OMP for low-energy α-particles has thus been obtained for nuclei in the mass range A∼100, which is of interest to basic nuclear physics as well as nuclear technology.

Improving explosive nucleosynthesis models via (n,α) measurements

Within the double folding formalism of the α-nucleus optical potential, used previously for a semi-microscopic analysis of the α-particle elastic scattering on A∼100 nuclei at energies below 32 MeV, effects due to changes of the nuclear density at a finite temperature are considered. Parameterizations of the double-folding (DF) real potential as well as of a regional phenomenological potential have been used in the study of the (n,α) reaction cross sections for the target nuclei 92,95,98,100Mo. Taking into account the microscopic DF potentials based on nuclear density distributions, we are able to fully describe the excitation functions of the (n,α) reactions. It is shown that the temperature dependence of the nuclear density distribution function can be an important aspect that has to be included in statistical model calculations even for a nuclear temperature smaller than 2 MeV.

Influence of a channel-forming peptide on energy barriers to ion permeation, viewed from a continuum dielectric perspective

The continuum three-dielectric model for an aqueous ion channel pore-forming peptide-membrane system is extended to account for the finite length of the channel. We focus on the electrostatic influence that a channel-forming peptide may exert on energy barriers to ion permeation. The nonlinear dielectric behavior of channel water caused by dielectric saturation in the presence of an ion is explicitly modeled by assigning channel water a mean dielectric constant much less than that of bulk water. An exact solution of the continuum problem is formulated by approximating the dielectric behavior of bulk water, assigning it a dielectric constant of infinity. The validity of this approximation is verified by comparison with a Poisson-Boltzmann description of the electrolyte. The formal equivalence of high ionic strength and high electrolyte dielectric constant is demonstrated. We estimate limits on the reduction of the electrostatic free energy caused by ionic interaction with the channel-forming peptide. We find that even assigning this region an epsilon of 100, its influence is insufficient to lower permeation free energy barriers to values consistent with observed channel conductances. We provide estimates of the effective dielectric constant of this highly polarizable region, by comparing energy barriers computed using the continuum approach with those found from a semi-microscopic analysis of a simplified model of a gramicidin-like charge distribution. Possible ways of improving both models are discussed.

Microscopic and semimicroscopic analysis of the reaction 27Al(p, alpha )24Mg in the energy range between 20 and 45 MeV.

The microscopic model of the distorted-wave Born approximation theory for (p,\ensuremath{\alpha}) reactions formulated in the isospin representation is compared with a semimicroscopic analysis using cluster form factors and SU(3) spectroscopic amplitudes. The differential cross sections of \ensuremath{\alpha} particles emitted in the reaction $^{27}\mathrm{Al}$(p,\ensuremath{\alpha}${)}^{24}$Mg have been measured at the bombarding energies 20, 24, 30.5, and 45 MeV. The microscopic as well as the semimicroscopic distorted-wave Born approximation analysis reproduces the angular distributions in a large range of incident energies when using energy-dependent optical potentials. The relative intensities of the transitions to the ground state and excited states up to ${E}_{x}$=6 MeV are described quite well in the semimicroscopic analysis.