Treatment of Coulomb Interaction in Momentum Space for p-3He Elastic Scattering

Applying the method proposed by C.M.Vincent and S.C.Phatak to p-³He elastic scattering,we studied the treatment of Coulomb interaction in momentum space.The differetial cross sections and spin observables at 500,400,300 and 200MeV are calculated.The present results are discussed and compared with previous results and experimental data.     

Treatment of Coulomb Interaction in Momentum Space for p-3He Elastic Scattering

Applying the method proposed by R.Crespo and J.A.Tostevin to p-³He elastic scattering,we study the treatment of Coulomb interaction of momentum space.The differential cross sections and spin observables at 500 and 300 MeV are calculated with R=7fm.The present results are compared with those given in V-P method.It shows that the applicable range of angular momentum and momentum transfer in R-J method are wider than those in V-P method.     

R-matrix formulation and phase shifts for n-He and p-He scattering for energies up to 20 MeV

An R-matrix formulation for a single level with a background approximation has been used to analyse n-⁴He and p-⁴He elastic scattering data below the inelastic thresholds near 22 MeV. For every partial wave a single level and a distant pole contribution constant with energy has been employed. Simple relations between neutron and proton scattering parameters have been sought to possibly derive more dependable values for neutron phase shifts and analysing powers at energies where little experimental information exists. The R-matrix parameters corresponding to ⁵He and ⁵Li ground and 1st excited states, phase shifts up to 20 MeV and neutron analysing powers up to 15 MeV are given in tabular form and are compared to results of earlier analyses. Differences in n-⁴He phase shifts are discussed and shown to be due to a scarcity of accurate neutron scattering data above 11 MeV. Some typical fits to n-⁴He scattering data are shown.     

Proton-3He elastic scattering: A phase-shift analysis by a separable potential model

All the available experimental data (cross sections, projectile and target polarizations, polarization transfer coefficients) on p-³He elastic scattering up to ~10 MeV are analyzed on a unified basis in the framework of a separable potential model. This allows a phase-shift analysis which is model dependent, but is averaged over a wide energy interval (757 experimental points are reproduced by 27 model parameters). The calculations confirm some indications, already present in the literature, of a weak S-D tensor mixing, and strong singlet-triplet mixing in the P-states. Our conclusions are that probably the leading non-central effect is given by the coupling s₁ · l between the incident proton spin s₁ and the orbital angular momentum of relative motion. Finally, the phase shifts and observables are recalculated using the p-³He potential parameters, but switching off the Coulomb interaction. The results are compared with the (few) n-³H experimental cross sections of the literature, and the agreement is good, as expected on the basis of the charge-symmetry law.     

Sensitivity of p-3He scattering to meson exchange currents and NN phase shifts

Elastic p-³He scattering is calculated with a microscopic momentum space potential including full spin dependences. High sensitivity is found to the removal of meson exchange currents from the nuclear densities and to the choice of input NN phase shifts.     

Inelastic p-He scattering at 141 MeV

Inelastic p-⁴He scattering at 141±2 MeV has been investigated with a high-pressure cloud chamber filled with helium. Results are presented for the total cross sections of each reaction channel and the neutron spectra for the p(⁴He, pn)³He reaction.     

An Investigation of Relativistic Microscopic Optical Potential in Terms of Relativistic Brueckner-Bethe-Goldstone Equation

Relativistic microscopic optical potential of nucleon-nucleus is derived from the relativistic Brueckner-Bethe-Goldstone (RBBG) equation.The complex effective mass of a nucleon is determined by a fit to 200MeV p-⁴⁰Ca scattering data.The relativistic microscopic optical potentials with this effective mass are obtained from RBBG for p-¹⁶O,⁴⁰Ca,⁹⁰Zr and ²⁰⁸Pb scattering in energy range from 160 to 180MeV.The microscopic optical potential is used to study the proton-⁴⁰Ca scattering problem at 200MeV.The results,such as defferential cross section,analyzing power and spin rotation function are compared with those calculated from phenomenological relativistic optical potential.     

Charge Symmetry Breaking Effects in Elastic Nucleon Scattering From the 3H and 3He Mirror Nuclei

Using a microscopic momenteum space optical potential and the method for treating the Coulomb force, which is propose by R Crespo and J. A. Tostevin, we calculated the differential cross section of elastic nucleon scattering from the ³H and ³He mirror nuclei at 500MeV and the ratio of cross sections. The charge symmetry breaking effects due to the Coulomb force between the proton and nuclei are shown.     

Theoretical Calculation of S-factor in d(d,γ)α at low energy

We study one of the most important reactions ²H(d,γ)⁴He with an astrophysical interest. A phenomenological model is adopted where the D-state component of the colliding deuterons and D-components in ⁴He ground state are considered. Woods-Saxon potential parameters are obtained by reproducing the binding energy of d-d system and d-d elastic scattering phase shifts calculated by the resonating group method. A comparison of theoretical results with the experiment data is made at the energy range E_c.m.<3MeV. In particular, rather good agreement with the experiment data of the astrophysical S-factor can be obtained below 500keV. Due to the lack of experiment data at the energies around 0—20keV required in the investigation of the stellar nucleosynthesis, an theoretical extrapolation of the S-factor down to stellar energies is performed.     

A Simple Analytic K+N Two-Body Potential

The K⁺N two-body potential is calculated in the framework of the constituent quark model.The derived potential includes the central and spin-orbit contributions with a simple analytic form.The K⁺N scattering phase shifts are calculated and compared with experimental data.The results show that the potential can provide reasonable good explanation for the K⁺N data,particularly for the large phase shift of P-wave I=0,J=1/2channel.     

ANALYSIS OF QUASI-△33 DOORWAY STATE MODEL IN π NUCLEUS SCATTERING

Under Quasi-△₃₃ Doorway state model of π nucleus scattering, the differential cross sections and total cross sections of elastic π-⁴He and π-⁴⁰Ca at the different incident energies, (T_x^lab=110, 150, 180, 220, 260 MeV for π-⁴He, T_x^lab=115.5, 163.3, 241.0 MeV for π-⁴⁰Ca) are calculated. The approximate agreement between the theoretical results and experimential data is arrived at.We evaluate further the correction of spin-orbite coupling effects for π-⁴He, and the better agreements with experimential data are obtained.     

Phenomenological optical model for p-4He elastic scattering

The results of a Dirac equation optical model analysis of p-⁴He elastic scattering data are reported. The optical potential obtained at 1029 MeV reproduces the systematics of p-⁴He data over the energy range from 560 to 1730 MeV.     

A separable potential approach to nucleon-nucleus scattering with exact treatment of Coulomb interactions

A suitable, physically reasonable choice of separable nucleon-nucleus potential is made, which leads to very simple analytic expressions for the form factors in the Coulomb-state representation. This allows one to take account of Coulomb effects in an exact and simple way. The model is applied to the analysis of the elastic scattering of nucleons by ⁴He, ¹²C and ¹⁶O targets. A good fit of the experimental phase shifts is obtained with almost the same values of the potential parameters for neutron-nucleus and proton-nucleus elastic scattering.     

P-Matrix and J-Matrix Approaches: Coulomb Asymptotics in the Harmonic Oscillator Representation of Scattering Theory

The relation between the R- and P-matrix approaches and the harmonic oscillator representation of the quantum scattering theory (J-matrix method) is discussed. We construct a discrete analogue of the P-matrix that is shown to be equivalent to the usual P-matrix in the quasiclassical limit. A definition of the natural channel radius is introduced. As a result, it is shown to be possible to use a well-developed technique of R- and P-matrix theory for calculation of resonant states characteristics, scattering phase shifts, etc., in the approaches based on harmonic oscillator expansions, e.g., in nuclear shell-model calculations. The P-matrix is used also for formulation of the method of treating Coulomb asymptotics in the scattering theory in oscillator representation.     

Elastic scattering of light nuclei through a simple potential model

The phase function method is adapted to deal with the scattering on our proposed interactions for α–α and α–³He systems. The effect of the electromagnetic interaction is included in terms of a screened Coulomb potential. Based on our proposed potential models we present results for α–α and α–³He elastic scattering phase shifts which compare well with more detailed calculations.     

动量空间中能质子-12C弹性散射截面和自旋量的研究

在KMT理论框架下，应用微观的动量空间一级光学势，包括了库仑修正，自旋关联，NN振幅反对称，离壳效应，核子反冲和结合能转换，Lorentz不变的角变换.在整个中能区域系统地计算了质子-¹²C弹性散射微分截面和自旋观测量，并与实验数据及Glauber理论框架下或已有的其他理论计算结果做了比较，其结果显示，在200—1000MeV，该理论与实验结论符合程度较好.     

Investigation of low-energy scattering in the nnpp system on the basis of differential equations for Yakubovsky components in configuration space

The s-wave differential equations for the Yakubovsky components characterizing the nnpp system have been solved by the method of cluster reduction. Two-cluster scattering at energies below the three-particle threshold in the singlet and triplet spin states has been considered. The MT I–III potential model has been used to simulate nucleon-nucleon interaction, and the Coulomb interaction between the protons has been taken into account. The singlet and triplet scattering lengths have been calculated for proton interaction with the triton (³H) and for neutron interaction with the ³He nucleus, and the deuteron-deuteron scattering length has also been determined. The low-energy behavior of the phase shifts and inelasticity factors in the corresponding scattering channels has been investigated. The features of the 0⁺ resonance in the ⁴He nucleus have been determined.     

Universal correlations in pion-less EFT with the resonating group method: Three and four nucleons

The Effective Field Theory “without pions” at next-to-leading order is used to analyze universal bound-state and scattering properties of the 3- and 4-nucleon system. Results of a variety of phase shift equivalent nuclear potentials are presented for bound-state properties of ³H and ⁴He , and for the singlet S -wave ³He -neutron scattering length a ₀(³He-n) . The calculations are performed with the Refined Resonating Group Method and include a full treatment of the Coulomb interaction and the leading-order 3-nucleon interaction. The results compare favorably with data and values from AV18(+UIX) model calculations. A new correlation between a ₀(³He-n) and the ³H binding energy is found. Furthermore, we confirm at next-to-leading order the correlations, already found at leading order, between the ³H binding energy and the ³H charge radius, and the Tjon line. With the ³H binding energy as input, we get predictions of the effective field theory “without pions” at next-to-leading order for the root mean square charge radius of ³H of (1.6±0.2) fm, for the ⁴He binding energy of (28±2.5) MeV, and for Re{a ₀(³He-n)} of (7.5±0.6) fm. Including the Coulomb interaction, the splitting in binding energy between ³H and ³He is found to be (0.66±0.03) MeV. The discrepancy to data of (0.10±0.03) MeV is model independently attributed to higher-order charge independence breaking interactions. We also demonstrate that different results for the same observable stem from higher-order effects, and carefully assess that numerical uncertainties are negligible. Our results demonstrate the convergence and usefulness of the pion-less theory at next-to-leading order in the ⁴He channel. We conclude that no 4-nucleon interaction is needed to renormalize the theory at next-to-leading order in the 4-nucleon sector.     

Time reversal violation in the nuclear interaction and p-3He scattering

Using T-violating boson-exchange interactions T-violating effects in low energy p-³ He scattering are calculated. The results are below 10^?3 even for full strong (not millistrong) T-violation in the nucleon-nucleon system. It is argued, that the smallness of the effects is not a particularity of the p-³He system but a general property of low energy processes.     

Study on Charge Form Factors of the Exotic Nuclei 6,8He

Charge radius and charge form factors of different charge density distributions for ^6,8He are calculated with the relativistic Eikonal approximation. Detailed comparisons and discussions are presented. It is found that the charge form factors curves of ^6,8He are much lower than the experimental ones of ⁴He. This is, in principle, consistent with the experimental fact. Whereas detailed comparison among the charge form factors which correspond to different charge distributions show significant deviations. This indicates that the effects of the correlations between the halo neutrons and the α-core in ^6,8He with different charge density distributions are quite different. This result would provide a useful reference for the possible experiments on the next-generation electron-nucleus collider and for the tests of different theoretical models for the exotic nuclei ^6,8He.