Quasi-elastic electron scattering (e,e′p) and (e,e′d) from 6Li in a coincidence experiment

Coincidence cross sections for the reactions ⁶Li(e, e′p) and ⁶Li(e, e′d) have been measured in the region of quasi-elastic scattering. Using incident electrons of 2.5 and 2.7 GeV, the four-momentum transfers to the proton were 6.6 fm^?2, 10.0 fm^?2 and 11.6 fm^?2. The proton coincidence data agree with shell-model distributions assuming a Woods-Saxon potential and including short-range nucleon-nucleon correlations. The best fit to the deuteron coincidence data is obtained with a cluster wave function for the p-nucleons and a harmonic oscillator wave function for the s-nucleons taking into account the deuteron yield from the s-shell. The ratio of the deuteron cross section from ⁶Li divided by the elastic e-d scattering cross section depends only slightly on the four-momentum transfer and has a value of ≈ 2.     

The two-body photodisintegration of the 3He nucleus

The two-body photodisintegration of ³He is calculated using ³He and proton-deuteron wave functions obtained by assuming a separable interaction for the two-nucleon t-matrix. We show that the isotropic component of the cross section is unlikely to yield useful information on the D-state probability densities of the deuteron and ³He. A detailed comparison is made with the data on the cross section at 90°. The separable approximation can account for some of the experimental results, but other experiments suggest that a more sophisticated treatment of the nuclear interactions and wave functions is necessary.     

Mechanism of independent neutron transfer in elastic <Emphasis Type="Italic">α</Emphasis><Superscript>6</Superscript>He scattering and structure of the <Superscript>6</Superscript>He nuclear wave function

The presence of two topologically different configurations, a dineutron and a cigar-like one, in the spatial wave function for the neutron-rich nucleus ⁶He is predicted. In elastic α ⁶He scattering, the dineutron configuration leads to the appearance of backward maxima in the cross section for elastic α ⁶He scattering. The cigar-like configuration is responsible for the scattering mechanism involving independent sequential neutron transfer and the formation of the ⁵He-⁵He virtual system. In order to estimate the contribution of this mechanism, the matrix element for the two-step sequential particle transfer is calculated by a method that takes into account delay in the interaction and which is realized in the QUADRO code. Calculations performed on this basis make it possible to estimate the weight of the cigar-like component in the wave function for the ⁶He nucleus.     

Electroinduced two-nucleon knockout and correlations in nuclei

A model to calculate cross sections for electroinduced two-nucleon emission from finite nuclei is presented. Short-range correlations in the wave functions and meson-exchange contributions to the photoabsorption process are implemented. Effects of the short-range correlations are studied with the aid of a perturbation expansion method with various choices of the Jastrow correlation function. The model is used to investigate the relative importance of the different reaction mechanisms contributing to the A(e,e′pn) and A(e,e′pp) process. Representative examples for the target nuclei ¹²C and ¹⁶O and for kinematical conditions accessible with contemporary high-duty cycle electron accelerators are presented. A procedure is outlined to calculate the two-nucleon knockout contribution to the semi-exclusive (e,e′p) cross section. Using this technique we investigate to what extent far semi-exclusive (e,e′p) reactions can be used to detect high-momentum components in the nuclear spectral function.     

Elastic pd scattering at 5.55 GeV/c incident momentum

Based on 150 000 photographs taken at the ZGS with the 30 inch deuterium-filled chamber we present an analysis of the elastic $\text{p}$d scattering reaction. Due to unrecoreded small deuteron recoils we were only able to measure the elastic cross section in the four-momentum region |t| > 0.03 (GeV/c)². Extrapolation towards small |t| by two different methods gave us two compatible estimates of the total elastic cross section. The differential cross section was analyzed by means of the Glauber formalism both with and without the effects due to the D-wave part of the deuteron wave function. The differential cross sections of np at 5.4 GeV/c and $\text{pn}$ deduced from our data were compared and exhibit a crossover phenomenon.     

Comparative analysis of proton and pion scattering on the isotopes <Superscript>6,8</Superscript>Не within Glauber theory

The differential cross sections for p^6,8He and p^6,8He scattering at the RIKEN andGSI energies (0.073 and 0.7 GeV per nucleon) were calculated on the basis of Glauber theory. Pion and proton interaction with a nucleus is determined by the multiple-scattering series (Glauber operator), so that various collision multiplicities and their contributions to the summed cross section can be taken into account. The use of the α-n-n wave function for ⁶He and the wave function on the basis of the large-scale shell model (LSSM) for ⁸He makes it possible to calculate analytically scattering matrix elements.     

Selected Topics in Correlated Hyperspherical Harmonics

Correlated hyperspherical-harmonic basis functions are used to expand the three- and four-nucleon wave functions. Bound and scattering states are considered. Results for the binding energies of ³H, ³He, and ⁴He calculated using modern two- and three-nucleon forces are given and discussed. For scattering states, results for N-d differential cross section and vector analyzing powers are shown. The importance of the Coulomb and magnetic moment effects are discussed.     

Photoionization of the excited He atom in Debye plasmas

We present theoretical photoionization cross sections for He 1s2s ¹S and He 1s2p ¹P states in a Debye plasma environment by the complex coordinate rotation method, using a finite L² basis set constructed from one electron Laguerre orbitals. The plasma environment is found to appreciably influence the photoionization cross sections near the ionization threshold. In this regard, the photoionization cross sections of isolated He are compared with other theoretical and experimental results. Our results are in good agreement with the previous results. A new minimum appears in the photoionization cross section curve for the metastable 1s2s ¹S state. Results are given for the S- and D-wave partial photoionization for the excited 1s2p ¹P state.     

Relativistic Description of 3He (e, e�� p)2H

The relativistic distorted-wave impulse approximation is used to describe the ³He(e, e?? p)²H process. We describe the ³He nucleus within the adiabatic hyperspherical expansion method with realistic nucleon-nucleon interactions. The overlap between the ³He and the deuteron wave functions can be accurately computed from a three-body calculation. The nucleons are described by solutions of the Dirac equation with scalar and vector (S?CV) potentials. The wave function of the outgoing proton is obtained by solving the Dirac equation with a S?CV optical potential fitted to elastic proton scattering data on the residual nucleus. Within this theoretical framework, we compute the cross section of the reaction and other observables like the transverse-longitudinal asymmetry, and compare them with the available experimental data measured at JLab.     

Elastic scattering of protons from 9Li in inverse kinematics within diffraction theory

The differential cross section for elastic scattering of protons from the ⁹Li nucleus has been calculated within the framework of the Glauber multiple scattering theory. The calculations were carried out with two versions of cluster wave functions for the nucleus obtained within the α-t-2n and ⁷Li-n-n three-body models with realistic potentials of intercluster interactions. The differential cross section was calculated at E = 700 and 60 MeV/nucleon. A comparison with the experimental data allows the conclusion that the wave function in the ⁷Li-n-n model describes the cross section better than in the α-t-2n model.     

Improved optical potential for low and medium energy π−-4He elastic scattering

Effects of the second-order correction in multiple scattering theory and the nucleon binding correction to the optical potential are investigated in π^?-⁴He elastic scattering and total reaction cross-sections. The second-order correction includes not only nucleon-nucleon correlation effects but also the contribution from spin (isospin) double-flip processes. It is found that the latter has an ascendency over the former. We have also shown that the nucleon binding effect is very important to reproduce the energy dependence of the total elastic cross section and the total reaction cross section, especially in the low energy and resonance energy regions.     

Analysis of elastic and inelastic hadron scattering on 6,7Li nuclei within diffraction theory

Within Glauber-Sitenko multiple-scattering theory, the differential cross sections for elastic and inelastic proton, positive-pion, and positive-kaon scattering on ^6,7Li nuclei are calculated at incident-hadron energies ranging between 0.143 and 1.0 GeV. The ⁶Li and ⁷Li wave functions are taken in, respectively, the α2N and the αt clustermodel. The resulting cross sections are investigated as functions of the scattered-particle energy, parameters of the model wave functions, and various scattering multiplicities. It is concluded that a partial filling of the diffraction minimum in the cross section is due to the D-wave contribution to the wave function for the ⁶Li target nucleus.     

Self-consistent wave functions,center-of-mass motion and high-energy particle-nucleus scattering

Elastic electron and hadron scattering by ⁴He and ¹⁶O is calculated using for the latter nucleus Brueckner-Hartree-Fock (BHF) wave functions obtained in the harmonic oscillator representation. The effects of the center-of-mass motion spuriosity are estimated.     

ELASTIC SCATTERING OF HADRONS FROM NUCLEI AT HIGH ENERGY AND THE SHORT RANGE CORRELATION IN NUCLEI

The effects of short range correlation in nuclei on elastic scattering of hadronsfrom nuclei at high energy are studied by means of Glauber multiple diffraction the-ory, using Jastrow correlated wave functions. To this end, a determinant form ofJastrow correlated wave functions is used. Calculations have been carried out for π^--¹²C elastic scattering at 260 MeV, and they are compared with the experimentdata. The results show that the influence of the short range correlation on the dif-ferent cross section is quite important.     

Isoscalar electromagnetic form factors and the structure of the deuteron at high momentum transfer

We derive general expressions for isoscalar electromagnetic form factors of nuclei including meson-exchange processes such as π, ?, ω and ?πγ exchange. Meson-nucleon vertices for nonzero momentum transfer as well as the effect of the finite width of the ?-meson are taken care of. Specifically, the electromagnetic form factors of the deuteron are calculated up to a momentum transfer of q² ≈ 200 fm^?2. A detailed numerical discussion of the various effects on meson-exchange processes is given. The effect of different deuteron wave functions and two types of photon-nucleon form factors are also discussed.     

Universal behaviour of scattering amplitudes for scattering from a plane in an average rough surface for small grazing angles

Abstract

It is shown that for scattering from a plane in an average rough surface, the scattering cross section of the range of small grazing angles of the scattered wave demonstrates a universal behaviour. If the angle of incidence is fixed (in general it should not be small), the diffusive component of the scattering cross section for the Dirichlet problem is proportional to θ² where θ is the (small) angle of elevation, and for the Neumann problem it does not depend on θ. For the backscattering case these dependences correspondingly become θ⁴ and θ°. The result is obtained from the structure of the equations that determine the scattering problem rather than by use of an approximation.     

Excitation of states of medium-mass nuclei in the region of giant resonances in inelastic deuteron scattering

Results are presented that were obtained by measuring a continuum in the inelastic scattering of 37-MeV deuterons on ¹²C, ⁴⁸Ti, and ^58,64Ni nuclei in the angular range 16° ≤ θ ≤ 61°. Broad excitation maxima are found for deuteron scattering angles in the range θ ≤ 21°. The region of a broad maximum includes giant resonances of target nuclei, whose levels are excited quite readily at E _d = 37 MeV. Summation of the inelastic-scattering cross sections over all final states of the excited| nucleus and the use of completeness of the wave functions for these states make it possible to express the total cross section for inelastic (incoherent) deuteron scattering only in terms of the wave functions for the ground state of the target nucleus. The corresponding quasielastic-scattering amplitude is taken in the diffraction approximation. Nucleon correlations in the target nucleus are disregarded. Upon disregarding a small contribution of multiple quasielastic scattering at small scattering angles, the cross section for incoherent deuteron scattering is represented approximately as the product of known factors—the square of the absolute value of the amplitude for diffractive quasielastic scattering and the effective number of target nucleons scattering deuterons. The results of these calculations agree qualitatively with experimental data.     

Scattering of pions by <Superscript>9</Superscript>Ве nuclei in the context of the Glauber diffraction theory

The differential cross section of the elastic scattering of π^±-mesons by the ⁹Ве nucleus at energies of 0.6 and 1.0 GeV are calculated using the Glauber theory of multiple scattering. The wave function of the ⁹Ве nucleus is obtained in the three-cluster 2α-n model. The sensitivity of the differential cross sections to the wave functions of a target nucleus, calculated with different intercluster interaction potentials, and to the contribution from different orders of scattering in Glauber operator Ω is studied.     

Anomalous elastic scattering of X-ray emission by an atom with open shells

In the nonrelativistic approximation for one-electron wave functions, the differential cross section for anomalous scattering of linearly polarized X-ray emission by a sodium atom near the ionization threshold of the 1s ² shell is studied. The analysis takes into account the many-body effects of relaxation of atomic shells in the field of a deep vacancy, multiplet splitting, and the double excitation/ionization processes. The theoretical results obtained for the anomalous-dispersion scattering region are predictive.