Improved eikonal approach for charge exchange reactions at intermediate energies

In order to describe charge exchange reactions at intermediate energies,we implemented as a first step the formulation of the normal eikonal approach.The calculated differential cross-sections based on this approach deviated significantly from the conventional DWBA calculations for CE reactions at 140 MeV/nucleon.Thereafter,improvements were made in the application of the eikonal approximation so as to keep a strict three-dimensional form factor.The results obtained with the improved eikonal approach are in good agreement with the DWBA calculations and with the experimental data.Since the improved eikonal approach can be formulated in a microscopic way,it is easy to apply to CE reactions at higher energies,where the phenomenological DWBA is a priori difficult to use due to the lack,in most cases,of the required phenomenological potentials.     

Inclusive hadron-nucleus scattering at high energy

The multiple scattering series of Glauber and Matthiae for hadron-nucleus scattering is summed to a simple analytical expression. It reproduces quantitatively the main features of the experimental cross section for the reaction ${}^4\text{He}\text{+}{}^{\mathrm{A}}\text{Z →}{}^4\text{He + X}$ at 1 GeV/nucleon.     

Electron scattering by O2 at intermediate and high energies

A complex optical model potential correlated by the concept of bonded atoms, which considers the overlapping effect of electron clouds between two atoms in a molecule, is firstly employed to calculate the absolute differential cross sections, the integrated and momentum transfer cross sections for electrons scattered by O2 at intermediate and high energies by using additivity rule model at Hartree-Fock level. In the study,the complex optical model potential is composed of static, exchange, correlation polarization plus absorption contributions. The quantitative absolute differential cross sections, the integrated and momentum transfer cross sections are obtained. Compared with available experimental data, this approach presents good results. It is shown that the additivity rule model together with the complex optical model potential correlated by the concept of bonded atoms is completely suitable for the calculations of the absolute differential cross sections, the integrated and momentum transfer cross sections.     

Projectile fragmentation in hadron-nucleus collisions at high energies

Particle production in hadron-nucleus collisions at high energies is discussed in the projectile fragmentation region. The predictions of the constituent quark model are analyzed. The contribution of diffractive interactions is explicitly taken into account. Comparison with the recent Fermilab measurements shows good agreement with the quark model and strong effects of diffractive collisions in some of the analyzed reactions.     

A new space-time model for hadron-nucleus collisons at high energies

A new space-time model for hadron-nucleus collisions is proposed, where particles at the instant of creation are not only immature but their maturity rate is enhanced in the presence of other hadronic matter, as in a nucleus. With only one free parameter, the model can explain dn_A^p/dν, dn_A^π/dν, R_A^p(E_L), and the A-dependences of σ_in^pA and σ_in^πA.     

Alpha-nucleus elastic scattering at intermediate energies

Elastic scattering of 288,340,480 and 699 MeV Alpha-particles was measured on ²⁰⁸Pb, ¹¹⁶Sn and ⁵⁸Ni. The data were analysed in terms of a phenomenological optical model. The optical potentials obtained were found to vary consistently with the target nucleus and the incident energy. The radial zone where the potentials are well determined was studied in detail. The data for ²⁰⁸Pb were also analysed with a folding model. The energy dependence of the strong-absorption radius and of the reaction cross section shows that the nuclear surface becomes slightly transparent for incident energies above 150 MeV per nucleon.     

Deuteron-proton elastic scattering at intermediate energies

The deuteron-proton elastic scattering has been studied in the multiple-scattering expansion formalism. Primary attention has been given to such relativistic problems as a deuteron wave function in a moving frame and transformation of spin states due to Wigner rotation. Parametrization of the nucleon—nucleon t matrix has been used to take the off-energy-shell effects into account. The vector, A _y , and tensor, A _yy , analyzing powers of the deuteron have been calculated at two deuteron kinetic energies: 395 and 1200 MeV. The obtained results are compared with the experimental data. The text was submitted by the authors in English.     

Positron-helium elastic scattering at intermediate energies

Total cross sections for elastic positron-helium collisions have been computed and compared with other theoretical results. Integrated cross sections over small angular regions extending from zero angle, for which a set of experimental estimates is available, are also presented.     

Heavy-ion scattering at low energies: First-order correction to the eikonal phase shift

The first-order non-eikonal correction has been applied to calculate heavy-ion reaction cross sections at low energies. The numerical investigations show that, for many heavy-ion systems, reaction cross sections and elastic scattering angular distributions thus calculated, are in good agreement with the optical model calculations.     

Electron scattering by atoms at intermediate energies: I. Theoretical models

The theoretical methods used in recent investigations of electron scattering by atoms at intermediate energies are outlined and their relative merits examined critically. Comparison with experiment is made in selected cases.     

Production of multibaryon clusters in hadron-nucleus collisions at high energies

The results obtained by analyzing the production of multibaryon clusters in π ⁻C and p ²⁰Ne interactions at momenta of 40 and 300 GeV/c, respectively, are presented.     

Three-body elastic and inelastic scattering at intermediate energies

The Faddeev equation for three-body scattering at arbitrary energies is formulated in momentum space and directly solved in terms of momentum vectors without employing a partial wave decomposition. For identical bosons this results in a three-dimensional integral equation in five variables, magnitudes of relative momenta and angles. The cross sections for both elastic and breakup processes in the intermediate energy range up to about 1 GeV are calculated based on a Malfliet-Tjon type potential, and the convergence of the multiple scattering series is investigated.     

Topological cross sections in hadron-nucleon and hadron-nucleus collisions at very high energies

We apply our microscopic model for the topological cross section σ_n to produce n charged particles in hadron-proton interactions to hadron-nucleus scattering. The model is based on a stochastic branching process for hadronization. We calculate multiplicity distributions of hadron-nucleus collisions for 50 GeV ? E_L ? 400 GeV based on a multiple collision model. The production of “grey” $\text{(0.3 <}\text{ν}\text{c}\text{< 0.7)}$ particles is considered together with the shower $\text{(}\text{ν}\text{c}\text{> 0.7)}$ particles in order to test the model for higher number of collisions. The joint probability distribution of numbers of shower and grey particles F(n_s, n_g) is calculated. Finally, we critically compare the results to experimental data.     

Wave-spreading effects in nuclear scattering at intermediate energies

Based on the Fresnel approach discussed in a previous article the S-matrix for nuclear elastic scattering is factorized into an infinite product, the n-th term of which is essentially given by (n ? 1)-fold commutators of the interaction potential at n different z-coordinate positions. A subsequent cumulant expansion expresses the Fresnel phase shift as an infinite sum of many-body clusters. In constrast to eikonal-type expansions each term of this sum contains contributions of all orders in the inverse wave number. Because of this feature the present expansion is useful for scattering from light nuclei over a wide range of energies and scattering angles.     

Calculation of elastic electron-helium scattering at intermediate energies

The two-potential eikonal approximation is applied to the calculation of the differential cross section for elastic scattering of electrons by ground state helium atoms at energies 50 and 100 rV. The results agree very well with experiments.     

Coupled-channel calculations of positron-atom scattering at intermediate energies

We present the cross sections for positron collisions with the alkali atoms Li, Na and K in the close-coupling approximation within the framework of a single-active-electron model. Our target basis sets are represented by Li(2s, 3s, 2p, 3p), Na(3s, 4s, 3p, 4p), and K(4s, 5s, 4p, 5p) respectively. The effects of coupling to the lowest lying Ps channels have been investigated by augmenting the target basis sets with the Ps(1s, 2s, 2p) eigenstates. The calculations have been made for impact energies below 50 eV. The interaction between the positron and the alkali target atom is represented by a model potential obtained using a single-active-electron approximation. The effect on elastic scattering and excitation due to the coupling between the direct and the Ps formation channels is found to be of great significance at low impact energies. The case of K is of particular interest. The inclusion of the Ps channels quantitatively reproduces the maximum in the total cross section at about 6 eV as reported in a recent experiment by Parikh et al. We find that the calculated total cross sections for Na and K are in good agreement with the experimental data of Parikh et al. and Kwan et al. respectively in the energy range of 2–50 eV provided allowance is made for the incomplete elastic discrimination in the experiment. The Ps formation reduces the K(4s4p) cross section at all energies below 30 eV and a reduction is also seen in the elastic cross section for energies below about 7 eV. Similar effects are observed in the case of Li. In the case of Na for impact energies between 2 and 20 eV Ps formation significantly reduces the Na(3s3p) excitation cross section, while the elastic scattering cross section increases. The calculated total Ps formation cross sections for Na and K are in good agreement with the preliminary experimental data of Kwan, Stein and co-workers.