International Journal of Modern Physics E

A brief history of the continuum shell model with full correction for target recoil is provided. Past applications to nucleon induced reactions, nucleon capture, knockout reactions by pions and electrons, and strangeness exchange reactions are provided. Recent progress of the model is reviewed. Examples of continuum states for p-shell nuclei, derived from both two and three-body interactions, are given. Finally, the general model is presented in which any core states and any states of the composite system may be incorporated in a calculation.

Two types of cluster–cluster potentials are obtained for the lithium nuclei. The first is an attractive one and the second is a superposition of repulsive and attractive Gaussian forces. The ground-state wave functions of the lithium nuclei ⁶Li, ⁷Li, ⁸Li, and ⁹Li are expanded in terms of products of two wave functions: the first represents the set of A-4 nucleons and the second represents the set of the last four nucleons. In the construction of these wave functions, we have used the basis functions of the translation-invariant shell model. The expansion coefficients of the factorizations of these wave functions are products of four-particle orbital and spin-isospin fractional parentage coefficients. Two least-square formulas for the cluster–cluster potentials, which depend on the mass number A, are fitted for the lithium nuclei.

The physical properties of the nuclear shape have been investigated through the charge square radius (<r²>) and the quadrupole (Q₂) and hexadecapole (Q₄) moments of the even–even neutron-rich rare-earth nuclei. The single-particle energies used are those of a deformed Woods–Saxon mean-field. The pairing effects have been included by means of an exact projection method. The model has been tested for the "ordinary" nuclei near the shell closure N = 82 and has correctly reproduced the experimental data and particularly the "Kink" effect. The study has then been extended to the neutron-rich nuclei and has shown a stability of the <r²> and Q₂ results for N≃100 which may be attributed to the existence of a new magic number. On the other hand, a saturation of the prolate shape appears around N = 108 for the elements Nd, Sm and Gd and near N = 102 for the Dy, Er and Yb. These observations could not be confirmed by the investigation of the hexadecapole moment.

It is well known that a typical Yang–Mills Gauge Field is mediated by massless Bosons. It is only through a symmetry breaking mechanism, as in the Salam–Weinberg model that the quanta of such an interaction field acquire a mass in the usual theory. Here, we demonstrate that without taking recourse to the usual symmetry breaking mechanism, it is still possible to achieve this, given a noncommutative geometrical underpinning for spacetime.

It has been shown that the negative norm states necessarily appear in a covariant quantization of the free minimally coupled scalar field in de Sitter space.^1,2 In this process, ultraviolet and infrared divergences have been automatically eliminated.³ A natural renormalization of the one-loop interacting quantum field in Minkowski spacetime (λϕ⁴ theory) has been achieved through the consideration of the negative norm states.⁴ The one-loop effective action for scalar field in a general curved space-time has been calculated by this method, and a natural renormalization procedure in the one-loop approximation has been established.

A magnetohydrodynamic (MHD) model, which describes supersonic plasma flow inside the torch, is presented in this paper. It is a two-dimensional model but includes the K-epsilon model of turbulence, the gas viscous effects and compressible effects. The PHOENICS software is used for solving the governing equations, i.e. the conservation equations of mass, momentum, and energy together with the equations describing the K-epsilon model of turbulence. The calculated arc voltages and gas inflow rates are consistent with the experimental results when arc current and the working gas are the same as experiment. The plasma flow characteristics inside the supersonic plasma torch are analyzed in detail. Temperature, velocity, pressure and Mach number contours are presented to show the flow characteristics. Comparisons between turbulent and laminar models are made in detail also, and the results show the turbulent enhanced momentum and energy transport inside the supersonic plasma torch has little effect on the whole discharge area. The plasma flow inside the supersonic torch is mainly in the laminar state.

We study the ¹⁶O+⁵⁸Ni deep inelastic reaction by using coincident charged techniques. Inclusive as well as exclusive data of the C, N, and O fully-damped fragments and their associated light charged particles (p, d, t, and α-particles) have been collected at the IReS Strasbourg VIVITRON Tandem facility. The velocity distributions of the emitted protons and the associated multiplicity polar plots are analyzed by means of a model which describes simultaneously the nonequilibrium and the evaporative (equilibrated) components of a deep inelastic reaction mechanism. Estimates on polarization phenomena as well as the associated "decay times" of the reaction have been obtained. The hypothesis of a new "fan effect" is proposed for the proton sequential emission in the deep inelastic scattering of ¹⁶O+⁵⁸Ni at 8.25 MeV/nucleon.

A Variational Monte Carlo method (VMC) is described for the evaluation of the ground state properties of nuclear matter. Equilibrium properties of symmetric nuclear matter and neutron matter are calculated by the described VMC method. The Urbana ν₁₄ potential is used for the nucleon–nucleon interactions in the calculations. Three- and more-body interactions are included as a density dependent potential term. Total, kinetic and potential energies per particle are obtained for nuclear and neutron matter. Pressure values of nuclear and neutron matter are also calculated at various densities. The binding energy of nuclear matter is found to be -16.06 MeV at a saturation density of 0.16 fm^-3. The results obtained are in good agreement with those obtained by various authors with different potentials and techniques.

The quasimolecular optical potential with Incoming Wave Boundary Condition model is used to obtain the fusion and elastic scattering cross-section at the sub-Coulomb region and above. This has been done for the ¹⁶O+¹⁶O and ¹²C+¹²C systems. It is found that sudden potentials describe well the average trend in the fusion and elastic scattering cross-section using the Incoming Wave Boundary Condition Method. Potentials fits for low energy are then used to obtain cross-sections at higher energies. Excellent agreement is obtained for the location of various peaks observed experimentally, especially in the case of ¹⁶O+¹⁶O. The parameters from these potentials give information on the nuclei in these dynamical situations. We find that a larger radius and a low density in the central region is required to explain the phenomena. The range of Yukawa potentials used are also larger by a factor of two as compared to those used by other authors.

The influence of hole–hole propagation in addition to the conventional particle–particle propagation on the energy per nucleon and the momentum distribution is investigated. The results are compared to the Brueckner–Hartree–Fock (BHF) calculations with a continuous choice and a conventional choice for the single-particle spectrum. Also, the structure of nucleon self-energy in nuclear matter is evaluated. All the off-shell self-energies are calculated self-consistently. Using the self-consistent self-energy, the hole and particle self-consistent spectral functions including the particle–particle and hole–hole ladder contributions in nuclear matter are calculated using realistic NN interactions. We found that the hole–hole ladder brought about non-negligible contributions to the nuclear matter binding energy per nucleon.

We calculate the two-body relativistic boost interaction corrections as well as relativistic one-body and two-body kinetic energy corrections in cluster expansion of energy with AV18 and the new charge dependent Reid93 potentials within the lowest order constrained variational (LOCV) method. The equation of state of symmetric nuclear matter and pure neutron matter are calculated using the non-relativistic (H_NR), non-relativistic plus boost interaction corrections and plus kinetic energy corrections Hamiltonians. The relativistic boost interaction effects reduce the binding energies of symmetric nuclear matter for the AV18 interaction by ~3 MeV.