Table of contents

An original extrapolation technique developed previously is modified and applied to study nuclear reactions in the ⁶Li + T system at energies E = 0-2 MeV. Cross sections of gamma-ray-producing reactions ⁶Li(t,d₁)⁷Li*[0.478] and ⁶Li(t,p₁)⁸Li*[0.981] with important diagnostic implications are calculated. The (t,d₁) nuclear data found exceed those accepted elsewhere by 2.5-3.5 times at sub-barrier energies. The cross sections of the (t,p₁) reaction are calculated for the first time.

An effort is made to simplify the complications of computing hyperon-nucleon G-matrix elements arising from the Pauli exclusion operator contained in the integral equation. We perform a two-frequency shell-model folded-diagram calculation on hypernuclei using two different treatments for the Pauli exclusion operator Q₂, namely, a local density approximation where Q₂ is replaced by a nuclear-matter Pauli operator {}(ρ), with ρ being a density parameter, and an exact calculation where Q₂ is expressed in terms of shell-model wavefunctions. With a proper choice of ρ, it is possible to reach a reasonable accuracy by using a local density approximation for the Pauli operator. For heavy hypernuclei, this {}(ρ) can be used to save a tremendous amount of computing time.

The positive, high-spin states of the ^155-165Er isotopes are studied within the framework of the interacting boson-fermion model. The single fermion is assumed to be in the I = (13/2) orbit only. It was found that the calculated positive high-spin state energy spectra of the odd Er isotopes agree quite well with the experimental data. Also, the observed order reversal of the adjacent spin doublet states of the energy spectra for ^159-163Er has been successfully reproduced. The B(E2) values for ^157-163Er are calculated and compared with the experimental data.

Analytical solutions of dispersion integral relations, linking the real and imaginary parts of the nuclear optical model, have been derived. These are displayed for some widely used forms of the volume- and surface-absorptive nuclear potentials. When the analytical solutions are incorporated into the optical-model search code GENOA, replacing a numerical integration, the code runs three and a half to seven times faster, greatly aiding the analysis of direct-reaction, elastic scattering data.

Linearized state-dependent and central Jastrow correlated trial wavefunctions are used to study the ground state of spin-isospin saturated p-shell nuclei with V4-type forces. We extend the variational Monte Carlo method to incorporate this kind of operatorial correlation by introducing only minor changes with respect to the case of central correlations. Very good energies are obtained with this wavefunction for the nuclei studied. Finally, a discussion of the role of the different correlation mechanisms included in this trial wavefunction is performed in terms of both the momentum distribution and the one- and two-particle densities in position space.

A general discussion of the total cross sections for scattering and reactions employing polarized beams with spin s_b and polarized targets with spin s_t is presented together with its immediate relevance to the analysis of ongoing experiments on {}({},Nπ)N.

We demonstrate that the kernel of the Lippmann-Schwinger equation, associated with interactions consisting of a sum of the Coulomb plus a short-range nuclear potential, becomes degenerate below threshold. Taking advantage of this fact, we present a simple method of calculating the effective range function for negative energies. This may be useful in practice since the effective range expansion extrapolated to threshold allows us to extract the low-energy scattering parameters: the Coulomb modified scattering length and the effective range.

Isotope shifts and hyperfine structures have been measured on the 306.7 nm line in bismuth isotopes with A = 205-210, 210m, 212 and 213 by gas cell laser spectroscopy. More precise measurements were made for the A = 207-209 isotopes in atomic beam measurements. Nuclear magnetic and quadrupole moments were deduced. A detailed comparison of the nuclear charge radii systematics has been made in the region using a King plot technique.

We calculate the probability of pair creation in vacuum in d + 1 dimensions (with d = 3,2,1), by an alternating electromagnetic field, in three cases. First, we consider an electromagnetic field composed of an alternating electric field and of a constant uniform magnetic field. Next, we consider the situation when both the electric and magnetic fields are purely alternating. Finally, we complete this analysis with the case of production of Dirac particles in vacuum by a constant uniform electromagnetic field and a plane wave.

Possible sources of uncertainties in the calculations of the internal conversion coefficients are studied. The uncertainties induced by them are estimated.

Gangopadhyay and Levinger applied the quasi-deuteron model to the trinucleon, and found that the number of quasi-deuterons is constant. I use new data for the monopole form factor, and find that the number is constant for a wider range of momentum transfers than previously reported. The quasi-deuteron model fails at higher momentum transfers.