Hot nuclear matter is studied in the framework of quantum hadrodynamics. General principles of covariant thermodynamics and thermodynamic consistency are discussed, and these principles are illustrated by computing nuclear matter properties in an arbitrary reference frame, using the mean-field approximation to the Walecka model. The results are shown to be Lorentz covariant, and thermodynamic consistency is demonstrated by proving the equality of the ‘‘thermodynamic’’ and ‘‘hydrostatic’’ pressures. The mean-field results are used in a simple hydrodynamic picture to discuss the phenomenology of heavy-ion collisions and astrophysical systems, with an emphasis on new features that arise in a covariant approach.

The nucleus ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$ is studied with a multiconfiguration resonating-group calculation which consists of n${+}^7$Li, t${+}^5$He, n${+}^7$${\mathrm{Li}}^{\mathrm{*}}$, and ${}_{}{}^4{}_{}{}^{}$H+α cluster configurations. With no adjustable parameters, the results show that the calculated level spectrum agrees well with experiment and with the empirical level spectrum obtained by Knox, Resler, and Lane using an extensive R-matrix analysis. A calculation employing only the n${+}^7$Li configuration is found to be generally inadequate. Among the configurations t${+}^5$He, n${+}^7$${\mathrm{Li}}^{\mathrm{*}}$, and ${}_{}{}^4{}_{}{}^{}$H+α which are employed to enlarge the model space, the n${+}^7$${\mathrm{Li}}^{\mathrm{*}}$ configuration is shown to be the most important from an overall viewpoint. Comparisons between calculated and experimental scattering and reaction cross sections have also been made. Here one finds that the calculation explains all the main features of measured results. In particular, the triton production cross section of the ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$(n,n’t)α reaction is well reproduced. The calculated n${+}^7$Li total reaction cross section turns out to be somewhat too small, being equal to around 75% of the experimental value.

Excitation in the reaction ${}_{}{}^{148}{}_{}{}^{}\mathrm{Gd}$(p,t${)}^{146}$Gd to a $0^{+}$ level at 4.534 MeV can be identified with a proton two-particle, two-hole (2p-2h), neutron 2p-2h configuration where the proton 2p-2h configurations act across the Z=64 gap (particle moving in the 1$h_{11/2}$ orbital) and the neutron 2p-2h configuration acts across the N=82 closed shell. Here holes are moving mainly in the 1$h_{11/2}$ orbital, and the particles move in the high-j 2$f_{7/2}$, 1$h_{9/2}$, and 1$i_{13/2}$ orbitals. A calculation for the position of this $0^{+}$ 4p-4h configuration was performed starting from the proton and neutron pairing excitations and using a four-level model with residual proton-neutron interactions. This model predicts an energy of 4.76 MeV for the 4p-4h $0^{+}$ state, and the resultant model wave functions can qualitatively explain the transfer reaction cross sections. Existence of a 4p-4h band structure is discussed.

In the present paper a number conserving random phase approximation is derived as a special case of the recently developed random phase approximation in general symmetry projected quasiparticle mean fields. All the occurring integrals induced by the number projection are performed analytically after writing the various overlap and energy matrices in the random phase approximation equation as polynomials in the gauge angle. In the limit of a large number of particles the well-known pairing vibration matrix elements are recovered. We also present a new analytically number projected variational equation for the number conserving pairing problem.

The influence of nuclear rotation on pairing correlations is discussed using a simple solvable two-level model. Exact solutions are compared to approximate ones obtained with the generator coordinate method both with and without particle-number projection. The collective subspace associated with the generator coordinates used has a finite dimension and it can be exactly separated from the full Hilbert space of the generating functions. Analytical formulas for the norm matrix and Hamiltonian kernels are obtained. It is shown that the generator coordinate method improves considerably the calculations based on the random-phase-approximation approach, in particular near the critical frequency where the pairing gap collapses.

The charge form factors of ${}_{}{}^3{}_{}{}^{}\mathrm{H}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ are calculated using the Monte Carlo method and variational ground-state wave functions obtained for the Argonne two-nucleon and Urbana-VII three-nucleon interactions. The model for the charge density operator contains the two-body exchange contributions of longest range. With some spread due to the uncertainty in the electromagnetic form factors of the nucleon the calculated charge form factors are in good agreement with the empirical values over the whole experimentally covered range of momentum transfer.

In recent years we have developed a new mathematical treatment of large amplitude collective motion in the adiabatic limit and formulated a successful approximation method, called the generalized valley approximation. In this paper we discuss its application to adiabatic time-dependent Hartree theory, for which the method is ideally suited. We apply the method first to an exactly solvable limiting case (the Suzuki model), for which we have shown in a previous paper that the usual form of adiabatic time-dependent Hartree theory is not general enough to yield the exact solution. We introduce an extended theory that remedies this deficiency. The modified theory has also been applied to monopole models close to the Suzuki model that are not exactly solvable. The algorithm developed for this case is sufficiently general to serve as a prototype for those necessary to study more complex realistic models of collective motion.

A study is made of shell model state structures present in the three-body wave functions of low-lying positive parity levels of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ calculated with the Faddeev formalism.

Large basis space projected Hartree-Fock wave functions have been used to calculate the longitudinal and transverse (electric) form factors from the excitations of $2_1^{+}$ and $4_1^{+}$ states in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, and ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$. The results obtained by use of such large basis space models of structure are compared with limited basis space (shell-model) predictions to show that momentum-transfer-dependent corrections can be quite diverse.

An approximate restoration of the particle number symmetry, in the manner of Lipkin-Nogami, is numerically investigated in the context of constrained Hartree-Fock plus BCS calculations. Its effect is assessed in a variety of physical situations like potential energy landscapes in transitional nuclei, shape isomerism at low spin, and fission barriers of actinide nuclei.

Half-lives of 5.60(15) and 1.58(4) ns were measured for the $0_2^{+}$ levels in ${}_{}{}^{100}{}_{}{}^{}\mathrm{Zr}$ and ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}$, respectively, using a β-γ-γ fast timing method. Analysis of the revised ρ(E0) systematics in the crucial A≃100 region indicates that high values of ρ(E0) do not by themselves imply strong configuration mixing between two coexisting states as presently assumed.

The absolute electrofission cross section of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ was measured in the energy range 35–250 MeV, and the photofission cross section was deduced by means of the virtual-photon technique. A structure observed in the (γ,f) curve, around 200 MeV, was interpreted on the basis of recent calculations for the thermalization process which were performed in the framework of the intranuclear cascade model.

The half-life of the T=(3/2 nucleus ${}_{}{}^{13}{}_{}{}^{}\mathrm{O}$ has been remeasured to be $T_{1/2}$=(8.55±0.05) ms by observing a time spectrum of β-delayed protons. This value is appreciably smaller than previously reported. Branching ratios of the β transitions to the ground and excited states of ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ have been obtained from the proton energy spectrum and the proton-to-β intensity ratio. Mirror asymmetry in the ft value deduced for the ground-state transition is found to be consistent with the theoretical estimate which takes account of nuclear asymmetry due to the Coulomb interaction.

The momentum-transfer dependence of ratios of deep-inelastic nuclear structure functions arising from finite nucleon target mass corrections, of order $M_N^2$/$Q^2$, is found to be small.

We discuss the relevance of the explicit consideration of quark degrees of freedom for the understanding of experiments at multi-GeV electron accelerators such as the Continuous Electron Beam Accelerator Facility (CEBAF). We suggest that the ‘‘precocious scaling’’ seen in deep-inelastic scattering at low values of $Q^2$ may be understood on the basis of a relativistic quark model which contains nonperturbative features not present in a quark-parton model. We also observe that the rate at which scaling is achieved is determined by a parameter which specifies the momentum content of the quark wave function of our model.

It has been shown that there exist transformations that can be used to change the Lorentz transformation character of potentials, which appear in the Dirac equation for elastic scattering. We consider the situation for inelastic scattering described by coupled channel Dirac equations. We examine a two-level problem where both the ground and excited states are assumed to have zero spin. Even in this simple case we have not found an appropriate transformation. However, if the excited state has zero excitation energy it is possible to find a transformation.

The first complete calculations of electric quadrupole excitations in relativistic nucleus-nucleus collisions are presented herein. Neutron emission from ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$ is studied and quadrupole effects are found to be a significant fraction of the cross section.

$0^{+}$ spurious states arising due to the nonconservation of the number of particles, associated with the quasiparticle modified Tamm-Dancoff approximation method, up to the square of the number of particles operator are discussed. A procedure for eliminating the effects of these spurious states from the quasiparticle modified Tamm-Dancoff approximation basis states is prescribed and applied to structure studies of Ni isotopes employing the Kuo-Brown effective interaction, and the trends of the results thus obtained are compared with experiments and earlier calculations.

A suitable set of observables, a few of which have already been measured, is suggested. Using these, the p-d elastic scattering amplitudes may be completely reconstructed.

We give an empirically derived correction factor to an ad hoc procedure of including Coulomb corrections in the plane-wave calculation of the radiation tail accompanying elastic electron scattering from the atomic nucleus. Apart from regions of the radiation tail with very large Coulomb distortion effects, our corrected ad hoc results agree with a distorted-wave Born approximation calculation of the radiation tail to better than 5%.