Coupled-channel optical-model calculations are presented for pion double charge exchange (DCX) to the double giant-dipole resonance (DD). Systematic formulas for the transition matrix element to the giant-dipole resonance are presented. The calculations reproduce the available single-charge-exchange data. No further normalization is required to reproduce the DCX data. A smaller $0^{+}$ strength to the DD is calculated than previously expected. The quality of the calculation is reminiscent of that found for similar calculations to the double isobaric analog state.

Cross sections for the ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$(n,p${)}^{20}$F reaction at ${\mathit{E}}_{\mathit{n}}$=198 MeV were measured at five angles using the TRIUMF charge-exchange facility and a novel high-pressure (20 atm, or 2.03 MPa) gas target. The L=0, L=1, and L≥2 contributions to the cross sections were obtained from a multipole decomposition. Using an empirical proportionality between the cross section and Gamow-Teller (GT) strength from β decay, GT strength was deduced up to an excitation of 10 MeV in ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$. Most of the strength is concentrated in a discrete state at ${\mathit{E}}_{\mathit{x}}$=1.0 MeV, with the extracted strength of the ΔL=0 continuum at high excitation having a large error. These results are compared with measurements of GT strength using other probes. Comparison with the measured magnetic dipole (M1) strength in ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ shows that there is constructive interference between the spin part and a large orbital part of the M1 transition to the 11.26 MeV state in ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ (analog of the 1.0 MeV state in ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$). If all the strength from the multipole decomposition is used, we find agreement of the total GT strength compared to untruncated sd shell-model calculations which use free-nucleon operators, although experimental and theoretical distributions differ in detail. The confirmation of strong orbital M1 contributions at the beginning of the sd shell together with systematics of GT quenching in heavier sd shell nuclei may provide evidence for meson exchange currents in M1 transitions.

A mass-spectrometric technique, employing the Chalk River On-Line Isotope Separator at the Chalk River TASCC Facility, has been used to determine the mass ratios between some neutron-deficient isotopes. Two mass doublets ${}_{}{}^{103}{}_{}{}^{}\mathrm{-}_{}^{104}{}_{}{}^{}$In and ${}_{}{}^{104}{}_{}{}^{}\mathrm{-}_{}^{105}{}_{}{}^{}$In and the mass triplet ${}_{}{}^{103}{}_{}{}^{}\mathrm{-}_{}^{104}{}_{}{}^{}$In${\mathrm{-}}^{105}$In have been studied. We have also measured the mass ratio between ${}_{}{}^{72}{}_{}{}^{}\mathrm{Br}$ and ${}_{}{}^{73}{}_{}{}^{}\mathrm{Br}$ to a higher precision than that reported in our earlier work. When combined with the known masses of ${}_{}{}^{103}{}_{}{}^{}\mathrm{In}$, ${}_{}{}^{105}{}_{}{}^{}\mathrm{In}$, and ${}_{}{}^{73}{}_{}{}^{}\mathrm{Br}$ our data yield the atomic mass of ${}_{}{}^{104}{}_{}{}^{}\mathrm{In}$ and improve our earlier value for ${}_{}{}^{72}{}_{}{}^{}\mathrm{Br}$. The measured mass ratios are in good agreement with systematics. Our results for the ${}_{}{}^{104}{}_{}{}^{}\mathrm{In}$ and the ${}_{}{}^{72}{}_{}{}^{}\mathrm{Br}$ masses are 103 918 367 (126) and 71 936 430(294) μu, respectively.

High-spin states in ${}_{}{}^{189}{}_{}{}^{}\mathrm{Tl}$ have been populated through the ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$${(}^{28}$Si,4n) reaction and studied with in-beam γ-ray spectroscopy techniques. Both oblate and prolate structures associated with the i13/2 proton orbit are confirmed and extended to higher spins (19/2 and 41/2, respectively). However, only the oblate structure related to the πh9/2 has been observed meaning that the associated prolate structure is nonyrast contrary to expectation. This experimental result points clearly to a large amplitude of (πh9/2${)}^2$ in the wave function of the prolate minimum of ${}_{}{}^{188}{}_{}{}^{}\mathrm{Hg}$.

The solutions of the linearized Vlasov equation for a semi-infinite system are obtained and discussed. These solutions are based on the van Kampen method for homogeneous systems. The relevant aspects of the surface behavior are discussed in terms of the boundary conditions for the fixed surface, as well as for the free surface. An ad hoc surface tension is added to the model to simulate gradient effects and the finite range of nuclear forces. The comparison of the amplitudes of the fluctuations of the nucleon density and of the displacement of the surface along the perpendicular direction provides a suitable criterion to establish a distinction between predominantly volume-type modes and predominantly surface-type modes.

A relativistic kinetic equation with self-consistent mean field is derived for a field theory of nucleons coupled to neutral scalar and vector mesons. Contrary to previous approaches, our mean field includes the contribution of exchange forces. Due to the exchange terms, the mean field contains tensor, pseudoscalar, and pseudovector components, in addition to the scalar and vector components. By means of this kinetic equation the collective modes of nuclear matter are studied. Because exchange terms are not neglected, the kinetic equation presents additional solutions which correspond to oscillations of the spin density. The longitudinal spin-density wave becomes a tachyon for values of the Fermi momentum ${\mathit{p}}_{\mathit{F}}$>2.87 ${\mathrm{fm}}^{\mathrm{-}1}$. This fact is related to a spontaneous symmetry breaking: At large baryon densities the minimum of the energy density corresponds to a nonisotropic phase of nuclear matter.

The possible microscopic realization of interacting boson model (IBM) collective M1 modes is investigated for ${}_{}{}^{54,56}{}_{}{}^{}\mathrm{Cr}$ and ${}_{}{}^{56,58,60}{}_{}{}^{}\mathrm{Fe}$, using a shell-model space of protons in the 1${\mathit{f}}_{7/2}$ orbit and neutrons in the 2${\mathit{p}}_{3/2}$, 1${\mathit{f}}_{5/2}$, and 2${\mathit{p}}_{1/2}$ orbits. Distributions of the pair analogues of IBM-2 mixed-symmetry states, and of some g-IBM-2 states, over shell-model eigenstates are explicitly determined. For J=1, the mixed-symmetry SD strength is generally lower than that of the G-pair states, and responsible for most of the low-energy M1 strength. Structures incorporating extended sets of levels, including the M1 states, corresponding to the sd-IBM-2 U(5)⊃SO(6)⊃SO(5) dynamical symmetry representations [N-1,1] (N-1,1,0) (τ) are manifest in the shell-model spectra for ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{54}{}_{}{}^{}\mathrm{Cr}$. The correspondence with observed levels is discussed.

We have studied theoretically the proton pick-up (d${,}^3$He) reactions leading to deeply bound pionic atoms. The forward scattering cross sections for an incident energy ${\mathit{T}}_{\mathit{d}}$=600 MeV have been calculated using the effective number approach for the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ target nucleus. It was found that the pionic 2p state has the maximum cross section among all calculated states. We conclude that (d${,}^3$He) reactions produce pionic atoms in a detectable manner.

We examine the influence of meson exchange currents (MEC) on pion double charge exchange (DCX) using the Weinberg Lagrangian. We calculate the corresponding amplitude for DCX and examine its interplay with more conventional mechanisms of DCX for ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ at incident energies of 10 to 110 MeV and for the Ca isotopes at 35 MeV. The MEC effect includes the pion pole term and the contact term. In comparison to previous estimates, we find smaller but nevertheless non-negligible contributions of these effects to DCX. We stress the fact that the MEC contribution to DCX is strongly A dependent, with its effect in light nuclei comparatively larger than in heavy ones.

Angular distribution data on the elastic scattering of pions from a number of nuclei between ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ are studied at energies around the (3,3) resonance in terms of the strong absorption model of Frahn and Venter. The parameters thus obtained are employed for the analysis of the inelastic scattering leading to the $2_1^{+}$ state in a number of nuclei and the deformation parameters are extracted. The model is found to give a reasonably good description of both elastic and inelastic scattering of ${\mathrm{\pi }}^{\pm }$.

We have studied the compression properties of a finite nuclear system in the relativistic mean-field theory. Calculations have been carried out in the framework of the relativistic Thomas-Fermi approach. We have considered the derivative scalar coupling for the isoscalar sigma meson. It is shown that in the derivative coupling, the relativistic mean field leads to surface compression properties very close to those of the standard Skyrme interaction ${\mathrm{SkM}}^{\mathrm{*}}$. This shows that at about the saturation point the derivative coupling exhibits a behavior close to ${\mathrm{SkM}}^{\mathrm{*}}$. The high-density trend of the derivative coupling, however, diverges from that of ${\mathrm{SkM}}^{\mathrm{*}}$.

Comparison of the six states recently observed in ${}_{}{}^{168}{}_{}{}^{}\mathrm{Ho}$ with the states in ${}_{}{}^{166}{}_{}{}^{}\mathrm{Ho}$ suggests configurational assignments for all six states. The validity of these assignments is strengthened by the allowed unhindered beta decay of ${}_{}{}^{168}{}_{}{}^{}\mathrm{Dy}$ to the two $1^{+}$ states in ${}_{}{}^{168}{}_{}{}^{}\mathrm{Ho}$ and by microscopic theoretical calculations of the quasiparticle structure of the corresponding states in ${}_{}{}^{166}{}_{}{}^{}\mathrm{Ho}$ and ${}_{}{}^{168}{}_{}{}^{}\mathrm{Ho}$.

Coulomb instability in hot nuclei is discussed, using the Skyrme effective nucleon-nucleon interactions and a mean-field approach based on a finite-temperature real-time Green’s-function method. In the calculation, full degeneracy and symmetry corrections are included. It is found that the above precise treatment of degeneracy and symmetry corrections is necessary in the lower-temperature and higher-density region or for larger asymmetry. The calculated limiting temperatures are quite different for different sets of Skyrme effective interactions, which may be used as a sensitive test of the various Skyrme interactions to see which one can best describe the finite-temperature properties of nuclear matter. It is also found that the limiting temperature ${\mathit{T}}_{\lim }$ is approximately proportional to the critical temperature ${\mathit{T}}_{\mathit{C}}$, when the results for various Skyrme interactions are compared.

We present the numerical details for performing static Hartree-Fock and time-dependent Hartree-Fock calculations using a spline collocation method. Calculations are performed on a three-dimensional Cartesian lattice without any symmetry assumptions and quantal degeneracies. The three-dimensional Hartree-Fock calculations are compared with the solutions of the corresponding radial equations. The results demonstrate an unprecedented accuracy for relatively coarse meshes. We also present a zero impact parameter, time-dependent Hartree-Fock calculation for the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{16}$O system.

We perform shell-model calculations in ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$ for the summed magnetic dipole orbital strength and spin strength with a schematic interaction consisting of single-particle splitting, an isospin-conserving pairing interaction, and a quadrupole-quadrupole interaction. We consider four channels: orbital excitations to J=$1^{+}$ T=1 states, and then to J=$1^{+}$ T=2 states; spin excitations to J=$1^{+}$ T=1 states, and then to J=$1^{+}$ T=2 states. For the orbital T→T channel, the summed M1 strength varies quadratically with the size of the quadrupole interaction x for small values of this parameter when degenerate single-particle energies are used. Using realistic single-particle splitting does not destroy the quadrupole collectivity. The other three channels respond in different manners. We also consider linear-energy-weighted sum rules for which analytic results are obtained. The relevance of this work to experiments on orbital strengths and their relations to quadrupole excitations is discussed.

The level matrix corresponding to the scrK-matrix parametrization of a resonant nuclear reaction is derived and applied to the spectrum of α particles emitted following ${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$ β decay. The parametrized spectrum is fitted to data simultaneously with the E1 capture cross section of the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(α,γ${)}^{16}$O reaction and the p-wave phase shift of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(α,α${)}^{12}$C. Our analysis shows that new measurements of the α spectrum from ${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$ β decay could be used to significantly reduce the uncertainty of the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(α,γ${)}^{16}$O astrophysical S factor at 0.3 MeV. Various constraints on the parameters are analyzed and suggestions are made for further reducing the uncertainty in this crucial reaction rate.

The structure of low-lying states in odd-mass N=82 isotones (135≤A≤145) is investigated in terms of a number-projected one- and three-quasiparticles Tamm-Dancoff approximation. A surface-delta interaction is taken as the residual nucleon-nucleon interaction. Excitation energies, dipole and quadrupole moments, and B(M1) and B(E2) values are calculated and compared with the experimental data.

The validity of the quantum group ${\mathrm{SU}}_{\mathit{q}}$(2) expression for the nuclear rotational spectrum is investigated thoroughly. Analysis [including the Mallmann plots, the relations for the I(I+1) expansion coefficients, energy spectra, etc.] definitely display a systematical deviation of the ${\mathrm{Su}}_{\mathit{q}}$(2) prediction from the experimental data available for the even-even rare-earth and actinide nuclei. Only within a limited range of angular momentum the ${\mathrm{Su}}_{\mathit{q}}$(2) expression is suitable for rotational spectra. A significant angular momentum dependence of the q-deformation parameter is found. The q deformation is directly related to the nuclear softness.

Bulk properties like binding energies, rms radii, and quadrupole deformations of Ca, Ti, Cr, Fe, Ni, and Zn nuclei are calculated in the deformed relativistic mean field model. Excellent results for the experimentally known binding energies and radii of nuclei are obtained. The calculation is extended to nuclei near the neutron-drip line. Dips in quadrupole deformation are seen for the known closed-shell configurations and enhanced deformations are obtained for specific neutron numbers.

Accurate particle-number-conserving calculation shows that in a single-j model the yrast-yrare interaction V is always strong and no periodic oscillation of V with the degree of shell filling is found, in contrast to the results obtained by the Hartree-Fock-Bogoliubov approximation. To understand the behavior of V and bandcrossing frequency ${\mathrm{\omega }}_{\mathit{c}}$, the spin-alignment, seniority structure, configuration structure, and ‘‘quasiparticle structure’’ of the yrast and yrare bands are analyzed in detail. Calculation in a two-j model (high-j intruder orbits plus normal orbits of opposite parity) was also carried out to illustrate schematically that a weak yrast-yrare interaction may occur for certain single-particle level scheme. The coexistence of normal low-j orbits with high-j intruder orbits is indispensible for a sharp backbending observed in some realistic nuclei.