Lifetimes of high-spin states in two $\Delta I=1\mathrm{}$ bands and one $\Delta I=2\mathrm{}$ band in ${}^{109}\mathrm{Cd}$ have been measured using the Doppler shift attenuation method in an experiment performed using the ${}^{96}\mathrm{Zr}{(}^{18}\mathrm{O},5n)$ reaction with the GAMMASPHERE array. Experimental total angular momenta and reduced transition strengths for both $\Delta I=1\mathrm{}$ bands were compared with tilted axis cranking (shears mechanism) predictions and the $\Delta I=2\mathrm{}$ band with principal axis cranking predictions, based on configurations involving two proton $g_{9/2}$ holes and one or three valence quasineutrons from the $h_{11/2}$ and mixed $g_{7/2}{/d}_{5/2}$ orbitals. Good overall agreement for angular momentum versus rotational frequency has been observed in each case. The $\Delta I=2\mathrm{}$ band is shown to have a large ${\mathcal{J}}^{\mathrm{}\left(2\right)\mathrm{}}/B\left(E2\mathrm{}\right)\mathrm{}$ ratio suggestive of antimagnetic rotation. Additionally, both dipole bands show a decreasing trend in $B\left(M1\mathrm{}\right)\mathrm{}$ strength as a function of spin, a feature of the shears mechanism. The experimental results are also compared with a semiclassical model that employs effective interactions between the proton holes and neutrons as an alternate interpretation for the shears mechanism.

Power-counting arguments are used to organize the interactions contributing to the $N\overrightarrow{N}d\pi ,pn\pi$ reactions near threshold. We estimate the contributions from the three formally leading mechanisms: the Weinberg-Tomozawa (WT) term, the impulse term, and the Δ-excitation mechanism. Subleading but potentially large mechanisms, including S-wave pion rescattering, the Galilean correction to the WT term, and short-ranged contributions are also examined. The WT term is shown to be numerically the largest, and the other contributions are found to approximately cancel. Similarly to the reaction $p\overrightarrow{p}\mathrm{pp}{\pi }^0,$ the computed cross sections are considerably smaller than the data. We discuss possible origins of this discrepancy.

We measured the quasielastic scattering excitation function for the ${}^{32}\mathrm{S}{+}^{110}\mathrm{Pd}$ system at a backward angle and at energies around the Coulomb barrier. A fine enough energy step was adopted in order to obtain a representation of the barrier distribution through the first differentiation of the data. Our results were compared with the barrier distribution that was deduced from fusion data for the same system.

In the first part of this work, we study the quadrupole collective properties of $N_a=2,$ 4, 6, and 8 nucleons occupying the abnormal-parity intruder single-particle states with high angular momenta $j_a=\frac{9}{2},$ $\frac{11}{2},\hspace{0.5em}\frac{13}{2},$ and $\frac{15}{2}.$ This study is essential for a detailed understanding of the contribution made by these nucleons to the quadrupole collectivity of the yrast states of deformed nuclei. The properties studied include (i) the distribution of the angular momenta J contained in the intrinsic state of $N_a$ particles in the $|j_a{k}_a〉$ states, (ii) the relationship between the quadrupole moment $Q_0{(j}_a{,N}_a)$ of such an intrinsic state and the maximum angular momentum $J_{\max }$ contained in it, (iii) the complete set of reduced quadrupole matrix elements ${(J}^{\prime }||Q||J)$ for transitions between all the states $|J〉$ and $|J^{\prime }〉$ projected from the intrinsic state, (iv) the $B(E2:\overrightarrow{J}J-2)$ values, (v) the transition moments $Q_t\mathrm{}\left(J\right),$ and (vi) the spectroscopic quadrupole moment $Q\left(J\right).$ We compare these properties with similar properties of an intrinsic state having SU(3) symmetry which contains the same set of angular momenta as contained in the intrinsic state of a particular number of nucleons in a specific $j_a$ configuration. In the second part, we use the input from the first part to study the collective properties of the coupled system of protons and neutrons in abnormal-parity states. We show that the SU(3)-like features observed for the individual groups of abnormal-parity nucleons become stronger for the coupled system. Finally, in the third part, we consider the yrast bands of well-deformed nuclei projected from their Nilsson intrinsic states of valence nucleons in a major shell. We specify the structure of the wave function of each projected yrast state $|J〉$ in terms of the nucleons in both normal- and abnormal-parity states. These wave functions can be used to determine the individual contributions of the nucleons in normal- and abnormal-parity states to any specific property of the yrast state. In particular, we calculate the transition moments $Q_t\mathrm{}\left(J\right)\mathrm{}$ of the entire yrast band of even-even ${}^{160-166}\mathrm{Yb},$ ${}^{156,158}\mathrm{Dy},$ ${}^{232}\mathrm{Th},$ ${}^{234}\mathrm{U},$ and ${}^{236}\mathrm{U}$ projected from their respective Nilsson intrinsic states.

Collisions of deformed nuclei such as U may provide 40% more hard processes and about 30% larger energy densities, compared to central PbPb collisions. They also produce excited systems which are strongly deformed in the transverse plane, which are much larger than possible in peripheral PbPb collisions. We discuss how, even without a polarized target, one can study these phenomena by selecting particular events. Collisions are studied by a simple Monte Carlo model, and it is shown what can be achieved by making cuts in two control parameters—the number of participants and ellipticity. We also discuss how UU collisions may resolve a number of outstanding issues, from corrections to hard processes to elliptic flow (the existence of a quark-gluon plasma), to the mechanism of $J/\psi$ suppression.

An extended pairing plus QQ force model, which has been shown to successfully explain the nuclear binding energy and related quantities such as the symmetry energy, is applied to study $\alpha$-like four-nucleon correlations in ${1f}_{7/2}$-shell nuclei. The double difference of binding energies, which displays a characteristic behavior at $N\approx Z,$ is interpreted in terms of the $\alpha$-like correlations. The important roles of proton-neutron interactions forming the $\alpha$-like correlated structure are discussed.

A two-frequency shell model is proposed for investigating the structure of hypernuclei starting with a hyperon-nucleon potential in free space. In a calculation using the folded-diagram method for ${}_{\Lambda }^{16}\mathrm{O},$ the $\Lambda$ single particle energy is found to have a saturation minimum at an oscillator frequency $ħ{\omega }_{\Lambda }\approx 10\mathrm{MeV},$ for the $\Lambda$ orbit, which is considerably smaller than $ħ{\omega }_N=14\mathrm{}\mathrm{MeV}$ for the nucleon orbit. The spin-dependence parameters derived from the Nijmegen NSC89 and NSC97f potentials are similar, but both are rather different from those obtained with the Jülich-$B$ potential. The $\Lambda \mathrm{NN}$ three-body interactions induced by $\Lambda N-\Sigma N$ transitions are important for the spin parameters, but relatively unimportant for the low-lying states of ${}_{\Lambda }^{16}\mathrm{O}.$

The off-shell aspects of the one-pion-exchange potential (OPEP) are discussed. Relativistic Hamiltonians containing relativistic kinetic energy, relativistic OPEP with various off-shell behaviors, and Argonne $v_{18}$ short-range parametrization are used to study the deuteron wave functions. The OPEP off-shell behaviors depend on whether a pseudovector or pseudoscalar pion-nucleon coupling is used and are characterized by a parameter μ. We study potentials having μ=-1, 0, and +1 and we find that they are nearly unitarily equivalent. We also find that a nonrelativistic Hamiltonian containing local potentials and nonrelativistic kinetic energy provides a good approximation to a Hamiltonian containing a relativistic OPEP based on pseudovector pion-nucleon coupling and relativistic kinetic energy.

We propose an adiabatic mean-field model for dynamical collective state transitions of a nuclear system. The transition process is described in terms of the nuclear mean-field wave functions which are adiabatically determined in the course of the transition. A principal steering meson field approximation simplifies the model. In the simplified model, the Hamiltonian is expressed by a tridiagonal matrix on the basis of the adiabatic mean-field states, because the mean-field states are coupled by the residual interaction. The model has two degenerate lowest mean-field states. These states are separated by a potential barrier made of intermediate mean-field states and are coupled to each other by the interaction through the intermediate states. We solve the eigenvalue equation for the Hamiltonian both in an exact diagonalization and in a perturbation method. The perturbation expression for the splitting of the energies of the two almost degenerate ground states exhibits analytically a coherent structure in favor of the dynamical transition between the two isolated lowest mean-field states. The net current for the collective tunneling from an initial lowest mean-field state to the degenerate counterpart through the potential barrier is much smaller than the quantum mechanically fluctuating local currents. The energy eigenvalue equation for a tridiagonal Hamiltonian matrix leads to a Schrödinger difference equation on a finite range of integral discrete coordinates. Higher energy states on a repulsive parabolic potential on the finite range of discrete coordinate are shown to have some features resembling the energy states of a harmonic oscillator: equispacing energy levels and Gaussian distribution of the wave functions.

Compton scattering results are used to probe proton structure via measurement of higher order polarizabilities. Values for ${\alpha }_{E2\mathrm{}}^p,\hspace{0.5em}{\beta }_{E2\mathrm{}}^p,\hspace{0.5em}{\alpha }_{E\nu }^p,$ and ${\beta }_{E\nu }^p$ determined via dispersion relations are compared to predictions based upon chiral symmetry and from the constituent quark model. Extensions to spin polarizabilities are also discussed.

We will numerically investigate the two-particle correlation function of the CERN-SPS $158A$ GeV Pb+Pb central collisions in detail based on a (3+1)-dimensional relativistic hydrodynamical model with first order phase transition. We use the Yano-Koonin-Podgoretskiĭ (YKP) parametrization as well as the usual Cartesian parametrization and analyze the pair momentum dependence of the Hanbury Brown–Twiss radii extracted from the parametrizations. We find that the interpretation of the temporal radius parameter as the time duration in the YKP parametrization is not available for the hydrodynamical model where the source became opaque naturally because of expansion and surface dominant freeze-out. Finally, the effect of the phase transition on the source opacity is also discussed.

The invariant mass spectrum of the $e^{+}{e}^{-}$ and ${\mu }^{+}{\mu }^{-}$ pairs from decays of light unflavored mesons with masses below the $\phi \mathrm{}\left(1020\right)\mathrm{}$-meson mass to final states containing along with a dilepton pair one photon, one meson, and two mesons are calculated within the framework of the effective meson theory. The results can be used for simulations of the dilepton spectra in heavy-ion collisions and for experimental searches of dilepton meson decays.

We carry out realistic coupled-channel calculations for the ${}^{11}\mathrm{Be}{+}^{208}\mathrm{Pb}$ reaction in order to discuss the effects of breakup of the projectile nucleus on subbarrier fusion. We discretize in energy the particle continuum states, which are associated with the breakup process, and construct the coupling form factors to these states on a microscopic basis. The incoming boundary condition is employed in solving coupled-channel equations, which enables us to define the flux for complete fusion inside the Coulomb barrier. It is shown that complete fusion cross sections are significantly enhanced due to the couplings to the continuum states compared with the no-coupling case at energies below the Coulomb barrier, while they are hindered at above barrier energies.

The quasicontinuous spectra associated with the decay of the superdeformed bands in ${}^{192,194}\mathrm{Pb}$ have been extracted. The rapid rise in the $\gamma$-ray intensity in these spectra for $E_{\gamma }\lesssim 1.8$ MeV is interpreted to arise from the dramatic increase in level density above the energy gap for even-even nuclei. This energy gap has been found to be $\approx 0.95\left(10\right)\mathrm{}$ MeV at $6ħ$ in ${}^{194}\mathrm{Pb}$ and $\approx {0.4}_{-0.1}^{+0.4\mathrm{}}$ MeV at $10ħ$ in ${}^{192}\mathrm{Pb}.$

Tensor analyzing powers for ${}^2\mathrm{H}(\overrightarrow{d}{,d)}^2\mathrm{H}$ elastic scattering were measured at deuteron energies of 3.0, 4.75, and 6.0 MeV. The measured values are below 0.02 and increase with increasing energy. The data were compared to the results of an R-matrix parametrization and microscopic four-body calculations. The calculations indicate that the nucleon-nucleon p waves have a strong effect on the observables.

The properties of states in ${}^{207}\mathrm{Pb}$ populated with the ${(n,n}^{\prime }\gamma )$ reaction have been studied. γ-ray excitation functions, angular distributions, and coincidences have been measured, and the lifetimes of many excited states were determined with the Doppler-shift attenuation method. A sextuplet of states near 3.2 MeV is interpreted as resulting from weak-coupling of the $\nu f_{5/2}^{-1}$ first excited state of ${}^{207}\mathrm{Pb}$ with the octupole phonon of the ${}^{208}\mathrm{Pb}$ core. A number of $E1\mathrm{}$ transitions have been identified, and their reduced transition probabilities have been examined. The properties of low-lying levels in ${}^{207}\mathrm{Pb}$ have been studied in the framework of the particle-core coupling model.

Excited states in ${}^{111}\mathrm{Te}$ have been studied using the $4pn$ evaporation channel from the ${}^{58}\mathrm{Ni}{+}^{58}\mathrm{Ni}$ reaction at a beam energy of 250 MeV. A thin-target experiment was carried out using GAMMASPHERE coupled with the MICROBALL charged-particle detector array and an array of neutron detectors. A complementary thick-target experiment was performed with the Stony Brook six-Ge-detector array in order to measure the lifetime of an ${11/2}^{-}$ isomer observed in the GAMMASPHERE data. The structure of ${}^{111}\mathrm{Te}$ at low spin is dominated by the yrast $\nu h_{11/2}$ band, although a band assigned to the $\nu {(g}_{7/2}{d}_{5/2})$ configuration is also observed. Four collective bands have been found at higher spins. Experimental results are compared to the odd-$A$ Te systematics and to core-quasiparticle and total Routhian surface calculations.

We have observed the $\alpha$ decay of ${}^{217}\mathrm{Th}$ populating the low-lying two excited states in ${}^{213}\mathrm{Ra}.$ The branching ratio to the first and the second excited states in ${}^{213}\mathrm{Ra},$ which have expected $J^{\pi }$ values of ${\frac{5}{2}}^{-}$ and ${\frac{3}{2}}^{-},$ was determined to be ${2.6}_{-1.1}^{+1.6\mathrm{}}\%$ and ${5.1}_{-1.6}^{+2.0\mathrm{}}\%,$ respectively, and the energy of the second excited state in ${}^{213}\mathrm{Ra}$ was determined to be 834 keV for the first time. The systematical trend of the branching ratio for $N=125\mathrm{}$ isotones with even proton numbers near the ${}^{208}\mathrm{Pb}$ core was reasonably explained by the shell model of $\alpha$ decay, where the relative reduced width for specific neutron-orbital and angular momentum has an identical value for the nuclei in the systematics.

High-spin states in ${}^{86}\mathrm{Zr}$ up to ${30}^{+}$ and ${27}^{-}$ were observed via the ${}^{58}\mathrm{Ni}{(}^{32}\mathrm{S},4p)$ reaction at 135 MeV beam energy using the combined GAMMASPHERE and MICROBALL systems. Calculations performed with the configuration-dependent shell-correction approach show that these states are built from six $g_{9/2}$ neutrons and at most four protons excited from the $p_{1/2}{,p}_{3/2}{,f}_{5/2}$ subshells to the $g_{9/2}$ subshell at small deformation. The highest observed states at ${27}^{-}$ and ${30}^{+}$ are interpreted as band-terminating states with the latter having the highest spin available in the valence space for ${}^{86}\mathrm{Zr}.$

We introduce a local-scaling point transformation to allow for modifying the asymptotic properties of the deformed three-dimensional Cartesian harmonic oscillator wave functions. The resulting single-particle bases are very well suited for solving the Hartree-Fock-Bogoliubov equations for deformed drip-line nuclei. We then present results of self-consistent calculations performed for the Mg isotopes and for light nuclei located near the two-neutron drip line. The results suggest that for all even-even elements with $Z=10\mathrm{}$–18 the most weakly bound nucleus has an oblate ground-state shape.