Two new proton emitting states in the deformed nuclei ${}^{140}\mathrm{Ho}$ ${(E}_p=1086\mathrm{}\pm 10\hspace{0.5em}\mathrm{keV},$ $T_{1/2}=6\mathrm{}\pm 3\hspace{0.5em}\mathrm{ms})$ and ${}^{141m}\mathrm{Ho}$ ${(E}_p=1230\mathrm{}\pm 20\hspace{0.5em}\mathrm{keV},$ $T_{1/2}=8\mathrm{}\pm 3\hspace{0.5em}\mu \mathrm{s})$ have been identified. Experimental data are interpreted using the coupled-channels Schrödinger equation with outgoing wave boundary conditions. The observed resonances are discussed in terms of deformed single-proton orbitals close to the $Z=67\mathrm{}$ Fermi level.

The proton-rich isotopes ${}^{180}\mathrm{Pb},$ ${}^{182}\mathrm{Pb}$, and ${}^{184}\mathrm{Pb}$ were produced in ${}^{92}\mathrm{Mo}$ bombardments of ${}^{90}\mathrm{Zr},$ ${}^{92}\mathrm{Zr}$, and ${}^{94}\mathrm{Zr}$, respectively, and their $\alpha$-decay properties were investigated with the use of a fragment mass analyzer and a double-sided Si strip detector. These data yielded unambiguous identifications of ${}^{180}\mathrm{Pb}$ and ${}^{182}\mathrm{Pb}$ and half-lives for all three Pb nuclei that are more precise than previously available values. An examination of $\alpha$ reduced widths in the Pb mass region leads to the conclusion that the $Z=82\mathrm{}$ shell gap is greatly reduced for neutron numbers midway between 82 and 126. Available mass data, manifested in $\Delta Q_{\alpha }$ values and two-proton separation energies of even-even nuclei with the same neutron numbers, support this conclusion.

Quadrupole moment measurements of the ${1/2}^{+}\left[660\right]\hspace{0.5em}{(i}_{13/2})$ bands in ${}^{133}\mathrm{Nd}\hspace{0.5em}\mathrm{}(N=73\mathrm{})\mathrm{}$ and ${}^{135}\mathrm{Nd}\hspace{0.5em}\mathrm{}(N=75\mathrm{})\mathrm{}$ were performed using the Doppler-shift attenuation method. These results, coupled with the previously measured $Q_0$ for the same configuration in ${}^{137}\mathrm{Nd}\hspace{0.5em}\mathrm{}(N=77\mathrm{})\mathrm{}$, clearly demonstrate a trend of decreasing quadrupole deformation with increasing neutron number. The larger quadrupole moment in ${}^{133}\mathrm{Nd}$ compared with that in ${}^{135}\mathrm{Nd}$ and ${}^{137}\mathrm{Nd}$ offers evidence for the role played by the large shell gap at $N=72\mathrm{}$ for ${\beta }_2\sim 0.35–0.40$ in stabilizing the shape at enhanced deformation. The comparison of results from gating below and above the level of interest provides information on the time scale of the sidefeeding contributions to highly deformed structures in the $A\sim 130$ region.

Within a relativistic transport model for heavy-ion collisions, we show that the recently observed characteristic change from out-of-plane to in-plane elliptic flow of protons in midcentral $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions as the incident energy increases is consistent with the calculated results using a stiff nuclear equation of state $(K=380\mathrm{}\mathrm{MeV}).\mathrm{}$ We have also studied the elliptical flow of pions and the transverse momentum dependence of both the nucleon and pion elliptic flow in order to gain further insight about collision dynamics.

A calculation of deuteron Compton scattering using nonrelativistic perturbation theory is presented, with the primary motivation of investigating the feasibility of determining the neutron polarizabilities from this type of experiment. This calculation is expected to be valid for energies below 100 MeV. Pion-exchange, relativistic, and recoil corrections are also included. The low-energy theorem for gauge invariance is shown to be satisfied. The relative effects of the different terms and their effects on the determinations of the polarizabilities are discussed at energies of 49, 69, and 95 MeV. The cross section is dominated by the seagull, polarizability, and electromagnetic multipole interactions. Relativistic and pion-exchange terms are also important, while recoil corrections and multipoles of $L=2\mathrm{}$ and greater are negligible. The calculation provides a reasonable description of the experimental data points at 49 and 69 MeV. The polarizabilities are difficult to determine at these energies. A more accurate determination of the polarizabilities may be possible at 95 MeV.

Relativistic Hamiltonians are defined as the sum of relativistic one-body kinetic energy, two- and three-body potentials, and their boost corrections. In this work we use the variational Monte Carlo method to study two kinds of relativistic effects in ${}^3\mathrm{H}$ and ${}^4\mathrm{He},$ using relativistic Hamiltonians. The first is due to the nonlocalities in the relativistic kinetic energy and relativistic one-pion exchange potential (OPEP), and the second is from boost interaction. The OPEP contribution is reduced by $\sim 15\%$ by the relativistic nonlocality, which may also have significant effects on pion exchange currents. However, almost all of this reduction is canceled by changes in the kinetic energy and other interaction terms, and the total effect of the nonlocalities on the binding energy is very small. The boost interactions, on the other hand, give repulsive contributions of $\sim 0.4$ (1.9) MeV in ${}^3\mathrm{H}\hspace{0.5em}{(}^4\mathrm{He})$ and account for $\sim 37\%$ of the phenomenological part of the three-nucleon interaction needed in the nonrelativistic Hamiltonians. The wave functions of nuclei are not significantly changed by these effects.

It has been previously proposed to explain $\gamma$-ray staggerings in the deexcitation of some superdeformed bands in the ${}^{150}\mathrm{Gd}$ region in terms of a coupling between global rotation and intrinsic vortical modes. The observed $4ħ$ period for the phenomenon is suggested from our microscopic Routhian calculations using the Skyrme ${\mathrm{SkM}}^{*}$ effective interaction.

β decay rates for spherical neutron-rich r-process waiting-point nuclei are calculated within a fully self-consistent quasiparticle random-phase approximation, formulated in the Hartree-Fock-Bogoliubov canonical single-particle basis. The same Skyrme force is used everywhere in the calculation except in the proton-neutron particle-particle channel, where a finite-range force is consistently employed. In all but the heaviest nuclei, the resulting half-lives are usually shorter by factors of 2 to 5 than those of calculations that ignore the proton-neutron particle-particle interaction. The shorter half-lives alter predictions for the abundance distribution of r-process elements and for the time it takes to synthesize them.

Several isomers in ${}^{188}\mathrm{Pb}$ have been identified using pulsed beams, the recoil-shadow technique, and the ${}^{164}\mathrm{Er}{(}^{28}\mathrm{Si}{,4n)}^{188}\mathrm{Pb}$ reaction. Two of the isomers feed the ${10}^{+}$ state of the yrast sequence and are suggested to be the ${11}^{-}$ and ${12}^{+}$ states from oblate and spherical configurations, respectively. The ${12}^{+}$ isomer is fed weakly by another isomer with a relatively long lifetime, but it has not been characterized. A fourth isomer with a lifetime of about $1.2\hspace{0.5em}\mu \mathrm{s}$ leads via a complicated path to the $8^{+}$ and lower spin yrast states. It is a candidate for the $K^{\pi }{=8\mathrm{}}^{-},$ two-quasineutron state which occurs systematically in $N=106\mathrm{}$ prolate-deformed nuclei, supporting the assumption that the intruding collective well is prolate.

The giant resonance region in ${}^{24}\mathrm{Mg}$ was studied with inelastic scattering of 240 MeV α particles at small angles including 0°. The giant resonance peak was found to extend up to $E_X=41\mathrm{}\mathrm{MeV}.$ Isoscalar $E0,$ $E1,$ and $E2\mathrm{}$ strength corresponding to $72\pm 10\%,$ ${81}_{-14}^{+26\mathrm{}}\%,$ and $72\pm 10\%$ of the respective energy weighted sum rules was identified in the peak with centroids of $21.0\pm 0.6,$ $18.8\pm 1.7,$ and $16.9\pm 0.6\mathrm{MeV}$ and rms widths of $7.3\pm 1.2,$ $6.7\pm 1.0,$ and $3.4\pm 0.5\mathrm{MeV},$ respectively. Elastic scattering was measured from ${\theta }_{\mathrm{c}.\mathrm{m}.}=3\mathrm{}°$ to 33° and density dependent folding model parameters obtained. Inelastic scattering to states at 1.369, 4.122, 4.238, 6.010, 6.432, 7.349, 7.555, 7.616, and 8.358 MeV was measured and $B\left(\mathrm{EL}\right)\mathrm{}$ values obtained.

A simple parametrization for the octupole collective variables is proposed and the symmetries of the wave functions are discussed in terms of the solutions corresponding to the vibrational limit.

High-energy $\gamma$ rays emitted by the decay of the hot compound nucleus ${}^{194}\mathrm{Hg}$, formed in the reaction ${}^{30}\mathrm{Si}(142\mathrm{}\hspace{0.5em}\mathrm{MeV}{)+}^{164}\mathrm{Dy}$, have been measured in coincidence with different residual nuclei. The measured spectra and the relative residual-nucleus cross sections were simultaneously analyzed with the statistical model. Calculations assuming contributions from a GDR in superdeformed states were also made. No clear evidence was found that superdeformed shapes seen at $T=0\mathrm{}$ survive at average nuclear temperature $〈T〉\simeq 1.3\hspace{0.5em}\mathrm{MeV}$. Instead, an average nuclear deformation corresponding to $〈\beta 〉=0.3\mathrm{}$ constant with spin has been deduced for $20<I<\mathrm{}38\mathrm{}\hspace{0.5em}ħ$ by comparing the measured width to that predicted by the model of thermal shape fluctuations.

Based on the formalism, using a pion exchange quark-quark force, developed by us earlier [Phys. Rev. C 53, 50 (1996)] to study the charge symmetry breaking effects in nucleon-nucleon scattering we compute the difference in analyzing power for polarized neutrons and polarized protons at 477 MeV laboratory energy. The formalism enables us to express the scattering amplitude in two parts: (i) a direct term due to pion exchange at the nucleon level and (ii) a quark exchange term involving the quark substructure of nucleons in terms of the momentum-dependent form factors appearing explicitly. The latter has a structure that appears to be similar to the one obtained due to $\rho ,\omega$ exchanges between nucleons. Using these potentials we calculate the scattering amplitude for polarized neutron-proton scattering and compare the results with the earlier works as well as with the experimental observables.

High-spin states in ${}^{125}\mathrm{La}$ have been populated using the ${}^{94}\mathrm{Mo}{(}^{40}\mathrm{Ca},2\mathrm{}\alpha p)$ reaction at a beam energy of 180 MeV. Four of the five previously known rotational structures have been extended to higher spin $(I<~\frac{71}{2})$ and excitation energy. In addition, three new sequences were observed, two of which form a strongly-coupled band. This latter structure is likely based on the [404]9/2 proton orbital, which is associated with strong deformation driving behavior in nearby Pr and Pm nuclei. A systematic examination of the crossing frequencies based on the rotational alignment of $h_{11/2}$ protons and $h_{11/2}$ neutrons is also presented. The dependence of the crossing frequencies on deformation and Fermi surface can be inferred based on experimental observation and evidence for reduced proton and possibly neutron pairing fields is presented.

The recoil-distance Doppler-shift technique was employed to determine lifetimes of high-spin states in the semimagic nucleus ${}^{94}\mathrm{Ru}$. The nuclei were populated using the reaction ${}^{58}\mathrm{Ni}{(}^{40}\mathrm{Ca},4p)$ at a beam energy of 145 MeV, and the $\gamma$ radiation from their decay was detected in six EUROBALL cluster detectors. A total of 23 reduced transition probabilities and limits for fifteen further transitions were extracted and compared to large-scale shell model calculations, considering different configuration spaces and residual interactions. The information deduced on transition strengths turned out to be essential for the correct assignment of the calculated to the experimental excited states. The results indicate that the ${13}_2^{-}$ (6919 keV), ${14}_1^{-}$ (7970 keV), and the ${15}_1^{-}$ (8133 keV) levels have pure proton $\pi {(f}_{5/2}{)}^{-1}$ $\pi {(g}_{9/2}{)}^5$ configurations, whereas all other excited states above 6.3 MeV are built from a neutron $g_{9/2}\to d_{5/2}$ excitation across the $N=50\mathrm{}$ shell closure, coupled to up to six valence protons. Strong $M1\mathrm{}$ transitions were found in a stretched dipole cascade within the sequence of neutron core-excited states at positive parity, while the strengths of the transitions between core-excited and pure proton states were proven to be small, similar as in ${}^{95}\mathrm{Rh}$.

Ground-state properties of neutron-rich $N\approx 28$ nuclei are described in the framework of relativistic Hartree plus Bogoliubov (RH+B) theory. The model uses the NL3 effective interaction in the mean-field Lagrangian, and describes pairing correlations by the pairing part of the finite range Gogny interaction D1S. Two-neutron separation energies and ground-state quadrupole deformations that result from fully self-consistent RH+B solutions are compared with available experimental data. The model predicts a strong suppression of the spherical $N=28\mathrm{}$ shell gap for neutron-rich nuclei: the $1f7/\overrightarrow{2}\mathrm{fp}$ core breaking results in deformed ground states. Shape coexistence is expected for neutron-rich Si, S, and Ar isotopes.

The ground states of even-even $Z=N$ nuclei are determined with the isospin generalized BCS equations and the HFB equation. The calculations permit the simultaneous existence of the following Cooper pairs: $pp,$ $nn,$ $\mathrm{pn}(T=1\mathrm{}),$ and $\mathrm{pn}(T=0\mathrm{})\mathrm{}$ where the two nucleons in a pair occupy space-spin orbitals which are related by time reversal, as well as $\mathrm{pn}(T=0\mathrm{})\mathrm{}$ where the two nucleons are in identical space-spin orbitals. There is a transition from $T=1\mathrm{}$ Cooper pairs at the beginning of this isotope sequence to $T=0\mathrm{}$ Cooper pairs at the end of the sequence. Near the middle of the isotope sequence, there is coexistence of a $T=0\mathrm{}$ pair superfluid and a $T=1\mathrm{}$ pair superfluid in the same wave function. The fluctuation in the particle number is reduced if the wave function contains proton-neutron pairing. The fluctuation in the isospin is eliminated and isospin is conserved if the wave function contains only $T=0\mathrm{}$ pairing.

High-spin states in ${}^{124}\mathrm{Xe}$ were populated in the fusion-evaporation reaction ${}^{110}\mathrm{Pd}{(}^{18}\mathrm{O}{,4n)}^{124}\mathrm{Xe}$ at a beam energy of 86 MeV. The experiment was performed at the NORDBALL spectrometer in Risø, Denmark. The decay out of a magnetic dipole band was established for the first time in this nucleus. By means of angular correlations from oriented states the multipole mixing ratios for 9 of the 12 gamma transitions of the magnetic dipole band were deduced. The experimental $B(M1;\overrightarrow{I}I-1)/B(E2;\overrightarrow{I}I-2)$ values were compared to estimates of the Dönau-Frauendorf semiclassical model. The dipole band is inferred to be based on a prolate four-quasiparticle configuration of the type $[\nu {(h}_{11/2}\otimes g_{7/2})]\otimes [\pi {(h}_{11/2}\otimes d_{5/2}{/g}_{7/2}\left)\right].$

The inter-relationship arising from the use of two-body correlation functions for determining both nuclear source size and freeze-out temperature is discussed. Features which influence the interpretation of each are explored. Estimates of the differences between true and apparent volumes are made. Differences between volume measurements employing different correlation pairs are discussed and related to different “temperatures” examined in nuclear reactions.

An analysis of the effects of meson exchange and isobar currents in exclusive ${(e,e}^{\prime }p)$ processes from ${}^{16}\mathrm{O}$ under quasifree kinematics is presented. A model that has probed its feasibility for inclusive quasielastic ${(e,e}^{\prime })$ processes is considered. Sensitivity to final state interactions between the outgoing proton and the residual nucleus is discussed by comparing the results obtained with phenomenological optical potentials and a continuum nuclear shell-model calculation. The contribution of the meson exchange and isobar currents to the response functions is evaluated and compared to previous calculations, which differ notably from our results. These two-body contributions cannot solve the puzzle of the simultaneous description of the different responses experimentally separated.