Irradiation of Ta with a superconducting linear accelerator has provided data for the characterization of the reaction ${}_{}{}^{180}{}_{}{}^{}\mathrm{Ta}_{}^{\mathit{m}}{}_{}{}^{}$(γ,γ’${)}^{180}$Ta. The depopulation of the isomer ${}_{}{}^{180}{}_{}{}^{}\mathrm{Ta}_{}^{\mathit{m}}{}_{}{}^{}$ via an intermediate state or narrow band of states near 2.8 MeV has been found with an integrated cross section of 1.2×${10}^{\mathrm{-}25}$ ${\mathrm{cm}}^2$ keV. This large value exceeds, by nearly an order of magnitude, known cross sections for (γ,γ’) reactions producing isomers of other species. Another intermediate state or narrow band is also indicated by the data at an energy 0.6 MeV higher.

Two excited superdeformed bands in ${}_{}{}^{149}{}_{}{}^{}\mathrm{Gd}$ have been observed in γ-ray spectroscopy. Based on the behavior of the dynamical moments of inertia, we assign one band to a neutron excitation and the other to a proton excitation. The proton-excited-band γ-ray energies are nearly identical to those already known in ${}_{}{}^{150}{}_{}{}^{}\mathrm{Tb}$. In addition, two new members of the ${}_{}{}^{149}{}_{}{}^{}\mathrm{Gd}$ yrast cascade have been observed, extending the band to spin 135/2ħ. The results are discussed in terms of high-N intruder orbitals in the cranked-shell model.

Using coupling schemes derived for low-lying structures in doubly odd deformed nuclei in the framework of the particle rotor model and properties of orbitals which follow from pseudospin symmetry, likely explanations are given for identical superdeformed bands.

Off-shell effects due to momentum dependence of the optical potential are calculated for the relativistic approach to 200 MeV proton elastic scattering by ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$. Optical potentials are based on the optimally factorized impulse approximation using complete sets of invariant amplitudes based on the Utrecht meson-exchange model for the NN interaction.

The nuclear level density for solvable model Hamiltonians is calculated as a function of the excitation energy, taking into account both large-amplitude thermal and small-amplitude quantal fluctuations. The formalism, which is applied to simple systems displaying a phase transition (deformed to spherical, superfluid to normal) as a function of the temperature, accurately reproduces the exact solutions. The contribution of thermal fluctuations changes the level density by an order of magnitude. Quantal fluctuations are essential to reproduce the absolute energies of the system and thus to relate the excitation energy to temperature.

We investigate the shadowing phenomenon observed in deep inelastic lepton-nucleus scattering in the region of small x using a generalization of the vector meson dominance model which includes both the low mass vector meson resonances and the higher mass quark-antiquark continuum in the photon spectral function. Our description is consistent with the nucleon structure function ${\mathit{F}}_2^{\mathit{N}}$(${\mathit{Q}}^2$,x) in the low x region, including its scaling properties. We find that the nuclear multiple scattering of hadronic components of the virtual photon reproduces the experimental data for ${\mathit{F}}_2^{\mathit{A}}$/${\mathit{AF}}_2^{\mathit{N}}$ at x<0.1.

The effect of unequal neutron and proton masses on the binding-energy difference of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ is calculated using a wide variety of nuclear models. We find that this charge-symmetry-breaking mechanism contributes 14(2) keV to the 764 keV difference. We also demonstrate the importance of the mixed-symmetry wave function components in making the contribution of this mechanism fairly small, but rather model dependent.

Measurements of the ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(d→,γ${)}^4$He cross section σ(θ), the vector analyzing power ${\mathit{A}}_{\mathit{y}}$(θ), and the tensor analyzing power ${\mathit{A}}_{\mathit{y}\mathit{y}}$(θ) have been obtained at ${\mathit{E}}_{\mathit{d}}$(lab)=14.7 and 1.2 MeV and ${\mathit{E}}_{\mathit{d}}$(lab)≤0.8 MeV; the spherical tensor analyzing power ${\mathit{T}}_{20}$(θ) was also measured at ${\mathit{E}}_{\mathit{d}}$(lab)=14.7 MeV. ${\mathit{A}}_{\mathit{y}}$(130°) and ${\mathit{A}}_{\mathit{y}\mathit{y}}$(130°) were measured at eight bombarding energies between ${\mathit{E}}_{\mathit{d}}$(lab)=0.8 and 14.7 MeV and ${\mathit{T}}_{20}$(130°) at ten energies between ${\mathit{E}}_{\mathit{d}}$(lab)=5.4 and 14.7 MeV. A transition-matrix element analysis is performed by fitting to the available angular distribution data at ${\mathit{E}}_{\mathit{d}}$(lab)≤0.8 MeV and at ${\mathit{E}}_{\mathit{d}}$(lab)=1.2 and 14.7 MeV. The data are compared to the results of a multichannel resonating group model (MCRGM) calculation. The MCRGM model includes the tensor force in calculating both the continuum and bound states and provides a fairly good description of the data, especially above ${\mathit{E}}_{\mathit{d}}$=5 MeV. This calculation predicts a D-state probability in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ arising from the relative motion between the two deuterons of ${\mathit{P}}_{\mathit{D}}$=2.2%.

A model has been constructed of the interaction between two protons and applied to the calculation of spin-dependent elastic-scattering parameters over a range of beam momenta from 3 to 24 GeV/c. The interaction is one-boson exchange, augmented by a zero-range core and an imaginary potential to model absorption into inelastic channels. The model provides excellent agreement with experimental measurements of the unpolarized differential cross section, and reproduces the qualitative features of the transverse asymmetry and spin correlation. The absorptive potential is found to dominate the real potential, greatly attenuating the low partial waves. This suggests that perturbative quantum chromodynamics does not apply to elastic scattering at the energy scale examined here, since absorptive effects prevent the quarks from approaching to appropriately small separations.

The details of our procedure for including the magnetic moment interaction in nucleon-nucleon phase-shift analyses are given. The magnetic moment scattering amplitude in case of pp scattering is calculated in Coulomb distorted-wave Born approximation. Special attention is given to the construction of the nuclear amplitude in the presence of the complete electromagnetic (modified Coulomb, magnetic moment, and vacuum polarization) interaction. We compare our treatment with approximations that have appeared in the literature and show that these approximations are no longer found to be adequate for a proper description of recently published accurate scattering data.

We have calculated the asymptotic normalization constants (ANC) of the triton by comparing the asymptotic form of the triton wave function (obtained by the hyperspherical harmonics expansion method) with an appropriate tensor product of the deuteron wave function and the asymptotically free-neutron wave function. The convergence behavior of the binding energy (BE) and ANC have been studied for a simple S-projected potential (S3) and two exponential potentials. It is seen that convergence of the ANC needs many more partial waves than that of the BE, especially for potentials with a long tail.

The results of a study of high spin states of ${}_{}{}^{74}{}_{}{}^{}\mathrm{Se}$ using two reactions, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$${(}^{19}$F,3p) and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$${(}^{32}$S,α2p), are presented. The ground-state band is extended up to ${\mathit{J}}^{\mathrm{\pi }}$=(${24}^{+}$), and three other bands are also extended to higher spins than those known previously. Lifetimes of states in the ground-state band (J=6–16) and an odd-spin negative-parity band (J=9–13) measured by the Doppler-shift attenuation method are reported. A rotational band built on the 854-keV $0^{+}$ state is proposed, allowing the study of two coexisting ${\mathit{K}}^{\mathrm{\pi }}$=$0^{+}$ bands to high spin. It is also concluded that energy and lifetime information support an octupole-band interpretation for the odd-spin negative-parity band.

The systematic behavior of $3_1^{\mathrm{-}}$ states is used to identify N and Z values at which maximum octupole collectivity occurs. The results are used to suggest nuclei in which static octupole deformation might appear.

An investigation of low-lying energy levels of ${}_{}{}^{130,132}{}_{}{}^{}\mathrm{Ce}$, ${}_{}{}^{132,134}{}_{}{}^{}\mathrm{Nd}$, and ${}_{}{}^{134}{}_{}{}^{}\mathrm{Pm}$ has been made via β decay, especially of those levels in the ${\mathit{K}}^{\mathrm{\pi }}$=$2^{+}$ gamma band in the even-even nuclei. The radioactive parent nuclei were produced by the ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$${(}^{46}$Ti,xpyn) and ${}_{}{}^{112}{}_{}{}^{}\mathrm{Sn}$${(}^{28}$Si,xpyn) reactions with bombarding energies of 170 to 240 MeV. An isotope separator enabled A=134 mass identification. Level schemes of these five nuclei were constructed from γ-γ-t coincidence data. The β-decay half-lives of the parent nuclei, ${}_{}{}^{130}{}_{}{}^{}\mathrm{Pr}$, ${}_{}{}^{132}{}_{}{}^{}\mathrm{Pr}$, ${}_{}{}^{132}{}_{}{}^{}\mathrm{Pm}$, ${}_{}{}^{134}{}_{}{}^{}\mathrm{Pm}$, and ${}_{}{}^{134}{}_{}{}^{}\mathrm{Sm}$, were determined to be 40±4, 96±18, 8.8±0.8, 23±2, and 9.3±0.8 s, respectively. The suitability of the proton-neutron interaction boson model in describing ${}_{}{}^{130}{}_{}{}^{}\mathrm{Ce}$, ${}_{}{}^{132}{}_{}{}^{}\mathrm{Ce}$, ${}_{}{}^{132}{}_{}{}^{}\mathrm{Nd}$, and ${}_{}{}^{134}{}_{}{}^{}\mathrm{Nd}$ is supported by the comparison of experimental relative E2 transition probabilities with proton-neutron interaction boson model predictions.

The (α${,}^3$He) and (α,t) reactions on ${}_{}{}^{25}{}_{}{}^{}\mathrm{Mg}$ were measured at ${\mathit{E}}_{\mathrm{\alpha }}$=50 MeV. Cross sections obtained for 57 positive parity states in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ and ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$ were analyzed within the framework of the exact-finite-range distorted-wave Born approximation and compared to the full s-d shell model predictions. Reasonable agreement between the experimental strengths and the theory was obtained for the low lying states. Deviations of factors of 2 or more were found for some high lying $2^{+}$, $3^{+}$, and $4^{+}$ states in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$ and especially for the $1_1^{+}$ state in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$. The spectroscopic factors for the transitions to the analog states in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ and ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$ were compared between these reactions. The same strength was obtained for the $6_1^{\mathrm{-}}$, T=1 state in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ and ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$, whereas an enhancement of about 30% was observed for the $0_1^{+}$ and $3_1^{+}$, T=1 states in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$. Further, $1^{+}$ states in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ proposed around ${\mathit{E}}_{\mathit{x}}$=10 MeV through the (p,p’) reaction were also observed in the ${}_{}{}^{25}{}_{}{}^{}\mathrm{Mg}$(α${,}^3$He) reaction without the special enhancement for the 10.6 MeV $1^{+}$ state seen in the (p,p’) reaction. The total observed strengths for neutron stripping to the positive-parity states in the region of ${\mathit{E}}_{\mathit{x}}$=0–11 MeV almost attained the limit of the pure j-j coupling scheme. Those for the proton stripping were 70% of the limit in the region of ${\mathit{E}}_{\mathit{x}}$=0–8 MeV.

New levels strongly excited by 112-MeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions on even Ni and Zn isotopes are ${\mathit{J}}^{\mathrm{\pi }}$ assigned on kinematical and geometrical arguments, crude shell-model calculations, and distorted-wave Born approximation angular-distribution analysis. These tentative assignments are supported by the Bansal-French model. Because of the contribution of additional collective effects, the two-proton transfer reaction spectra are less selectively fed than those obtained with the analogous two-neutron transfer reactions induced on the same targets in a similar energy range.

The structures of the odd-neutron nuclides ${}_{}{}^{119,121}{}_{}{}^{}\mathrm{Te}$ have been investigated following beta decay of ${}_{}{}^{119,121}{}_{}{}^{}\mathrm{I}$. Gamma-ray and conversion-electron singles and coincidence measurements have been performed on mass separated sources using Ge gamma-ray detectors and Si(Li) electron detectors and a mini-orange positron filter. New levels and branching ratios have been determined for both nuclides. E0 components have been identified on M1 and M1/E2 transitions in ${}_{}{}^{119}{}_{}{}^{}\mathrm{Te}$ and interpreted as arising from coupling of particle-hole intruder states with the odd neutron.

Effects associated with the inclusion of scattering terms, in the random phase approximation treatment of a two-body interaction at finite temperature, are investigated. Numerical results, for the case of quadrupole excitations in ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$, are discussed. It is found that these terms could influence the low-energy region of the intensity distribution, for multipole excitations at finite temperature.

The widely used coupled cluster method (CCM) in quantum many-body theory has recently provided very accurate descriptions of a large number of extended systems. Although its earlier applications to closed-shell and neighboring finite nuclei were also very successful, they have been shrouded in algebraic and technical complexity. Furthermore, they are difficult to compare with more traditional calculations of generalized shell-model theory since, at least at the important level of two-body correlations, they have been largely implemented in relative-coordinate space rather than the more usual oscillator configuration space. The CCM is reviewed here in the precise context of applications to simple finite systems. Special attention is paid to formulate it in such a way that comparison may be made with generalized shell-model or configuration-interaction (CI) theories. Particular regard is paid to an exact incorporation of translational invariance, so that any spuriosity associated with the center-of-mass motion is always avoided. An important side benefit is that the number of many-body configurations in the usual oscillator basis is dramatically reduced. We are thereby able to present both CI and CCM calculations on ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ up to the essentially unprecedented level of 60ħω in oscillator excitation energy, for two popular and quasirealistic choices of the nucleon-nucleon interaction for which exact Monte Carlo results are available for this nucleus. Although even our simplest approximations attain about 95% of the total binding energy, the convergence in the oscillator configuration space is shown to be both very slow and of a complicated nonuniform nature. Strong implications are drawn for standard implementations of generalized shell-model techniques for heavier nuclei.

The meson exchange current contributions (MEC) to the ${}_{}{}^6{}_{}{}^{}\mathrm{He}_{\mathrm{g}.\mathrm{s}.\mathrm{}}^{}{}_{}{}^{}$${\to }^6$${\mathrm{Li}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ beta decay are computed for various nuclear amplitudes. We use particle-hole symmetry properties of one- and two-body matrix elements and find relationships between the A=6 beta decay and the anomalously suppressed ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}_{\mathrm{g}.\mathrm{s}.\mathrm{}}^{}{}_{}{}^{}$${\to }^{14}$${\mathrm{N}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ beta transition, for which these have been studied previously. We find MEC contributions to be small for the mass-six case, bringing the calculated axial vector form factor closer to the experimental value. Implications for the positive pion photoproduction transition between the same states are discussed.