The structure of ${}_{}{}^{111}{}_{}{}^{}\mathrm{Cd}$ was studied using the ${}_{}{}^{110}{}_{}{}^{}\mathrm{Pd}$${(}^3$He,2nγ${)\mathrm{}}^{111}$Cd reaction, which populated a number of new nonyrast states. The experiments included γ-ray excitation functions, γ-ray angular distributions, and γ-γ coincidences. Even though ${}_{}{}^{111}{}_{}{}^{}\mathrm{Cd}$ is only two protons away from the closed Z=50 shell, there is evidence that it is slightly deformed. A symmetric particle-plus-rotor model has been used to interpret the results, and shows that rotational features are present.

High-spin states in ${}_{}{}^{103}{}_{}{}^{}\mathrm{Rh}$ have been studied using the ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}$${(}^7$Li,4nγ) reaction at 45 MeV. The in-beam techniques employed included relative γ-ray excitation functions, γ-γ coincidences, and γ-ray angular distribution measurements. Low-lying collective bands built on the 1$g_{9/2}$ and 2$p_{1/2}$ quasiproton states show large signature splitting. At higher excitation energies (2.346 and 3.399 MeV), two strong ΔI=1 cascades are also observed with small signature splitting. These latter bands probably arise from three quasiparticle configurations. The one quasiparticle bands are interpreted within the framework of the axially symmetric rotor-plus-particle model with a variable moment of inertia, the generalized particle-asymmetric-rotor model, and the interacting boson-fermion model. High-spin features of ${}_{}{}^{103}{}_{}{}^{}\mathrm{Rh}$ are compared with the predictions of the cranked shell model. All of the models indicate that ${}_{}{}^{103}{}_{}{}^{}\mathrm{Rh}$ is a soft nucleus which exhibits shape coexistence.

A total of 776 interactions with AgBr in nuclear emulsion has been used to analyze the exclusive data for collective flow from ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$, ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$, ${}_{}{}^{84}{}_{}{}^{}\mathrm{Kr}$, and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ at 1.8, 2.1, 1.52, and 0.95A GeV, respectively. The transverse momentum technique has been employed to study this effect which becomes stronger with the increase of incident energy as well as with the decrease of impact parameter.

We study the angular distributions of low energy protons for various multiplicity cuts in $E_L$=0.8 GeV/nucleon heavy nuclear collisions in terms of the nuclear cascade model. The differential cross sections for low energy protons ($E_c$<100 MeV, with $E_c$ being the proton energy in the center-of-mass frame) in the lateral direction move up relatively with respect to those in the forward direction as the multiplicity cut increases. For the case of La+La collisions, for example, the differential cross section becomes maximum at ${\theta }_c$=90° above the multiplicity cut M>60.

Gamma rays from ${}_{}{}^{69}{}_{}{}^{}\mathrm{Se}$ have been investigated using the reaction ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${(}^{32}$S,2pn γ${)}^{69}$Se between 80 and 110 MeV beam energy. Isotopic identification was based on excitation functions, n-γ and n-γ-γ coincidences, as well as genetic relationships. An isomeric state ($T_{1/2}$=853±78 ns) was found at 575.0±0.4 keV decaying to the first excited state which was located at 40.2±0.3 keV. The isomeric state lifetime reveals the same degree of inhibition as in analogous M2 ${\left(\right(9/2\mathrm{}}^{+}$→${(5/2\mathrm{}}^{\mathrm{-}}$) transitions and the excitation energy displays the systematic trend of the first ${(9/2\mathrm{}}^{+}$ state in the N=35 and N=37 isotones. The observed γ decay properties are consistent with $J^{\pi }$${=(3/2\mathrm{}}^{\mathrm{-}}$ for the ${}_{}{}^{69}{}_{}{}^{}\mathrm{Se}$ ground state, in agreement with the indications given by previous beta decay studies. A first level scheme, including four levels in ${}_{}{}^{69}{}_{}{}^{}\mathrm{Se}$, is proposed.

The charge and mass distribution of orbiting yields from the ${}_{}{}^{28}{}_{}{}^{}$Si${+\mathrm{}}^{14}$N interaction have been studied at center of mass energies between 30 and 56.7 MeV. The data indicate that the orbiting system lives sufficiently long for the exit channel yields to be determined by phase space considerations. The data are compared with compound nucleus and orbiting calculations, and clearly favor the latter. Further comparisons between the data and the orbiting calculations indicate that full phase space equilibration of the orbiting yields is hindered at low excitation energies by the inaccessibility of single nucleon transfer channels. Also evident in the data is a correlation in the behaviors of the charge width, mass width, and final product kinetic energies, which is interpretable as arising from a maximum angular momentum that the ${}_{}{}^{28}{}_{}{}^{}$Si${+\mathrm{}}^{14}$N orbiting composite can sustain.

A new and transparent model for the theoretical simulation of proton singles spectra from heavy ion collisions is introduced. Working with few assumptions about momentum space geometry in heavy ion collisions, this model is able to explain the double differential singles cross sections. Predictions for proton-proton coincidence data are also obtained in the framework of this model and compared with data.

Light particle emissions in the energy region slightly above the Coulomb barrier were studied. Energy spectra and angular distributions of p, d, t, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, and α particles from the ${}_{}{}^{12}{}_{}{}^{}$C${+\mathrm{}}^{64}$Ni reaction were measured for the eight different incident energies below 70 MeV. The absolute cross sections and the contour plots of the Galilean-invariant cross sections $d^2$σ/pdΩdE are presented. The experimental proton energy spectra for E${(\mathrm{}}^{12}$C)≥50 MeV have been well reproduced by the moving source model. This model includes two sources: a slow source moving at the velocity of the center of mass of the collision system, and a fast source moving at a velocity of about a half of the projectile velocity. The extracted source velocity and temperature parameters for the fast source were found to follow the previous systematic trend. The nonequilibrium components of some composite particles (d, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, α), obtained by subtracting the relative equilibrium component from every measured spectrum, were accounted in terms of a generalized coalescence model.

The coupled, two-variable integral equations that determine the ${}_{\mathrm{\Lambda }}{}^4{}_{}{}^{}\mathrm{He}$ and ${}_{\mathrm{\Lambda }}{}^4{}_{}{}^{}\mathrm{H}$ ground and first excited states, when the NN and ΛN-ΣN interactions are represented by separable potentials, are solved numerically. We find the spin-isospin suppression of the Λ-Σ conversion due to the composite nature of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ nuclear cores to be a significant factor in understanding the $0^{+\mathrm{-}}$$1^{+}$ binding energy difference.

New data are presented on elastic and inelastic proton scattering by ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ at 333 and 498 MeV and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ at 318 MeV. We have analyzed these data using phenomenological distorting potentials and potentials generated by folding neutron and proton densities with a free nucleon-nucleon t matrix or with a medium modified nucleon-nucleon interaction. Making use of electromagnetic matrix elements, or charge transition densities, we have calculated neutron-proton transition matrix element ratios in the vibrating potential–vibrating density model (‘‘collective form factors’’), or with a scaling model in which the neutron transition densities are taken as proportional to the proton densities. In addition, we have calculated, neutron-proton matrix element ratios from earlier (p,p’) results at 25–800 MeV for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. We conclude that, although there are some irregularities, the derived neutron/proton matrix element ratios for natural parity states show a tendency to decrease in magnitude with decreasing proton energy in the range 500–100 MeV. A quantitatively similar effect is seen in the ratio of experimental to theoretical cross sections, where the latter are calculated using transition densities adjusted to fit electron or 800 MeV proton scattering. We attribute these results to a failure of the impulse approximation and the vibrating potential model in this energy region.

Differential cross sections for ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$(${\pi }^{\pm }$,${\pi }^{\pm }$${)}^{13}$${\mathrm{C}}^{\mathrm{*}}$ were measured at an incident pion energy of 65 MeV. Data were gathered for several states up to 11.8 MeV in excitation energy. The experimental results are compared to distorted wave impulse approximation calculations and to other pion scattering data from the same nucleus at higher beam energies. The striking enhancement of ${\pi }^{\mathrm{-}}$ over ${\pi }^{+}$ scattering to the 9.5 MeV ${(9/2\mathrm{}}^{+}$ state observed in previous studies at resonance energies is found to persist at 65 MeV.

We establish the formal connection between the spin difference function and the loss of symmetry of the correlation function in (p,p’γ) experiments. The same sensitivity to relativistic effects present in (p→,p→ ’) spin observable differences is also found in (p,p’γ) reactions. We performed a relativistic distorted wave calculation of the asymmetry and found sizable effects.

A corrected closure approximation is used to calculate the reduced rates for radiative capture of negative pions from 1s and 2p orbitals in ${}_{}{}^3{}_{}{}^{}\mathrm{H}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. For ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ the calculated rates are in good agreement with experimental data. In the case of ${}_{}{}^3{}_{}{}^{}\mathrm{H}$, the calculated value for 1s capture is combined with the measured radiative capture branching ratio to obtain a value of ${\Gamma }_{\mathrm{tot}{}^{1s}=2.2\mathrm{}\pm 0.4}$ eV for the total width of the 1s level in the ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ pionic atom. This value when compared to the measured total width of the 1s level in pionic ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ implies a small but definite contribution of singlet spin nucleon pairs to absorption of s-wave pions.

Using the quasiparticle random phase approximation, we calculate the nuclear matrix elements governing two-neutrino and neutrinoless double-beta decay. We show that a consistent treatment, including both particle-hole and particle-particle interactions, helps to resolve the longstanding discrepancy between experimental and calculated two-neutrino decay rates. The particle-particle force, which allows us to bring calculated EC/${\beta }^{+}$ decay rates in semimagic nuclei into closer agreement with experiment, is in large part responsible for suppressing calculated two-neutrino decay rates that are otherwise too fast. We test the validity of our procedure by comparing quasiparticle random phase approximation results with exact solutions for a solvable model, in which the suppression of two-neutrino decay by the particle-particle interaction is confirmed. We then extend our approach to the neutrinoless decay associated with a finite Majorana neutrino mass and, conceivably, with majoron emission, and demonstrate that the nuclear matrix elements governing these processes are also suppressed. We present predicted half-lives for both two-neutrino and neutrinoless double-beta decay in several candidate nuclei, and discuss the difficulties associated with the calculation of such highly suppressed quantities.

Double and triple gamma-ray angular correlations are reported for cascades in ${}_{}{}^{110}{}_{}{}^{}\mathrm{Cd}$ following the decay of ${}_{}{}^{110}{}_{}{}^{}\mathrm{Ag}$. The 764-1505-658 keV triple correlation helps to resolve a long-standing ambiguity concerning the E2/M1 multipole mixing ratio of the 1505-keV transition. The potential of triple correlations to contribute to nuclear spectroscopy is thereby demonstrated.

The nuclear structure of the parent and daughter nuclei in the decays ${}_{}{}^{34}{}_{}{}^{}\mathrm{Al}$(${\beta }^{\mathrm{-}}$${)}^{34}$Si, ${}_{}{}^{36}{}_{}{}^{}\mathrm{Si}$(${\beta }^{\mathrm{-}}$${)}^{36}$P, and ${}_{}{}^{37}{}_{}{}^{}\mathrm{P}$(${\beta }^{\mathrm{-}}$${)}^{37}$S are considered in a spherical shell model comprising the (2s,1d,1f,2p) configuration space. Energy spectra and beta and gamma transition strengths are calculated. These predictions are used to construct decay schemes from recent ${\beta }^{\mathrm{-}}$-delayed γ-ray singles spectra for the three decaying nuclei. The predicted half-lives of ${}_{}{}^{34}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{36}{}_{}{}^{}\mathrm{Si}$, and ${}_{}{}^{37}{}_{}{}^{}\mathrm{P}$ are 0.037(7), 0.8(4), and 2.0(9) s, where the uncertainties are due to mass uncertainties of the decaying bodies. These predictions are in agreement with recent experimental results of 0.050(25), 0.54(15), and 2.31(13) s, respectively.

We report the first observation of the beta decay of ${}_{}{}^9{}_{}{}^{}\mathrm{C}$ to the ground state and to two low-lying excited states of ${}_{}{}^9{}_{}{}^{}\mathrm{B}$. Branching ratios to these states were measured, and a previously reported branch to a level near 12 MeV was confirmed. The branching ratio to the $J^{\pi }$${=(3/2\mathrm{}}^{\mathrm{-}}$ ground state is 60±10 %, and the branching ratios to the narrow ${(5/2\mathrm{}}^{\mathrm{-}}$ level at 2.36 MeV and to the broad ${1/2}^{\mathrm{-}}$ level near 2.9 MeV are 17±6 % and 11±5 %, respectively. Because of the three-body nature of the ${}_{}{}^9{}_{}{}^{}\mathrm{B}$ decay, the ${}_{}{}^9{}_{}{}^{}\mathrm{C}$ ions were implanted in the active volume of silicon detectors, and the total decay energies of the states in ${}_{}{}^9{}_{}{}^{}\mathrm{B}$ were directly measured. We compare these results to shell model calculations, to the analog decay of ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ to ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, and to the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$(p,n${)}^9$B reaction. The comparison to ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ decay indicates an asymmetry in the beta-decay matrix elements to the ${(5/2\mathrm{}}^{\mathrm{-}}$ level larger than any such asymmetry previously observed.

We study the ${}_{}{}^3{}_{}{}^{}$H${\mathrm{-}\mathrm{}}^3$He binding energy difference, taking into account the Coulomb interaction and charge symmetry breaking of the nuclear force consistent with recent NN experimental data. Realistic interactions are generated which describe the charge symmetry violations reflected in the different nucleon-nucleon scattering lengths. The influence of nuclear charge symmetry breaking on the perturbative Coulomb contribution to the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ binding energy is discussed. It is shown that the experimental mass difference can be explained by these and theoretical estimates of other known effects.

The static properties of neutron stars are probed using phenomenological equations of state. These properties include the maximum mass, radii, central densities, and binding energies. It is found that quite different equations of state can produce similar neutron stars. Likewise, it is also found that equations of state which are quite similar near saturation density can produce very different neutron stars, since it is the high density behavior which is most important. Symmetric matter results cannot be used to uniquely constrain neutron matter because of model dependence on the symmetry energy.

A microscopic combinatorial approach is used to investigate the influence of the nuclear deformation on the distributions of quasiparticle states. It is shown that nuclear deformation tends to suppress strong fluctuations observed in the similar calculations performed in the space of spherical shell-model basis vectors. The dependence of the pairing effects on the deformation is analyzed. The applicability of the formula by Williams is examined and found to be only valid for strongly deformed medium and heavy nuclei.