Measurements of the tensor polarization $t_{20}$ in ${\pi }^{+}$d elastic scattering have been performed at ${\theta }_d^{\mathrm{lab}=15\mathrm{}}$° between $T_{\pi }$=116 and 145 MeV. Angular distributions at 133 and 140 MeV were also determined. These results resolve the discrepancy that has existed between the measurements made by other groups at SIN and at LAMPF, as our values are negative for all energies and angles investigated and consistent with the LAMPF data. Our results are also in good agreement with the corresponding measurements of analyzing powers. Lack of any significant oscillatory nature is in general agreement with theories at these kinematic regions and does not lend support to exotic effects such as dibaryon resonances.

The energy of a gamma transition in the decay of ${}_{}{}^{83}{}_{}{}^{}\mathrm{Kr}_{}^{\mathrm{m}}{}_{}{}^{}$ has been determined to be 32 147.3(16) eV in a comparison with transitions in ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$ decay. This value, substantially more precise than previous ones, leads to a corresponding improvement in precision in the atomic mass difference between ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ as determined from an experiment on the beta decay of free molecular tritium. The mass difference, 18 589.0(26) eV, is in agreement with some independent determinations but disagrees with others, most notably with some recent ion-cyclotron-resonance data. The latter disagreement calls into question the 17-eV lower limit on the mass of the electron antineutrino claimed by Boris et al.

${}_{}{}^{54}{}_{}{}^{}\mathrm{Mn}$ has previously been observed in cosmic rays where is it expected to decay by ${\beta }^{+}$ and ${\beta }^{\mathrm{-}}$ transitions with a half-life of a few million years. The present experiment to measure the ${\beta }^{+}$ decay branch in the laboratory establishes an upper limit of 4.4×${10}^{\mathrm{-}8}$ for the branching ratio, and a lower limit of 13.3 for the logft value of this second forbidden unique transition. If it is assumed that the ${\beta }^{\mathrm{-}}$ decay branch has the same logft value, then its partial half-life must be greater than 4×${10}^4$ years.

The structure of ${}_{}{}^{145}{}_{}{}^{}\mathrm{Pr}$ has been investigated by measuring the gamma-ray singles, gamma-ray coincidence, and gamma-ray angular correlation spectra, along with conversion-electron singles spectra for the decay of 3.0-min ${}_{}{}^{145}{}_{}{}^{}\mathrm{Ce}$ to levels of ${}_{}{}^{145}{}_{}{}^{}\mathrm{Pr}$. A level scheme is proposed that includes a number of new levels as well as new spin and parity assignments for several levels. The conversion-coefficient measurements establish the presence of a low-energy ${(3/2\mathrm{}}^{\mathrm{-}}$ level at 787 keV whose strong population in beta decay confirms negative parity for the ground state of ${}_{}{}^{145}{}_{}{}^{}\mathrm{Ce}$. Interacting boson-fermion model calculations for ${}_{}{}^{143}{}_{}{}^{}\mathrm{Pr}$ and ${}_{}{}^{145}{}_{}{}^{}\mathrm{Pr}$ are found to be in reasonable agreement with the observed low-energy positive-parity levels, while the presence of the low-energy ${(3/2\mathrm{}}^{\mathrm{-}}$ level suggests the coexistence of more deformed configurations.

The ${}_{}{}^{104}{}_{}{}^{}\mathrm{In}_{}^{\mathrm{g}}{}_{}{}^{}$ and ${}_{}{}^{104}{}_{}{}^{}\mathrm{In}_{}^{\mathrm{m}}{}_{}{}^{}$ nuclei have been produced by means of the following reactions: ${}_{}{}^{106}{}_{}{}^{}\mathrm{Cd}$(p,3n), ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$${(}^{14}$N,2n), ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$${(}^{16}$O,p3n), ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$${(}^{20}$Ne,3p5n). Their decay has been investigated after mass separation. From ${\beta }^{+}$, γ, and x direct spectra and γ-γ-T, γ-x-T, and β-γ-T coincidences, a ${}_{}{}^{104}{}_{}{}^{}\mathrm{Cd}$ level scheme has been constructed. The observation of an intense background of statistical γ rays, emitted after strong β decay to high energy levels, resolves the problems of previously published work concerning β-ray intensities, spin determinations, and $Q_{\mathrm{EC}}$ values.

Shell-model calculations are performed for the odd- and even-parity states of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Cl}$ and the $0^{+}$ ${}_{}{}^{40}{}_{}{}^{}$S ground state. The ${}_{}{}^{40}{}_{}{}^{}\mathrm{Cl}$ odd-parity states and the ${}_{}{}^{40}{}_{}{}^{}\mathrm{S}$ $0^{+}$ levels were considered in full (2s,1d${)}^{21}$(1f,2p${)}^3$ and (2s,1d${)}^{20}$(1f,2p${)}^4$ configurational spaces, respectively. For the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Cl}$ even-parity states it was necessary to use a highly truncated (2s,1d${)}^{20}$(1f,2p${)}^4$ configurational space. Besides energy spectra and binding energies, observables calculated are first-forbidden and allowed ${\beta }^{\mathrm{-}}$ decay of ${}_{}{}^{40}{}_{}{}^{}\mathrm{S}$, γ transitions in ${}_{}{}^{40}{}_{}{}^{}\mathrm{Cl}$, and one-body density overlaps of the odd-parity states of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Cl}$ with the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ ground state. The results are compared to experiment. For example, the half-life of ${}_{}{}^{40}{}_{}{}^{}\mathrm{S}$ is predicted to be in the range 6.2–16.6 s (depending on the assumed level scheme) as compared to the experimental value of 8.8±2.2 s.

The deuteron quadrupole and magnetic moments are calculated assuming light-front dynamics. The advantage of this approach is that conventional bound-state wave functions and empirical nucleon form factors can be used to construct eigenfunctions of the four-momentum and the spin, together with a representation of the electromagnetic current, in such a way that the current-density operator and the wave functions transform consistently under a unitary representation of the Poincaré group. The sensitivity of our model to the choice of the deuteron bound-state wave functions is tested by using Reid soft core, Argonne $v_{14}$, Paris, and Nijmegen nucleon-nucleon interactions, as well as three Bonn potentials. The exact results increase both quadrupole and magnetic moments by small amounts compared to the nonrelativistic values. Expansions in powers of the nucleon velocity are found to be unreliable.

The comparison between effective Hamiltonians, constructed within the framework of symmetry restoring techniques, is discussed for the case of intrinsic $K^{\pi }$${=1\mathrm{}}^{+}$ vibrations in deformed systems. The methods, which are based on self-consistent and global rotational invariance conditions, allow for the separation of rotational and vibrational degrees of freedom.

The ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ and ${}_{}{}^9{}_{}{}^{}\mathrm{B}$ spectra are investigated in a microscopic three-cluster model, using the generator-coordinate method. Both nuclei are described by a ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$ core surrounded by a nucleon. We present the n${+}^8$Be and p${+}^8$Be phase shifts, and the electromagnetic transition probabilities in ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$. A good overall agreement is found with the available experimental data. We suggest spin assignments for different poorly known states. The energy of the ${(1/2\mathrm{}}^{+}$ first excited state in ${}_{}{}^9{}_{}{}^{}\mathrm{B}$ is in excellent agreement with a recent experimental investigation.

The connection between the strong-coupling approximation to quantum chromodynamics and nuclear properties observed at low and medium energies and momentum transfer is examined. The strong-coupling approximation to quantum chromodynamics indicates that, for nuclei, the Pauli principle is obeyed at the hadronic level, so that quarks in different hadrons are treated as distinguishable objects. Furthermore, the gluonic effects of flux-tube rearrangement are small. Instead, a more significant strong-coupling approximation to quantum chromodynamics string-breaking term leads to meson emission from baryons. This mechanism is used to compute meson-nucleon and delta coupling constants and form factors. Qualitative agreement with experiment is achieved. Thus the strong-coupling approximation to quantum chromodynamics reproduces the salient features of the meson-baryon picture of low momentum transfer nuclear physics.

Dyson mapping is directly applied to J=0 states of a system of six fermions in a single-j shell. It is found that the quality of the wave functions is drastically reduced when bosons of higher angular momentum are omitted. Nevertheless, a truncated Dyson boson method of calculating energies is explored.

The Δ component in the nuclear ground state is evaluated in connection with the Δ dynamics. The various microscopic processes which could originate such components are separately studied. The role of short-range correlations is emphasized, as well as that of random-phase-approximation corrections. It is shown moreover that a rather large number of Δ’s in a nucleus does not lead to contradictions with the standard shell model.

Changes in shape in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ are studied at T≠0 both in finite-temperature mean-field calculations and in the exact canonical ensemble. With increasing temperature the canonical ensemble average of the rotational energy spectrum tends toward a more equispaced harmonic spectrum. This deformed to spherical transition gives rise to a peak in the specific heat which is also seen in finite-temperature Hartree-Fock approximation albeit at a slightly higher temperature. The canonical ensemble average of the quadrupole moment does not, however, appear to vanish at the critical temperature as is the case in the finite-temperature Hartree-Fock approximation.

The level structure and grouping into quasibands of ${}_{}{}^{154}{}_{}{}^{}\mathrm{Dy}$ and ${}_{}{}^{156}{}_{}{}^{}\mathrm{Dy}$ is derived in the dynamic pairing-plus-quadrupole model and the analysis is extended to five quasibands in ${}_{}{}^{154}{}_{}{}^{}\mathrm{Dy}$ and seven collective K bands in ${}_{}{}^{156}{}_{}{}^{}\mathrm{Dy}$. The absolute E2 moments, relative B(E2) values for interband transitions and X(E0/E2) are compared with experimental data and the predictions from the boson expansion model and the interacting boson model. The transition at N=88–90 for all observed quantities is reproduced. The anomaly of small $0_g$-$2_{\beta }$ strength in ${}_{}{}^{156}{}_{}{}^{}\mathrm{Dy}$ is explained from our analysis, retaining the collective β-vibration character.

A new three-parameter formula is presented and is used to analyze systematically the rotational spectra up to very high spins (below band crossing). An overall and excellent agreement between the calculated and the observed spectra is obtained for all the actinide and the rare-earth deformed nuclei. In the derivation of this formula from the phenomenological Bohr Hamiltonian, a small axial asymmetry and vibrational effects (including anharmonic vibration) have been taken into account.

The isovector giant dipole resonances in hot rotating light nuclei in the calcium region are studied using a rotating anisotropic harmonic oscillator potential and a separable dipole-dipole residual interaction. The influence of temperature on the isovector giant dipole resonance is assumed to occur through the change of deformation of the average field only. Calculations are performed for the three nuclei ${}_{}{}^{40}{}_{}{}^{}$,42Ca and ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ti}$ which have spherical, oblate, and prolate ground states, respectively, to see how their shape transitions at higher excited states affect the isovector giant resonance frequencies built on them. It is seen that, while the width fluctuations present at T=0 vanish at T=0.5 MeV in ${}_{}{}^{40}{}_{}{}^{}$,42Ca, they persist up to T=1.5 MeV in the case of ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ti}$. This behavior brings out the role of temperature on shell effects which in turn affects the isovector giant dipole resonance widths.

The reaction cross section of ${}_{}{}^{127}{}_{}{}^{}\mathrm{I}$(γ,xn) has been measured from 8 to 23 MeV. The reported measurement is discussed with particular reference to the differing results obtained at Saclay and Lawrence Livermore National Laboratory, and reconciles the differences.

The thermal cross section for the reaction ${}^{10}\mathrm{B}+\mathit{n}\to {}^3\mathrm{He}+{}^4\mathrm{He}+{}^4\mathrm{He}$ is determined to be 4.47±0.15 mb by neutron irradiation of ${\mathrm{H}}_3$${\mathrm{BO}}_3$ followed by measurement of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ (from decay of ${}_{}{}^3{}_{}{}^{}\mathrm{H}$) and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ in a static mass spectrometer. Some samples contained boron of normal isotopic composition and some were enriched in ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$, and irradiations were carried out in a highly thermalized neutron flux and in the core of a light-water-moderated reactor.

Angular distributions for the elastic scattering of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ from ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ have been measured at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}=14.17\mathrm{}}$, 16.15, and 18.65 MeV over an angular range from 20° to 176°. The angular distributions, which exhibit an oscillatory enhancement of the cross section at backward angles, are described by a scattering matrix parametrization, by adding a very narrow l window to the normal, strong absorption S matrix.

We show that in Elliott’s SU(3) limit ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ has a $1^{+}$ T=1 state identifiable as a scissors mode. We also show that this state is the leading component of the $1^{+}$ T=1 level experimentally seen at 11.26 MeV.