The standard cloudy bag model description of πN scattering is extended to include contributions at the two-pion level. The ππ scattering amplitudes are parametrized in phenomenological, separable forms consistent with the known ππ S- and P-wave phase shifts. These amplitudes are embedded in the πN description to account for scattering of the incident pion from the nucleon’s virtual pion cloud. A self-consistent analysis of the coupled πN, πΔ, and π${\mathrm{N}}^{\mathrm{*}}$ (1470) systems results in excellent reproduction of the phase shifts in the πN $P_{33}$ channel to energies above the pion production threshold. In the $P_{11}$ channel, without two-pion intermediate states, no acceptable fit to the data is possible for any values of the bag parameters. It is shown that the additional attraction provided by ππ scattering is essential to reproduce the low-energy phase shifts and fix the sign change at the correct energy.

The relativistic description of proton-nucleus elastic scattering using the Dirac equation is extended to deuteron-nucleus elastic scattering. The connection between the spin-one Proca and Weinberg equations is discussed and it is shown that they are not equivalent in the presence of interactions. Close similarities between the Weinberg and Dirac equations as regards the generation of interactions and low energy properties are found. Deuteron scattering is described using the Weinberg equation within the framework of the deuteron folding model, assuming that nucleons interact with the nucleus through Dirac vector and scalar potentials. The resulting deuteron central potential is like that obtained with the nonrelativistic folding model but the spin-orbit is only one-half as strong because the g factor for spin one is 1. Possible explanations for this discrepancy are discussed.

By assuming a smooth energy dependence of the s- and p-wave strengths, optical model fits have been made to low energy ${}_{}{}^{16}{}_{}{}^{}({\pi }^{+}$,${\pi }^{+}$) data. Constraints are imposed to ensure that the potential does not violate unitarity and avoids the Kisslinger singularity. Such an analysis removes many experimental uncertainties from the potential strength and provides a simple way of generating distorted waves for the study of inelastic scattering.

An isospin-invariant optical-potential framework is used to make a coordinated analysis of low-energy pion elastic and single- and double-charge-exchange scattering to isobaric analog states. The form of the potential studied here is motivated by the work of Stricker, McManus, and Carr, who emphasized the importance of isoscalar absorption-dispersive and correlation effects for low-energy pion elastic scattering. In this paper we examine the influence of the corresponding isovector and isotensor nuclear correlations on low-energy charge exchange. Comparison of our results to 50 MeV data supports the existence of the isovector correlation terms, but shows a need for an additional isotensor effect. A distorted-wave Born approximation analysis confirms that distortions are weak (the mean density of interaction is roughly 50% of the central value), but demonstrates that distortions of the pion waves by the nuclear medium cannot be neglected in describing charge exchange.

It is shown that in the single j shell model, the double beta decay matrix element of the operator [σ(1)×σ${\mathrm{}\left(2\right)\mathrm{}]}^{\lambda }$$t_{+}$(1)$t_{+}$(2) from the ground state of the magic nucleus ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ to the $2_1^{+}$ state of ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$ vanishes. This is due to a signature selection rule. Other matrix elements in this region are also discussed. The asymptotic Nilsson model is also discussed, especially for λ=2. The relation of this operator to double beta decay operators is discussed. The possible confusion of (j${)}^n$ states with intruder states is also considered.

We investigate the time-dependent Hartree-Fock flow pattern of a two-level many fermion system interacting via a two-body interaction which does not preserve the parity symmetry of standard SU(2) models. The geometrical features of the time-dependent Hartree-Fock energy surface are analyzed and a phase instability is clearly recognized. The time evolution of one-body observables along self-consistent and exact trajectories are examined together with the overlaps between both orbits. Typical time scales for the determinantal motion can be set and the validity of the time-dependent Hartree-Fock approach in the various regions of quasispin phase space is discussed.

Significant underbinding for the triton of a quantum-chromodynamically motivated realistic NN potential containing a superdeep short-ranged attraction and a forbidden state in the S waves has been reported from a previous Faddeev calculation. In the present paper, this feature is reproduced with a simple S-wave-interaction model of this NN potential, generalized into a wide range in the form of a short distance node, and explained in terms of short-ranged NN D-wave components which the nodal S-wave components introduce inevitably through the three-body kinematics. The strengths of the NN D-wave interactions are estimated to be not sufficient to compensate for the kinetic energies arising from these D-wave components, which means a significant loss for 3N binding. This is in sharp contrast to the strong 3α binding in the forbidden state αα potential model which is supported by strong D- and G-wave interactions. The present study indicates that a noticeable short distance node in the 2N wave function is unlikely.

The deformation of nuclei around A∼80 is found to vary systematically as a function of the product of the number of protons and neutrons (or holes) ($N_{\mathrm{p}{N}_{\mathrm{n})}}$ in the shell extending from 28 to 50 particles. A similar result was reported previously for heavier even A nuclei, but this is the first investigation of a region in which neutrons and protons fill the same major shell and the first application of the technique to odd A nuclei. The systematic behavior is seen in both energy level spacings and electromagnetic quadrupole transition strengths and in both even-even and odd A nuclei. These systematics hold for the measures of deformation not involving the positions of the $0^{+}$ states, which are strongly affected by the coexistence of weakly and strongly deformed shapes in some A∼80 nuclei. A rather surprising result is that the deformations of the odd-Z–even-N nuclei are substantially larger than those of the even-Z–odd-N nuclei.

The quadrupole vibrations of rotating light nuclei around calcium are analyzed in the framework of the Fermi liquid drop model. The input parameters of shape and deformation are those obtained by the Mottelson-Nilsson method for the rotating light nuclei. The surface diffuseness and its changes with spin which could affect the giant resonances in the light nuclei are automatically taken care of in this method. The experimental energies of the giant quadrupole resonance are reproduced in the Fermi liquid drop model for the nonrotating case. The rotation produces the expected splitting of the giant quadrupole resonance modes with the appearance of soft modes. The nature of such splitting may explain the observed changes in the widths of giant resonances at high spins.

The ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(d, γ${)}^4$He cross section was measured for deuteron laboratory energies between 0.7 and 4.5 MeV. Angular distributions were obtained at laboratory energies of $E_{\mathrm{d}=1.38\mathrm{}}$, 2.05, 9.6, and 15.0 MeV. These data indicate that the D state of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, which can be populated via S-wave capture in this reaction, has a large effect on the energy and angle dependence of this low energy capture cross section. The data are shown to imply an asymptotic D-to-S state ratio ρ=-0.2±0.05. The implication of this observation for the absolute cross section below 1.0 MeV is discussed.

Proton and α-particle emission from giant resonances in ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ excited by inelastic α scattering at 129 MeV into 0° has been investigated. By this choice of kinematic conditions quasifree contributions to the coincidence cross sections were eliminated. The sequential decay processes show a population of low-lying states which exceed Hauser-Feshbach predictions substantially, indicating >40% direct contributions to the charged particle decay of the isoscalar giant resonances near $E_x$=17 MeV.

Excitation function measurements in the ${}_{}{}^{16}{}_{}{}^{}$O${+\mathrm{}}^{16}$O system in the energy range $E_{\mathrm{c}.\mathrm{m}.\mathrm{}=8.5\mathrm{}–}$12.5 MeV in 25 and 5 keV steps reveal intermediate and compound structures simultaneously. Decay widths of compound (Γ=25 keV) and intermediate (Γ=130 keV) states have been determined using the spectral density method and the peak counting method. Relative cross sections for the decay of compound and intermediate states are deduced.

An anomaly in the d-p bremsstrahlung cross section, observed previously near the breakup threshold, was unexplained on the basis of an on-shell calculation of the cross section. An improved experiment using a solid target of (${\mathrm{CH}}_2$${)}_{\mathrm{n}}$ has confirmed the energy of this strong anomaly. Off-shell and various neglected on-shell effects are prime candidates for its explanation. Estimates of these effects are calculated. Means of implementing necessary experimental improvements of the art are discussed.

Using the effective pion propagator approximation, the two-body pion exchange current contributions to the form factor of the inelastic electron scattering from closed-shell nuclei are explicitly calculated in terms of nuclear densities (nucleon density, kinetic energy density, . . .). The electroexcitation of some high-spin magnetic stretched states in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ is studied to illustrate our approach, and the goodness of the agreement with the exact results is discussed.

The effect of the Coulomb interaction of the ejected β ray with the residual atomic electron is derived in a most general form for the β decay of a tritium atom. Corrections are calculated to first order, and transition probabilities to excited states of helium are shown to be modified by at most 0.02% from the usual sudden approximation. Detailed comparison is made with the work of Williams and Koonin who neglected the difference between atomic energy levels.

The hole-transition rates are calculated as a function of Fermi energy and hole energy via the Boltzmann master equation. The quadratic hole energy dependence found previously by Gadioli et al. is confirmed. The dependence of rates on Fermi energy is illustrated.

The anomalous change in the low-lying spectrum from ${}_{}{}^{105}{}_{}{}^{}\mathrm{Pd}$ to ${}_{}{}^{103}{}_{}{}^{}\mathrm{Ru}$ in the sequence of N=59 isotones is investigated. A possible attribution of this effect to the onset of a phenomenological exchange force in the interacting boson-fermion model is investigated.

The influence of the residual ph tensor force on the wave function of the 5.846 MeV isoscalar $1^{+}$ state in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ is investigated. While the (e,e’) form factor is well described within a 1p1h random-phase-approximation model and is fairly insensitive to the strength of the tensor force, medium energy proton scattering experimental angular distributions are not reproduced within this model. It is demonstrated that the inclusion of 2p2h excitations yields screening corrections to the effective tensor force which reduce its strength considerably. Thus the apparent failure of the 1p1h random-phase-approximation wave function to describe the inelastic proton scattering data at medium energy can be resolved.

For the inelastic scattering of ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, we have calculated the population probability $P_1$ for obtaining ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}_{}^{\mathrm{*}}{}_{}{}^{}$${(2\mathrm{}}^{+}$,4.44 MeV) with ‖m‖=1 and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ in its ground state. Multistep processes involving the transfer of a neutron were able to produce values of $P_1$ of comparable magnitude to the data. There was, however, considerable sensitivity to the optical parameters and this is discussed.

It is shown that the recently proposed existence of F-spin multiplets in nuclear regions where the nuclei contained in the multiplets differ by four nucleons gives rise to a simple prediction for the relative spectroscopic factors for ground state to ground state alpha transfer reactions among them.