Excited states in the very neutron deficient isotope ${}_{}{}^{83}{}_{}{}^{}\mathrm{Nb}$ were observed for the first time in the reaction ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$${(}^{58}$Ni,2np${)}^{83}$Nb at 195 MeV. Identification was made with a recoil separator and a cross section of σ=180(80) μb estimated. Eight transitions were arranged in a level scheme which resembles the N=41 isotones ${}_{}{}^{77}{}_{}{}^{}\mathrm{Kr}$ and ${}_{}{}^{79}{}_{}{}^{}\mathrm{Sr}$ rather than the heavier, weakly deformed Nb isotopes. This suggests that a shape transition to a strong deformation exists in the light Nb isotopes. A ground state spin of 5/$2^{+}$ is suggested.

The branching ratio for ${}_{}{}^{10}{}_{}{}^{}\mathrm{C}$ superallowed Fermi β decay has been measured accurately by a newly developed method. The result is 1.473±0.007 %. The Ft value is derived as 3065.4±14.7 sec, which is consistent with the Ft values determined accurately for heavier nuclei and with predictions of conserved vector current hypothesis. The method developed here can be applied to the high precision β-γ spectroscopy.

The four-momentum-transfer dependences of the quasielastic and Δ peak positions seen in electron-nucleus scattering are interpreted in terms of momentum-dependent potentials. We have used data on the Δ peak position for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, C, and Fe, approximately corrected for the effects of competing reaction mechanisms, to estimate the depth and momentum range of the real part of the potential felt by a Δ resonance in nuclei. We find that the Δ-nucleus potential is deeper than the nucleon-nucleus potential for q<950 MeV/c.

The problem of elastic proton-deuteron scattering at medium energies is examined within the framework of light-front Hamiltonian particle dynamics. Deuteron wave functions and off-shell nucleon-nucleon scattering amplitudes from models which fit NN data are used as input. The contributions to cross section and spin observables from single and double scattering are calculated.

Simple formulas for the neutron and proton polarizations in polarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ targets are derived assuming (1) quasielastic final states; (2) no final-state interactions; (3) no meson-exchange currents; (4) large momentum transfers; (5) factorizability of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ SU(4) response-function components. Numerical results from a wide variety of bound-state solutions of the Faddeev equations are presented. It is found that this simple model predicts the polarization of neutrons in a fully polarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ target to be 87%, while protons should have a slight residual polarization of -2.7%. Numerical studies show that this model works very well for quasielastic electron scattering.

The question of whether one can consistently define and extract nucleon-delta scattering parameters, phase shifts, and inelasticities from the partial-wave NN→NΔ amplitudes is discussed. We have studied the unitarity relation and identified the conditions under which the extraction of such quantities is meaningful. Then these conditions were tested in several coupled-channel models of the NN-NΔ system.

A single integrodifferential equation in two variables, valid for A nucleons interacting by pure Wigner forces, which has previously only been solved in the extreme and uncoupled adiabatic approximations, is now solved exactly for three- and four-nucleon systems. The results are in good agreement with the values obtained for the binding energies by means of an empirical interpolation formula. This validates all our previous conclusions, in particular that the omission of higher (than two) order correlations in our four-body equation only produces a rather small underbinding. The integrodifferential equation approach is here also extended to spin-dependent forces of the Malfliet-Tjon type, resulting in two coupled integrodifferential equations in two variables. The exact solution and the interpolated adiabatic approximation are again in good agreement. The inclusion of the hypercentral part of the two-body interaction in the definition of the Faddeev-type components again leads to substantial improvement for fully local potentials, acting in all partial waves.

The effects of the residual nucleon-delta interaction proposed by Ferreira et al. to eliminate the discrepancies between theory and experiment in πd elastic scattering are studied for the breakup reaction at 228 and 294 MeV. It is found that in first order the residual interaction lowers the cross section particularly in the region of the neutron-proton final-state interaction. However, the effects of higher-order corrections generated by the NΔ interaction are found to be non-negligible, which implies that the parameters extracted by Ferreira et al. probably must be modified.

The structure function S(q,ω) for quasielastic electron scattering on a nonrelativistic two-nucleon model system is evaluated numerically. These S values are considered as pseudodata to study sum rules, y scaling, and the cumulant expansion. For the force models considered it is found that the reduced structure function (q/2m)S(q,ω) in the limit q→∞ scales to the longitudinal momentum distribution ${\mathit{P}}_{\mathit{L}}$(y) in the target. Except for small y values, this limit, however, is reached only very slowly, which may be due to the strictly nonrelativistic treatment. The cumulant expansion based on low-order cumulants is not useful. We also derive the analytical result that in our potential model S(q,ω)=O(${\mathrm{\omega }}^{\mathrm{-}5.5}$) for ω→∞ and fixed q. This shows that higher-order cumulants do not exist.

The elastic magnetic form factor of ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$ has been determined by 180° electron scattering in the momentum-transfer range 0.9–2.0 ${\mathrm{fm}}^{\mathrm{-}1}$. An analysis of the data indicates that the amplitudes of the M3 and M5 multipoles are quenched by factors of 0.57±0.16 and 0.68±0.07 relative to the simple shell model. In contrast, the magnitude of the M7 form factor is in good accord with this model. Calculations that include multiparticle-multihole configurations in the 1${\mathit{f}}_{7/2}$ and 1${\mathit{d}}_{3/2}$ subshells, first-order core polarization to higher excited orbitals, and meson exchange currents give reasonable agreement with the data for all multipoles. The rms radius of the 1${\mathit{f}}_{7/2}$ neutron orbit was determined by means of a combined analysis of our results and previous data obtained at higher momentum transfers. After correcting for core polarization and meson exchange currents, the radius was found to be 3.96±0.05 fm, in agreement with the predictions of mean-field calculations.

Doubly differential cross sections and spin-flip probabilities have been measured for 800-MeV proton scattering on ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ at 3.2°, 4°, 5°, and 7° in the laboratory, for excitation energies up to 45 MeV. The features of these observables in the continuum are discussed. The data indicate that nuclear spin excitations are enhanced at high excitation energy for angles corresponding to momentum transfers around 100 MeV/c, as previously observed for incident energies around 300 MeV. The relative nuclear spin response derived from these data is roughly independent of energy. This suggests that the dominance of spin-transfer excitation at high excitation energies for momentum transfers around 100 MeV/c is an intrinsic feature of the nuclear structure of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$.

The (α${,}^2$He) reaction has been investigated at bombarding energies around 56 MeV on targets of ${}_{}{}^{40,42,44,48}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{50,52,54}{}_{}{}^{}\mathrm{Cr}$, ${}_{}{}^{54,56,58}{}_{}{}^{}\mathrm{Fe}$, ${}_{}{}^{58,60,62,64}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{64,66}{}_{}{}^{}\mathrm{Zn}$, and ${}_{}{}^{70,72}{}_{}{}^{}\mathrm{Ge}$. The angular distributions of prominent two-neutron states were analyzed with the distorted-wave Born approximation. Preferential population of states with dominant (${\mathit{f}}_{5/2}$,${\mathit{g}}_{9/2}$${)}_7^{\mathrm{-}}$, (${\mathit{g}}_{9/2}$${)}_8^{+2\mathrm{}}$, and (${\mathit{g}}_{9/2}$,${\mathit{d}}_{5/2}$${)}_6^{+}$ configurations was observed for all nuclei with a closed ${\mathit{f}}_{7/2}$ neutron shell. The binding energies of the $7^{\mathrm{-}}$, $8^{+}$, and $6^{+}$ states are linearly dependent on the mass number and the isospin and well described by the weak-coupling model. The extracted parameters agree with the averaged values of a similar analysis for ${\mathit{f}}_{5/2}$, ${\mathit{g}}_{9/2}$, and ${\mathit{d}}_{5/2}$ single-particle states in the corresponding odd-even nuclei. The excitation energies of the high-spin states could be well reproduced by a simplified shell model where only pure configurations are considered and the residual interaction energy is neglected. The simple structure of the experimentally observed states is further tested by large-scale shell-model calculations. Two-body matrix elements are extracted from the data for the (${\mathit{f}}_{5/2}$,${\mathit{g}}_{9/2}$${)}_7^{\mathrm{-}}$ and (${\mathit{g}}_{9/2}$${)}_8^{+2\mathrm{}}$ configurations.

The scattering of 84-MeV/nucleon ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ ions by ${}_{}{}^{118}{}_{}{}^{}\mathrm{Sn}$ has been studied. Inelastic cross sections for excitation of the 2.327-MeV state ($3^{\mathrm{-}}$), the giant quadrupole resonance, and the giant monopole resonance are reproduced by distorted-wave approximation calculations using the deformed potential model and assuming isoscalar transitions. A minimum predicted in the angular distribution at ${\mathrm{\theta }}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$=1.9° from utilization of the small B(E2)↑ strength suggested by ${\mathrm{\pi }}^{+}$/${\mathrm{\pi }}^{\mathrm{-}}$ scattering is not apparent in the data.

High spin states in ${}_{}{}^{77}{}_{}{}^{}\mathrm{Kr}$ were populated using the ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$${(}^{32}$S,2pn${)}^{77}$Kr reaction with a 106 MeV ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ beam from the Florida State University Tandem-LINAC accelerator. Three Compton-suppressed Ge detectors at 95° and one at 18° were used to determine γ-γ coincidence relations, directional correlation ratios and Doppler-shift attenuation lifetimes. The level scheme for the positive-parity band agrees with previous studies up to spin 37/$2^{+}$. New levels at 9913 keV (41/$2^{+}$) and 11 760 keV (45/$2^{+}$) have been identified. The negative-parity band was extended to a probable spin state of 27/$2^{\mathrm{-}}$, with three new levels identified. The kinematic and dynamic moments of inertia in the positive-parity band converge to a rather constant value of (22–24) ${\mathrm{ħ}}^2$/MeV. The transition quadrupole moments average about 2.6 e b in this band and decrease somewhat after the π${\mathit{g}}_{9/2}$ alignment. The magnetic transition strengths alternate with signature and increase to about a nuclear magneton after the alignment. The kinematic moment of inertia in the negative-parity band increases with rotational frequency and exhibits the beginnings of a band crossing at ħω≊0.55 MeV, while the transition quadrupole moments decrease steadily with frequency. Cranking model calculations with the Nilsson plus BCS potential were performed for the quasiparticle energies and electromagnetic transition rates for both the positive- and negative-parity bands. The experimental data were reproduced well. As for the positive-parity band, β(3qp)>β(1qp) has been shown to be necessary in addition to γ(3qp)>0 to reproduce the signature dependence of the energies and B(M1) values.

Mean lifetimes of the yrast ${\mathit{J}}^{\mathrm{\pi }}$=${16}^{+}$-${26}^{+}$ states in ${}_{}{}^{130}{}_{}{}^{}\mathrm{Ce}$ have been measured using the Doppler-shift-attenuation method in conjunction with the reaction ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}$${(}^{36}$S,4n${)}^{130}$Ce. A realistic computer simulation of the measured γ-ray line shapes was used in the Doppler-shift-attenuation analysis for the slowing down of ions and description of delayed feeding cascades from yrast and side bands. The measured transition strengths are by a factor of 1.5 to 2 higher than reported previously. The results are compared with the microscopic calculations based on a realistic nucleon-nucleon interaction.

We investigate the structure of the intrinsic states for the symmetric and antisymmetric β vibrations in the O(6) limit of the neutron-proton interacting boson model and of the low-lying configurations projected from these intrinsic states. We study the decay modes of these low-lying states, particularly the antisymmetric $0^{+}$ state. This level appears to decay only to the $1^{+}$ and $2^{+}$ mixed-symmetry states. The signature for these decays is that the M1 and E2 strengths go to zero for ${\mathit{N}}_{\mathrm{\pi }}$=${\mathit{N}}_{\nu }$.

We calculate ground-state correlation quantities implied by the relativistic random-phase approximation. The present work is based on our previous mean-field-based work which excludes expilict vacuum polarization effects. Summing over the positive-energy excitation spectrum up to 80 MeV, we find small correlation effects which modestly improve agreement with experiment and which are consistent with earlier nonrelativistic calculations. We calculate energy shifts, density correlations, and spectroscopic factors for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$.

We examine the Dirac equation for a proton in a nucleus, with a shell-model potential consisting of nuclear and Coulomb parts. When the Dirac equation is reduced to a Schrödinger-like equation, the effective potential W in it exhibits two Coulomb-related effects that are absent in the usual nonrelativistic treatment: (I) W contains a Coulomb-nuclear interference term; (II) W depends strongly on the proton energy, which in turn depends on the Coulomb energy. If the shell-model potential consists of a strongly attractive Lorentz scalar and a strongly repulsive Lorentz vector, effect I by itself is very large. However, effect II counteracts effect I, leaving a small yet significant decrease in the Coulomb energy as compared with its nonrelativistic counterpart.

The excitation function for the (${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^0$) reaction on ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ to analog states in ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ in the range of 250 to 650 MeV pion kinetic energy is calculated. The Glauber model with microscopic shell-model wave functions is used. The effects of antisymmetry and spin flip were explicitly evaluated; experimental πN partial waves up to l=3 were included in the calculation. The calculated cross section is too large compared to experiment. The effects of two- and three-body pion absorption are calculated and found to reduce the calculated cross section by a small amount to values nearer experiment.

An analytic formula is reported for general matrix elements of the microscopic quadrupole-quadrupole operator in the U(3)-boson approximation. The complete infinite-dimensional basis of A-fermion wave functions is compatible with the harmonic-oscillator shell model and consists of np-nh configurations, with spurious center-of-mass excitations removed, which are symmetry adapted to the Elliott U(3) and symplectic Sp(3,R) models. The formula expresses the general ${\mathit{Q}}_2$⋅${\mathit{Q}}_2$ matrix element with respect to this complete orthonormal basis as a Racah SU(3) U coefficient times a closed-shell matrix element. An oscillator closed-shell matrix element of ${\mathit{Q}}_2$⋅${\mathit{Q}}_2$ is a square root of a rational function of the integer quantum numbers of the U(3) basis.