Data are presented for pion double charge exchange on targets of ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{80}{}_{}{}^{}\mathrm{Se}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, and ${}_{}{}^{118}{}_{}{}^{}\mathrm{Sn}$. These and earlier data are used to examine the mass dependence of double-isobaric-analog transitions and nonanalog ground-state-to-ground-state transitions in the energy region $T_{\pi }$=100 to 300 MeV. The implications of the mass dependence to the interpretations of the underlying reaction mechanisms of double charge exchange are discussed.

Single particle inclusive spectra have been measured for the production of several isotopes of H, He, Li, and Be from the interaction of 300 MeV protons with Be and Ag targets. ${}_{}{}^1{}_{}{}^{}$,2H and ${}_{}{}^3{}_{}{}^{}$,4He fragments are measured over a wide range of energies which approach the upper kinematic limits at many of the angles measured. Measurements of the isotopically resolved He, Li, and Be fragments over a more limited energy range are also reported for 190 MeV protons incident on the same two targets. The spectra have been fitted with a phenomenological moving-source model used successfully in earlier studies. However, good fits were not obtained over the extended kinematic ranges measured in this study. A model-independent invariant cross section analysis applied to the ${}_{}{}^3{}_{}{}^{}$,4He data at 300 MeV is used to illuminate the problems that any statistical model will face in trying to explain fragment production at intermediate energies.

The reactions C(π,p), C(π,3p), H${(}^3$He,t), and C${(}^3$He,t) are analyzed for possible bound Δ states in analogy to hypernuclei. Though the widths and the resonance positions which were shown in the experimental data may be different from the free 3,3 resonance, kinematics and capture structure probability functions may distort the resonance which could be misinterpreted as a Δ bound state.

We investigate Δ(1232) production via charge-changing weak currents ${\mathrm{e}}^{\mathrm{-}}$+p→${\Delta }^0$+${\nu }_{\mathrm{e}}$ and ${\mathrm{e}}^{+}$+p→${\Delta }^{++}$+ν${¯}_{\mathrm{e}}$ at electron/positron beam energies in the range of a few GeV. A general formalism is introduced for the N→Δ transition form factors, including the weak magnetism, weak quadrupole, and weak scalar form factors for the polar-vector current and the axial, pseudoscalar, recoil, and weak electric form factors for the axial current. The form factors related to the polar-vector current are related to Δ(1232) electroproduction on a nucleon target. For nucleons and deltas, we adopt in this calculation the flavor SU(6) wave functions, with quarks described as confined Dirac particles. The quark wave function adopted is of the form given by the MIT bag model, with or without the sharp boundary smoothened out. In the few GeV range, it is found that cross sections can be as large as ${10}^{\mathrm{-}38}$ ${\mathrm{cm}}^2$ and are sensitive to induced form factors such as the weak magnetism form factor. It is also found that, for a beam energy of around 4.0 GeV, the predicted cross sections depend sensitively on whether or not the sharp boundary in the quark wave function is smoothened out.

Pionic fusion reactions ${}_{}{}^4{}_{}{}^{}\mathrm{He}$,${\pi }^{+}$${)}^7$Li and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$,${\pi }^0$${)}^7$Be at the subthreshold energy are studied theoretically. The cross section is enhanced largely by the clustering correlation. The general trend of target-mass dependence of the A${(}^3$He,${\pi }^{+}$)C reaction is also studied.

Forward-angle differential cross sections for the ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$(${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^0$${)}^{165}$Er(IAS) reaction have been measured at $T_{\pi }$=98.0, 163.2, and 228.3 MeV in the angular range &≲14°. The shapes of the angular distributions at 98.0 and 163.2 MeV are compared to predictions arising from the strong absorption model of pion single-charge exchange scattering. Extrapolated 0° cross sections are compared with trends previously established with mostly spherical and near-spherical nuclei. The measurement demonstrates the possibility of using the (${\pi }^{+}$,${\pi }^0$) reaction for studying neutron density deformations in oriented ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$.

Cross sections have been measured for ${\pi }^{+}$ and ${\pi }^{\mathrm{-}}$ inelastic scattering to the $2_1^{+}$ levels of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$, ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}$, and ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$. The data are used to infer neutron and proton quadrupole-matrix elements for these transitions. The matrix elements extracted from the pion data are in good agreement with their corresponding electromagnetic matrix elements. These results indicate that the use of the distorted-wave impulse-approximation is a valid procedure for this class of transition.

Differential cross sections were measured for pion elastic and inelastic scattering from ${}_{}{}^{48}{}_{}{}^{}$,50Ti, ${}_{}{}^{52}{}_{}{}^{}\mathrm{Cr}$, and ${}_{}{}^{54}{}_{}{}^{}$,56Fe at $T_{\pi }$=180 MeV. Elastic scattering data were analyzed using a standard Kisslinger potential. Inelastic scattering data were analyzed using distorted-wave impulse-approximation calculations with collective-model transition densities. Ground-state neutron density parameters and matrix elements for some of the transitions were extracted and ${\pi }^{+}$/${\pi }^{\mathrm{-}}$ differences investigated.

Previous calculations of the self-consistent effective πN t matrix are extended to include a complete, consistent treatment of the pion crossing symmetry. The self-consistent πN t matrix equation is rewritten as a set of four coupled integral equations in order to facilitate the inclusion of crossing symmetry. The πN amplitudes are obtained by means of a Low expansion as in previous papers. The insertion of the crossed πN scattering amplitudes into the nuclear medium is studied in the context of time ordered perturbation theory in order to determine the correct energy at which the crossed amplitudes should be evaluated in the medium. The self-consistent equations are evaluated in nuclear matter. The resonant contribution to the optical potential is found to be broadened by an additional 15–25?when compared to similar calculations which do not include the crossed amplitudes.

The relativistic impulse approximation is used to generate scalar and vector optical potentials for p¯ atoms which are used to investigate spin and isospin dependent effects. These potentials describe the isospin dependence of shifts and widths for the oxygen isotopes very well. Definite predictions are made for the spin-orbit dependence of the shifts and widths in Yb and Th, for which experimental results are becoming available. There appear to be significant discrepancies. The importance of including the electromagnetic spin-orbit interaction and the long tails of weakly bound nucleons is pointed out.

The inclusive inelastic scattering of α particles on ${}_{}{}^2{}_{}{}^{}\mathrm{H}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ has been measured at 7.0 GeV/c incident momentum, between 2° and 15° in the laboratory. The momentum spectra of the recoiling α particles are richly structured, suggesting that scattering takes place, at least partially, on nuclear substructures. The differential cross sections for the three reactions show a diffractive behavior comparable to that of the corresponding elastic processes.

Differential cross sections for the double-isobaric-analog-state transition in the reaction ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$(${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^{\mathrm{-}}$${)}^{48}$Ti at an incident energy of 35 MeV were measured over the angular range 20°–80°. The cross section extrapolated to 0° is 3.1±0.8 μb/sr, and the angular distribution shape is nearly isotropic. The results are compared to second-order optical-potential calculations and to the systematics of low-energy double-charge-exchange reactions. Measurements were also made at 50 MeV at scattering angles of 25° and 40°. The analog-state transition could not be clearly observed above the background of non-analog-state transitions.

The electromagnetic structure functions of the deuterons are investigated, based on the hybrid quark-hadron model. The six-quark effects are important, and even dominant for the magnetic form factor for $q^2$≳15 ${\mathrm{fm}}^{\mathrm{-}2}$. The calculated results are in good agreement with experiment.

The experimental isovector quadrupole strength in the charge exchange channels is smaller than predicted by random phase approximation calculations using conventional nuclear interactions. The introduction of nonlocal components in the interaction combined with the existence of a low-lying 0ħω rotational $2^{+}$ quadrupole state in the daughter nucleus can explain this behavior. These nonlocal interactions do not play a role in the properties of the isovector monopole and dipole resonance.

Relativistic microscopic calculations are presented for proton elastic scattering from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ at laboratory kinetic energies near 200 MeV. The calculations go beyond the original relativistic impulse approximation to include (a) medium modifications from Pauli blocking, (b) the resolution of ambiguities in the relativistic NN amplitude by using pseudovector πN coupling, and (c) an explicit treatment of exchange terms in the optical potential. The results quantitatively reproduce all measured spin observables (both analyzing power and spin rotation function) except at very large angles. The energy dependence and sensitivities are discussed.

We show that the binding energies of ${}_{\mathrm{\Lambda }}{}^5{}_{}{}^{}\mathrm{He}$ and p-shell hypernuclei can be satisfactorily explained in the folding model approach using a density dependent effective ΛN interaction. Our analysis predicts a very reasonable value of the range of the ΛN interaction. The calculated value of $B_{\Lambda }$ of ${}_{\mathrm{\Lambda }}{}^7{}_{}{}^{}\mathrm{Li}$ using the cluster model density for ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ and the best fit parameters of this potential supports the view that ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ possesses an α-d cluster structure. Using this potential we also determine the average size parameter ($a_0$) of the oscillator shell model density of nucleons in N≠Z core nuclei from fitting the $B_{\Lambda }$ values of the corresponding hypernuclei. The effect of different forms of density distribution of core nuclei on the values of potential parameters is investigated and is found to be very small. As regards the form of density dependence, a ${\rho }^{2/3}$ form is found to be the most appropriate for this purpose and is used throughout this work. Other forms do not give a satisfactory account of the data.

Detailed spectroscopy measurements have been made of the gamma rays that follow the deexcitation of ${}_{}{}^{168}{}_{}{}^{}\mathrm{Er}$ levels populated in the electron capture decay of ${}_{}{}^{168}{}_{}{}^{}\mathrm{Tm}$. These results, when combined with a reanalysis of Coulomb excitation and inelastic scattering data, provide level lifetime information and support octupole-state Coriolis-coupling calculations. The {[521 (1/2)][633 (7/2)]} two-neutron configurational pair deexcitation rates are compared and some evidence for K mixing among the octupole bands is presented.

Gamma rays from the β decay of ${}_{}{}^{20}{}_{}{}^{}\mathrm{O}$, produced in the ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$(t,p${)}^{20}$O reaction at $E_{\mathrm{t}=3.1\mathrm{}}$ MeV using a Van de Graaff beam and a rabbit target-transfer system, were measured in a Ge-NaI(Tl) Compton-suppression spectrometer. In addition to the principal γ ray, measured as 1056.818(4) keV, a γ ray of 3488.21(10) keV was observed with an intensity corresponding to an ${}_{}{}^{20}{}_{}{}^{}\mathrm{O}$ β-ray branch of 0.027(3)% to the 3488.54(10)-keV $1^{+}$ level of ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ with logft=3.65(6). Limits were placed on other β- and γ-ray branches; in particular the β branch to the probable $1^{+}$ level at 3172.6 keV in ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ is <0.012% with logft>5.1. The result for the new β branch to the 3488.5-keV level is in excellent agreement with a recent shell-model prediction for the decay to the second $1^{+}$ state of the (2s,1d${)}^4$ model space. The electromagnetic decays of some of the low-lying levels of ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ are calculated in this model space and a comparison to experiment reveals a serious discrepancy for level lifetimes in the <50 fs range. An incidental result is an adopted value of 8.2(6)×${10}^{\mathrm{-}3}$% for the β-ray branching of ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ to the 4966.5-keV level of ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$.

Conversion electrons have been measured for E0 transitions between the first excited $0^{+}$ states and the ground states of ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}$, ${}_{}{}^{102}{}_{}{}^{}\mathrm{Mo}$, ${}_{}{}^{106}{}_{}{}^{}\mathrm{Ru}$, ${}_{}{}^{108}{}_{}{}^{}\mathrm{Pd}$, ${}_{}{}^{110}{}_{}{}^{}\mathrm{Pd}$, and ${}_{}{}^{112}{}_{}{}^{}\mathrm{Pd}$. The ${\rho }_{21}^2$ and $X_{\mathrm{ijk}}$ values are calculated from the measured E0/E2 branching ratios and level lifetimes that were either measured in this experiment or obtained from the literature. The results are discussed briefly in terms of neutron-proton interacting boson model mixed-configuration calculations and intruder states.

The high-spin spectrum of ${}_{}{}^{84}{}_{}{}^{}\mathrm{Zr}$ is studied using the Strutinsky-Bogolyubov cranking model with a Woods-Saxon average potential. Calculations explain observed irregularities in the ${}_{}{}^{84}{}_{}{}^{}\mathrm{Zr}$ yrast line in terms of band crossings involving aligned $g_{9/2}$ proton and neutron bands. A transition to the superdeformed shape is predicted to occur around I∼30ħ. Experimental data are consistent with the nucleus having a well deformed (${\beta }_2$≃0.3) and triaxial (γ≃-20°) shape.