The spin of the lowest level observed in the superdeformed band in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Dy}$ is determined to be ${\mathit{I}}_0$=25 rather than the previously assigned ${\mathit{I}}_0$=22. As a result, we have ${\mathit{scrI}}^{\mathrm{}\left(1\right)\mathrm{}}$>${\mathit{scrI}}^{\mathrm{}\left(2\right)\mathrm{}}$ and both ${\mathit{scrI}}^{\mathrm{}\left(1\right)\mathrm{}}$ and ${\mathit{scrI}}^{\mathrm{}\left(2\right)\mathrm{}}$ decrease very slowly with rotational frequency. From the spin determination of the two pairs of identical bands in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Dy}$ and ${}_{}{}^{151}{}_{}{}^{}\mathrm{Tb}_{}^{\mathrm{*}}{}_{}{}^{}$, ${}_{}{}^{151}{}_{}{}^{}\mathrm{Tb}$ and ${}_{}{}^{150}{}_{}{}^{}\mathrm{Gd}_{}^{\mathrm{*}}{}_{}{}^{}$, evidence has been obtained to support the assumption of quantized alignments in units of ħ/2.

We have explored the sensitivity of pp¯-nn¯ isospin mixing in L=0,1 atomic states of protonium to changes in the multipion-exchange contribution to the nucleon-antinucleon (NN¯) potential. The resulting annihilation probabilities ${\gamma }_{\mathit{I}}^{\mathrm{\alpha }}$ for isospin I=0,1 and state α${=}^{2\mathit{S}+1\mathrm{}}$${\mathit{L}}_{\mathit{J}}$ are combined with the spin-flavor weights for transitions NN¯→${\mathit{M}}_1$${\mathit{M}}_2$ in the ${}_{}{}^3{}_{}{}^{}$${\mathit{P}}_0$ model, and confronted with selected measured branching ratios. Some problems with the phenomenology of the ${}_{}{}^3{}_{}{}^{}$${\mathit{P}}_0$ model are identified. We compare the ${}_{}{}^3{}_{}{}^{}$${\mathit{P}}_0$ model with a phenomenological ansatz suggested by Klempt, in which branching ratios are written as a product of spin, isospin, and orbital factors, multiplified by ${\gamma }_{\mathit{I}}^{\mathrm{\alpha }}$.

Using a resonance coupled channel model that provides a good description of the experimental data on the reaction d+t⇆n+α and d-t elastic scattering in the region of the resonance ${}_{}{}^5{}_{}{}^{}\mathrm{He}$(3/$2^{+}$), we find the disposition of the S-matrix poles on the different Riemann sheets. An investigation of the motion of the poles with variation of the coupling strengths reveals the structure of the resonant state. The role of scattering and confined channels in the formation of the physical resonance is considered with the use of the probability sum rule for the confined channel. We demonstrate that the resonance ${}_{}{}^5{}_{}{}^{}\mathrm{He}$(3/$2^{+}$) proves to be a coupled channel pole associated predominantly with the d-t system.

Proton-proton bremsstrahlung calculations are compared to the 280-MeV experimental results from TRIUMF, which use a polarized proton beam. Calculations are included for all experimental results. The Bonn radial potential is compared to a modified Hamada-Johnston and the Bryan-Gersten potentials. Potentials with different short-range radial behavior are compared in order to examine the penetration of the photon radiation. Rather good agreement with experiment for the Bonn potential is achieved without the arbitrary normalization of 2/3 applied to the TRIUMF cross-section data. The rescattering included in our work accounts for an increase of up to approximately 20% in the cross section, which is not large enough to explain the differences with other calculations, and it contributes up to a factor of 2.5 in the analyzing power. Our present results include partial waves up to ${\mathit{J}}_{\max }$=6.

We present a systematic representation of the low-energy pion-trinucleon scattering problem derived from a reduction of the exact four-body formulation which is due to Haberzettl and Sandhas. This method removes many of the difficulties usually associated with the assignment of the parametric energy of pion-nucleon scattering in the pion-trinucleon center of mass which occur in the traditional optical potential approach based on multiple-scattering theories. In the present formulation both the pion-nucleon and nucleon-nucleon interactions provide the dynamical input and the quasideuteron mechanism appears naturally as a low-order approximation in our approach.

A model for the nucleon-antinucleon interaction is presented, which is based on meson-baryon dynamics. The elastic part is the G-parity transform of the Bonn NN potential; annihilation is accounted for by microscopic baryon-exchange processes with two-meson intermediate states involving π, ρ, σ, ω, δ, K, and ${\mathit{K}}^{\mathrm{*}}$. Results for cross sections and polarization data are compared with a phenomenological treatment of annihilation based on a simple, state- and energy-independent optical potential.

The annihilation of the nucleon-antinucleon (NN¯) system into two mesons including π, η, η’, ρ, ω, δ, ${\mathrm{a}}_1$, ${\mathrm{a}}_2$, ${\mathrm{f}}_2$ as well as K and ${\mathit{K}}^{\mathrm{*}}$ is studied in a distorted-wave Born-approximation approach, in the conventional framework based on nucleon, delta-isobar, and hyperon (Λ,Σ,${\mathit{Y}}^{\mathrm{*}}$) exchange. Results for branching ratios are in fair agreement with the data; they show a strong sensitivity to the kind of initial-state interaction used. For polarizations and backward differential cross-section data of pp¯→${\mathrm{\pi }}^{+}$${\mathrm{\pi }}^{\mathrm{-}}$,${\mathit{K}}^{+}$${\mathit{K}}^{\mathrm{-}}$, there are characteristic discrepancies between experiment and model predictions; possible reasons are discussed.

An s-wave local potential model of n-d scattering at collision energies above the breakup threshold is solved using a pseudochannel extension of the coupled-reaction-channel method. Results obtained for both quartet and doublet scattering agree within a few percent with the benchmark solutions of Friar et al., Phys. Rev. C 42, 1838 (1990), for the same model.

The shift in binding energy that results from allowing one explicit Δ in the triton is studied using the Hannover one-Δ force model. The one-Δ analysis extends through J≤4, subject only to L(NΔ)≤4. Our main result is a 103-channel triton binding energy of 7.83 MeV, which corresponds to a net attractive one-Δ effect of 370 keV. The corresponding (repulsive) dispersive effect is found to be 600 keV, so that the full one-Δ three-body-force effect is 970 keV. Appropriately restricted J≤2 calculations substantiate the basic results of the original Hannover triton calculations, although differences are found. The original J≤2 figures are in good agreement with our full results and dissecting our results shows this to be largely due to cancellations among the various truncations employed in the original calculations. A numerical correction is obtained for each truncation and these are found to be relatively independent of each other. This forms a reliable basis for subsequent ΔΔ studies. The Hannover one-Δ model is also critically examined for physical consistency and the ${}_{}{}^1{}_{}{}^{}$${\mathit{S}}_0$ effective range is found to be about 0.1 fm too low, a defect which could be responsible for about half of the net 370-keV increase in triton binding. The approach, methods, and numerical checks that underlie our investigations are also detailed.

Two experiments were carried out to study the γ-ray spectroscopy and lifetimes of the high-spin states of ${}_{}{}^{169}{}_{}{}^{}\mathrm{Hf}$, using the reaction ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$${(}^{44}$Ca,5n). The yrast band has been extended to ${\mathit{I}}^{\mathrm{\pi }}$=81/$2^{+}$ from the previously known ${\mathit{I}}^{\mathrm{\pi }}$=45/$2^{+}$. Three other bands were also extended to higher spin. The experimental Routhians, alignments, and signature splittings were interpreted within the framework of the cranked shell model (CSM). Good agreement is obtained between experimental results and the CSM calculations for the first band crossings due to ${\mathit{i}}_{13/2}$ neutron alignments. The nature of the second upbends observed in (+, +1/2), (-,+1/2), and (-,-1/2) bands is discussed. Lifetimes of 17 high-spin levels within range 39/2<I< 61) / 2 in four different bands were measured by using the Doppler shift attenuation method. The values of transition quadrupole moments derived from the measured lifetimes are compared with the results of total Routhian surface calculations, and a general agreement is obtained.

Average magnetic moments as well as information on the time evolution of the continuum structure of ${}_{}{}^{152}{}_{}{}^{}\mathrm{Dy}$ at high spin have been obtained using the transient hyperfine magnetic field acting on fast ions traversing a thin, magnetized gadolinium foil. ${}_{}{}^{152}{}_{}{}^{}\mathrm{Dy}$ nuclei were populated by the ${}_{}{}^{76}{}_{}{}^{}\mathrm{Ge}$${(}^{80}$Se,4n${)}^{152}$Dy fusion-evaporation reaction at E${(}^{80}$Se)=326.5 MeV. The target-ferromagnet arrangement corresponds to a time window of about 70<t<1100 fs, during which the excited nuclei experience the transient field interaction. The statistical γ rays, as well as the high-energy, ${\mathit{E}}_{\gamma }$>1200 keV, γ rays contributing to the collective E2 ‘‘bump,’’ exhibit a negligible precession, in accordance with the very short lifetimes of these states. The precession of the angular distribution of discrete yrast γ rays deexciting the nucleus from spin I∼35ħ down yields an average magnetic moment for states with 43ħ≥I≥31ħ. The resulting 〈g〉=0.21(2) is considerably lower than the collective value Z/A∼0.43 and indicates an appreciable contribution from aligned neutrons to the lower-spin region populated within the above time frame. The results are discussed in the framework of model calculations of the γ-ray cascade.

Mass yield curves in low-energy proton-induced fission of ${}_{}{}^{233}{}_{}{}^{}\mathrm{U}$, ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$, ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$, ${}_{}{}^{237}{}_{}{}^{}\mathrm{Np}$, ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{242}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{244}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$, and ${}_{}{}^{243}{}_{}{}^{}\mathrm{Am}$ were investigated in the energy range of 8–32 MeV. The gross features of mass yield curves were compared either at the same excitation energy or for the same charge of the compound nucleus with different neutron number. The results are briefly discussed in terms of (1) the weighted mean mass number of the light and heavy asymmetric peak, (2) the FWHM of the heavier asymmetric peak, and (3) the peak-to-valley ratio.

The measurement of the energy spectrum of ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ nuclei emitted in the spontaneous radioactivity of ${}_{}{}^{223}{}_{}{}^{}\mathrm{Ra}$ and ${}_{}{}^{224}{}_{}{}^{}\mathrm{Ra}$ has been carried out, using thin and intense sources (480 MBq for ${}_{}{}^{223}{}_{}{}^{}\mathrm{Ra}$ and 3550 MBq for ${}_{}{}^{224}{}_{}{}^{}\mathrm{Ra}$). The sources were obtained by implanting mass-separated beams into Al and vitreous C catchers. The measurement was performed with a superconducting solenoidal spectrometer. Our discovery, previously reported, of fine structure in the energy spectrum of ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ emission from ${}_{}{}^{223}{}_{}{}^{}\mathrm{Ra}$, which is analogous to the one known for α emission, is confirmed. Only 13% of the branching ratio in ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ decay leads to the ground state of the residual nucleus, while 81% to the first excited state. For ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ emission from ${}_{}{}^{224}{}_{}{}^{}\mathrm{Ra}$, a lower limit of 2 for the hindrance factor has been measured for the transition to the first excited state in the residual nucleus. Also, a precise identification in Z with an E×ΔE telescope has been performed for the radiation from the ${}_{}{}^{223}{}_{}{}^{}\mathrm{Ra}$ source. Our measurements of fine structure in ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ emissions open this field to nuclear structure studies.

Beta-decay half-lives and delayed neutron emission probabilities of very neutron-rich nuclides from Li to Al have been measured by a delayed coincidence technique. Neutron-rich nuclides were produced by reaction of 800-MeV protons on a ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ target and were individually identified by use of the time-of-flight isochronous spectrometer. For 16 previously measured nucides, the half-lives determined here agree with literature values within the uncertainties. The previously unmeasured half-lives for ${}_{}{}^{25}{}_{}{}^{}\mathrm{F}$ (59±40 ms) and ${}_{}{}^{28}{}_{}{}^{}\mathrm{Ne}$ (14±10 ms) have been determined. Delayed neutron emission has been measured for ${}_{}{}^{12}{}_{}{}^{}\mathrm{Be}$, ${}_{}{}^{14}{}_{}{}^{}\mathrm{B}$, ${}_{}{}^{17}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{N}$, ${}_{}{}^{25}{}_{}{}^{}\mathrm{F}$, and ${}_{}{}^{28}{}_{}{}^{}\mathrm{Ne}$. Emission probabilities are reported for 19 precursors and upper limits are reported for 12 other nuclides. These data are compared with predictions of several beta-decay models.

The method of configuration mixing within the neutron-proton interacting boson model has been expanded to consider the simultaneous mixing of several multiparticle-multihole configurations, obtained by exciting pairs of protons and/or neutrons across major shell gaps. The determination of parameters to be employed for each configuration is discussed, along with methods for choosing the multiparticle-multihole excitation energies. As a test, the method is applied to the nucleus ${}_{}{}^{192}{}_{}{}^{}\mathrm{Hg}$.

We develop methods for the calculation of the hadronic tensor that describes the response of nuclear matter to an electromagnetic probe and study the role of final-state interactions, making use of the theory of Horikawa, Lenz, and Mukhopadhyay. Recently, extensive calculations of such final-state interaction effects in quasielastic (e,e’) reactions have been performed by Chinn, Picklesimer, and Van Orden for finite nuclei. Our nuclear matter calculations reproduce the qualitative features found by those authors, including a significant ‘‘quenching’’ of the longitudinal response, if one uses a relativistic description of the process. While we are able to achieve an improved fit to a body of experimental data for the longitudinal response using this formalism, definitive conclusions cannot be drawn without performing a gauge-invariant calculation. We also find quenching of the transverse response in the region of the quasielastic peak; however, it is unclear as to whether that creates a problem for the theory, since the transverse response is known to have contributions from the excitation of the delta resonance and various multinucleon processes. As part of our study, we provide a spectral representation of the Green’s function of a nucleon propagating in relativistic nuclear matter.

We study nuclei far from the stability line using the relativistic Hartree theory. We calculate the properties of various elements of the Periodic Table up to the proton and neutron drip lines with several parameter sets. After comparing the numerical results, we discuss nuclear properties near the drip lines in detail for the parameter sets that include nonlinear terms in the sigma-meson Lagrangian.

The Gamow-Teller decays of N=50 nuclei are calculated, making use of an interaction determined by a least-squares fit to the spectra of N=51 nuclei. Core polarization is taken into account by evaluating various first-order diagrams, and when these and other corrections are included the calculated strengths are, in most cases, in good agreement with experiment.

Expressions are derived for the relative locations of the different isospin components of double isovector excitations. The splittings between the isospin components are found to be similar in magnitude to the isospin splittings in single excitations. Formulas are given for the relative strengths for exciting the different isospin components of the double excitations. Energy-weighted centroids are calculated in terms of isovector and isotensor energies. Examples are given, using available data for the double giant-dipole resonance. The Lane potential is found to be similar in magnitude to that for the single giant-dipole resonance.

We have used Lie’s method of extended group to obtain explicit forms of the generators and the structure of the maximal symmetry group of point transformations of the time-dependent Schrödinger equation for motions of nucleons interacting with two-body harmonic potential. The generators of the symmetry group correspond to different states of motion of the system. The maximal symmetry group is found to be a semidirect product of an infinite parameter Abelian invariant subgroup and a proper subgroup. For Z protons and N neutrons, this proper subgroup is a Lie group with 1/2[9Z(Z-1)+9N(N-1)+40] generators. Different nuclear modes of excitations have been assigned to the different generators. In particular the giant resonance mode and other collective modes of motion are shown to be consequences of the symmetry of the system.