We use the N/D formalism to perform a bootstrap calculation of a neutral, scalar resonance coupled to longitudinal WZ gauge bosons. We find that a consistent solution only exists for a mass value very close to 2.01 gauge-boson masses. The solution does not constrain the couplings and requires large scattering lengths.

We show that the Goldberg-Miyazawa-Oehme sum rule provides a relatively model-independent way of predicting a value for the pion-nucleon coupling constant, which we find to be below the canonical value of ${\mathit{f}}^2$/4π=0.079. The connections between this result, the low-energy theorem (LET) for pion photoproduction, and the pion-nucleon scattering lengths are discussed. We show that a value of ${\mathit{f}}^2$/4π near 0.073 results in consistency between the LET, the Goldberger-Miyazawa-Oehme sum rule, and a Fubini-Furlan prediction for the difference between the isospin 1/2 and 3/2 pion-nucleon scattering lengths.

The charge distribution of nuclear fragments for the nonfissile events of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ at 0.96A GeV in nuclear emulsion is fitted with a power law. The method of scaled factorial moments is used to study fluctuations in the nuclear fragmentations. An intermittent behavior is found in the data, but no clear evidence of critical phenomenon is observed in nuclear fragmentation.

Classical bound-state solutions for the baryon number =2 sector of the Skyrme model have been found by numerical simulation in 3+1 dimensions. The Bohr-Sommerfeld level of quantization is implemented. Properties of the deuteron obtained by quantization about the periodic classical solution improve on previous work based on quantization about the minimum energy static toroidal configuration.

The damping of dipole and quadrupole motion in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ at zero and finite temperature is studied including particle-particle and particle-hole interactions to all orders of perturbation. We find that the dipole dynamics in these light nuclei is well described in terms of mean-field theory (time-dependent Hartree-Fock), while the quadrupole motion is strongly damped through the coupling to more complicated configurations. Both the centroid and the damping width of the quadrupole and dipole giant resonances show a clear stability with temperature as a consequence of the weakening of the interaction, which contrasts with the increase of the phase space.

We have measured the first complete angular correlations of α-particle emission from the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ isoscalar giant quadrupole resonance (${\mathrm{GQ}}_0$R) following excitation by inelastic electron scattering. Analysis of these determines the ${\mathrm{GQ}}_0$R strength distribution and resolves a discrepancy between previous results from photonuclear excitation and inelastic α scattering.

Long-lived ${10}^{+}$ isomers in ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sn}$ and ${}_{}{}^{124}{}_{}{}^{}\mathrm{Sn}$ have been identified among the products of ${}_{}{}^{124}{}_{}{}^{}\mathrm{Sn}$+325 MeV ${}_{}{}^{76}{}_{}{}^{}\mathrm{Ge}$ collisions. The measurements virtually complete a series of B(E2) determinations for (ν${\mathit{h}}_{11/2}$${)}^{\mathit{n}}$ states in ${}_{}{}^{116\mathrm{-}130}{}_{}{}^{}\mathrm{Sn}$, which pinpoint half filling of the ν${\mathit{h}}_{11/2}$ subshell very close to N=73. Results for these Z=50 isotopes and for the N=82 isotones are contrasted, and an enlightening comparison between the effective E2 charges observec in tin and lead isotopes is developed.

An ultrasensitive laser spectroscopic method has been developed to perform hyperfine spectroscopy of heavy-ion-induced reaction products. It is based on resonance ionization in a buffer gas cell combined with radioactive decay detection. The feasibility has been demonstrated using the β-active ${\mathrm{isotope}}^{208}$ Tl. A sensitivity of 1.3×${10}^{\mathrm{-}3}$ of the two-step resonance-ionization process via the n=17 Rydberg level has been determined, utilizing a pulsed excimer-dye-laser combination. The previously unknown nuclear magnetic moment μ${(}^{208}$Tl) = 0.292(13)${\mathrm{\mu }}_{\mathit{n}}$ (${\mathrm{\mu }}_{\mathit{n}}$ is the nuclear magneton) and a rms radius difference between ${}_{}{}^{208}{}_{}{}^{}\mathrm{Tl}$ and ${}_{}{}^{207}{}_{}{}^{}\mathrm{Tl}$ of δ〈${\mathit{r}}^2$〉=0.099(15) ${\mathrm{fm}}^2$ were deduced from the 6p ${}_{}{}^2{}_{}{}^{}$${\mathit{P}}_{1/2}$–7s ${}_{}{}^2{}_{}{}^{}$${\mathit{S}}_{1/2}$ transition.

We report the first application of an ultrasensitive detection scheme in on-line collinear-laser spectroscopy. It is based on radioactive detection of optical depopulation pumping, using state-selective charge exchange as an intermediate step. This extends the calcium isotope shift measurements beyond the ${\mathit{f}}_{7/2}$ shell closure. The extracted ${}_{}{}^{50}{}_{}{}^{}\mathrm{Ca}$ mean-square charge radius constitutes the first experimentally determined one of a short-lived neutron-rich isotope beyond the N=28 shell closure. The steep increase in radius after the doubly magic ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ nucleus indicates a strong coupling between the ${\mathit{p}}_{3/2}$ neutrons and the core protons.

A global formula for the asymptotic Lamb shifts of the Rydberg states of helium is obtained by calculating the electric field perturbation due to the Rydberg electron on the ${\mathrm{He}}^{+}$ (1s) Lamb shift. The result substantially reduces theoretical uncertainties in calculated transition frequencies. A comparison with experiment for transitions among the n=10 states of helium reveals systematic discrepancies much larger than expected corrections due to higher-order relativistic and Casimir-Polder effects.

Calculations of inner-shell photoionization of excited atoms are performed which demonstrate a general class of states for which ionization plus excitation is the dominant process. The phenomenon is explained in terms of relaxation effects and examples for Li are presented.

The cross section for double bremsstrahlung differential in the radiated photon energies and angles has been measured for 70-keV electrons on targets of Al, Cu, Ag, Tb, and U for photons radiated at ±45° to the incident beam for photon energies in windows from 10 to 30 keV. In contrast with previous experiments at ±90°, the results are in reasonable agreement with the relativistic first Born approximation at lower Z. However, the results exhibit a Z dependence which disagrees with the first Born ${\mathit{Z}}^2$ dependence, suggesting the need for consideration of a second Born approximation.

High-resolution measurements of dielectronic recombination cross sections for neonlike xenon (${\mathrm{Xe}}^{44+}$) are presented. The experimental method consists of the formation and interaction of ions with electrons in an ion trap followed by an analysis of the extracted ions to determine relative yields. Low beam currents are used to obtain an energy resolution of 16 eV FWHM. Reductions in the number of initial ions of more than 3 orders of magnitude are observed as the strongest resonances are scanned. The relative contributions of the LMM, LMN, LMO, LMP, and LMQ groups of resonances are compared to theoretical calculations. The agreement with theory is excellent.

Recent experiments using polarized electron beams have shown that spin exchange effects for elastic collisions with ${\mathrm{O}}_2$ and NO are much smaller than for Na atoms. We report calculated spin-flip differential cross sections for elastic collisions of polarized electrons with ${\mathrm{O}}_2$ in agreement with experiment. In general, we can attribute the large variation of the spin-flip differential cross sections to resonances and interference effects. Such features arising from interference, however, may be washed out in the molecular case due to the average over orientations. Calculations with oriented ${\mathrm{O}}_2$ molecules show strong exchange effects as for Na.

We report time-resolved measurements of the phase of the Stokes beam produced by stimulated Brillouin scattering in gases. We observed phase jumps, slow phase drifts, and sudden frequency shifts during the temporal evolution of individual Stokes pulses. Phase jumps, and the intensity variations that accompany them, are macroscopic manifestations of the noise that initiates and sustains stimulated scattering.

Long-time numerical solutions of a low-dimensional model of the reduced MHD equations show that, when this system is driven quasistatically, the response is punctuated by impulsive events. The statistics of these events indicate a Poisson process; the frequency of these events scales as Δ${\mathit{E}}_{\mathit{M}}^{\mathrm{-}1}$, where Δ${\mathit{E}}_{\mathit{M}}$ is the energy released in one event.

Filamentation and Brillouin-enhanced four-wave-mixing instabilities caused by the cooperative interaction between two counterpropagating electromagnetic waves are shown to possess larger convective growth rates and smaller absolute instability thresholds than the conventional single-pump instabilities. These cooperative instabilities may be important in certain laser-plasma interaction experiments.

Electrostatic turbulence and transport has been measured in the tokamak edge as the safety factor (and, concomitantly, the energy-confinement time) and the edge equilibrium gradients are varied substantially. The turbulence is largely independent of safety factor, but strongly sensitive to the local-density gradient, which itself depends upon the limiter configuration.

We describe results from the gun-injected spheromak device SPHEX, which show that the power required to sustain the plasma is initially deposited in a column, about 8 cm in radius, along the geometric axis of the device, and is transmitted from the column to the remainder of the plasma by a radially propagating oscillation at about 20 kHz. These results are relevant to the process of relaxation in spheromak systems.

The spheromak device SPHEX has been modified by adding a current-carrying rod along the geometric axis, providing a preexisting toroidal field. We show that plasma can be successfully injected into such a field from a helicity source; the field assists plasma ejection from the gun and improves the coupling between gun and plasma, so that ${\mathit{T}}_{\mathit{e}}$, ${\mathit{T}}_{\mathit{i}}$, and the toroidal current all increase with rod current. The mechanism of plasma sustainment appears to be the same as that of the spheromak. These results represent a step towards the achievement of steady-state tokamak operation.