Hydrogenic fluorine atoms in the $2S_{\frac{1}{2}}$ metastable state were produced at 64 MeV by use of a tandem electrostatic accelerator and suitable combinations of stripper and adder carbon foils. A pulsed HBr laser centered at 2382.52 ${\mathrm{cm}}^{-1\mathrm{}}$ was Doppler-shift tuned through the $2S_{\frac{1}{2}}-2\mathrm{}{P}_{\frac{3}{2}}$ energy separation to yield a resonance in Lyman-$\alpha$ x rays at 826 eV. This technique yields a value for the Lamb-shift splitting ($2S_{\frac{1}{2}}-2\mathrm{}{P}_{\frac{1}{2}}$) equal to 3339±35 GHz which is presently in agreement with several quantum electrodynamic calculations.

We present direct evidence on the saturation of resonant two-photon transitions in the optical region. Saturation manifests itself as a broadening of the transition linewidth and as a deviation from the low-level intensity dependence for both third-harmonic generation and two-photon-induced fluorescence. These effects may greatly limit the extent of attainable resonant enhancement in experiments which require high intensity for excitation.

We report observations of saturation of two-photon-resonant third-harmonic generation and of fluorescence following two-photon absorption in cesium vapor. Weakening dependence of these processes on fundamental power and broadening of the resonance line with increased fundamental power are both seen. It is shown that hole burning is important in a certain power range with the resonance becoming predominantly homogeneously broadened at higher power levels.

Heavy-ion-atom collisions at medium energies (∼0.8 MeV/amu) yield a considerable probability for multiple inner-shell ionization. In the Ni-Ni, Ni-Fe, Fe-Ni, and Fe-Fe cases, distinct lines in the x-ray spectra are observed, which must be interpreted as a correlated two-electron jump into the doubly ionized $K$ shell followed by the emission of only one photon carrying away the total transition energy.

Under certain modes of operation of very large tokamaks such as the proposed two-component torus (TCT), it is possible to create oppositely directed density and temperature gradients ($\nabla n·\nabla T<\mathrm{}0\mathrm{}$) in the hotter central region of the plasma and the usual profile ($\nabla n·\nabla T>\mathrm{}0\mathrm{}$) on the colder outer edge. Such configurations are found to be very favorable to stability against trapped-particle modes.

We discuss the generation of dc magnetic fields due to the resonant excitation of plasma waves by an obliquely incident, plane-polarized laser beam. We show that the averaged forces on the electrons due to the plasma waves produce magnetic fields perpendicular to the plane of incidence. Megagauss field levels may be reached. Computer simulations verify our theoretical predictions.

The stability of a plasma consisting of two, unequal, isotropic, ion beams streaming along a uniform magnetic field has been investigated by numerically solving the full electromagnetic, Vlasov, linear dispersion relation for high-$\beta$ plasmas. Three instabilities are found: One is closely associated with the usual Alfvén mode and the two others with the "fast" or magnetosonic mode. The importance of these instabilities for certain neutral-beam-injection experiments and in the solar wind is emphasized.

A careful calculation of the one-phonon dispersion in diamond reveals a shallow maximum in the [100] direction for the ${{\Delta }_2}^{\prime }\left(\mathrm{L}\mathrm{O}\right)$ branch. The two-phonon (overtone) density of states shows a sharp peak near twice the Raman frequency. This supports the interpretation of an observed peak in two-phonon Raman scattering as a simple overtone without the need to invoke a two-phonon bound state.

Using a model for the magnetic properties of solid ${\mathrm{He}}^3$ which includes both Heisenberg exchange and the motion of ground-state vacancies (concentration ∼ ${10}^{-4\mathrm{}}$), we predict via mean-field theory a first-order paramagnetic- to ferromagnetic-phase transition.

Logarithmic anomalies in the temperature-dependent resistivity of a series of amorphous alloys have been measured and shown to be nonmagnetic in origin. We associate these anomalies with the noncrystalline structure.

The transmission and two reflection spin-resonance signals for single-crystal $\mathrm{Ag}\mathrm{Gd}$ are shown to have the same crystal-field parameter, and hence are attributable to an isolated local moment. This identification illustrates why $S$-state resonance data need re-examination. The ratio of the averages of $J(k, k^{\prime })$ appropriate to the exchange field and relaxation rate of the local moment is ≃ 3 which may be difficult to interpret within the framework of presently accepted models.

The surface impedance of a metal containing local moments includes a resonace of the spin response at high wave vector, which differs from the resonances at low wave vector. This resonance is observable in reflection but not in transmission, and is the resonance seen in reflection for low concentration $\mathrm{Ag}\mathrm{Gd}$. At high concentration, low-wave-vector resonances dominate, and transmission and reflection agree. This new identification suggests that prior reflection-resonance data be reexamined.

We prove that the susceptibility of an isotropic, two-component, classical vector spin system, e.g., the rigid rotator, diverges in three or four dimensions as the magnetic field $h\to 0$, at all temperatures for which there is a spontaneous magnetization. The divergence is at least as strong as $h^{\frac{1}{2}}$ in three and as $\left|\ln h\right|$ in four dimensions. We also obtain bounds on the rates of exponential decay of the parallel- and transverse-pair correlation functions.

With use of the ordinary quadrupole-quadrupole (Q-Q) interaction, a total splitting of the $K=0, 1, 2$ components in the giant quadrupole resonance (GQR) of about 6 MeV is predicted for deformed ${}_{}{}^{154}{}_{}{}^{}\mathrm{Sm}$. A 0.8±0.3-MeV broadening of the GQR is observed for ${}_{}{}^{154}{}_{}{}^{}\mathrm{Sm}$ relative to spherical ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$ with inelastic $\alpha$ scattering. A model requiring rigorous self-consistency is proposed which modifies the Q-Q interaction, reduces the predicted splitting to about 2 MeV, and removes inconsistencies in the strength of the interaction for $K=0\mathrm{}$ and $K=2\mathrm{}$ components in low-lying $\beta$ and $\gamma$ bands.

A set of $\Delta J=1\mathrm{}$ rotational bands has been observed on deformed (prolate) ${\frac{9}{2}}^{+}$ states in ${}_{}{}^{113}{}_{}{}^{}\mathrm{Sb}$, ${}_{}{}^{115}{}_{}{}^{}\mathrm{Sb}$, ${}_{}{}^{117}{}_{}{}^{}\mathrm{Sb}$, and ${}_{}{}^{119}{}_{}{}^{}\mathrm{Sb}$ via (${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, $3n\gamma$) reactions on stable even Cd targets. The pattern of band spacings is suggestive of a $j={\frac{9}{2}}^{+}$ state coupled to a triaxial rotor. The energy systematics of the deformed states relate to the deformation-energy surfaces in this $Z=50\mathrm{}$ closed-shell region.

A new method is proposed to obtain information about $\eta$, the asymptotic $D$-state-to-$S$-state ratio for the deuteron. The method is based on the fact that polarized-beam measurements for sub-Coulomb ($d, p$) reactions are sensitive to the deuteron $D$ state.

New isotopes ${}_{}{}^{186,188}{}_{}{}^{}\mathrm{Tl}$ (${T_{\frac{1}{2}}}^{186}={4.5}_{-1.5\mathrm{}}^{+1.0\mathrm{}} \mathrm{and} 28\pm 2$ sec and ${T_{\frac{1}{2}}}^{188}=71\mathrm{}\pm 1$ sec, respectively) have been identified. Conversion-electron, $\gamma$, $\gamma -\gamma$, and $e-\gamma$ studies helped establish in ${}_{}{}^{186,188}{}_{}{}^{}\mathrm{Hg}$ two bands, one built on a slightly deformed ground state and one on a more strongly deformed shape with $0^{+}$ band heads at 522 and 824.5 keV, respectively. Their crossing explains the anomalous behavior of $\mathcal{I}$ in the yrast cascades. States above and below the crossing in both bands support the existence of a well-defined second minimum in ${}_{}{}^{188}{}_{}{}^{}\mathrm{Hg}$.

Coulomb excitation with Kr and Xe ions has excited the ground-state band of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ up to the ${22}^{+}$ (tentatively ${24}^{+}$) state and the lowest octupole vibrational band up to ${19}^{-}$. No back-bending is observed. The behavior of the octupole band at high spins suggests a Coriolis-induced alignment of the rotational and vibrational angular momenta.

Magnetic octupole and scalar spin-spin interactions have been observed in ${}_{}{}^{127}{}_{}{}^{}\mathrm{I}_2^{}{}_{}{}^{}$ by precisely measuring (line centers located to 1 part in ${10}^{11}$) the hyperfine spectrum on the $P\left(13\right)\mathrm{}$, 43-0 line using laser-molecular-beam techniques. The values of the coupling strengths obtained from fitting the spectrum are, for the electric quadrupole, $\mathrm{eQ}{q}^{\prime }=-554\mathrm{}094\pm 13$ kHz and $\mathrm{eQ}{q}^{\prime \prime }=-2\mathrm{}448025\pm 10$ kHz; for the spin-rotation, $C^{\prime }-C^{\prime \prime }=186.71\mathrm{}\pm 0.10$ kHz; for the tensor spin-spin, ${D_t}^{\prime }-{D_t}^{\prime \prime }=-100.5\mathrm{}\pm 1.0$ kHz; for the scalar spin-spin, ${D_s}^{\prime }-{D_s}^{\prime \prime }=-2.72\mathrm{}\pm 1.0$ kHz; and for the magnetic octupole, $\Omega m^{\prime }-\Omega m^{\prime \prime }=-2.17\mathrm{}\pm 0.70$ kHz.

High-amplitude electron waves with relativistic group velocities were induced on a magnetically focused unneutralized relativistic electron beam. These waves were moving antiparallel to the beam direction and were found to modify drastically the macroscopic beam parameters. The group velocity of these waves depends on the axial magnetic field intensity and on the wave frequency. The importance of this effect to certain applications for relativistic electron beams is discussed.