By considering the evolution of an initially localized disturbance, we show that collisionless trapped-particle modes in a Tokamak geometry remain highly localized in the radial direction up to the point of nonlinear saturation. The inferred localization dimension of only a few "banana" widths is considerably less than the normal-mode picture has indicated. We discuss the implications of our results on estimates of the turbulent diffusion coefficient.

The velocity of second sound in He II was measured for $\epsilon \equiv 1-\frac{T}{T_{\lambda }}>~2\times {10}^{-5\mathrm{}}$ between saturated vapor pressure (SVP) and the melting curve. For $P>\mathrm{}\mathrm{SVP}$, the corresponding superfluid fraction $\frac{{\rho }_s}{{\rho }^{\prime }}$ cannot be described by a simple power law in $\epsilon$. When reasonable general assumptions are made about higher-order singular contributions, the asymptotic behavior of $\frac{{\rho }_s}{\rho }$ may be deduced and agrees well with scaling and universality.

The energy loss of a beam of cesium ions traversing a near-thermal equilibrium cesium plasma has been measured as a function of plasma density at ion-beam energies of 35 to 150 eV. The plasma electron/ion temperature was 2100°K, and the charged-particle density was varied from (0.1 to 3.7)×${10}^{11}$ ${\mathrm{cm}}^{-3\mathrm{}}$. The measured energy loss is found to agree very well with theoretical predictions.

From infrared photoelectric measurements, we have obtained a density of the interface states lying between 0.745 and 0.825 eV from the silicon conduction band at a Pt-Si interface. We show the following: The transitions occur preponderantly from a level ∼ 0.3 eV below the platinum Fermi level; a peak exists in the interface-state density at 0.79 eV from the silicon conduction band; and the pseudo Fermi level in the semiconductor moves up with forward bias.

We present a theory for the lattice dynamics of dilute impure quantum crystals which is quantum mechanically exact within the self-consistent phonon approximation. The theory predicts that mass-defect-induced changes in properties depending linearly on the scattering amplitude (e.g., specific heat) are largely canceled by a self-consistent force-constant renormalization. Changes depending on even powers of the scattering amplitude (e.g., thermal resistivity) are enhanced by the quantum-crystal effects.

We describe a new method for calculating two-dimensional energy bands in thin films. The method has the advantage that the potential varies continuously between film and vacuum regions and may even be made self-consistent. A band calculation has been performed for a 13-layer (1,0,0) Li film. We display graphs of the charge density and of the wave function of a surface state found in the (½, ½, 0) energy gap.

A detailed analysis of this double-resonance experiment shows that the emission takes place from the ${}_{}{}^3{}_{}{}^{}P$ excited level whose degeneracy is lifted by the Jahn-Teller coupling to $E_{\mathrm{g}}$ modes of vibration. An energy-level crossing effect is observed and its origin discussed.

We have made a ferromagnetic-resonance study of thin single-crystal yttrium iron garnet disks in perpendicular resonance and compared the experimental results with existing theory. For small transverse wave vectors good agreement is observed between theory and experiment for both pinned and unpinned films.

We present a calculation of $0^{+}$ excited states in the actinides for a pairing-force theory of the type suggested by Griffin, Jackson, and Volkov. Contrary to previous results, we find that such a theory does not explain low-lying $0^{+}$ excited states in the actinides any better than does a conventional pairing-force theory.

By utilizing particle-identification techniques to detect the two breakup $\alpha$ particles from ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$, we have studied the reactions ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$)${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$)${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$. The (${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$) reaction strongly populates the positive-parity four-particle, four-hole rotational band of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ based on its 6.05-MeV ($0^{+}$) state, and both the positive- and negative-parity rotational bands of ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ based on its ground-state ($0^{+}$) and 5.80-MeV ($1^{-}$) state, respectively.

Although nonrelativistic estimates of single-particle kinetic-energy expectation values appear to have invalidated the Hartree-Fock relation between total binding energy, single-particle eigenvalues, and kinetic-energy expectation values, a recent relativistic Hartree calculation has been successful at reproducing finite nuclear properties for closed-shell nuclei. Using the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ nucleus, it is demonstrated that this success is due to a reduction in the expectation values of the relativistic analog of the kinetic-energy operator.

The phase-shift analysis of $p$-${}_{}{}^3{}_{}{}^{}\mathrm{He}$ elastic scattering is modified by using peripheral values for the phase shifts for $l$ values corresponding to impact parameters greater than the nuclear radius. We observe a marked improvement in the weighted variance. We obtain a value of about 2.2 for the normalization of the tail of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ wave function.

We have observed two decays analyzed as examples of the decay $K^{+}\to {\pi }^0{\pi }^0{e}^{+}\nu$ in a heavy-liquid bubble chamber. All four converted $\gamma \text{'}\mathrm{s}$ are seen. We report a branching ratio of ${1.8}_{-0.6\mathrm{}}^{+2.4\mathrm{}}$×${10}^{-5\mathrm{}}$ for this decay. The form factor $f_1$ for the decay is reported as $\left|f_1\right|={0.97}_{-0.19\mathrm{}}^{+0.50\mathrm{}}$. These results are in good agreement with $\Delta I=\frac{1}{2}$ predictions.

Speculations are made concerning the fluctuation in the multiplicity in the fragmentation of hadrons in high-energy collisions. We analyze implications for the two-particle distribution function ${\rho }_2$ and higher-order distributions ${\rho }_{\nu }$.

The direct observation of anharmonic effect in coherently driven molecular vibrations is reported for low-pressure ${\mathrm{H}}_2$. Under intense excitation of the gas by light waves of frequencies $\omega$ and ${\omega }^{\prime }$, both electrical and mechanical anharmonicities contribute to a coherent polarizability modulation at $2(\omega -{\omega }^{\prime })$. The corresponding anharmonic scattering dominates, at low pressure, the usually observed harmonic double scattering. We discuss application of the effect to the determination of the second-order polarizability derivative.

The effect of nuclear mass on the $g$ factor of the bound electron has been determined by measuring $G=\frac{g_j\left(\mathrm{H}\right)}{g_j\left(\mathrm{D}\right)}$ to a precision of 3 × ${10}^{-11\mathrm{}}$ using a pulsed double-mode hydrogen maser. The result, $G=1+(7.22\mathrm{}\pm 0.03)\times {10}^{-9\mathrm{}}$, is in excellent agreement with the theory of Grotch and Hegstrom.

A normal molecular vibration is strongly excited by a picosecond light pulse. The rise and decay of the excess population of the first excited vibrational state (electronic ground state) is observed with a delayed probe pulse. These measurements give, for the first time, values of the lifetimes of molecular vibrations in liquids.

InSb samples at 4 K and $B_{\mathrm{ext}}=0\mathrm{}$ are observed to emit narrow-band radiation in two bands near 400 and 600 MHz. The frequency ratio of the two bands strongly suggests that the emission is due to nuclear electric-quadrupole transitions $\frac{3}{2}\to \frac{1}{2}$ of ${\mathrm{Sb}}^{121}$ and ${\mathrm{Sb}}^{123}$ nuclei located near impurity atoms. The nuclear electric quadrupole hypothesis explains simply many of the previously puzzling aspects of Insb microwave emission.

We report the observation of strong line narrowing of microwave radiation (870 MHz) emitted from a continuously operated, dc-pumped ${\mathrm{Bi}}_{92}$${\mathrm{Sb}}_{08}$ semiconducting alloy at 1.6 K. Bandwidths of less than 1 kHz are observed. The origin of the line narrowing is thought to be a maser effect involving the $\frac{3}{2}\to \frac{1}{2}$ nuclear electric-quadrupole transition of the ${\mathrm{Bi}}^{209}$ nucleus. A new dc pumping mechanism is proposed to explain the effect. In this effect the nuclei are pumped by electronic spin levels, saturated as in the Overhauser effect, except that saturation is achieved by carrier avalanche, instead of rf pumping.

The classical equations of motion for a finite chain of particles with a nearest-neighbor Lennard-Jones interaction are solved numerically and, for a broad class of initial conditions, Planck-like distributions are obtained for the time averages of the energies of the normal modes. For physical values of the parameters in the problem, the action constant entering such a distribution turns out to be of the order of magnitude of Planck's constant.