Nuclear density oscillations coming from a semi-infinite nuclear matter calculation in the local-density approximation are compared with the density oscillations obtained by the Green's-function method of Thorpe and Thouless. A new, simpler method without use of Green's functions which easily leads to higher terms in density expansion is proposed. The appearance of the first "bump" in density on the rising density curve was justified. Connection with Regge-type oscillations is discussed.

Angular and energy distributions of fragments emitted from fast nucleus-nucleus collisions (Ne→ U at 250, 400, and 800 MeV/N) are calculated with use of nuclear fluid dynamics. A characteristic dependence of the energy spectra and angular distributions on the impact parameter is predicted. The preferential sideward emission of reaction fragments observed in the calculation for nearly central collisions seems to be supported by recent experimental data.

The effect of dispersion around the mean classical path on the angular correlation between promptly emitted ligth particles and heavy ejectiles from deep-inelastic reactions is studied in a simple model. A relation between the asymmetry in the angular correlation about the beam direction and the polarization of the heavy residual is given.

Self-broadenings and frequency shifts of $n^{2}S$ and $n^{2}D$ Rydberg levels (up to $n\sim 70$) have been measured for rubidium in the pressure range of 3 to 100 mTorr, and the general dependence on principal quantum number $n$ has been established for this low-pressure regime. A closer examination has revealed large (almost evenly spaced) oscillations in the dependence of linewidth on principal quantum number for the ${}_{}{}^2{}_{}{}^{}S$ levels in the region of largest linewidth ($n\sim 20 \mathrm{to} 30$).

A picosecond coherent probing technique is used to determine the homogeneous vibrational linewidth in liquids. Isotope effects on the symmetric C${\mathrm{H}}_3$-stretching vibration in methanol and acetone provided a sensitive test for various vibrational dephasing theories. Theories based on binary-collision or hydrodynamic models do not correctly account for the observed isotope effect. Exchange theory is shown to be qualitatively consistent with the results.

It is found, by means of numerical simulations, that an ion-acoustic instability ($v_d<v_{\mathrm{te}}$) results in the formation of double layers in a sufficiently long system. Anomalous resistivity generated by the ion-acoustic instability causes the buildup of a dc potential which in turn accelerates electrons further to enhance the original instability leading to the formation of double layers.

Electron-beam-induced fluorescence has been used to measure the vibrational energy of nitrogen molecules desorbing from a polycrystalline iron surface, following atomic permeation and recombination on the iron surface. The vibrational temperature of the desorbing nitrogen is found to be significantly greater than the temperature of the iron surface, indicating that a fraction of the nitrogen-atom recombination energy remains with the desorbing nitrogen molecule as internal excitation.

Chlorine nuclear quadrupole resonance spectra of ${\mathrm{K}}_2$Os${\mathrm{Cl}}_6$ crystals containing hydrogen ions are observed at 77 and 298 K. The relative positions and intensities of the observed satellite lines indicate that the impurity ions are situated at the vacant octahedral sites in the lattice. Further, the results provide evidence for the motion of the hydrogen ions through the lattice at 298 K with a characteristic residence time of the order of ${10}^{-4\mathrm{}}$ sec.

Measurements of the primary and secondary photocurrent for photon energies above 0.58 eV in $a$-Si: H solar-cell structures determine the absorption coefficient and give information about the density of valence-band-tail states as well as show that holes are mobile deep in the bandgap.

In the sudden approximation for surface penetration, a wake-bound electron emerges into vacuum with no net velocity relative to the ion it follows. After exit, the wake electron and ion interact via Coulomb attraction which introduces diffraction structure in the projectile-frame electron velocity distribution. Modeling of the detection process is done in order to compare with experimental results.

The angular distributions of ${\mathrm{Ni}}^{+}$ and ${\mathrm{Ni}}_2^{+}$ ejected from Ni(001) by bombardment with 2-keV ${\mathrm{Ar}}^{+}$ have been shown to exhibit large azimuthal anisotropies. The experimental results have been well reproduced by classical dynamical calculations of the ion impact event. For the dimers, the peak in the distribution arises from a unique ejection mechanism such that the atoms in the dimer are known to form from specific surface locations relative to the ion impact position.

An exactly solvable continuous-spin model with general exchange interactions is constructed and studied for cases of simple crystalline symmetry. For lattice dimensionality $D=2\mathrm{}$ the transition temperature $T_c$ goes to zero at the Lifshitz point. A particular case with $D=3\mathrm{}$ exhibits a phase transition with no long-range order.

Consideration of a new class of interactions is proposed. These contain certain velocity-dependent terms which lead to confined systems by not permitting scattering. The relativistic two-body system is discussed as an example. Applications to quark-quark interactions are conceivable.

Pion attenuation following nucleon decay within a nucleus is examined. It is found that predictions of pion survival may be made by use of established phenomenology. The reduction in pion flux is a factor of 2 for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ or ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. This implies that the number of observable ${\mu }^{+}\text{'}\mathrm{s}$ for a water source would be 0.55 times that from a free-nucleon mixture. For the ${\pi }^0-e^{+}$ mode the probability of survival as a correlated pair is 0.33.

A new search for three-photon decays of the neutral pion has been made. No signal in excess of background was observed. The upper limit for the ${\pi }^0\to 3\gamma$ branching ratio is 3.8×${10}^{-7\mathrm{}}$ (90% confidence level).

In grand unified models, the abundance of superheavy magnetic monopoles in the universe can be suppressed if (1) the phase transition which creates the monopoles occurs after much supercooling; and (2) immediately after the phase transition, the effective monopole mass is large compared with the temperature. These requirements impose constraints on the history of the early universe. The Georgi-Glashow SU(5) group probably breaks to SU(4) ⊗ U(1) before it reaches SU(3) ⊗ SU(2) ⊗ U(1).

A total of ∼ 249 000 neutrino interactions were observed at Fermilab in a high-angular-resolution electromagnetic shower detector, with ∼ 0.947× ${10}^{19}$ protons of 350-GeV energy incident upon the production target. Based on a data sample of 0.71×${10}^{19}$ protons, 46 electrons were observed with ${\theta }_e<~10$ mrad. Of these 46 events, 34 are attributed to the process ${\nu }_{\mu }+e^{-}\to {\nu }_{\mu }+e^{-}$, and 12 are attributed to background processes. This leads to the following results: $\sigma =(1.40\mathrm{}\pm 0.30)\times {10}^{-42\mathrm{}}{E}_{\nu }$ ${\mathrm{cm}}^2$ and ${{sin}^2\theta }_{\mathrm{W}}={0.25}_{-0.05\mathrm{}}^{+0.07\mathrm{}}$.

The photoelectrons produced by ionization of argon and xenon atoms with linearly polarized vacuum-ultraviolet radiation of the helium resonance wavelength 58.43 nm have been analyzed simultaneously as to their energy, angle of emission, and spin. Degrees of spin polarization up to 0.5 have been found. The results verify the theoretically predicted angular dependence of the photoelectron polarization. The asymmetry parameter $\beta$ describing the angular distribution of the cross section is determined via electron intensity and polarization measurements.

If the excited-state energy spectrum of a free atom is such that the energy needed for excitation to a localized orbital is higher than one to a delocalized orbital, the ligand field of the coordination atoms in a molecule may reverse their energy order and violate the $Z+1\mathrm{}$ analogy. The comparison of a self-consistent calculation with the experimental $K$-edge absorption spectra of ionic potassium in molecular complexes shows that the energy order of $3d$ and $4s$ orbitals of potassium is reversed, contrary to the $Z+1\mathrm{}$ analogy.

Results are reported of electron-cyclotron-heating experiments in which 80 kW of microwave power from a 35-GHz gyrotron is injected into a tokamak with large single-pass absorption. For 10-ms microwave pulses, incident from the high-field side of the torus, the central electron temperature increases from 850 to 1250 eV, in agreement with empirical transport-code calculations. For the first time it is demonstrated that electron temperature in a tokamak scales linearly with electron-cyclotron-heating power.