The Helsinki temperature scale, used earlier in measurements of the heat capacity of liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ (1-10 mK), is compared with the National Bureau of Standards (NBS) noise and nuclear-orientation temperature scale. The superfluid transition temperature ($T_c$) of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ at zero pressure and the superconductive transition temperatures of tungsten and beryllium were used as fixed points. $T_c$ on the NBS scale was found to be 1.025 ± 0.02 mK, in close agreement with the Helsinki value 1.04 mK. The results support the Helsinki data on the heat capacity of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$.

A theory is formulated that explains the observed bond-length change in graphite intercalation compounds in terms of the charge transfer $f$. The values of $f$ obtained via the bond-length changes are in good agreement with those derived with other methods. The present analysis also provides information on the electron-phonon coupling that defines the maximum conductivity.

Detailed far-infrared measurements at temperatures from 25 to 300 K provide strong support for a charge-density-wave mechanism for the dc conductivity and microwave dielectric constant of tetrathiafulvalene tetracyanoquinodimethane (TTF-TCNQ). At low temperatures the charge-density wave is pinned at 40 ${\mathrm{cm}}^{-1\mathrm{}}$ while at higher temperatures it appears at zero frequency. Values are obtained for the effective mass ($20m^{*}$) and lifetime (1.6×${10}^{-12\mathrm{}}$ sec at 60 K) of the charge-density wave.

The Dean-Henry-Kukimoto model of GaP: O calls for very large lattice relaxation in the transition ${\mathrm{O}}^0$→${\mathrm{O}}^{-}$. We show that spectroscopic data from the transition ${\mathrm{O}}^{+}$→${\mathrm{O}}^0$, augmented with ideas developed by our Green's-function and total-energy calculations, predict a new ${\mathrm{O}}^{-}$ state with very little lattice relaxation and exceedingly weak Ga-O bonds. For this to be compatible with the Dean-Henry-Kukimoto model, the state must be metastable. We cite evidence which supports its existence.

In this work, by using many-body techniques we propose a new method for calculating equilibrium charges for ions moving in a uniform electron gas, within any range of velocities. Our procedure has been applied to protons, and our calculations show good agreement with the experimental evidence.

Bremsstrahlung isochromat spectroscopy has been employed to measure the density of unoccupied electronic states on GaAs(110). The experiment was carried out at a quantum energy of 70 eV, resulting in a maximum of surface sensitivity. The theoretically predicted empty surface states ${B_1}^{\prime }$, ${S_1}^{\prime }$, ${B_2}^{\prime }$ and ${S_2}^{\prime }$, are identified. Their energetic positions as well as relative strengths are in excellent agreement with calculations based on the bond-relaxation model. A binding energy of 1.0 eV for the Ga $3d$ surface exciton is obtained.

Inelastic neutron scattering from the crystal electric field transitions in ${\mathrm{La}}_{1-x}{\mathrm{Tb}}_x{\mathrm{Al}}_2$ single crystals has revealed an abrupt increase in the lifetimes of these transitions when the system becomes superconducting. An increase in the integrated intensities is also observed. The lifetime effects are quantitatively reproduced by existing theories, which take into account the reduced scattering of the conduction electrons by the magnetic ions due to the creation of the superconducting energy gap $2\Delta \mathrm{}\left(T\right)\mathrm{}$.

We report on a new phenomenon in solid-state photoemission, the emission of spin-polarized electrons from nonmagnetic crystals by unpolarized light. It becomes observable in fully energy-, angle-, and electron-spin-resolved measurements, the first of which is presented here. It is explained in terms of "final-state spin-polarization effects," a new theoretical approach which is outlined. Fairly good agreement between experimental and theoretical results is found. These polarization effects also suggest a new way for analyzing photoelectron spin polarization.

Ultraviolet observations are presented that for the first time provide a better lower limit on the lifetimes of 16-20-eV/${\mathit{c}}^2$ neutrinos than do laboratory muon-decay experiments.

A lattice model for equilibrium polymerization which allows for loop polymers is presented with critical behavior described by $n=1\mathrm{}$, rather than $n\to 0$ predicted by the theory of Wheeler, Kennedy, and Pfeuty. The specific heat of sulfur above and below $T_c$ is consistent with Ising critical behavior.

We have measured the linear polarization correlation of the photons emitted in a radiative atomic cascade of calcium. A high-efficiency source provided an improved statistical accuracy and an ability to perform new tests. Our results, in excellent agreement with the quantum mechanical predictions, strongly violate the generalized Bell's inequalities, and rule out the whole class of realistic local theories. No significant change in results was observed with source-polarizer separations of up to 6.5 m.

A general theory of the interaction of superfluid helium with a gravitational field is developed within the framework of general relativity by using a covariant generalization of the Gross-Pitaevskii equation. The general relativistic Sagnac effect for the superfluid Josephson interferometer is obtained in the stationary case. The influence of a plane-polarized gravitational wave on a recently proposed superfluid gravitational antenna as well as a new antenna is determined.

We present evidence that the observed scaling violations in deep-inelastic scattering are likely to be low-$Q^2$ phenomenon, as predicted by the massive-quark model.

The angular dependence of the deuteron tensor polarization $t_{20}$ in $\pi -d$ elastic scattering has been measured for the first time. The results, at an incident pion energy of 142 MeV, are found to be in disagreement with all present theoretical predictions.

A parity nonconservation asymmetry was observed in the reaction ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$($\overrightarrow{p},{\alpha }_0$${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. Longitudinally polarized protons with an energy of 670 keV hit a S${\mathrm{F}}_6$ gas target. The resonant proton capture leads to the 13.482-MeV, $1^{+}$, $T=1\mathrm{}$ state in ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$. The analyzing power for this reaction was determined for six proton energies around 670 keV. The maximum of the analyzing power $A_{max}=(6.6\mathrm{}\pm 2.4)\times {10}^{-3\mathrm{}}$ was deduced from a bestfit interference curve to these points.

Energy spectra from ${\pi }^{+}$ inelastic scattering on ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ have been measured at $T_{\pi }=100, 160, \mathrm{and} 220$ MeV. These spectra have prominent features which are qualitatively consistent with quasifree scattering from nucleons. For ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ at low energies, true absorption becomes the dominant fraction of the reaction cross section, and inelastic scattering is strongly inhibited. This is in marked contrast to the behavior of the partial reaction cross sections for the other nuclei.

Beta-delayed two-neutron emission has been observed for the first time in a fission-product nuclide, ${}_{}{}^{98}{}_{}{}^{}\mathrm{Rb}$. The two-neutron emission probability is (0.060±0.009)%.

Polarization measurements have been performed on radiation emitted by ${\mathrm{He}}^{+}$ ions (468.6 nm) in transmission (beam foil) and reflection (grazing incidence) geometries, with use of both carbon foil and silicon single-crystal targets. Comparison of the results of the two geometries and the two different targets indicates that the excited-state formation occurs at the exit surface. The impact of these results on current theories is discussed.

The band oscillator strength of OH was found to be essentially independent of rotational excitation for the (1,0) transitions, but to decrease with rotation for the (0, 0) transitions. This difference in the rotational dependence is a result of competition between a rotationally induced decrease in the electronic transition moment and rotationally induced changes, which may be either an increase or decrease, in the Franck-Condon factor for these bands.

Experimental measurements of electron impact ionization cross sections for the transition-series ions ${\mathrm{Ti}}^{+3\mathrm{}}$, ${\mathrm{Zr}}^{+3\mathrm{}}$, and ${\mathrm{Hf}}^{+3\mathrm{}}$ demonstrate that excitation-autoionization increases the cross sections by more than an order of magnitude over that anticipated for direct ionization. Theoretical predictions of both the energies and approximate magnitudes of these excitation cross sections provide confidence that this important indirect contribution to the total ionization can be estimated for many cases.