Fluctuations in the superconducting order parameter above the transition temperature result in structure in the tunneling density of states. From the shape of this structure a value is derived for the decay rate of the fluctuations.

While concentrated Cu-Ni alloys show local correlations characteristic of clustering, it is re-emphasized, in light of the recent claim of Kidron, that normal solution heat treatment of them (which includes nearly any cooling procedure) yields a small deviation from randomness of the atomic arrangements and no Guinier-zone formation or phase separation.

We consider the magnetic properties and spin correlation functions of a two-dimensional Ising model with random impurities near the critical temperature and find that the usual parametrization provided by the exponents $\gamma$, $\delta$, and $\eta$ and the correlation length $\xi$ for $T\gtrsim T_c$ does not describe our results. Experimental implications of this breakdown of the critical exponent forms are discussed.

The differential photoneutron cross section for ${\mathrm{Mg}}^{26}$ at 135° has been measured as a function of photon energy from 10 keV to 1.5 MeV above threshold by the threshold photoneutron technique. Several prominent resonances have observed, including one located at 54.3 keV above threshold. The existence of this resonance in the ${\mathrm{Mg}}^{26}$ compound system might provide, through the reaction ${\mathrm{Ne}}^{22}(\alpha , n){\mathrm{Mg}}^{25}$, the primary production mechanism for neutrons in stars.

A new state of "ferro" magnetism in a degenerate electron gas is found and shown to be stable. This magnetism is the sum of all microscopic magnetic moments associated with electrons in their respective Landau levels while the Landau levels of the system are in turn maintained by this macroscopic magnetization. The maximum field in the Landau orbital ferromagnetism state is ${10}^7$ G for white-dwarf densities and ${10}^{12}$ G for neutron-star densities.

We have determined with 90% confidence an upper limit of 1.90×${10}^{-4\mathrm{}}$ for the branching ratio of the decay mode $K^{+}\to {\pi }^{+}+{\pi }^0+\gamma$ in the range of $T_{{\pi }^{+}}$ from 55 to 80 MeV. We discuss the implications of this result for a possible $\mathrm{CP}$ nonconservation in radiative $K_{\pi 2}$ decay.

A $\Lambda p$ system with high statistics and mass resolution was studied in detail. The broad bump in the low-mass region can be attributed to contribution from both the impulse and final-state-interaction mechanisms. The low-energy $\Lambda p$ scattering parameters are deduced to be $a_0=-2.0\mathrm{}\pm 0.5$ and ${\mathcal{r}}_0=3.0\mathrm{}\pm 1.0$ F. The higher mass spectrum can be fitted to two Breit-Wigner resonant structures with $M_1=2128.7\mathrm{}\pm 0.2$, ${\Gamma }_1=7.0\mathrm{}\pm 0.6$, and $M_2=2138.8\mathrm{}\pm 0.7$, ${\Gamma }_2=9.1\mathrm{}\pm 2.4$ MeV. Attempts were carried out to understand these peaks via a $\Sigma N$ final-state-interaction model.

The effects of a nearby tunneling level are observed in the ESR of the lowest optically excited ${\Gamma }_8$ level of ${\mathrm{Eu}}^{2+}$ in Ca${\mathrm{F}}_2$. These results are substantiated by the previous observation of this level by other workers using piezospectroscopic techniques. The ESR evidence for such a level can be found in other systems and may allow its approximate position and symmetry to be determined in these cases.

The quantum-phase-noise-limited Lorentzian power spectral densities of ${\mathrm{Pb}}_{0.88}$${\mathrm{Sn}}_{0.12}$Te diode lasers were directly measured. Linewidths as narrow as 54 kHz were observed and quantitatively analyzed. The predicted inverse dependence of linewidth on laser power was also demonstrated. These results were obtained from the beat-note spectra produced by heterodyning the diode laser, operating cw at 10.6 μm, with a stable, single-frequency C${\mathrm{O}}_2$ gas laser.

In an efficient ion heating mode recently discovered in the Burnout-V turbulent-heating experiment, the line profiles of emission spectra exhibit three noteworthy features: (1) a marked Doppler broadening (full width at half-maximum ≈10 Å) of the Balmer lines, (2) a "red"/"blue" asymmetry dependent on the geometry of the plasma container, and (3) non-Gaussian line shapes near the central wavelengths.

The osmotic pressure of ${\mathrm{He}}^3$-${\mathrm{He}}^4$ mixtures has been measured down to 0.027°K. The results are used (a) to check the validity of the ${\mathrm{He}}^3$-${\mathrm{He}}^3$ effective interaction deduced from transport data using recent exact solutions of the Boltzmann transport equation, (b) to obtain the limiting solubility of ${\mathrm{He}}^3$ in ${\mathrm{He}}^4$ as a function of pressure, and (c) to demonstrate the metastability of supersaturated mixtures of ${\mathrm{He}}^3$ in ${\mathrm{He}}^4$ in the absence of a free surface.

The ordering of one- and two-dimensional systems with a continuous symmetry is considered in the absence of a symmetry-breaking field. It is shown rigorously that no spontaneous ordering can occur; bounds on the order-order correlation function integrated over a subdomain indicate how the short-range order decays with distance.

The resistivity of liquid copper as a function of particle density in the range (1.2-3.3) × ${10}^{22}$ ${\mathrm{cm}}^{-3\mathrm{}}$, as obtained in an exploding-wire experiment, is explained by Ziman's theory of resistivity using a structure factor based on the hard-sphere model.

The increase in flow stress which occurs at the transition from the superconducting to the normal state has been measured as a function of work hardening, strain rate, and temperature in specimens of pure lead and indium. The results show that this flowstress increase is strain-rate independent and proportional to $1-{\left(\frac{T}{T_c}\right)}^2$ to an accuracy of ± 5%. The lack of strain-rate dependence is inconsistent with the simple model which relates the flow stress to the viscous drag force required to move a dislocation through an electron gas.

A zero resistance has been observed in three single crystals of gallium at liquid-helium temperatures for the case of magnetic field parallel to current parallel to $a$ axis, for fields greater than 2 kG. The onset of zero resistance is insensitive to impurity content as measured by the value of the residual resistance ratio, and to temperature in the range 2 to 4.2°K. The most probable explanation of our results is in terms of magnetic breakdown. Calculation of energy gaps from our data range from 1.4×${10}^{-2\mathrm{}}$ eV to 4.7×${10}^{-3\mathrm{}}$ eV, dependent on the effective mass used.

It is shown that the potential barrier ${\varphi }_{max}$ in a thin-film metal-insulator-metal system increases rapidly with increasing insulator thickness when electrons are immobilized in deep traps in the insulator, and at low voltage biases $\frac{d{\varphi }_{max}}{\mathrm{dV}}$ is independent of the insulator parameters. This effect may be an explanation of the observations of Lewicki and Mead.

A new method, the GI method, for electronic wave functions has been applied to the study of energy bands in bcc lithium metal. The GI method leads to energy bands for lithium comparable with the Hartree-Fock bands except that small gaps occur within the first Hartree-Fock Brillouin zone. This leads to a compelling interpretation of several anomalous experimental properties of alkali metals (such as the very low optical absorption threshold and the lack of saturation of the transverse magnetoresistance).

The thermoluminescence characteristic of single crystals of zinc sulfide was studied before and after room-temperature irradiation with monoenergetic electrons. A new trapping state with a threshold energy at 175-195 keV was observed and, in the same specimens, the production of a trapping state with a threshold energy of 235-245 keV was confirmed.

We report 5.5°K cooling at 20°K in the ferrimagnet ytterbium iron garnet accompanying an increase of magnetic field. The cooling abruptly ceases at the phase boundary between a collinear and canted sublattice configuration. A cooling of 10°K at 18°K and 3.7 °K at 6°K was observed in dilute ytterbium iron garnet.

Magnetic-susceptibility measurements on cerium magnesium nitrate covering frequencies from dc to 200 Hz indicate that it undergoes an antiferromagnetic phase transition in the millikelvin range.