We observe electron spin polarization in photoemission from nickel, undetected in earlier experimental investigations. The saturation electron spin polarization for films prepared on hot substrates is higher than for films on cold substrates and the preferential direction of the magnetic moment is parallel to the magnetization even for electrons excited from energy states near the Fermi level.

The dependence and magnitude of noise currents in superconducting point contacts on dc current and voltage has been measured. The results are in good agreement with the theoretical predictions of Scalapino and Stephen. As expected, in the shot-noise limit at sufficiently high junction voltage the noise current does not vary with temperature.

A new continuous solvent-extraction technique has been developed for fast chemical isolation and identification of short-lived radioisotopes. It was applied to a search for ${}_{}{}^{116}{}_{}{}^{}\mathrm{Pd}$ as a product of 14-MeV neutron-induced fission of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. The ${}_{}{}^{116}{}_{}{}^{}\mathrm{Pd}$ was identified through its daughter ${}_{}{}^{116}{}_{}{}^{}\mathrm{Ag}$, and found to have a half-life of 13.6 ± 1.2 sec. At the same time the half-lives of ${}_{}{}^{113}{}_{}{}^{}\mathrm{Pd}$ and ${}_{}{}^{115}{}_{}{}^{}\mathrm{Pd}$ were confirmed to be 91 ± 12 sec, and 30 ± 2 sec, respectively.

The ($\alpha$, $2\alpha$) reaction on ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ has been studied at an incident energy of 42.8 MeV. At this energy, a sharp resonance in the free $\alpha -\alpha$ scattering cross section is used to test the validity of the impulse approximation. The experimental results are analyzed with this model.

With no free parameters the particle-vibration model is used to describe the ${\mathrm{½}}^{+}$ doorway resonance observed in ${\mathrm{Pb}}^{209}$ at 500 KeV with a width of 58 KeV. We find that the ($2g_{\frac{9}{2}}$, $4^{+}$) state which occurs at nearly the experimental energy has a width of about 1 to 2 times the measured value.

34 excited states have been studied between 2.3 and 3.5 MeV in ${}_{}{}^{167}{}_{}{}^{}\mathrm{Er}$, ${}_{}{}^{179}{}_{}{}^{}\mathrm{Hf}$, ${}_{}{}^{191}{}_{}{}^{}\mathrm{Ir}$, and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ by observing the decay of the isomeric levels in these nuclei following electron and photon activation. 28 of these states are observed for the first time. Of the 34 observed transitions, $M1+E2\mathrm{}$ multipolarity assignment is made to 20, two are identified as $E0\mathrm{}$ transitions, and one is assigned $E1\mathrm{}$ multipolarity. Accurate values for the isomeric half-lives are also presented.

The flux of celestial gamma rays from discrete sources (for example, pulsars) is calculated, showing that these sources emit fluxes of several ${10}^{-6\mathrm{}}$ quanta/${\mathrm{cm}}^2$ sec over regions of several tens of degrees (among them Vela X). Hence they should be observable. The calculations show further that the high gamma-ray flux values of OSO-III follow from the expected correlation of cosmic-ray sources with regions of large hydrogen density.

A two-step nonlinear optical interaction consisting of the spontaneous parametric downconversion and upconversion processes with simultaneous phase matching has been observed in ammonium dihydrogen phosphate. The spontaneous emission associated with upconversion in nonlinear optics is measured for the first time and found to be in reasonable agreement with theoretical estimates.

Photoabsorption cross sections in hydrogen and deuterium have been measured from 3.7 to 17.9 GeV. The energy dependences are similar to those of strong-interaction total cross sections, as expected from the vector-meson-dominance model. The magnitude of ${\sigma }_T\left(\gamma p\right)$ can be compared with data from $\gamma p\to {\rho }^{0}p$ to determine a $\gamma -p$ coupling constant, $\frac{{{\gamma }_{\rho }}^2}{4\pi }=0.37\mathrm{}\pm 0.03$. This value disagrees with that obtained on the $\rho$ mass shell, and hence there is only qualitative agreement with the vector-meson-dominance model.

Photon-neutron total cross sections have been evaluated from the data for the proton and deuteron presented in the preceding paper. Simple Regge-pole fits have been made to ${\sigma }_T\left(\gamma p\right)$ and ${\sigma }_T\left(\gamma n\right)$, both of which extrapolate to 94 ± 4 μb at infinite energy. Over the range of our data, 3.7 to 17.9 GeV, ${\sigma }_T\left(\gamma n\right)<\mathrm{}{\sigma }_T\left(\gamma p\right)$, which can be interpreted to give a ratio of exchange contributions, $\frac{A_2}{P^{\prime }}=0.19\mathrm{}\pm 0.04$. A fit to ${\sigma }_T\left(\gamma p\right)$ is also important for predictions of the proton cosmic-ray spectrum.

Evidence is presented for zeros in the $\pi$-exchange contribution to ${\rho }^0{\Delta }^{++}$ and in the $\rho$-exchange contribution to ${\omega }^0{\Delta }^{++}$ production. The position of the $\pi$-exchange zero is consistent with a $\pi$ trajectory with ${{\alpha }_{\pi }}^{\prime }\mathrm{}\left(0\right)\mathrm{}\approx 1.2 {\left(\frac{\mathrm{GeV}}{c}\right)}^{-2\mathrm{}}$. Evidence is also presented suggesting that the $A_2$ chooses the Gell-Mann mechanism (nonsense choosing). A model of $\pi$ exchange with exact $\pi -B$ exchange degeneracy is found to describe the data quantitatively.

The forward differential cross section of $\rho \Delta$ production is shown to be reproduced quantitatively by an evasive Reggeized one-pion-exchange model which smoothly reduces to the Born term at the pion pole. Assuming exact $\pi -B$ exchange degeneracy leads to predictions for $\omega \Delta$ production which are in agreement with the experimental $s$ and $t$ dependences. Similar agreement is found for $K^{*}\Delta$ production.

A field-theoretic model is written to describe the structure function $W_2$ of deep-inelastic $e-p$ scattering. Strict Bjorken scaling is found not to hold; nevertheless, the model provides a modest fit to the experimental data. A variant of the Drell-Yan-West relation between the elastic limit of $W_2$ and the asymptotic falloff of the electromagnetic form factors is obtained.

The ratio of muon to proton magnetic moment $\frac{{\mu }_{\mu }}{{\mu }_p}$ has been measured to high precision in three chemical environments. The agreement shows that the "Ruderman correction" is not applicable. The result is $\frac{{\mu }_{\mu }}{{\mu }_p}=3.183\mathrm{}347\left(9\right)\mathrm{} \left(2.8\mathrm{} \mathrm{ppm}\right)$; in terms of the muon mass, this implies $\frac{m_{\mu }}{m_e}=206.7683\mathrm{}\left(6\right)\mathrm{}$.

The probabilities and differential cross sections for charge transfer to the $2p$ state of hydrogen in 4- to 20- keV proton-helium collisions have been measured for specific impact parameters by detecting in delayed coincidence the scattered neutral hydrogen atom and the resulting $2p-1s$ Lyman-$\alpha$ photon. These $2p$ probabilities are compared with the total charge transfer and $2s$ state probabilities, and with the coupled atomic state calculations of Sin Fai Lam.

Stimulated emission has been observed in the $P$ -branch lines of the 3-10, 4-11, 5-12, 6-13, and 7-13 Lyman bands ($v^{\prime }-v^{\prime \prime }$, $B{}_{}{}^1{}_{}{}^{}{\Sigma }_{\mathrm{u}}_{}^{+}{}_{}{}^{}\to X{}_{}{}^1{}_{}{}^{}{\Sigma }_g_{}^{+}{}_{}{}^{}$) of molecular hydrogen near 1600 Å. Light pulses of approximately 2 nsec duration and 1.5 kW maximum power were produced using a Blumlein parallel-plate transmission line discharging through hydrogen gas at pressures between 20 and 150 Torr.

We present experimental evidence for the presence of current-driven ion-wave turbulence within a collisionless shock. The frequency and wave-number spectra of this turbulence have been measured by scattering light from the shock front. These measurements are compared with the assumptions and predictions of nonlinear theory.

The molecular-field description of the isotropic-nematic phase transition in liquid crystals is investigated. It is found that the effects of fluctuations may be observable, and the first corrections due to fluctuations to the light scattering and magnetic birefringence in the isotropic phase are determined. The effects of applied fields on the phase transition are investigated. It is found that if the molecules prefer to line up transverse to an applied field there is a critical field above which the phase transition is second order.

We have observed a divergence of the magnetic birefringence, and a critical increase and slowing of the fluctuations in order in the isotropic phase of a nematic liquid crystal. Our results are quantitatively described by a mean-field model except for a critical region close to the ordering temperature where the fluctuations are so large that the meanfield approximation fails.

Eilenberger's transportlike equations for a superconductor of type II can be simplified very much in the dirty limit. In this limit a diffusionlike equation is derived which is the generalization of the de Gennes-Maki theory for dirty superconductors to arbitrary values of the order parameter.