Intense spectator-proton peaks were observed in the reaction $\mathrm{D}({}_{}{}^3{}_{}{}^{}\mathrm{He},tp)p$. Their shapes were well fitted by plane-wave Born-approximation calculations, assuming either knockout or ${}_{}{}^3{}_{}{}^{}\mathrm{He}-n$ quasielastic scattering accompanied by charge exchange to be the mechanism. Their intensities relative to the quasielastic peaks from $\mathrm{D}({}_{}{}^3{}_{}{}^{}\mathrm{He},{}_{}{}^3{}_{}{}^{}\mathrm{He}p)n$ were correctly predicted by charge-exchange calculations, but only when an unrealistic mixture of exchange forces was used. All direct knockout calculations gave relative intensities at least ten times too small.

We have measured the reaction $\gamma +n\to {\pi }^0+n$ at a photon energy of 4 GeV for $0.2<~-t<~1.8{\left(\frac{\mathrm{GeV}}{c}\right)}^2$. The cross section is slightly less than that with protons as a target.

In an attempt to make second-order weak interactions finite, we have modified the usual current-times-current theory by the introduction of nonpolynomial functions $\exp \left[f{\varphi }^{†}\varphi \right]$ of a scalar field $\varphi$. Choosing the various minor coupling constants $f$ to be complex leads naturally to the appearance of $\mathrm{CP}$-invariance violation in $O\left(G^2\right)$. We use the model to study the $K^0-{\overline{K}}^0$ system and find ${\eta }_{+-}\cong {\eta }_{00}$, which is consistent with recent preliminary experimental results.

The effect of metastable-metastable ionizing collisions has been neglected in previous measurements of the electronic recombination coefficient of molecular helium ions. In this study, a source of free electrons was taken into account and the recombination coefficient was observed to be much larger than previously reported. Over the pressure range from 15 to 50 Torr, we have measured this coefficient to range from (1.8 to 4.3) ×${10}^{-8\mathrm{}}$ ${\mathrm{cm}}^3$ ${\sec }^{-1\mathrm{}}$.

Within the framework of many-body perturbation theory, a calculation has been carried out for the process of double electron ejection in photoabsorption, $\gamma +\mathrm{Ne}\left(1\mathrm{}{s}^{2}2s^{2}2p^6\right)\to {\mathrm{Ne}}^{++}\left(1\mathrm{}{s}^{2}2s^{2}2p^4\right)+e+e$. Excellent agreement with experiment has been obtained. The importance of electron-electron correlation and the dominant physical processes involved are discussed.

We have measured the angular dependence and total intensity of light scattered by carbon dioxide near its critical point, shown that the Ornstein-Zernike theory is inadequate, and determined the temperature dependence of the isothermal compressibility $K_T$ and the long-range correlation length $\xi$. The exponents describing the divergences of $K_T$ and $\xi$ above the critical temperature are $\gamma =1.219\mathrm{}\pm 0.01$ and $\nu =0.633\mathrm{}\pm 0.01$, respectively. The exponent describing the departure from the Ornstein-Zernike theory is $\eta =0.074\mathrm{}\pm 0.035$.

Time correlations between neutron and x-ray emissions from a plasma-focus discharge are strongly dependent on photon energy. The time history of neutron emission coincides with that of nonthermal x-ray emission above 30 keV, in a manner consistent with an acceleration model for neutron production. Plasma x radiation below 5 keV corresponds to $T_e=0.4\mathrm{}$ keV and does not correlate with neutron emission.

We have shown experimentally that both the ac and dc properties of small Dayem bridges are fully determined at all temperatures by their normal-state Ohmic resistances. The behavior can be described by a two-fluid model where the normal component is governed by the normal-state resistance and the superfluid component determined by the two Josephson equations. The normal-state resistance also determines the maximum super-current.

We observed a temperature-dependent lowering of the paramagnetism of Gd ions in ${\mathrm{La}}_{3-x}{\mathrm{Gd}}_x$ In ($x=0.064\mathrm{}$) above the critical temperature. We attribute this effect to the influence of thermodynamic fluctuations of the superconducting order parameter on the Pauli spin susceptibility affecting in this way the indirect coupling of Gd spins. The result is in qualitative agreement with recent calculations by Fulde and Straessler.

Ultrasonic attenuation measurements are reported for clean niobium in the region from $H_{c2\mathrm{}}-H=100\mathrm{}$ G to $H_{c2\mathrm{}}-H=0\mathrm{}$. The results agree qualitatively with the theory of Maki and Houghton which develops regimes of attenuation which are "gapless" near the transition and BCS-like farther away.

Standard perturbation theory applied to the low-energy electron-diffraction problem does not appear to give accurate results even when carried to second order. A new scheme, renormalized forward-scattering perturbation theory, retains the advantage of being fast to execute, but at the same time is very accurate. The new theory is subjected to the stringent test of comparison with exact results for a realistic model of the copper (100) surface.

We report electron microscopy experiments showing that the spatial distribution of damage produced in metals by implanted ions is generally quite different from that of the ions themselves. We discuss how this affects hyperfine-interaction measurements.

The crystal-field theory for a rare-earth ion in tetragonal symmetry is studied in a semiclassical description. The low-lying quantum states are interpreted as tunneling states between classical minima. At low temperatures, spontaneous lattice distortions occur to lower some of the minima relative to others. The model is applied to DyV${\mathrm{O}}_4$ and TbV${\mathrm{O}}_4$ and is shown to lead to a good understanding of why they show phase changes and unusual paramagnetic properties.

$M1\mathrm{}$, $\Delta T=0\mathrm{}$ radiative widths ${\Gamma }_{\gamma }$ in the $2d-1s$ shell are compared with the widths computed with the Gamow-Teller $\beta$-decay $\mathrm{ft}$ values, ${\Gamma }_{\beta }$. For twelve of nineteen cases, ${\Gamma }_{\gamma }=(2\mathrm{}\pm 1){\Gamma }_{\beta }$.

Angular distributions of (${}_{}{}^3{}_{}{}^{}\mathrm{He},p$) reactions are investigated for some odd-even target nuclei, which allow orbital-angular-momentum transfers $L_{\mathrm{np}}=0,2$ for $T_{\mathrm{np}}=0,1$ transitions. "Pure" $L_{\mathrm{np}}=0\mathrm{}$ distributions are observed for the $n-p$ pair transfer with $T_{\mathrm{np}}=1\mathrm{}$ leading to the analog state and to the corresponding state with the same nucleon configuration but with $T=T_{<}$. "Mixed" $L_{\mathrm{np}}=0+2\mathrm{}$ distributions are observed for $T_{\mathrm{np}}=0\mathrm{}$ transfers.

The regular behavior of multinucleon transfer cross sections in reactions between heavy ions as a function of the $Q$ values $Q_{\mathrm{gg}}$ for the ground-state transitions is explained in the molecular-wave-function method. The coupled equations of the scattering problem are solved analytically.

The cross section for ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}\mathrm{}(p,2p)\mathrm{}$ ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$ has been measured to be 19 ± 6 and 25 ± 8 mb at 150 and 600 MeV, respectively. These values show that the tertiary production of ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$ in cosmic rays is very important. However, it still appears likely that an actual isotope abundance measurement in cosmic rays will be necessary to utilize this nuclide as a cosmic-ray "clock."

We have measured muonic x rays in the energy region 150 to 440 keV in nine elements with an absolute precision of 15 to 21 eV for transitions with small nuclear effects. Calculated transition energies were found to be consistently larger than those measured by an amount that varied from 15 ± 16 eV at 157 keV to 137 ± 22 eV at 438 keV. For these transitions, the principal correction to the Dirac energy is the vacuum polarization. The discrepancy, however, lies outside the expected validity of quantum-electrodynamic calculations and we are unable, at present, to offer an explanation for this effect.

The angular distribution for the reaction $n+p\to d+\gamma$ has been measured at neutron energies of 475, 560, 625, and 750 MeV. Results based on 31 000 events at nine scattering angles are reported and compared with existing data for the inverse reaction, $\gamma +d\to n+p$. The angular distributions are found to agree, as predicted by time-reversal invariance.

New results are presented for the reactions ${\pi }^{-}p\to m^{0}n$ at 3.65 $\frac{\mathrm{GeV}}{c}$, where $m^0$ represents $\eta$ or ${\eta }^{\prime }$ decaying to $\gamma \gamma$. We have seen 31 ${\eta }^{\prime }$ events over a small background, leading to a branching ratio $\frac{({\eta }^{\prime }\to \gamma \gamma )}{({\eta }^{\prime }\to \mathrm{all})}={0.020}_{-0.006\mathrm{}}^{+0.008\mathrm{}}$. Over 2000 $\eta$ events were observed, and the differential cross section exhibits a dip at —$t=1.5\mathrm{}{\left(\frac{\mathrm{GeV}}{c}\right)}^2$.