We have measured the two-body photodisintegration process $\gamma {}_{}{}^3{}_{}{}^{}\mathrm{He}\to \mathrm{pd}$ in the energy region sensitive to intermediate photoexcitation of one nucleon to the isobar $\Delta \mathrm{}\left(1238\right)\mathrm{}$. We present angular distributions at center-of-mass angles from 30° to 150° for incoming photon energies 200-600 MeV. Magnetic dipole excitation appears to be suppressed.

We report on the measurement of the formation of ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{++}{}_{}{}^{}$ in the collision of protons and deuterons, with the emission of a single photon. Energies and angles as chosen allow a comparison with the inverse process $\gamma {}_{}{}^3{}_{}{}^{}\mathrm{He}\to \mathrm{pd}$. These data restrict possible $T$-invariance-violation effects in the electromagnetic interaction.

We present results from a measurement of the differential cross sections for ${\Sigma }^{-}p$, ${\Xi }^{-}p$, and ${\pi }^{-}p$ elastic scattering at 23 GeV/c. We have collected samples of 6200 ${\Sigma }^{-}p$ events, 67 ${\Xi }^{-}p$ events, and 30 000 ${\pi }^{-}p$ events in the interval $0.10<\mathrm{}\left|t\right|<0.23\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$.

A search has been made in neutron-beryllium interactions for neutral narrow enhancements produced at Feynman $x>~0.2$. Upper limits are presented for production cross-sections times branching ratio into the two-body channels ${\pi }^{+}{\pi }^{-}$, ${\pi }^{+}{K}^{-}$, and $p\overline{p}$ for masses in the interval $2 \mathrm{GeV}\lesssim m\lesssim 4 \mathrm{GeV}$. Comparisons are made with $\psi$ production observed in the same experiment.

It has been demonstrated that multiple Coulomb excitation is an effective method for studying levels in the backbending region. Members of the ground band above the backbend in ${}_{}{}^{164}{}_{}{}^{}\mathrm{Er}$ have been excited. The ground-band $B\left(E2\mathrm{}\right)\mathrm{}$ values obey the rigid-rotor relation within ± 25%. A two-band mixing analysis shows that the intersecting bands have remarkably small interaction matrix elements at the backbend, i.e., < 40 keV. This weak band interaction is expected in the rotation-alignment model.

Basic properties for the emission of radiation are derived from the diagonalization of the matrix (${\Gamma }_{\mathrm{ij}}$), where an element ${\Gamma }_{\mathrm{ij}}$ gives the coupling between two atoms $i$ and $j$ via the electromagnetic field. This method gives naturally an estimate of the solid angles in which the radiation can take place. By using these estimates, we discuss whether the emission process can be described by a one- (two-) mode model. As expected, this model fails in the two limiting cases of large and small Fresnel numbers. Also for Fresnel numbers of the order of a of few units, it is not obvious whether such a model is valid.

We report the first observation of ionization of dense Na vapor by laser radiation. A 1-MW pulsed laser at 589.6 nm produced almost complete ionization of a 10-Torr-cm column of Na. Measurements of the ${\mathrm{Na}}^{+}$ photoionization cross section, the neonlike series $2s^{2}2p^6\to 2s^{2}2p^5\mathrm{ns}$ and $\mathrm{nd}$, and several autoionizing resonances of the type $2s^{2}2p_6^6\to 2s2p^6\mathrm{np}$ were obtained using a spark source to provide the continuum background for absorption spectroscopy of the ion.

We show that second-order coherent sum-frequency generation via quadrupole transitions in metal vapors can be easily detected. The process is as strong as the allowed third-order processes. Our experimental results agree very well with theoretical predictions.

A linearly polarized laser beam produces a time-averaged radiative force along its electric vector when interacting with a magnetized plasma. This magnetic force, for a field of 5 MG, is as large as the ponderomotive force with a gradient scale of 3 μm.

X-ray-scattering measurements on TTF-TCNQ (tetrathiafulvalene-tetracyanoquinodimethane) above 54 K clearly reveal a new one-dimensional scattering at the wave vector $(0.59\mathrm{}\pm 0.02)b^{*}$ interpreted as $4k_{\mathrm{F}}$ scattering and attributed to an additional phonon anomaly which also condenses at low temperature. This $4k_{\mathrm{F}}$ scattering is still clearly visible at 220 K in contrast to the earlier reported $2k_{\mathrm{F}}$ scattering which is found to disappear at 150 K in agreement with the neutron scattering results of Shirane et al.

We demonstrate experimentally that optical four-wave mixing can be used to study surface polaritons in solids. The dispersion characteristics of surface polaritons in GaP are measured and compared with theoretical calculations.

Photoelectrons emitted from nickel single-crystal surfaces defined by low-energy-electron diffraction and Auger-electron-spectroscopy analysis exhibit negative electron-spin polarization at threshold. The abrupt change from negative to positive polarization occurs at $h\omega \simeq \Phi +0.05\mathrm{}$ eV, where $\Phi$ is the work function. This excludes an interpretation based on a simple band theory of magnetism and also explains why the negative electron-spin polarization has not been observed in earlier experiments on polycrystalline films.

Surface-state photoemission from W(100) is observed for photon energies up to 40.8 eV, contrary to previous measurements. The linewidth of this feature shows an excitation-energy dependence, which extrapolates to the field-emission value. Asymmetric broadening occurs at higher photon energies and is interpreted in terms of many-body effects associated with a heavy-hole state, implying a relaxation shift of the energetic position of the surface state.

Small-angle neutron scattering measurements on $\mathrm{Au}\mathrm{Fe}$ alloys containing 10 and 13 at.% Fe are reported. These show a series of $q$-dependent freezing temperatures [sharp discontinuities in the forward scattering intensity $I\left(q\right)\mathrm{}$ as a function of $T$] in contrast to a unique freezing temperature (sharp cusp) observed in the low-field magnetic susceptibility of the alloys.

Invoking some gross features of the band structure, we show that the resonance energy in the mixed crystal ${\mathrm{Hg}}_{1-x}{\mathrm{Cd}}_x\mathrm{Te}$ as a zero-gap semiconductor should increase continuously as the molar fraction of CdTe increases. The increase becomes very strong near the point where an energy gap begins to open up in the alloy. This prediction is in qualitative agreement with experiments. We also give comments on two different models for explaining some observed conductivity anomalies.

The reaction ${\overline{\nu }}_e+e^{-}\to {\overline{\nu }}_e+e^{-}$ has been observed using a 15.9-kg plastic scintillation target in a composite plastic-NaI-liquid detector exposed to a ${\overline{\nu }}_e$ flux of 2.2×${10}^{13}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ from an 1800-MW fission reactor. Tests rule out a reactor-associated signal produced by inverse $\beta$ decay, neutrons, or gamma rays. The measured cross section is consistent with $V-A$ and the Weinberg model with parameter ${{sin}^2\theta }_{\mathrm{W}}=0.29\mathrm{}\pm 0.05$.

It has been found that the infrared divergences in non-Abelian guage theories cancel for physically sensible transition rates to lowest nontrivial order in fermion-fermion or fermion-antifermion scattering. The finite radiative correction is given explicitly.

The total fusion cross sections for the systems ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, and ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ have been measured as a function of bombarding energy and compared with results for other light heavy-ion systems. The presence or absence of oscillations in the fusion excitation function and the overall magnitude of the cross section at high energies appear to depend on the structure of the colliding nuclei.

Products of the completely damped deep inelastic collisions of 120-MeV ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ with ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ have kinetic energies significantly larger than expected to occur from Coulomb repulsion at the time of scission. The contribution to the fragment kinetic energy from rapid rotation of the fissioning system is comparable to the kinetic energy resulting from Coulomb repulsion.

It is shown that using a quantum time-dependent method one can account for the angular distribution in strongly damped collisions between very heavy ions. The theory is applied to the study of the angular distribution of the reaction ${}_{}{}^{84}{}_{}{}^{}\mathrm{Kr}$ + ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ at 600 and 700 MeV.