Total cross sections of $\overline{p}p$ and $\overline{p}d$ have been measured between 360 and 1050 MeV/c, with high statistical precision. Structures are observed in both cross sections at about the same momenta. For $\overline{p}p$, the central mass is 1932±2 MeV/${\mathit{c}}^2$, and a fit to the data with a simple Breit-Wigner resonance plus background gives $\Gamma =9_{-3\mathrm{}}^{+4\mathrm{}}$ MeV/${\mathit{c}}^2$. The data suggest that the structures are in the isospin-1 state.

The energy dependence of backward ${\pi }^{+}p$ elastic scattering has been measured for incident $\pi$ momenta 2.0-6.0 GeV/c in steps of typically 100 MeV/c. Values are presented for both the differential cross section extrapolated to 180° and the slope of the backward peak as a function of momentum. In the $s$ channel we see the effects of the established ${\Delta }^{++}$ resonances and evidence for the $\Delta \mathrm{}\left(3230\right)\mathrm{}$. Also, the data show the existence of a negative-parity $\Delta$ resonance with mass ∼2200 MeV/${\mathit{c}}^2$.

${\pi }^{+}p$ and $\mathrm{pp}$ interactions at 100 GeV/c are studied in the National Accelerator Laboratory 30-in. bubble chamber with a tagged beam. Charged multiplicities in ${\pi }^{+}p$ and $\mathrm{pp}$ interactions are compared. The average inelastic multiplicity of ${\pi }^{+}p$ interactions is higher than for $\mathrm{pp}$ interactions (6.80 ± 0.14 versus 6.49 ± 0.10). However, negative particle multiplicities for events with more than six charged particles follow Poisson statistics with similar means, 2.56 ± 0.09 and 2.61 ± 0.08, for ${\pi }^{+}p$ and $\mathrm{pp}$ interactions.

We study the diffractive component in $\mathrm{pp}$ collisions at 102 and 405 GeV and examine its energy dependence in $M^2$ and $x$ variables. The total cross section for $\mathrm{}\left|x\right|>0.9\mathrm{}$ remains approximately constant: 6.6±0.5 and 6.8±0.7 mb at the two energies. However, both $\frac{d\sigma }{\mathrm{dx}}$ and $\frac{d\sigma }{d{M}^2}$ show strong energy dependence within the $\mathrm{}\left|x\right|>0.9\mathrm{}$ region. The energy and $M^2$ dependences of $\frac{d\sigma }{d{M}^2}$ do not have the characteristics of a triple-Pomeron term for $0.90<\mathrm{}\left|x\right|<0.99\mathrm{}$.

We present evidence for the decay ${A_2}^0\to \omega {\pi }^{+}{\pi }^0$ with a branching ratio $\frac{\Gamma (A_2\to \omega \pi \pi )}{\Gamma (A_2\to \rho \pi )}=0.28\mathrm{}\pm 0.09$ and for the decay $\omega \mathrm{}\left(1675\right)\mathrm{}\to \omega {\pi }^{+}{\pi }^{-}$ with a branching ratio $\frac{\Gamma \left(\omega \mathrm{}\right(1975)\mathrm{}\to \omega {\pi }^{+}{\pi }^{-})}{\Gamma \left(\omega \mathrm{}\right(1675)\mathrm{}\to \rho \pi )}=0.47\mathrm{}\pm 0.18$. Evidence is given for an intermediate $B\left(1235\right)\mathrm{}\pi$ state in the $\omega \mathrm{}\left(1675\right)\mathrm{}$ decay.

We report steady-state self-focusing, self-trapping, and self-defocusing of a cw dye laser beam in sodium vapor for frequencies within several Doppler widths of the $D$-line resonance transitions. We measured the variation of the beam profile as the light propagates through the vapor. We observed a 20-mW beam self-trapped in a 12-cm-long filament having a half-power diameter of 70 μm.

The atomic capture of negative mesons is examined in detail, using the model of Fermi and Teller. We calculate the initial distribution in angular momentum of the mesons upon capture and that after de-exciting through the electron cloud. The mesonic x-ray intensities are computed from a quantum-mechanical cascade and compared with experiment for $K^{-}$ mesons. Our results agree fairly well with the average (over $Z$) of the experimental data.

The parametric process where the electromagnetic wave drives two Langmuir oscillations near $2{\omega }_p$ can be shown to be temporally unstable even in inhomogeneous plasmas. The instability arises because of wave trapping which prevents the convection of wave energy out of the unstable region.

Turbulence generated by a rapidly imploding current sheath in a high-voltage $\theta$ pinch has been investigated by C${\mathrm{O}}_2$ laser scattering and by emission spectroscopy of forbiddenline satellites in helium. Waves indicative of a saturated ion-sound instability are seen in the current sheath. In a region well behind the sheath, waves are seen with wave numbers near $k_{\mathrm{D}}$. These waves may be the result of mode coupling from short-wave-number turbulence generated earlier by the passage of the current sheath.

Pressure waves propagate through a superleak in both ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-$A$ and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-$B$, showing that both are superfluids below $T_c$. Superfluid relative density is obtained from velocity measurements over a wide pressure range above and below the polycritical point.

We report on measurements of relaxation times for the decay of isothermal concentration gradients in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ mixtures over the temperature range ${10}^{-5\mathrm{}}\lesssim \left|\epsilon \mathrm{}\right|=|\mathrm{}\frac{T}{T_{\lambda }}-1|\lesssim {10}^{-2\mathrm{}}$. The data yield a mass diffusivity $D$ which diverges when $T_{\lambda }$ is approached from higher temperatures. When fitted with $D\propto {\epsilon }^{-z}$, they give $z=0.40, 0.36, \mathrm{and} 0.33$ for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ concentrations 0.100, 0.208, and 0.399, respectively. The estimated uncertainty for $z$ is ±0.06. These results are consistent with theoretical predictions, but differ from experimental results by others.

Measurements of the velocity of third sound on films as thin as 2.1 atomic layers yield the healing length of superfluid He II down to temperatures of 0.1 K. It is argued that these films are two-dimensional superfluids.

An application of Symanzik's method for treating exceptional momenta (the Callan-Symanzik equations combined with operator-product expansions) yields the leading corrections to the large-momentum behavior of the correlation function near the critical point. The result is used to argue that the conclusion drawn from numerical calculations, namely, that strong scaling is violated, is unwarranted.

The recent observation of backbending in the dispersion curves of surface plasmons on silver can be explained by use of Fresnel's equations. In the presence of damping, the results of attenuated-total-reflection measurements can be displayed as dispersion curves either with or without backbending. The measurements for silver with backbending are expected for experiments in which the frequency is fixed and the propagation constant (or angle of incidence) is swept.

Tellurium crystallizes in parallel-packed helixlike chains of covalent-bound atoms. The bonds between the chains are much weaker than the ones within the chains; thus the dislocations in Te arrange themselves parallel to the crystallographic $c$ axis to avoid cutting covalent bonds. Electrons bound to the dislocation lines therefore form quasi-one-dimensional states. We used magneto-optical absorption to study the nature of these bound states. They split up into highly anisotropic sub-bands, depending on strength and orientation of the magnetic field.

Paramagnetic resonance line shapes and linewidths of the ${\mathrm{Fe}}^{3+}$-$V_0$ center in SrTi${\mathrm{O}}_3$ above $T_c$ permit the determination of an effective relaxation rate $\Delta {\omega }_l\mathrm{}\left(T\right)\mathrm{}$ for the local rotations of the oxygen octahedra by observation of the crossover from Lorentzian to Gaussian line shapes with different settings of the applied field. We find that $\Delta {\omega }_l$ decreases as $T\to {T_c}^{+}$, clearly indicating critical slowing down. In addition, the relaxation rate ${\Gamma }_c$ for the $R$-point (order-parameter) collective mode is estimated from the line-widths in the region of Lorentzian shapes, indicating a "central peak" of width ${\Gamma }_c\approx 0.6\times {10}^8 invsec\approx 0.1\Delta {\omega }_l$ at $T=T_c+2\mathrm{}$ K.

The high-frequency electro-optic tensor of succinonitrile is measured throughout the plastic crystalline phase. Its strength, due to cooperative molecular response to the orienting optical field, is a generalized susceptibility increasing rapidly near the plastic-solid transition. Its anisotropy describes long-range cubic order of the average molecular orientation. This orientational order parameter decreases rapidly near the plastic-liquid transition, suggesting that the hitherto neglected average orientational order is essential to the plastic phase stability.

The volume dependence of the Raman frequencies ${\omega }_i$ in $\alpha$-${\mathrm{N}}_2$ has been measured yielding the following values of the Grüneisen parameter ${\gamma }_i\equiv -\frac{\partial \ln {\omega }_i}{\partial \ln V}$ at 8°K: 2.09±0.12, 1.74±0.10, and 1.70±0.10, where $i$ refers to the $E_{\mathrm{g}}$, low-frequency $T_{\mathrm{g}}$, and high-frequency $T_{\mathrm{g}}$ modes, respectively. These values are insensitive to temperature within experimental errors. The broad feature between 70 and 100 ${\mathrm{cm}}^{-1\mathrm{}}$ is identified as a two-libron band.

We report a detailed neutron-scattering study of the spin dynamics in Cu${\mathrm{Cl}}_2$·2N(${\mathrm{C}}_5$${\mathrm{D}}_5$), a physical realization of the one-dimensional $S=\frac{1}{2}$ Heisenberg antiferromagnet. At $T=1.3\mathrm{}$ K well-defined excitations are observed over the whole zone with energies given by $E\left(q\right)=\pi J_{\mathrm{nn}}sin\mathrm{}\left(\mathrm{qc}\right)\mathrm{}$, the celebrated des Cloizeaux-Pearson exact solution for the spectrum of first excited states, but with intensities approximately those expected from classical spin-wave theory. At $T=8\mathrm{}$ K the excitations are broad and ill defined.

The reaction ${}_{}{}^6{}_{}{}^{}\mathrm{Li}(d, tp){}_{}{}^4{}_{}{}^{}\mathrm{He}$ has been studied for two values of residual ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ momentum (${\overrightarrow{\mathrm{k}}}_{\alpha }=0\mathrm{} \mathrm{and} -30\mathrm{}$ MeV/c). The shift of the first minimum in the angular distribution of the reaction ${}_{}{}^6{}_{}{}^{}\mathrm{Li}(d, tp){}_{}{}^4{}_{}{}^{}\mathrm{He}$, for fixed ${\overrightarrow{\mathrm{k}}}_{\alpha }$, with respect to the first minimum in the angular distribution of the reaction $d(d, t)p$, has been used to investigate the structure of the $d$ cluster in the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ nucleus.