The critical exponent $\beta$ of Gd is measured directly for the first time by a new technique of ferromagnetic transmission resonance in zero external field. The technique consists of measuring the microwave power transmitted through a thin Gd film (47 μm) as a function of temperature. Analysis of the resulting line shape yields conductivity $\sigma =0.745\mathrm{}\times {10}^{16}$ ${\sec }^{-1\mathrm{}}$, spin relaxation time $\tau =7.3\mathrm{}\times {10}^{-11\mathrm{}}$ sec, Curie temperature $T_{\mathrm{C}}=295\mathrm{}°$K, and critical exponent $\beta =0.31\mathrm{}\pm 0.05$.

We confirm that the previously conjectured $N$-soliton solution of the self-induced-transparency equations is a solution for all $N$. The solution is transformed to give an exact solution of the since-Gordon equation describing multiple collision of $N$ kinks with different velocities. Simple asymptotic forms of both solutions are given.

The polarization parameter $P\left(t\right)\mathrm{}$ for the reaction ${\pi }^{-}p\to {\pi }^{0}n$ has been measured at 3.5 and 5.0 GeV/c over the range $0.2<~-t<~1.8$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. The two $\gamma$ rays from the ${\pi }^0$ decay were detected in a large lead-glass hodoscope. The results agree with the positive polarization values found in earlier Argonne National Laboratory data at $-t<\mathrm{}0.35\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. $P\left(t\right)\mathrm{}$ drops to a small value near $t=-0.6\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ and remains the same out to $t=-1.8\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$.

Using the results of recent $\pi N$ charge-exchange polarization measurements at Argonne National Laboratory we have determined the amplitudes for $\pi N$ scattering 3.6 and 6.0 GeV/c. Two different methods, individual $t$-by-$t$ analysis and $t$-dependent analysis, have been adopted, and uncertainties of these amplitudes are discussed.

The diffractive electroproduction of longitudinal $\rho$ mesons sets, via unitarity and the Schwarz inequality, a lower bound to the longitudinal cross section in inelastic electron-proton scattering. Recent $\rho$ electroproduction data may be used to infer that the longitudinal-to-transverse ratio $R$ in total electroproduction at $\omega \simeq 16$, $q^2\simeq 1$ Ge${\mathrm{V}}^2$ is an order of magnitude greater than is predicted by models yielding $R=\frac{q^2}{{\nu }^2}=\left(\frac{4{m_N}^2}{q^2}\right){\omega }^{-2\mathrm{}}$.

A new beam-velocity-independent data analysis is used in a zero-field quantum-beat measurement for the determination of the magnetic-dipole hyperfine-interaction constants of the $3{}_{}{}^3{}_{}{}^{}P$ and $4{}_{}{}^3{}_{}{}^{}P$ states of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$.

Electron free precession and electron spin echoes have been detected for molecules in their excited triplet states in zero field by monitoring the microwave-induced modulation of the phosphorescence. The technique is capable of measuring as few as ${10}^4$ excited-state spins and should be applicable to a wide variety of problems.

Two sharp peaks have been observed in the magnetic field dependence of the proton spin-lattice relaxation rate of $\gamma$-irradiated 4-methyl 2,6-ditertiarybutylphenol at liquidhelium temperatures. The peaks are attributed to resonances between the frequencies of tunneling rotation of the 4-methyl groups and the Larmor frequency of the unpaired electron spins associated with free radicals. One peak is assigned to the tunneling resonance of the methyl groups of the free radicals and the other to undamaged molecules.

A technique has been demonstrated for concentrating electron beams to 5×${10}^6$ A/${\mathrm{cm}}^2$ plasmas on the axis of diodes. A two-dimensional particle code has been used to illustrate the importance of both the $\overrightarrow{\mathrm{E}}\times \overrightarrow{\mathrm{B}}$ motion in vacuum and the self-pinch of the beam within the plasma.

Bound states in the pair potential well produced in a normal metal by contact with a superconductor have been observed by tunneling in Pb/Zn-zinc oxide-Pb junctions.

The acoustically induced optical harmonic coefficient is evaluated, using a simple bond model. Good agreement with experiment is obtained. We find several important internal contributions to the direct interaction, as previously described by the theory of Nelson and Lax.

A new theory of the extended x-ray-absorption fine structure (EXAFS) is presented which avoids the inaccurate approximations of previous ones. It is shown that, in addition to structure determination, EXAFS gives detailed information on the shielding of the singly ionized absorbing atom. Experimental verification of the theory is obtained from EXAFS data for Ge and Cu, explicitly showing shielding oscillations for Cu.

Photoemission studies of very thin overlayers of Cu and Pd on Ag substrates show resonant bound $d$ states with half-widths $\Gamma \simeq 0.5, \mathrm{and} 0.8$ eV centered at 2.5 and 1.2 eV below the Fermi energy $E_{\mathrm{F}}$, respectively, for depositions ≲ 2 average monolayers, and show the formation of bulk band structure for deposition ≳ 4 monolayers. The $d$-resonance position for Pd on Ag (1.2 eV below $E_{\mathrm{F}}$) is markedly different from that of dilute Pd in AgPd alloys (2 eV below $E_{\mathrm{F}}$), while the level widths are comparaable.

The magnetic moment of small indium particles with a diameter of $d\simeq 50$ Å embedded in paraffin has been measured between 1.5 and 4.2 K in magnetic fields up to 50 kG. A saturating paramagnetic moment was observed. However, the low saturation fields cannot be understood on the basis of existing theories on electronic quantum size effects. A simple model using orbital magnetism is presented which qualitatively accounts for the observations.

It is observed that for a normal threshold ${\left|\overrightarrow{q}\right|}^2={q_x}^2+{q_y}^2+{q_z}^2=0\mathrm{}$, for a triangular anomalous threshold ${q_{\perp }}^2={q_x}^2+{q_y}^2=0\mathrm{}$, and for a box anomalous threshold ${q_y}^2=0\mathrm{}$, when scattering is taking place in the $\mathrm{xz}$ plane, with incident (or outgoing) particles moving along the $z$ axis.

Primordial turbulence in the radiation era generates a weak seed magnetic field on all scales of the turbulence. This field is stochastically amplified by turbulence motions, and it is possible for magnetic and small-scale kinetic energies to attain equipartition within an expansion time. Field generation ceases at the epoch of equal radiation and matter densities, when the field strength is of the order of 1 G. It is estimated that the present intergalactic magnetic field has an intensity of ∼${10}^{-8\mathrm{}}$ G and a scale-length of ∼Mparsec.

The collisional quenching of slow metastable hydrogen atoms by rare-gas targets is analyzed in the framework of a pseudopotential method. We find that the experimental results of Kass and Williams are in full agreement with theory if the anomalously large elastic scattering is taken into account.

I have investigated the effect of the nuclear motion on the energy eigenvalues in muonic atoms. In addition to the usually used reduced-mass correction, I have calculated the relativistic influences including the magnetic and retardation interaction between the nucleus and the muon for the inner orbitals of muonic atoms.

Relativistic electron-beam current densities as high as 2.7 MA/${\mathrm{cm}}^2$ and power fluxes of 1.87 TW/${\mathrm{cm}}^2$ have been generated and diagnosed on a pulsed electron-beam accelerator. The beam was field emitted from a 2-mm-diam glass cathode toward a transmission anode. Current densities were inferred by passing the beam through apertures as small as 1 mm and measuring the transmitted current with a Faraday cup.

The implications of magnetic symmetry on the spin-wave spectrum of ferromagnets are examined. Contrary to the usual result, the spin-wave dispersion relation is found to contain a term linear in the wave vector for a definite set of magnetic symmetries. This linear dispersion is shown to be a consequence of antisymmetric exchange.