The recombination kinetics of transient high-density electron-hole plasmas in germanium has been measured by time-resolved free-carrier absorption with picosecond optical pulses. Density-dependent recombination rates as high as 4 × ${10}^9$ ${\sec }^{-1\mathrm{}}$ have been observed in plasmas with initial densities up to 3.4 × ${10}^{20}$ ${\mathrm{cm}}^{-3\mathrm{}}$. At this density the band-to-band Auger rate constant, ${\gamma }_3=n^{-3\mathrm{}}\frac{\partial n}{\partial t}$, is found to be 1.1 × ${10}^{-31\mathrm{}}$ ${\mathrm{cm}}^6$ ${\sec }^{-1\mathrm{}}$ at room temperature in germanium.

The dependence of photoemission on the azimuthal emission angle at fixed polar angle of 45° was measured for the (100) face of NaCl and KCl single crystal cleaved in situ. The initial- and final-state energy was scanned using synchrotron radiation. Strong variations of the angular pattern are observed for different final-state energies. Below the electron-electron scattering threshold the pattern depends only on the final-state energy. Electron-phonon scattering can account for this fact.

We report the first use of low-frequency, nonresonant ($\Delta m=0\mathrm{}$) ultrasound to investigate the dominant spin-lattice relaxation processes in dilute paramagnetic systems. A theory of the interaction of paramagnetic spins with ultrasonic waves is presented which emphasizes the coupling of acoustic waves to $〈{S_z}^2-\frac{1}{3}S(S+1\mathrm{})\mathrm{}〉$, the $l=2\mathrm{}$, $m=0\mathrm{}$ spin quadrupole. Results of experiments over the range 4.2 to 30 K, using 30-MHz longitudinal ultrasonic waves in single-crystal MgO: ${\mathrm{Fe}}^{2+}$, are consistent with theoretical predictions.

A marked frequency dependence of the far-infrared cyclotron effective mass of inversion-layer electrons in a Si metal-oxide-semiconductor device has been observed for the first time. A qualitative interpretation of these data in terms of electron-electron interactions is presented.

We report the direct observation of energy migration and spectral diffusion in the ${}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}$ state of La${\mathrm{F}}_3$: ${\mathrm{Pr}}^{3+}$ using the technique of time-resolved fluorescence line narrowing on the resonant ${}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}\to {}_{}{}^3{}_{}{}^{}H_4^{}{}_{}{}^{}$ transition. The temperature dependence of the migration process has been measured and various possible transfer mechanisms are discussed. In addition a variation in the excited-state lifetime as a function of absorption frequency and a concentration broadening at zero delay in the nonresonant transition ${}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}\to {\left({}_{}{}^3{}_{}{}^{}H_6^{}{}_{}{}^{}\right)}_1$ (the lowest Stark level) are reported.

Radiative decays of $\eta$ and ${\eta }^{\prime }$ allow us to test the color hypothesis and to distinguish between fractional- and integral-charge quark models. Accurate measurements of ${\eta }^{\prime }\to \gamma \gamma$ and ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}\gamma$ are essential to test the analysis and the preliminary conclusion, which favors the three-color model with fractional charges.

Inclusive ${\Delta }^{++}\mathrm{}\left(1236\right)\mathrm{}$ production in ${\pi }^{+}p$ and $\mathrm{pp}$ interactions is consistent with one-pion exchange. The average charged multiplicity recoiling from the ${\Delta }^{++}$ is studied as a function of missing mass, $M^2$, for both interactions.

The nuclear-polarization and extended-space corrections are calculated for x-ray transitions of muonic atoms of ${}_{}{}^{169}{}_{}{}^{}\mathrm{Tm}$, ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$, and ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$ for acceptable values of the three parameters: the half-radius of the charge distribution, the surface thickness, and the intrinsic quadrupole moment. It is shown that there is enough variation in the values of the corrections for the transitions in a given nuclide to preclude the assignment of a constant amount to all the transitions.

For the case of the Reid soft-core potential the elastic neutron-deuteron scattering is studied. The three-nucleon equations are solved exactly for the pure $s$-wave parts of the two-nucleon $T$ matrix while the higher partial-wave components of the force are treated perturbatively. Results are presented at 14.1 and 46.3 MeV. In particular, it is found that the pronounced minimum in the elastic cross section at higher energies, calculated with pure $s$-wave interactions, is filled in predominantly by the $d$-wave component of the deuteron.

Cross sections are presented for the production of ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ in the $\alpha +\alpha$ reaction between threshold and 140 MeV. Implications of these measurements for the problem of the origin of ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ in the universe are discussed.

The multipolarity ($L$) dependence of the inelastic form factor for heavy-ion-induced excitations predicted by the folding model is confirmed in the analysis of the scattering of ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ at 155 MeV. Agreement between the target deformation lengths (${\beta }_L{R}_t$) of these measurements and those from electromagnetic and proton experiments is found when the strongly $L$-dependent folding-model form factor is employed.

It is shown that as a result of density fluctuations, the phase velocity domain of the gentle bump instability can be greatly broadened, leading to a different saturation of the instability. A part of the beam is accelerated and the turbulence power at saturation is lowered.

We observe amplification of extraordinary waves which is interpreted as negative absorption of the relativistic magnetized plasma confined in a mirror machine. Experimental results are explained well by the relativistic kinetic theory with the assumption of an isotropic peaked distribution, $f\left(p\right)\mathrm{}\propto p^l\exp (-\frac{\epsilon }{T})$.

Evidence is presented for a new meson resonance at 2340±20 MeV, with a width of 180±60 MeV, decaying primarily into $\rho \rho \pi$. The resonance, which is observed in 15-GeV/c ${\pi }^{+}p$ interactions, has isotopic spin 1 or 2 and odd $G$ parity. The cross section for production of the $\rho \rho \pi$ state is 7.3±1.7 μb. Branching ratios into $\rho \rho \pi$ and other decay modes are given.

A two-component model of deep inelastic lepton-nucleon scattering is presented in which the phenomena that the usual quark-parton model attributes to the presence of the core (wee) quarks are instead described by a generalized vector-meson-dominance model, modified to take into account a correction arising from the finite size of the nucleon and the uncertainty principle. The model predicts the core-quark distribution in satisfactory agreement with the results of neutrino experiments.

Scale invariance is tested in ratios of muon scattering cross sections from an iron target at pairs of $q^2$ values ranging to 40 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ and differing by a factor of $\frac{3}{8}$. The apparatus was changed with incident energy to preserve acceptance and resolution in scaled variables. The scale-noninvariant departure from unity of these ratios displays a statistically significant $\omega$ dependence. The effect exceeds the systematic uncertainty by a factor of 1.7.

Scale noninvariance is observed in 150- and 56-GeV muon scattering from an iron target. In the range $1<\mathrm{}{q}^2<40\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$, $\nu W_2$ rises with $q^2$ at fixed ${\omega }^{\prime }\gtrsim 6$ and falls at ${\omega }^{\prime }\lesssim 6$. The scale breaking is statistically and systematically significant, and persists with alternative choices of scaling variable. It is parametrized roughly by a constant $b=\frac{{\partial }^2\ln (\nu \times W_2)}{\partial \ln \left({\omega }^{\prime }\right)\partial \ln (q^2}$ with a value near 0.09.

By use of finite-difference methods we solve the classical relativistic equations of motion for the head-on collision of two heavy nuclei. For ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ projectiles incident onto various targets at laboratory bombarding energies per nucleon ≤2.1 GeV, curved shock waves develop. The target and projectile are deformed and compressed into crescents of revolution. This is followed by rarefaction waves and an overall expansion of the matter into a moderately wide distribution of angles.

An upper limit of ${10}^{-4\mathrm{}}$ has been obtained for the branching ratio for the emission of two photons ($E_{\gamma }>0.57\mathrm{}$ MeV) following thermal neutron capture in hydrogen. This limit was obtained with two Ge(Li) detectors shielded so as to reduce $\gamma$-ray scattering from one detector into the other and is a factor of 10 lower than has been recently reported.

A very-high momentum-transfer ($q=780\mathrm{}$ MeV/c), elastic electron-scattering experiment on ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ has been performed using the 600-MeV linac of Saclay. The charge density, extracted from ($e, e$) and muonic-x-ray data, exhibits considerably less structure than predicted by Hartree-Fock calculations.