Quasielastic electron scattering ($0.1\lesssim Q^2\lesssim 1$ Ge${\mathrm{V}}^2$) may be well suited to measure modifications of nucleons in nuclei. From an analysis of the longitudinal and transverse structure functions for inelastic electron scattering off ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ in the region $0.1\lesssim Q^2\lesssim 0.25$ Ge${\mathrm{V}}^2$, indications are found for increases of the charge radius and the magnetic moment of nucleons in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$. The mean square radius of the magnetic form factor shows virtually no increase.

We report a measurement of the reaction $\gamma \gamma \to K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}$ in both tagged and untagged events at PEP. The cross section rises with invariant $\gamma \gamma$ mass to about 15 nb at 2 GeV and falls slowly at higher masses. We find clear evidence for the processes $\gamma \gamma \to \phi {\pi }^{+}{\pi }^{-}$ and $\gamma \gamma \to K^{*0\mathrm{}}\mathrm{}\left(892\right)K\pi$. Upper limits (95% C.L.) of 1.5 and 5.7 nb in the mass range from 1.7 to 3.7 GeV are obtained for $\phi {\rho }^0$ and $K^{*0\mathrm{}}{\overline{K}}^{*0\mathrm{}}$ production, respectively.

Data from the high-resolution spectrometer at PEP have been used to study the inclusive production of $\phi$ mesons and $F^{\pm }$ mesons decaying into $\phi {\pi }^{\pm }$. Fragmentation functions and cross sections are presented and compared to existing data. The total $\phi$ cross section at 29 GeV is 40±6 pb. The observed $F$ signal in the region $z>\mathrm{}0.4\mathrm{}$, given the assumption that $\frac{R\left(F\right)\mathrm{}}{\mathrm{}\left[R\right(F)+R(D\left)\right]}=0.15\mathrm{}$, corresponds to an $F\to \phi \pi$ branching ratio of (3.3±1.1)%. The measured $F$ mass is 1963±3±3 MeV/${\mathit{c}}^2$.

The cross section for the reaction $\overline{p}N\to {\mu }^{+}{\mu }^{-}X$ with muon pairs in the mass range $4<M<\mathrm{}9\mathrm{}$ GeV/${\mathit{c}}^2$ and $x_F>0\mathrm{}$ was measured to be $\sigma =0.104\mathrm{}\pm 0.005\pm 0.008$ nb/nucleon. The distributions $\frac{d\sigma }{d{x}_F}$ and $\frac{M^{3}d\sigma }{\mathrm{dM}}$ were compared to the QCD-improved Drell-Yan model and to calculations including first-order QCD corrections, with use of deep-inelastic structure functions. Excellent agreement with the data was obtained if the calculations were multiplied by factors of 2.45 and 1.41, respectively.

We show that the data of Aubert et al. on the structure function of iron is in apparent violation of the energy-momentum sum rule. The systematics of the finite-$q^2$ corrections, when compared to data of Arnold et al., are an important ingredient to the argument. The discrepancy can be removed by an approximately 5% renormalization of the data of Aubert et al.

The charged-particle multiplicities of hadronic events deriving from produced bottom or charm quarks have been measured in the Mark II detector at PEP in $e^{+}{e}^{-}$ annihilation at 29 GeV. For events containing one semileptonic and one hadronic weak decay, we find multiplicities of 15.2±0.5±0.7 for bottom and 13.0±0.5±0.8 for charm. The corresponding multiplicities of charged particles accompanying the pair of heavy hadrons are 5.2±0.5±0.9 for bottom, and 8.1±0.5±0.9 for charm.

The level scheme of ${}_{}{}^{156}{}_{}{}^{}\mathrm{Er}$ has been determined by use of an array of nine Compton-suppressed Ge detectors. Two new types of behavior have been observed. The first is a terminating band ending on a ${42}^{+}$ fully aligned state. The second is a strong cross feeding among four negative-parity bands, due most likely to a severe reduction or collapse of the neutron pairing.

A concept for collective acceleration and focusing of a high-energy electron bunch is presented. The scheme combines an intense relativistic electron beam propagating in low-density gas with a trailing picosecond laser pulse for prompt photoionization of the gas to create the intense collective fields.

Static quadrupole moments ($Q$) of $8^{+}$ isomers in ${}_{}{}^{88,90}{}_{}{}^{}\mathrm{Zr}$ and the ${\frac{21}{2}}^{+}$ isomer in ${}_{}{}^{91}{}_{}{}^{}\mathrm{Zr}$, as well as $Q$ ratios of $8^{+}$ isomers in ${}_{}{}^{90,92,94}{}_{}{}^{}\mathrm{Mo}$, have been measured with the time-differential perturbed-angular-distribution technique. The isomers were excited by pulsed heavy-ion beams and recoil implanted into single crystals of Zr in which their quadrupole precession was observed. Our results, the first such data for high-spin isomers in the $g_{\frac{9}{2}}$ shell, yield large $E2\mathrm{}$ effective charges for the $g_{\frac{9}{2}}$ proton and the $g_{\frac{9}{2}}$ neutron. The systematics of these charges are comprehensively explained by particle-vibration coupling and the blocking effect.

We report the first observation of electromagnetically trapped neutral atoms. Laser cooled and stopped sodium atoms are confined in a magnetic quadrupole trap formed by two opposed, separated, coaxial current loops. The decay time constant for atoms in the trap is 0.83(7) s and is limited mainly by collisions with background gas atoms.

We report the first observation of an assisted ${\mathrm{He}}^{+}$ yield arising from single collisions between a $\mathrm{He}(2\mathrm{}{}_{}{}^1{}_{}{}^{}S, 2{}_{}{}^3{}_{}{}^{}S)$) atom beam on a $\mathrm{He}\left(1\mathrm{}{}_{}{}^1{}_{}{}^{}S\right)$ target in the presence of an intense laser field. A time-of-flight analysis shows that the pulsed laser-assisted ion signal is reproducible, energy dependent, and appears in addition to the continuous ion flux coming from a known field-free diabatic channel. From the estimated value of the diabatic ionization cross section ${\sigma }_d$, the order of magnitude of the assisted-ionization cross section ${\sigma }_a$ is given.

We report on the first experimental measurement of principal Hugoniots in aluminum for shock pressures of 0.3-12 Mbar generated by laser-driven ablation. These were derived from independent measurements of the shock speed, shock pressure, and shock-heated target temperature. The results showed excellent agreement with LASNEX simulations and with calculations using SESAME equation-of-state data. More importantly, the results indicated that the shock speed and temperature Hugoniot may provide useful equation-of-state studies in laser-generated shock-wave experiments.

A plasma which is immersed in superthermal radiation suffers velocity-space diffusion which is enhanced by the photon-induced Coulomb-field fluctuations. This enhanced diffusion universally produces a power-law distribution ${\left(\frac{E}{E_0}\right)}^{-\kappa }$ at energy $E$ larger than a critical energy $E_0$ where the transition energy $E_0$ and the power $\kappa$ are inversely proportional to the photon-field intensity.

Phase-separation processes in FeCr and AlZn alloys were studied by a small-angle scattering instrument installed at the KENS pulsed neutron source. Two stages were found in the decomposition process. In the late stage, after annealing time $t$, dynamical scaling holds for the scattering function $S(q, t)$ which exhibits $q^{-4\mathrm{}}$ dependence for high $q$ values. At the earlier stage $S(q, t)$ cannot be described by the same scaling law, and $q^{-2\mathrm{}}$ dependence appears at high $q$. This relation can be well described by the nonlinear theory of Langer, Bar-on, and Miller.

Secondary-electron images of cleaved highly oriented pyrolytic-graphite surfaces, showing topographic and primary-ion-channeling contrast, exhibit pleated structures, revealing detailed morphology of flat microcrystallites and low-angle grain boundaries. We also observed, for the first time, the lateral extent of Daumas-Hérold domains by direct imaging of the surface distribution of the intercalant on freshly cleaved Sb${\mathrm{Cl}}_5$-intercalated graphite. The intercalant forms domains of typical dimension ∼200 nm and accumulates along crystal-surface defects.

From an analysis of diffraction data for Au(111), we deduce that the observed 23-fold periodicity in the $〈110〉$ direction can be described by a regular superstructure of one-dimensional extended stacking faults. We propose that this surface is a realization of the Frenkel-Kontorova model of competing interactions and that the periodic changes in stacking from $\mathrm{ABC}$ to $\mathrm{ABA}$ may thus take the form of solitons. The solitons, of half-width 11.8 Å, lead to an average compression of 4% in the $〈110〉$ direction.

Resonant Raman scattering experiments on GaAs(Si doped)-${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ quantum-well structures show transitions involving the ground state of the donors and narrow resonant donor states derived from higher conduction subbands. These new impurity-related features, which occur at slightly higher energies than the associated conduction intersubband excitations, have been studied as a function of power density, temperature, and well width.

The energy versus position of a single Si adatom on a two-dimensionally infinite Al(001) substrate is calculated. The only physical approximations made are the Born-Oppenheimer approximation and the use of a local exchange-correlation potential. Computed binding energies, force constants, and bond charges for two different bonding geometries confirm earlier more approximate calculations for the Si/Al adsorption system.

We discuss a calculation of the nonlinear current fluctuations in a model metallic resistor at low temperatures in a constant electric field, $E$. The model used here neglects electron-electron and electron-phonon scattering. For a very large range of frequencies, electron-localization effects lead to low-frequency corrections to Johnson noise of the form $\frac{E^2}{{\left|\omega \right|}^{\frac{\mathrm{}(4-d)\mathrm{}}{2}}}$. Here $\omega$ is the frequency and $d$ is the dimensionality of the system ($d=2, 3$). The relevance of our results to recent theoretical attempts to explain $\frac{1}{f}$ noise is discussed.

The $5f$ spectral weight in the heavy-fermion materials U${\mathrm{Al}}_2$ and U${\mathrm{Pt}}_3$ has been measured by electron spectroscopy, and compared to that in density-functional calculations. The one-electron $5f$ widths are both too large to account for the enhanced values of the specific-heat coefficient $\gamma$, and too small to account for the measured widths. In the Anderson Hamiltonian, both discrepancies arise from the $5f$ Coulomb interaction. It is pointed out that an enhanced $\gamma$ value does not imply enhanced magnitude of the $5f$ spectral weight at $E_{\mathrm{F}}$.