The nature and dose dependence of the disorder produced by 125-keV P implantation in Ni single crystals was studied via in situ channeling experiments using the 380-keV ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ beam of the implanter. At 90 K, disordering (and presumably amorphization) occurs around the depth of the maximum in the implanted P concentrations; at 300 K, it occurs mainly at the surface and progresses inwards until the P projected range and peak in deposited energy profile are reached. In both cases, the lattice is randomized at a local P concentration of ∼0.20.

Molecular-dynamics calculations have been used to investigate the nature of critical fluctuations in the paraelectric phase of NaN${\mathrm{O}}_2$. Although the ${\left(\mathrm{N}{\mathrm{O}}_2\right)}^{-}$ anions are found to reorient rapidly, predominantly about the crystal $c$ axis, the simulation reveals the existence of long-lived fluctuations of antiferroelectric character. The reorientational motion is found to couple to optic rather than acoustic modes, in agreement with a recent theoretical prediction.

The molar volumes of ammonia solid I and solid II were measured from 0.5 to 14.0 kbar and 185 to 320 K. Over regions that extend 3 kbar and 20 K into the solid phases, variations in compressibility and thermal expansion can be described by power laws with exponents similar to those usually associated with critical transitions. It is suggested that breaking of hydrogen bonds may account for the extreme softening of solid ammonia.

The free decay of a turbulent field in superfluid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ is studied by using pulsed-ion techniques. The decay process is found to exhibit strikingly simple behavior. Analysis of the results indicated that current theoretical models need further refinement.

Magnetocapacitance measurements on a nonpolar paramagnetic system of antiferromagnetically exchange-coupled neutral donors in the temperature range 4.2 to 1.1 K reveal a strongly temperature-dependent coefficient of the $H^2$ term much larger in magnitude than the usual weak diamagnetic effect. The new effect arises from the Zeeman effect of the excited triplet spin state of donor pairs and is proportional to the difference between the singlet- and triplet-state polarizabilities. The temperature dependence is like that of the Schottky specific-heat anomaly.

The thermoelectric power and resistance of ${\mathrm{Eu}}_x{\mathrm{Mo}}_6{\mathrm{S}}_8$ have been measured as functions of temperature and pressure. Anomalies are found that resemble a smeared charge-density-wave transition which opens a gap over part of the Fermi surface. From the competition of this transition and superconductivity for states at the Fermi surface, the pressure dependence of the superconducting transition temperature can be quantitatively explained.

Magnetoabsorption experiments on the $A$ exciton in InSe have been performed in search of a unified correspondence relation between low and high magnetic field levels of a hydrogenlike state. Results show that the nodal-surface conservation rule of Shinada et al. is a more appropriate representation of this relationship than the so-called noncrossing rule.

The treatment of first-order phase transitions for standard grand unified theories is shown to break down for models with radiatively induced spontaneous symmetry breaking. It is argued that proper analysis of these transitions which would take place in the early history of the universe can lead to an explanation of the cosmological homogeneity, flatness, and monopole puzzles.

A description of the decay into the bulk of surface perturbations in a system at its critical point is presented. The description, justified by detailed renormalization-group calculations, yields asymptotic order-parameter decay, $z^{-\frac{(d-2+\eta )}{2}}$, along with power-law behavior connected with surface exponents under suitable conditions. Comparison with the phenomenological theories of Widom and of Fisher and de Gennes is also made.

It is pointed out that the factorization of disconnected Wilson loop amplitudes implies a major reduction in the dynamical degrees of freedom in the large-$N$ limit of lattice gauge theory; the original model may be replaced by a much simpler one ($d$ is the space-time dimensionality), $Z=\Pi \stackrel{}{\mu }\left[\int d U_{\mu }\exp \right({\beta }_{\nu \ne }\Sigma \stackrel{d}{\mu \ne \nu =1\mathrm{}}\mathrm{tr}{U}_{\mu }{U}_v{U_{\mu }}^{†}{U_{\nu }}^{†}\left)\right]$ Thus the field theory may be reduced to an integration over a finite number of matrices in large-$N$ limit.

Rates are calculated for the processes $\mathrm{gg}\to s\overline{s}$ and $u\overline{u}$,$d\overline{d}\to s\overline{s}$ in highly excited quarkgluon plasma. For temperature $T>~160$ MeV the strangeness abundance saturates during the lifetime (∼${10}^{-23\mathrm{}}$ sec) of the plasma created in high-energy nuclear collisions. The chemical equilibration time for gluons and light quarks is found to be less than ${10}^{-24\mathrm{}}$ sec.

Data on inclusive kaon production in $e^{+}{e}^{-}$ annihilations at energies in the vicinity of the $\Upsilon \mathrm{}\left(4S\right)\mathrm{}$ resonance are presented. A clear excess of kaons is observed on the $\Upsilon \mathrm{}\left(4S\right)\mathrm{}$ compared to the continuum. Under the assumption that the $\Upsilon \mathrm{}\left(4S\right)\mathrm{}$ decays into $B\overline{B}$, a total of 3.38±0.34±0.68 kaons per $\Upsilon \mathrm{}\left(4S\right)\mathrm{}$ decay is found. In the context of the standard $B$-decay model this leads to a value for $\frac{(b\to c)}{(b\to \mathrm{all})}$ of 1.09±0.33±0.13.

Ground-state and radially excited quarkonium configurations are all coherently produced in radiative $\psi$ decays with amplitudes which depend on the wave function at the origin. Configuration mixing in the mass matrix due to annihilation into gluons also depends on the wave function at the origin and shows the same coherence. Small interference and mixing amplitudes can produce large coherent effects which invalidate conventional arguments used to distinguish between glueballs and quarkonia.

Hydrogenlike atoms consisting of a pion and a muon can be formed in ${K_L}^0\to \pi \mu \nu$ decays. In an intense, high-energy ${K_L}^0$ beam, 320 pi-mu atoms were detected and simultaneously the ${K_L}^0$ flux was monitored by recording ordinary ${K_L}^0\to \pi \mu \nu$ decays. The first measurement is reported of the branching ratio $R=\frac{\Gamma ({K_L}^0\to \mathrm{p}\mathrm{i}-\mathrm{m}\mathrm{u}\mathrm{a}\mathrm{t}\mathrm{o}\mathrm{m}+\nu )}{\Gamma ({K_L}^0\to \pi \mu \nu )}=(3.88\mathrm{}\pm 0.41)\times {10}^{-7\mathrm{}}$, using a subset of 155 atoms. This ratio may be sensitive to anomalous interactions between the pion and the muon. In the absence of such interactions, theory predicts $R=(4.43\mathrm{}\pm 0.12)\times {10}^{-7\mathrm{}}$.

Inelastic scattering of vector polarized deuterons near $E_d=20\mathrm{}$ MeV has been measured for a series of target nuclei ranging from the $\mathrm{sd}$ shell to ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$. Isoscalar transition rates deduced from a collective-model analysis are found to be in agreement with the corresponding electromagnetic quantities for the quadrupole and octupole excitations of $T=0\mathrm{}$ nuclei and of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. For the quadrupole excitation in ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$, ${}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}$, ${}_{}{}^{154}{}_{}{}^{}\mathrm{Sm}$, and ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ about 20% smaller values are obtained, which imply a larger proton than neutron deformation for these nuclei.

The fluctuation properties of nuclear energy levels are analyzed with new spectrally averaged measures. A remarkably close agreement between the predictions of random-matrix theories and experiment is found.

Kinematically complete experiments have been performed on the three-body exit channels in 12.5-MeV/u ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$ on ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sn}$. The events observed result from a sequential fission process taking place in 1×${10}^{-21\mathrm{}}$ s. The angular distribution of the fission axis is approximately collinear with the axis of the first scission, and the mass distribution of the fission is asymmetric with the heavier mass preferentially emitted opposite to the direction of the third particle. These effects show the existence of a new phenomenon of nonequilibrium fission.

Kinematically complete experiments have been performed on the two- and three-body exit channels in 12.4-MeV/u ${}_{}{}^{84}{}_{}{}^{}\mathrm{Kr}$ on ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ and ${}_{}{}^{166}{}_{}{}^{}\mathrm{Er}$, and 12.5-MeV/u ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$ on ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sn}$. Three-body events occur with a high probability. They arise predominantly from two-step reactions, with large energy losses in the first step leading to fission in the second. Strong proximity effects, observed in the final three-body state of the Xe-Sn reaction, establish a scission-to-scission time of about 1×10${}_{}{}^{-21\mathrm{}}{}_{}{}^{}\mathrm{s}$.

Molecular weight distributions of hydrogen cluster ions produced by the expansion of refrigerated ionized gas in a supersonic nozzle are reported. Relatively narrow distributions with most probable masses up to a mass-to-charge ratio of 369 have been observed.

Observations are reported on the rotationally resolved $3d^2\Delta \leftarrow 2p^2\Pi$ electronic transition in the LiHe van der Waals molecule. These observations, which represent the first optical double-resonance measurements of the rovibrational structure of any alkalirare-gas molecule, have been analyzed, using standard techniques, to yield values for the $3d^2\Delta$ state well depth $D_e=430\mathrm{}\left(70\right)\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$ and equilibrium separation ${\mathcal{r}}_e=3.6\mathrm{}\left(1\right)\mathrm{}{a}_0$. The experimental scheme, which should allow spectroscopy of excited states in a number of excimer molecules, is also described.