The hypernetted chain (HNC) equation can be linearized in $h\left(\mathcal{r}\right)=g\left(\mathcal{r}\right)-1\mathrm{}$ if a polymer solution is dilute and near the $\theta$ point or if the solution is concentrated and hence nearly uncorrelated. The linearized HNC equation is elementary for the Flory-Krigbaum potential, and both high- and low-density expansions for $g\left(\mathcal{r}\right)$ can be calculated analytically to give exact limiting forms for the radial distribution function. A phase transition is predicted.

Measurements of the transverse differential susceptibility in MnP suggest that the para-ferro-fan triple point is a Lifshitz point (LP). At this point all phase boundaries are tangent to each other, and the $\lambda$ line exhibits an inflection point. These features agree with predictions for a LP characterized by $d=3\mathrm{}$, $n=m=1\mathrm{}$, which is expected for this crystal symmetry. A crossover exponent $\phi =0.634\mathrm{}\pm 0.03$ is obtained, in agreement with theory.

With use of compressional cooling, ordering in solid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is observed and identified by a null in the pressurization rate for reversible compressions in magnetic fields up to 7.2 T. At this field the ordering is above 3 mK. Entropies at $T_A$ deduced from $\frac{(P_{A2\mathrm{}}-P_{A1\mathrm{}})}{(T_{A2\mathrm{}}-T_{A1\mathrm{}})}$ are shown to be lower than expected from the various models. Irreversible magnetic heating at high fields which limits the effective cooling power is also observed.

The magnetization of solid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ has been measured at a density of 24.2 ${\mathrm{cm}}^3$/mole for fields between 0.8 and 5.8 kG, and for temperatures from 0.55 to 2.0 mK. The measurements reveal the magnetic properties of the phases previously observed by Kummer, Mueller, and Adams, and are in qualitative agreement with the phase lines obtained by them. A new second-order transition has been observed for a narrow range of fields above 4.1 kG.

The drift of free excitons in an applied strain gradient in Si is directly observed for the first time. The exciton luminescence is detected with temporal, spatial, and spectral resolution in order to map the local force field and measure the exciton velocity. An absolute measurement of the momentum relaxation time $\tau$ is made between 1.3 and 20 K and is well explained by acoustic-phonon scattering. Both diffusion and drift regimes are observable, revealing extremely high exciton mobilities.

The Hamiltonian, $H$, of a spinless particle moving in two dimensions in an axially symmetric magnetic field $B\left(\rho \right)$ is considered. If $B\left(\rho \right)\sim {\rho }^{-\alpha }$ for $\rho$, large with $0<\mathrm{}\alpha <1\mathrm{}$, then it is shown that $H$ has spectrum [$0, \infty$) with only eigenvectors and eigenvalues dense in [$0, \infty$). If $\alpha =1\mathrm{}$, then the spectrum is a dense point spectrum in [0, $c$] for suitable $c$ and absolutely continuous in [$c, \infty$).

The galvanomagnetic properties of random normal-superconducting composites have been calculated assuming the components are simply a free-electron metal and a perfect conductor. For fixed large reduced fields below $H_{c2\mathrm{}}$ of the superconducting component, the transverse magnetoresistance is found first to rise with increasing concentration of superconductor, then to fall to zero at the percolation threshold, in agreement with experiment. The Hall coefficient is predicted to go smoothly to zero at the percolation threshold.

It is shown that in unified theories containing only fermions and gauge fields and in which scale invariance is spontaneously broken, radiative corrections induce an order-$R$ term in the vacuum action functional which is uniquely determined by the flat-space-time theory.

When expanded in powers of $\overline{\alpha }$ where $\overline{\alpha }$ is chosen to satisfy $\overline{\alpha }\left({Q_0}^2\right)=\frac{4\pi }{{\beta }_0\ln \left(\frac{{Q_0}^2}{{\Lambda }^2}\right)}={\alpha }_{\overline{\mathrm{MS}}}\left({Q_0}^2\right)$ with ${Q_0}^2\approx 10$ Ge${\mathrm{V}}^2$, the quantum chromodynamics (QCD) perturbation series seems to be extremely well behaved. In particular, the large third-order corrections discussed recently by Moshe do not appear when this $\overline{\alpha }$ is used as the QCD expansion parameter.

We have searched for narrow states of the $\overline{p}p$ system in the mass range from 2000 to 2400 MeV/${\mathit{c}}^2$ in the inclusive channel ${\pi }^{-}+\left(p \mathrm{or}\mathrm{C}\right)\to \overline{p}p+X^0$. No statistically significant enhancements in the data have been observed.

Fission of ${}_{}{}^{242}{}_{}{}^{}\mathrm{Pu}$ induced by radiationless muonic transitions is studied. By solving the time-dependent Schrödinger equation for the muonic wave function in an axially symmetric spatial grid, one finds an observable dependence of the muonic final state-both in the localization of the muon and its excitation probability—on fission dynamics. More refined studies should allow one to extract information about the friction coefficient in fission.

The 800-MeV ($p, p^{\prime }$) inclusive proton spectra at forward angles are considered. A plane-wave impulse approximation is used to calculate quasifree nucleon knockout and quasifree isobar production. When the quasifree peaks are normalized to data, it is found that the integrated cross section for the two processes can account for the total reaction cross section.

Within the framework of the close-coupling method, ab initio calculations of parameters of multichannel quantum-defect theory have been carried out for several Rydberg series of Ca, Sr, and Ba. A local-density approximation, commonly used in solid-state calculations, including self-consistent, self-energy corrections, was made to the exchange-correlation potential. Good agreement with experimental values of multichannel quantum-defect theory parameters is obtained, permitting accurate prediction of highly excited-state binding energies.

A probabilistic method for the solution of the Vlasov equation has been applied to the Chirikov-Taylor model. The analytical solutions for the probability function and its second velocity moment have been obtained. Good agreement between the theory and numerical computations has been found.

A linewidth minimum in the (220) electron-channeling-pattern (ECP) reflection in tungsten has been measured at 10.50±0.05 keV incident beam energy. This is interpreted as a second-order critical-voltage effect and is the first reported observation of such an effect in ECP's. The experimental critical voltage has been used to refine the tungsten (110) Fourier lattice-potential coefficient. The shape of the line-narrowing curve is used to estimate the depth of ECP information.

Incoherent, inelastic scattering of neutrons by hydrogen in surface hydroxyl groups has been used to probe the dynamics of 60-70-Å-diameter spheres of amorphous silica. The high-temperature spectra indicate a pronounced "small-particle" enhancement of low-frequency vibrational modes as predicted by theory. At low temperatures, the scattering changes in character and shows evidence of hindered rotational transitions.

A new class of layered materials has been prepared by alternate deposition of two dissimilar metals. Strong experimental evidence is shown that coherent structures with layer thicknesses approaching interatomic spacing can be prepared in this fashion. The experimental x-ray measurements are found to be in good qualitative and quantitative agreement with model calculations.

Neutron scattering studies of elementary excitations can now, for the first time, be extended to the microelectronvolts resolution range by the use of the newly developed neutron spin-echo method. The first such experiment is described, and its results are shown to complement substantially previous knowledge on the temperature dependence of the energy and lifetime of the roton excitation, and the suggested onset of three-phonon decay beyond the roton minimum in superfluid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$.

The ratio of Stokes-to-anti-Stokes phonon Raman scattering of a proble laser pulse at 405 nm is used to obtain a direct measure of the lattice temperature in silicon within 10 nsec after a heating pulse at 485 nm. A lattice temperature rise of only 300°C is found with a heat pulse power density of ∼1 J/${\mathrm{cm}}^2$. Since silicon melts at 1412°C, this result is direct evidence that strictly thermal melting models of laser annealing are inappropriate.

X-ray diffraction investigations of both nematic and smectic phases of a number of compounds containing cyano end groups have revealed several of them to have a novel structure. This consists of two coexisting mass density fluctuations (heavily damped for the nematics) with incommensurate wavelengths corresponding, respectively, to some-what less than the molecular length $l$ and to the cyano "bilayer" spacing ($\sim 1.4l$).