We present measurements of the superconducting transition temperature of ultrathin aluminum films grown epitaxially on silicon. The transition temperature is found to be near the bulk $T_c$ and is significantly lower than that found in disordered films. Some initial experiment on growing epitaxial Pb films on PbTe are also discussed.

From a study of the ($p, t$) reaction on ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}$ and ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ca}$, $J^{\pi }$ of the 1.41-MeV state in ${}_{}{}^{43}{}_{}{}^{}\mathrm{Sc}$ is inferred to be ${\frac{7}{2}}^{-}$. It is found that both the absolute cross sections and angular distribution shapes for this transition are almost identical with those for the transition to the 1.84-MeV $0_2^{+}$ state in ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$ (as are the corresponding ground-state transitions). It is suggested that the 1.41-MeV state in ${}_{}{}^{43}{}_{}{}^{}\mathrm{Sc}$ consists primarily of the $0_2^{+}$ excited state of the ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$ core with an $f_{\frac{7}{2}}$ proton weakly coupled to it, just as ${}_{}{}^{43}{}_{}{}^{}\mathrm{Sc}$(g.s.) consists mainly of ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$(g.s.) plus an $f_{\frac{7}{2}}$ proton.

In the reaction 34-GeV ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}+\mathrm{Au}\to Z$, fragments with $6<~Z<~15$ are emitted with higher than geometric cross section and with a broad distribution of energies extending down to ∼ 0.8 MeV/nucleon. Such low kinetic energies are far below the hard-sphere Coulomb barrier and may imply extreme distortions of a nucleus raised to high temperature by the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ ion.

The force of radiation pressure on the free surface of a transparent liquid dielectric has been observed using focused pulsed laser light. It is shown that light on either entering or leaving the liquid exerts a net outward force at the liquid surface. This force causes strong surface lens effects, surface scattering, and nonlinear absorption. The data relate to the understanding of the momentum of light in dielectrics.

We report measurements of ${\rho }^0$ and $\varphi$ electroproduction at 19.5 GeV in a wide-aperture spectrometer which detected the scattered electron and the decay products of the vector mesons. As $\left|q^2\right|$ increases, the $\rho$ mass spectrum shape changes, the momentum-transfer distribution broadens, and the ratio of the $\rho$ cross section to the total cross section decreases. The ratio of longitudinally to transversely polarized ${\rho }^0$ mesons is ${0.45}_{-0.10\mathrm{}}^{+0.15\mathrm{}}$ at $\left|q^2\right|=m{\rho }^2$, and the interference between longitudinal and transverse amplitudes is almost maximal. The relative $\varphi$-meson cross section also decreases as $\left|q^2\right|$ increases.

Backward scattering in the reaction ${K_L}^{0}p\to p{K_S}^0$ is studied in the momentum interval 1.0 to 7.5 GeV/c. Comparison of ${K_L}^{0}p\to p{K_S}^0$ and $K^{+}p\to p{K}^{+}$ backward scattering, where respectively $\Sigma$ exchange and $\Lambda$ plus $\Sigma$ exchange can contribute in the $u$ channel, reveals that ${\left(\frac{d\sigma }{d\Omega }\right)}_{180°}({K_L}^{0}p\to p{K_S}^0{\left(\frac{d\sigma }{d\Omega }\right)}_{180°}(K^{+}p\to p{K}^{+})$ above the resonance region. This result provides direct evidence for the dominance of the $\Lambda$ contribution over the $\Sigma$ contribution in the $K^{+}p\to p{K}^{+}$ production amplitude.

We have measured the differential photoproduction cross section $\frac{d\sigma }{\mathrm{dt}}$ for the production of $\varphi$ mesons as a function of $t$ at a photon energy of 12 GeV from $\mathrm{}\left|t\right|=0.2\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ to $\mathrm{}\left|t\right|=1.0\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$, and as a function of photon energy from 6 to 19 GeV at a $\mathrm{}\left|t\right|\mathrm{}$ of 0.6 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. Our results, and all other world data, fall on a universal curve. The slope of the Pomeranchukon trajectory deduced from this experiment is ${\alpha }^{\prime }=-0.03\mathrm{}\pm 0.13$.

Studies of the single-particle transfer reactions ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}(d, p){}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$ and ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}(d, t){}_{}{}^{238}{}_{}{}^{}\mathrm{Pu}$ indicate that—contrary to theoretical expectations—the ratios of the cross sections for population of the $K^{\pi }=0^{+}$ excited states to those for population of the ground states are of the same order of magnitude as the ratios for the equivalent ($p, t$) reactions.

The requirement of unitarity, together with the theory of the refractive index, puts a limit on the wave number of a pion (of given energy) in nuclear matter (of given density). A paradox in the conventional theory of pion scattering by complex nuclei is thereby avoided.

An improved method of particle detection is described, utilizing both the x-ray transition radiation and the ionization of a gas by the particle.

The orbit equations of Papapetrou are the basis for a study of spinning test bodies in a Schwarzschild or Kerr metric field. The constant of the motion for a Killing vector of an arbitrary metric field is given. An analysis of test-body equatorial motion suggests that significant departures from the results of geodesic motion such as larger maximum binding and orbits completely stable against capture may be expected for objects with large intrinsic spin.

The nonlinear development of the instability excited by a cold, weak electron beam injected into a one-dimensional plasma is examined with a fast electron velocity analyzer. The distribution of the electrons in phase space is observed as the instability grows, traps the beam, and oscillates. The observed distributions mirror those first seen in computer simulations which lead to the trapping hypothesis.

We show that a many-body Hamiltonian, expressed in terms of renormalized quasiparticle operators, has interactions only on the energy shell. Our result justifies the method of Havlin and Luban, who resolve the discrepancy between the theoretical and experimental velocity of sound in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. It also follows that the phonon spectrum must be concave at low momenta.

It is shown that the linear splitting in a magnetic field of the thermal anomaly ($A$) observed recently in liquid ${\mathrm{He}}^3$ at about 2.5 mK can be explained by postulating pairing in a state of odd relative angular momentum. Further structure is predicted, and implications of the theory and experiment are discussed.

In a cold beam-plasma system unstable for $f>\mathrm{}{f}_{\mathrm{ce}}$, two waves are launched, one at $f_0$, with large growth rate, and a small test wave at $f_T$, with small growth rate. The wave at $f_0$ saturates because of beam trapping, independent of the test-wave amplitude. After the beam is trapped, the test wave ceases growing and exhibits amplitude oscillations in phase with large wave. This is consistent with a linear interaction of the test wave with the modified electron beam.

The resonant nonlinear interactions of two waves with the gyromotion of the electrons stabilize the high-frequency modes of the $\overrightarrow{\mathrm{E}}\times \overrightarrow{\mathrm{B}}$ electron drift instability, but further destabilize the low-frequency modes. However, the total wave energy is stabilized by this mechanism, whereas wave-wave scattering processes transfer energy from the unstable region of the spectrum toward the nonlinearly damped one. The predicted turbulence level at $K=\frac{1}{{\lambda }_{\mathrm{D}}}$ is in good agreement with experimental results.

Calculations predict that carefully timed laser pulses can implode small DT spheres and shells to extreme densities such that thermonuclear burn ensues. We characterize the implosion quality as a function of the pulse time scale, growth law, and initial intensity. Phenomenological rules for mass scaling, input energy threshold, and yield ratio $Y_R=\frac{E_{\mathrm{out}}}{E_{\mathrm{in}}}$ are presented. We find that $Y_R=4.7\mathrm{}$ for only 1.9 kJ of C${\mathrm{O}}_2$ laser input energy to a 3-μg shell. The performance of shells is compared to spheres.

The superconducting transition temperatures of "amorphous" transition-metal alloys have been measured. The variation of $T_c$ as a function of the electron-to-atom ratio is consistent with the presence of an atomiclike parameter characterizing the systematics of $T_c$, with, however, an unexplained peak at the half-filled $d$ shell. The data do not support a recent explanation based entirely on a simple averaging or smearing of the crystalline electronic density of states.

Ultrasonic spin echoes, or phonon echoes, have been observed under nearly ideal conditions from $\Delta M=1\mathrm{}$ and $\Delta M=2\mathrm{}$ transitions of ${\mathrm{Fe}}^{2+}$: MgO. The echo decays were found to be the same as the magnetic echo decay, and to follow an $\exp (-k{t}^2)$ dependence. These results are attributed to Lorentzian spectral diffusion.

Isospin-dependent potentials, determined from observed quasielastic ($p, n$) angular distributions, and a good set of proton optical potentials, are used to determine a set of neutron optical potentials. The elastic scattering predictions from these neutron potentials agree with existing neutron scattering data.