We have observed substantial ${\Delta }^{++}\mathrm{}\left(1236\right)\mathrm{}$ production in the inclusive reaction $p+p\to {\Delta }^{++}+\mathrm{everthing}$ at 303 GeV/c ($\sqrt{s}=23.9\mathrm{}$ GeV). This process with $t_{p,\Delta }<1.0\mathrm{}$ Ge${\mathrm{V}}^2$ accounts for ∼14% of the total $\mathrm{pp}$ inelastic cross section. The mean invariant mass of "everything" is ∼11 GeV, which implies that the ${\Delta }^{++}$ is usually part of a higher-multiplicity system moving in its hemisphere. The distribution in squared transverse momentum to the ${\Delta }^{++}$ falls off exponentially with a slope of about 12 Ge${\mathrm{V}}^2$.

The specific heat is calculated in the transition region for an extreme type-II bulk superconductor [zero-temperature Ginzburg-Landau (GL) coherence length $\xi \mathrm{}\left(0\right)\mathrm{}\approx 48$ Å, dirtiness parameter $\frac{{\xi }_0}{l}\approx 120$, GL parameter $\kappa \approx 67$] for various values of applied magnetic field $H$, and compared with previously published data. Nonlocality is neglected and the quartic term in the GL free-energy functional is treated in a Hartree approximation. The calculated and measured transitions broaden with increasing $H$, the latter in a manner suggestive of an approach to the theoretically predicted one-dimensional form.

$K$ Auger-electron and $K$ x-ray yields of Ne have been measured simultaneously in 30-MeV ${\mathrm{O}}^{7+}$ collisions with Ne. Both spectra are dominated by satellite transitions. The Ne $K$-shell fluorescence yield is 2.4 times larger than found in identical measurements using 5-MeV incident protons.

The variation with temperature of the destruction rate of metastable states in He II is accounted for in terms of their roton-limited diffusion. Rough estimates of the reaction distance at which collision-induced destruction occurs are consistent with a "bubble" model for the metastable systems.

The measurement of the dc electric plasma resistivity perpendicular to the magnetic surface in a toroidal device was carried out using the FM-1 spherator. It was found that the perpendicular resistivity is inversely proportional to the neutral gas density and is independent of plasma density for a ${\mathrm{He}}^{+}$ plasma at $T_e=1\mathrm{}$ eV. These parametric dependences are consistent with the resistivity expected from classical collisional processes.

Observations of anomalous growth of electrostatic modes in computer simulations of the Weibel instability have led to the formulation of a second-order analytic description of the coupling of transverse magnetostatic modes to longitudinal electrostatic modes. Comparison of the theoretical values for the coupling constants with those measured in numerical experiments shows agreement to within 5% for both magnitude and phase.

We demonstrate that a circularly polarized electromagnetic wave propagating through a cold plasma and strong enough to make electrons relativistic (${\nu }_0\equiv \frac{e{E}_0}{m_{e}c{\omega }_0}\gtrsim 1$) is subject to a new pinching type of instability. The linearized equations are solved exactly, without the necessity of introducing an infinite determinant. This allows our results to describe the transition from nonrelativistic to extreme-relativistic electron motion. In the relativistic limit, the growth rates are as high as $0.47{\omega }_0$.

Unsupported films with thicknesses of the order of the wavelength of light are shown to have Brillouin peaks with triplet or quadruplet structure, reflecting the discrete values of the phonon wave vector perpendicular to the surface of the film. The observation of this structure in the spectra of a polymer and a crystal film is reported here. The feasibility of making a high-frequency phonon spectrometer using thin films is discussed.

Electrical conduction in Nb/${\mathrm{Al}}_2$${\mathrm{O}}_3$ cermet films at low temperatures shows the presence of a new form of hopping conduction through localized states. In this mechanism the dielectric plays an essential role, behaving like an amorphous wide-band-gap semiconductor and acting as host to a distribution of localized states due to Nb dispersed, on an atomic scale, in the alumina matrix.

We present thermomodulated optical absorption data near the fundamental edge of SrTi${\mathrm{O}}_3$ which gives, at the cubic-to-tetragonal phase transition, the first evidence of a second-order transition affecting the electronic energy levels. Enhanced absorption at the indirect gap energy is observed and attributed to relaxation of momentum conservation, via electron scattering at fluctuating domain boundaries. This extra absorption peaks at the transition temperature, where phase fluctuations are maximum.

Total neutron cross sections of deuterium have been measured from less than 1 keV to 1000 keV. We also performed a three-body calculation of $n-\mathrm{D}$ total scattering cross sections, using separable potentials. The theoretical and experimental results show good agreement. A marked increase in cross section is observed for decreasing energy below 300 keV. We discuss the implications of the results with respect to discrepancies in previously measured $n-\mathrm{D}$ scattering lengths.

The reaction ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}\mathrm{}(t,h)\mathrm{}{}_{}{}^{58}{}_{}{}^{}\mathrm{Co}$ has been studied at an incident triton energy of 23.5 MeV. Among the low-lying levels are several $1^{+}$ states which are selectively populated. Based on this selectivity and their energy centroid, it is proposed that these states contain an appreciable fraction of the $T_0+1\mathrm{}$ analogs of the giant $M1\mathrm{}$ resonance in ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$.

We have measured the polarization of the recoil proton in the reactions $\gamma p\to {\pi }^{0}p$ and $\gamma p\to \gamma p$ for incident photon energies between 3 and 7 GeV, and $t$ values from -0.2 to -0.65 Ge${\mathrm{V}}^2$. The polarization in neutral-pion production varies from 0 to -1 over this range. Contrary to expectation, it does not agree completely with the polarized-target asymmetry.

We have measured the differential cross section for small angle $p-p$ scattering from 25 to 200 GeV incident energy and in the momentum transfer range $0.015<\mathrm{}\left|t\right|<0.080\mathrm{} {\left(\frac{\mathrm{GeV}}{c}\right)}^2$. We find that the slope of the forward diffraction peak, $b\left(s\right)\mathrm{}$, increases with energy and can be fitted by the form $b\left(s\right)=b_0+2\mathrm{}{\alpha }^{\prime }$ lns, where $b_0=8.3\mathrm{}\pm 1.3$ and ${\alpha }^{\prime }=0.28\mathrm{}\pm 0.13 {\left(\frac{\mathrm{GeV}}{c}\right)}^{-2\mathrm{}}$. Such dependence is compatible with the data existing both at higher and lower energies. We have also obtained the energy dependence of the $p-p$ total cross section in the energy range from 48 to 196 GeV. Within our errors which are ± 1.1 mb the total cross section remains constant.

From observations of photon conversions into electron pairs in the 30-in. hydrogen bubble chamber exposed to a 205-GeV proton beam at the National Accelerator Laboratory, we have measured topological and differential cross sections for the inclusive reaction $p+p\to {\gamma }^{+}$ anything. Comparison with data on the same reaction at the CERN intersecting storage rings suggests that ${\pi }^0$ production in $\mathrm{pp}$ collisions has reached a scaling limit by 205 GeV. We find that for multiplicities up to about 12, the average number of ${\pi }^0$'s per inelastic $\mathrm{pp}$ collision increases with the number of charged particles produced.

The forward peak in $n-p$ charge-exchange reactions is accounted for by a simple Born model. The value of the peak is shown to be due to $u$-channel ${\pi }^0$ exchange, whereas its shape is found to be determined by the interference between the above mentioned ${\pi }^0$ contribution and a ${\pi }^{+}$ exchange in the $t$ channel. The agreement with the data is fairly good for all incident momenta above 3 $\frac{\mathrm{GeV}}{c}$ and for a range of momentum transfer $0<\mathrm{}\left|t\right|<0.005\mathrm{} {\left(\frac{\mathrm{GeV}}{c}\right)}^2$.

Assuming a weak interaction invariant under $\mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_M\otimes \mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_I$, we show that $M$-spin conservation leads to the rule $A\left({\nu }_e{e}^{-}\right|{\nu }_e{e}^{-})-A({\nu }_{\mu }{e}^{-}\left|{\nu }_{\mu }{e}^{-}\right)=A\left({\nu }_e{\mu }^{-}\right|{\nu }_{\mu }{e}^{-})$ and to other sum rules for leptonic, semileptonic, and trident production processes. The additional assumption of total isospin conservation yields simple relations for lepton-hadron scattering. We also show that $\mu$ decay is forbidden in lowest order for various symmetry schemes such as the SU(3) and O(3) theories based upon the Konopinski-Mahmoud assignment of lepton number.

An electron transmission experiment is used to study the resonances in the total scattering cross section of atomic hydrogen below the threshold of the first excited state. The three lowest resonances, designated ${}_{}{}^1{}_{}{}^{}S$, ${}_{}{}^3{}_{}{}^{}P$, and ${}_{}{}^1{}_{}{}^{}D$, are observed and their energies and decay widths are found to be in good agreement with the values predicted theoretically using close coupling with correlation.

Parametric resonances associated with zero-field level crossings of the $2^3{S}_1$ level of ${\mathrm{He}}^4$ have been investigated using transverse optical pumping. A steady-state technique based on the $n=0\mathrm{}$, $p=0\mathrm{}$ resonance (Hanle effect) is used to measure spin-state lifetimes and determine the dependence of the thermal relaxation time on the state of the active helium discharge. The $n=0\mathrm{}$, $p=1\mathrm{}$ resonance is quite strong and suitable for measuring weak magnetic fields. A sensitivity of 1.0 × ${10}^{-8\mathrm{}}$ G is demonstrated for this measurement technique.

New measurements of the polarization of the $6^1{S}_0-6^3{P}_1$ (2537-Å) line of mercury are presented for electron impact energies between threshold at 4.9 and 8.0 eV. A large negative threshold polarization is indicated which falls to zero within a few tenths of an eV, rising again to maximum of - 46% at 6.5 eV. Correlation of structure in the polarization and excitation functions suggests a compound-ion formation.