We present a new measurement of the decay rates of the $K\left(1420\right)\mathrm{}$ produced in $K^{-}p$ interactions. In addition to improved statistics, the $K\left(1420\right)\mathrm{}$ is observed in final states where the absence of the $Q$ enhancement allows an unambiguous determination of the branching ratios. The values obtained agree with SU(3) predictions.

We have demonstrated the feasibility of a new method of polarizing high-energy photons, by preferential attenuation of photons polarized in one plane as a result of coherent pair production on passage through a single crystal of specific orientation. Highly oriented graphite is a particularly favorable material. The method, feasible at presently available energies, is predicted to be especially useful at higher energies.

We report a comparison of the Dalitz-plot distributions of 1.6 million ${\tau }^{+}$ decays ($K^{+}\to {\pi }^{+}{\pi }^{+}{\pi }^{-}$) and an equal number of ${\tau }^{-}$ decays. No significant asymmetry has been found in any region of the plot. In terms of the difference in the slope parameters $a^{+}$ and $a^{-}$ for the odd-pion c.m.-energy spectra, the asymmetry is $\Delta =\frac{(a^{+}-a^{-})}{(a^{+}+a^{-})}=-0.0070\mathrm{}\pm 0.0053$. We also present a preliminary result for the slope parameter itself: $a=0.283\mathrm{}\pm 0.005$. New measurements of the ${\tau }^{\pm }$ decay rates and their difference confirm previous results.

We report a high-statistics experiment measuring the structure of $e^{+}{e}^{-}$ mass spectrum from photoproduction of $\rho$ and $\omega$ mesons. At 5.1 GeV, based on 4000 events, analysis of the spectra yields a ratio of vector-meson-photon coupling constants $\frac{{{\gamma }_{\omega }}^2}{{{\gamma }_{\rho }}^2}={9.4}_{-1.6\mathrm{}}^{+2.6\mathrm{}}$ and a $\rho -\omega$ phase difference ${\varphi }_{\omega \rho }={41}^{\circ }\pm {20}^{\circ }$.

We have measured large-angle electron-positron pairs from the reaction $\gamma +\mathrm{Be}\to \mathrm{Be}+e^{+}+e^{-}$ in the $e^{+}{e}^{-}$ invariant-mass region $610<m<\mathrm{}850\mathrm{} \frac{\mathrm{MeV}}{c^2}$. The phase of the photoproduction amplitude of the $\rho$ meson at 4.1-6.1 GeV was found to deviate from pure imaginary by 11.8°±4.4° which corresponds to a ratio of the real to imaginary $\rho$-nucleon amplitude of $\beta =0.2\mathrm{}\pm 0.1$.

We measured the polarization of the recoil proton in the process $\gamma p\to p{\eta }^0$, at 90° in the center-of-mass system, at incoming photon energies from 0.8 to 1.1 GeV. Detection of all three particles in the final state $p\gamma \gamma$ permitted observation of this process with little background. Subsequent rescattering off carbon nuclei yielded sizable polarization values for the protons, indicating considerable $S-P$—wave interference in the production process.

Antiproton-neutron annihilations at rest ($L=0\mathrm{}$) into $G$-parity states of opposite sign are incoherent. This permits a measurement of the ratio $R=\frac{(\omega \to {\pi }^{+}{\pi }^{-})}{(\omega \to {\pi }^{+}{\pi }^{-}{\pi }^0)}$ in the absence of $\omega \mathrm{\rho }$ interference. In this way we find the upper limit $R<\mathrm{}4.3\%$ at the 97.5% confidence level ($\Delta {\chi }^2=4\mathrm{}$).

The structure of the pole-cut combination in $\pi N$ charge-exchange scattering for $t<~0$ is represented by a pair of complex poles. Excellent fits to the $\pi N$ charge-exchange differential cross section, polarization, and total cross-section difference ${\sigma }_t\left({\pi }^{-}p\right)-{\sigma }_t\left({\pi }^{+}p\right)$ are obtained for the two examples considered, $\mathrm{Im}\alpha =g\sqrt{-t}$ and $\mathrm{Im}\alpha =g$. The phases of the residues are allowed to vary and a zero in $\mathrm{Im}{A}^{{\prime }^{\mathrm{}(-)\mathrm{}}}$ (the "crossover" zero) is obtained.

We present a comparison of ${A_2}^{-}$ and ${A_2}^0$ production. The cross section for the production of ${A_2}^0$ falls much more rapidly with increasing energy than the ${A_2}^{-}$ cross section. The characteristics of the production processes seem to be very similar in other respects. These facts are hard to understand in terms of a Regge picture of the production process.

A beam of hydrogenic ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}_{}^{5+}{}_{}{}^{}$ atoms in the metastable $2S$ state has been produced. By quenching the state in a known motional electric field and measuring the decay length, an indirect measure of the Lamb shift $\mathcal{S}$ is obtained. A preliminary result of $\mathcal{S}=744\mathrm{}$ GHz, with a statistical uncertainty of less than 1%, is reported as compared with a theoretical prediction of $\mathcal{S}=783\mathrm{}$ GHz. Possible systematic effects which may reduce the discrepancy are considered.

The spatial variation in the response of the electronic charge distribution of an atom to an applied electric field is shown to be observable by means of a measurement of the spontaneous parametric decay of an x-ray pump into the optical region.

The lifetime of the $1s2s{}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}$ state of the heliumlike atom Ar XVII has been measured by observing the decay in flight of the metastable component of a fast foil-excited beam. The decay occurs predominantly by relativistic magnetic-dipole emission, a process first discussed by Breit and Teller. The result, $\tau \left(2\mathrm{}{}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}\right)=(172\mathrm{}\pm 30)\times {10}^{-9\mathrm{}}$ sec, is compared with a recent calculation by Drake of the $M1\mathrm{}$ transition probability.

The work reported here establishes the existence of $\mathrm{He}_3^{}{}_{}{}^{+}$ and $\mathrm{He}_4^{}{}_{}{}^{+}$ at room temperature (300°K) in a helium afterglow. The data presented in this paper indicate that the often-measured electron-ion recombination coefficient in 300°K helium afterglows is mainly attributable to electron recombination with $\mathrm{He}_3^{}{}_{}{}^{+}$ rather than, as is usually assumed, with the dominant ion $\mathrm{He}_2^{}{}_{}{}^{+}$.

Total relative emission cross sections for the production of He I, Ne I, and Ne II radiation have been measured as a function of energy in low-energy ${\mathrm{He}}^{+}$-Ne and ${\mathrm{Ne}}^{+}$-He collisions. These are the first ion-atom excitation measurements of atomic states populated through two different incoming pseudomolecular-potential curve channels. The oscillatory structure in the ${\mathrm{He}}^{+}$-Ne data can be explained in terms of phase-interference effects between potential curves at pseudocrossings occurring at large internuclear distances.

The asymptotic time behavior of the velocity autocorrelation function and of the kinetic parts of the correlation functions for the shear viscosity and the heat conductivity is derived. The results are expressed in terms of the transport coefficients and the specific heats and are valid for all densities.

Velocity correlation functions $\rho \mathrm{}\left(t\right)\mathrm{}$ in hard-disk and hard-sphere fluids are discussed on the basis of the kinetic theory of gases. It is found in $d$ dimensions that $\rho \mathrm{}\left(t\right)\mathrm{}\sim \alpha {\left(\frac{t}{t_0}\right)}^{-\frac{d}{2}}$ with $\alpha =O\left({\rho }^{d-1\mathrm{}}\right)$ (${t_0}^{-1\mathrm{}}=\mathrm{collision}\mathrm{frequency}$; $\rho =\mathrm{reduced}\mathrm{density}$). Expressions for $\alpha$ are given that seem correct at low densities and a good approximation at least up to half the close-packing density. The agreement with Alder and Wainwright's computer results is good.

The constant-volume heat capacity of liquid ${\mathrm{He}}^4$ has been measured from 0.3 K to above the $\lambda$ point. Below 0.9 K the phonon heat capacity corresponds to a dispersion relation $\epsilon =cp(1-\gamma p^2)$ with $\gamma$ varying from -4.1 × ${10}^{37}$ ${\mathrm{g}}^{-2\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\sec }^2$ at the saturated vapor pressure to 19.6 × ${10}^{37}$ ${\mathrm{g}}^{-2\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\sec }^2$ near the freezing pressure.

Experiments on nonlinear Landau damping and growth of longitudinal plasma waves that propagate nearly perpendicular to a magnetic field have been carried out. The measured value of the nonlinear wave-particle coupling coefficient is in good agreement with theory.

Electron cyclotron waves are shown to grow unstably in the presence of small relative drifts of a warm ion distribution perpendicular to the $B$ field. Numerical simulations show that this instability causes anomalous diffusion of plasma across the magnetic field and heating of the electron thermal spread to values much greater than the relative ion-electron drift velocity.

Magnetic field splitting of the quasiparticle energy states in superconducting aluminum films has been observed in a tunneling experiment. The magnitude of the splitting was found to be $2\mu H$, and is attributed to the magnetic moment of the quasiparticles. The observed tunneling conductance is in qualitative agreement with theory.