A measurement of the separation between the components of the binary star $\mu$-Cassiopeiae to yield the stellar masses has been made. Applying the mass-luminosity law, we find a helium abundance $Y\sim 0$ where a $1``\sigma "$ and $2``\sigma "$ random error allows, respectively, $Y\sim 0.05$ and $Y\sim 0.34$. The measured abundance places an upper limit on the helium production in a big bang cosmological model.

We measured six differential cross sections for ${\pi }^{-}p\to n\gamma$ at 490-MeV/c incident ${\pi }^{-}$ momentum. Our data do not agree with recent theoretical predictions. We find no evidence, in the sense suggested by Donnachie, for the classification of the Roper resonance, $P_{11}\mathrm{}\left(1460\right)\mathrm{}$, in an SU(3) antidecuplet. Our angular distribution is consistent with the classification of the Roper resonance in an octet, as predicted by the simplest quark models. Using detailed balance, our results agree well with the reported cross sections for the inverse reaction, which are deduced from $\gamma d$ data.

Two idealized collapse models, involving a magnetic dipole and a gravitational quadrupole, are analyzed, treating departures from sphericity as small perturbations. Radiative leakage (largely downwards through the Schwarzschild radius) causes externally observable asymmetries to decay to zero in an oscillatory fashion, with a period of the order of the Schwarzschild characteristic time $\frac{2Gm}{c^3}$. These results have significant consequences for astrophysics; they imply in particular that a "black hole" cannot be a source of synchrotron radiation.

A search is reported for octets among baryons of spin $<~\frac{5}{2}$, using the Gell-Mann-Okubo mass formula as a selection criterion. The likely number of unphysical "chance" octets so selected is estimated by another search using unphysical mass formulas. The findings discourage reliance on mass formulas for classification purposes, and tend somewhat against the existence of further octets.

The recently proposed fixed cuts are dualized. The resulting functions apparently allow construction of parity-doubling-free models for arbitrary processes. Applications are made to the reciprocal and meson bootstraps.

Experimental observations have been made of wave-particle interactions in counter-penetrating electron beams in a static magnetic field. A new technique is used to measure the electron-distribution function at every stage of wave growth, saturation, and decay. The particular instability discussed here occurs at one half the cyclotron frequency and has a density threshold for onset. As the wave grows, trapping of resonant particles in the wave-potential troughs becomes significant and the velocity distribution is appreciably broadened. Finally, "finite-temperature" stabilization prevails and the wave decays. The experimentally observed resonance width is in agreement with the predictions of strong turbulence theory.

Several types of vibrational surface modes have been found within the bulk continua in calculations for model crystals.

Using electron tunneling, we have made direct observation of a surface bound state of electrons localized in a narrow accumulation layer at the InAs-oxide interface. The Landau-level structure of the two-dimensional energy band, associated with the bound state, has been studied in a magnetic field up to 85 kG.

The electronic band structure of copper is calculated using the empirical pseudopotential method. A nonlocal $d$-wave potential with a damping factor is used to provide the potential for the $d$ electron. The results agree well with the available experimental data and with theoretical band calculations using other methods. It is anticipated that the empirical pseudopotential method can be used for other noble metals and even extended to noble metal compounds, transition metals, and transition metal compounds.

Measurements of high-resolution photoemission-energy distributions have been extended beyond 11.6 eV (LiF-window cutoff) for Cu, Ag, and Au. Surprisingly sharp structure ($\Delta E\sim 0.3$ eV, i.e., resonance $\Delta \equiv \frac{E}{\Delta E}\simeq 50$) is resolved at these high energies. These new results show $d$-band widths of 3.0, 3.5, and 5.7 eV for Cu, Ag, and Au, respectively, and show dramatic evidence (nonstationary structure and amplitude effects) for direct transitions.

We show that the appearance of a localized moment on Ni atoms in the critical range of concentration is accurately described by a simple environment-dependent model of the Jaccarino-Walker type, and that this model implies a "clustering" of magnetic moments, even on the basis of a random distribution of atoms. The fit with experimental data is promising in view of the approximations made.

The $g$ factor of the (${h_{\frac{9}{2}}}^2$) $8^{+}$ state of ${}_{}{}^{210}{}_{}{}^{}\mathrm{Po}$ has been determined to be 0.911 ± 0.010 by the pulsed generation of the aligned isomeric state in the reaction ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}(\alpha , 2n)$. This $g$ factor agrees within 1% with that of the $h_{\frac{9}{2}}$ ground state of ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$, indicating that the $h_{\frac{9}{2}}$ proton carries the same renormalized anomalous magnetic moment both in ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ and in ${}_{}{}^{210}{}_{}{}^{}\mathrm{Po}$.

The photoneutron cross section for ${\mathrm{Mg}}^{25}$ has been measured from 30 to 2000 keV above threshold. The locations of the isobaric analogs of the ground and first excited states of ${\mathrm{Na}}^{25}$ have been assigned and lower limits for their neutron-decay widths have been determined.

Angular distributions previously found to be characteristic of the spin change for (${}_{}{}^3{}_{}{}^{}\mathrm{He}$, $t$) transitions in even-mass $f_{\frac{7}{2}}$-shell nuclei are found to characterize transitions for a number of even- and odd-mass nuclei in the $s-d$ shell. It appears that this may be due to certain strong selectivities in the orbital angular momentum transfer.

Using a highly realistic effective interaction, it is shown that nuclear ferromagnetism in neutron-star matter is not possible for densities of $k_{\mathrm{F}}<1.8\mathrm{}$ ${\mathrm{fm}}^{-1\mathrm{}}$.

Evidence is presented to confirm the existence of a new $\Lambda \pi$ resonance in the $\Lambda {\pi }^{+}{\pi }^{-}{\pi }^{-}$ final state from $K^{-}d$ interactions at 4.5 GeV/c. A mass of 1642 ± 12 MeV and a width of 55 ± 24 MeV are obtained. Upper limits on $\Sigma \pi$ and $\Lambda \mathrm{}\left(1405\right)\mathrm{}\pi$ branching ratios are obtained for the first time. The branching ratios are found to be consistent with an octet assignment.

We have measured the momentum-transfer dependence of the cross section and density matrix elements for single-pion production in pion-nucleon collisions. The results show nonevasive contributions for small $t$. A forward peak is seen in the extrapolated transverse cross section, in qualitative agreement with some versions of vector-meson dominance.

We present results on measurements of photoproduction of ${\rho }^0$ mesons from seven different nuclei. The forward cross sections are analyzed in terms of the $\rho$-nucleon total cross section and the $\gamma -\rho$ coupling constant, giving $\sigma (\rho , N)=26.8\mathrm{}\pm 2.4$ mb and $\frac{{{\gamma }_{\rho }}^2}{4\pi }=0.62\mathrm{}\pm 0.12$.

We show how electron-positron storage rings may be used to obtain information on hadronic states with even charge conjugation. This is illustrated by studying the reaction $e^{-}{e}^{+}\to {\pi }^{-}{\pi }^{+}\gamma$, the analysis of which should reveal information on even-$C$ di-pion resonances, such as the existence of the $\epsilon$ meson.

A sharp-pinch model of a dense constant-pressure plasma surrounded by a pressureless plasma with force-free magnetic fields of constant $\alpha$ is shown to be completely magnetohydrodynamically stable with respect to kinks, surface-layer modes, and modes of the pressureless plasma. Its property of having a high shear will also suppress Suydam modes.