New atomic-mass determinations are reported which establish the masses of ${}_{}{}^{174}{}_{}{}^{}\mathrm{Hf}$ and ${}_{}{}^{180}{}_{}{}^{}\mathrm{W}$ with significantly improved precision, and lead to new values for the double-neutron separation energies $S_{2n}$ of ${}_{}{}^{176}{}_{}{}^{}\mathrm{Hf}$, ${}_{}{}^{180}{}_{}{}^{}\mathrm{W}$, and ${}_{}{}^{182}{}_{}{}^{}\mathrm{W}$. A plot of $S_{2n}$ in the region $94<~N<~114$ now shows systematic downward breaks at $N=98, 104, \mathrm{and} 108$. These features are interpreted in terms of energy gaps above the Nilsson single-particle levels ${\frac{9}{2}}^{+}\mathrm{}\left[624\right]\mathrm{}$ ($N=108\mathrm{}$), ${\frac{5}{2}}^{-}\mathrm{}\left[523\right]\mathrm{}$ ($N=98\mathrm{}$), and ${\mathrm{½}}^{-}$[512] ($N=104\mathrm{}$).

Neutron particle-hole states in ${}_{}{}^{142}{}_{}{}^{}\mathrm{Nd}$ have been populated in the reaction ${}_{}{}^{142}{}_{}{}^{}\mathrm{Nd}(p, p^{\prime })$ on the 9.50-MeV, ${\frac{7}{2}}^{-}$ analog resonance and in the reaction ${}_{}{}^{143}{}_{}{}^{}\mathrm{Nd}(d, t)$. Analysis of the inelastic scattering data gives inelastic partial widths and spectroscopic factors. These results are compared with the distorted-wave Born-approximation analysis of the reaction ${}_{}{}^{143}{}_{}{}^{}\mathrm{Nd}(d, t)$.

We discuss differences which differing mechanisms for multiparticle production imply for inclusive nuclear scattering.

$K\alpha$ transitions of neon are resolved, with a curved-crystal spectrometer, into eight components corresponding to varying amounts of multiple $L$-shell ionization. The degree of multiple $L$-shell ionization of neon increases with an increase of the projectile charge state of 30-MeV oxygen ions. The change in the neon satellite structure for the ${\mathrm{O}}^{+7\mathrm{}}$ case as compared to the ${\mathrm{O}}^{48}$ case (bare nuclear charge) is substantial. An effective fluorescence yield is extracted from the data and agrees with a recent value obtained from poor-resolution Auger-electron and x-ray measurements.

Observational evidence and the theoretical interpretation indicate that magnetic disturbances exterior to the plasmasphere boundary (within the magnetosphere) can excite damped, sinusoidal oscillations, which can be inferred as a magnetohydrodynamic surface eigenmode, at the plasmapause. The wave frequency and damping rate can be used to infer the plasma density inside the plasmapause and the plasma density gradient at the plasmapause.

The isotropic-cholesteric and cholesteric-smectic-$A$ phase transitions in cholesteryl oleyl carbonate have been studied for pressures up to 7 kbar. The latter transition possesses a tricritical point at 2.66 kbar and 60.3°C, where the behavior changes from first to second order.

We investigate the properties of a one-dimensional model of the electron-phonon system which exhibits the Peierls instability. The instability tends to suppress BCS pairing, and the resulting Peierls state below the structural transformation is semiconducting. Results of the conductivity calculation compare favorably with recent measurements on most samples of tetrathiofulvalinium tetracyanoquinodimethane but cannot explain the extraordinary conductivity peaks found in a few samples.

Experimental data are presented which indicate that the trapping rate of positrons per unit vacancy concentration in gold is temperature independent.

Investigations of intrinsic surface states have been generalized beyond the nearly free-electron model. Simple conditions for the existence of surface states have been derived, and these results are presented. Detailed calculations have been made for transition metals, in particular for copper, and reveal that a substantial density of surface states (i.e., ∼ 1 per surface atom) is a common occurrence.

The neutron-proton differential cross section at 50.0 MeV has been measured to a precision of ≃ 2% for backward-hemisphere c.m. angles and ≃ 3% for forward angles, both relative. The present data are not in good agreement with the previous $n-p$ measurements near this energy. A preliminary phase-shift analysis using the present data produces more satisfactory results, particularly for the ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ phase shift.

Elemental yields have been measured for the nuclei produced in the reactions of 100- and 180-MeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ on ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$. Fusion cross sections, including those followed by fission, are derived using charge conservation. At 180 MeV the apparent limiting angular momentum for fusion is $40\hslash$, in excellent agreement with a liquid-drop calculation. Fission does not account for more than 18% of the fusion cross section at 180 MeV, unless that fission is of an extremely asymmetric nature indistinguishable from the evaporation of small particles.

The daughter x-ray identification technique has been applied to the identification of element 104. The characteristic $K$-series x rays from the $\alpha$-decay daughter isotope, nobelium ($Z=102\mathrm{}$), have been observed in coincidence with $\alpha$ particles from the decay of 4.5-sec ${}_{}{}^{257}{}_{}{}^{}104$, thus providing an unequivocal determination of the parent atomic number, $Z=104\mathrm{}$.

Carbon, oxygen, and heavier nuclei have been observed below 8 MeV per nucleon during solar quiet times. We find that the C/O abundance ratio is 0.8±0.4, the N/O ratio is 0.4±0.25, and the differential energy spectra below 1 MeV per nucleon have the form $K{E}^{-4.9\mathrm{}\pm 0.3}$. We infer from this spectral form that most of these particles are likely to be of solar origin. The large errors on the abundance ratio do not allow a decisive answer to the likely origin.

We report results from a high-statistics study of the reaction ${\pi }^{-}p\to n{\pi }^0{\pi }^0$ between 1.6 and 2.4 GeV/c, in which all the final-state particles were detected. The $2{\pi }^0$ mass spectrum exhibits a marked enhancement in the region of 800 MeV, which is narrower in width than predicted by the recently reported "down-down" solution for $I=0\mathrm{}$, $S$-wave, $\pi -\pi$ phase shifts.

Exact SU(3) predicts equal production of ${\pi }^{+}{\pi }^{-}$ and $K^{+}{K}^{-}$ final states, while $K^0{\overline{K}}^0$ is forbidden as a result of cancelation between isovector and isoscalar photon contributions. Symmetry breaking destroys coherence between $p$-, $\omega$-, and $\varphi$-like photon components. Branching ratios $\frac{\frac{{\pi }^{+}{\pi }^{-}}{K^{+}{K}^{-}}}{\frac{K^0}{{\overline{K}}^0}}$ calculated under various coherence assumptions give different results. Experimental measurements should test this interference and give insight into the role of photon SU(3) structure in deep annihilation.

Recent $S$-matrix arguments for the existence of nonplanar contributions to scattering amplitudes are reviewed and compared with experiment. The correct normalization of the two-particle correlation function is discussed.

We suggest that baryon-number conservation may not be absolute and that an integrally charged quark may disintegrate into two leptons and an antilepton with a coupling strength $G_B{m_p}^2\lesssim {10}^{-9\mathrm{}}$. On the other hand, if quarks are much heavier than low-lying hadrons, the decay of a three-quark system like the proton is highly forbidden (proton lifetime ≳ ${10}^{28}$ y). Motivation for these ideas appears to arise within a unified theory of hadrons and leptons and their gauge interactions. We emphasize the consequences of such a possibility for real quark searches.

Differential cross sections have been measured for the reaction ${\pi }^{-}p\to \overline{p}d$. At 4 GeV/c the total cross section is 0.58 ± 0.08 μb with an angular distribution consistent with isotropy. At 5 GeV/c a pronounced forward dip occurs. In contradiction to simple baryon-exchange models, the cross section is found to be an order of magnitude smaller than that for the line-reversed reaction $\mathrm{pp}\to {\pi }^{+}d$. Upper limits for ${\pi }^{-}d\to \overline{p}t$ were also found.

New experimental measurements of the frequency separations of 30 pairs of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${}_{}{}^{16}{}_{}{}^{}\mathrm{O}_2^{}{}_{}{}^{}$ laser lines in the 10.4-μm band and 26 pairs in the 9.4-μm band have been made with Lamb-dip—stabilized lasers. The use of a Josephson junction as the frequency-mixing element simplified the measurements. Uncertainties in existing rotational constants for the laser vibrational levels were reduced 20 to 30 times and an additional rotational constant $H_v$ was determined for the first time.

Angular correlations were measured by delayed coincidences between electrons of incident energy about 80 eV scattered inelastically from helium and photons from excited $3{}_{}{}^1{}_{}{}^{}P$ and $2{}_{}{}^1{}_{}{}^{}P$ states. From the angular correlation in each case we deduce the ratio of the differential cross sections for exciting the magnetic sublevels of the excited state and the phase between the corresponding excitation amplitudes. We compare the atomic radiation patterns with those predicted by the Born approximation.