A concept of asymptotic symmetry is formulated and applied to the determination of mixing parameters between the ${\pi }^0$, ${\eta }^0$, and ${\eta }^{{\prime }^0}\mathrm{}\left(958\right)\mathrm{}$ in broken SU(3) and SU(2) symmetries. One of the solutions gives rise to a rather large violation of the $\left|\Delta \overrightarrow{\mathrm{I}}\right|=\frac{1}{2}$ rule in the $K_{l3\mathrm{}}$ decays which is not inconsistent with present experiment.

It is shown that many of the features of the recent data on the reaction $\overline{p}n\to {\pi }^{-}{\pi }^{+}{\pi }^{-}$ may be explained without recourse to a Veneziano model. A direct fit of particle parameters is obtained by parametrizing the amplitude in terms of the resonance poles in the two nonexotic channels. The existence of daughters is found to be crucial to the fit to the data. No evidence is seen of higher spin resonances; and in all cases, the daughter mass is not degenerate with the parent mass.

We investigate the use of a tunable spin-flip Raman laser in infrared absorption spectroscopy. The Raman laser is tunable from 10.9 to 13.0 μm with linearity and resettability of tuning better than ∼4 ÅA at ∼12.0 μm. This limit is set by the present measurement capability. A study of the absorption spectrum of N${\mathrm{H}}_3$ in the 12.0-μm region shows that the spin-flip Raman laser is superior to a conventional grating spectrometer in attainable resolution.

Differential collision cross sections in the elastic scattering of helium beams are reported. A supersonic room-temperature primary beam and a multichannel low-temperature secondary beam have been used. The first quantum oscillation has been resolved. The results are compared with cross sections computed numerically, describing the interaction by means of potentials previously reported in the literature. Computed predictions are in fair agreement with experimental results.

Measurements of electron spin polarization resulting from inelastic electron scattering by mercury (excitation of the $6{}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ state; 6.7-eV energy loss) are reported. The angular dependence of the polarization has been measured for incident energies of 25, 30, 50, and 180 eV.

We prove that for quantum systems with hard-core or repulsive interactions, the pressure is a continuous function of the density, for Boltzmann particles and for bosons at low density.

The Slater KDP (potassium dihydrogen phosphate) model of hydrogen-bonded ferro-electrics is generalized by relaxing the ice condition. For a class of realistic choices of energy parameters, it is shown that this model is equivalent to an Ising model and consequently exhibits an Ising-type transition. Our result suggests that the singularity in the specific heat of an Ising model can be asymmetric if crossing interactions are included. It also suggests that experiments on the hydrogen-bonded ferroelectrics may yield information on the critical behavior of the three-dimensional Ising model.

A number of lattice models of phase transitions and critical points can be related to one another by variation of linear parameters appearing in the Hamiltonian. It is suggested that the critical indices as functions of these parameters remain constant except possibly at points where the nature of the associated first-order phase transition is itself altered by varying a parameter. Several models exhibiting critical phenomena are consistent with this proposal.

We report accurate measurements of the caliper dimensions of the molybdenum Fermi surface. From these measurements, we estimate the separation between the electron jack and the hole octahedra along the $〈100〉$ directions to be (7.5±1)% of the $\Gamma H$ dimension. This large separation implies that spin-orbit coupling is much greater than expected for metallic molybdenum.

Just below the Néel temperature of CoO, the intensity of neutrons scattered by the anti-ferromagnetic lattice of ${\mathrm{Co}}^{2+}$ ionic spins should vary as $I\propto {(T_{\mathrm{N}}-T)}^{2\beta }$. We measure $\beta =0.244\mathrm{}\pm 0.015$, or substantially lower than the Ising prediction of 0.3125 which CoO should assume. By applying a phenomenological correction for the measured tetragonal lattice contraction below $T_{\mathrm{N}}$, similar in form to Heller's correction for the contraction in Mn${\mathrm{F}}_2$, we make $T_{\mathrm{N}}=T_{\mathrm{N}}\mathrm{}\left(T\right)\mathrm{}$ which raises $\beta$ to a value of 0.290±0.025. By thus adjusting for nonrigidity of the lattice we bring $\beta$ into a range which includes the rigid-lattice Ising prediction.

Calculations of dipole-exchange spin waves in thin films using a microscopic model show no evidence of surface modes above the lowest bulk frequency, in contrast to recent results based on a macroscopic model. The apparent absence of the surface branch in the former model is explained in terms of the admixture of bulk and surface waves. Nearly exact quantitative agreement between the two models is obtained for wave vectors as large as ${10}^7$ ${\mathrm{cm}}^{-1\mathrm{}}$.

The breakup of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ in the Coulomb field of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ was studied at 20-, 21-, 24-, and 26-MeV incident energy. The discrepancies between the experimental and theoretical values indicate that some of the simplifying assumptions of the theoretical description have to be improved.

The photoneutron cross section for ${\mathrm{He}}^3$ has been measured with monenergetic photons from threshold to 30 MeV. The cross section rises to a maximum value of 0.95 mb at 15 MeV; the integrated cross section is 13.0 MeV-mb. Some structure is evident.

Distorted-wave Born-approximation calculations of polarization effects in ($d, p$) stripping reactions near the Coulomb barrier have been carried out which predict large polarization values and strongly $j$-dependent patterns for the angular distributions of polarization. Coulomb-wave calculations showed that for reactions in the Coulomb field the coupling of the orbital angular momentum to the spin of the captured neutron is simply related to the predominant sign of the polarization.

An isotope of element 105 with mass number 260 has been formed by bombarding ${}_{}{}^{249}{}_{}{}^{}\mathrm{Cf}$ with ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ ions. The $Z$ and $A$ of the nuclide have been unambiguously identified by recoilmilking the 30-second ${}_{}{}^{256}{}_{}{}^{}\mathrm{Lr}$ daughter. ${}_{}{}^{260}{}_{}{}^{}105$ has a (1.6±0.3)-sec half-life and decays by alpha-particle emission with groups at 9.06 (55%), 9.10 (25%), and 9.14 MeV (20%). Branching decay by spontaneous fission is less than 20%. Some comments are made on the earlier results of the Dubna group concerning a few alpha-particle events at 9.4 and 9.7 MeV which they claim to be due to element 105.

Stripping reactions on target nuclei with spin generally involve at least two values of the angular-momentum transfer $j$ of the captured nucleon. The probabilities $p_j$ for transfer of a neutron with total angular momentum $j$ were determined using vector-polarized deuterons to initiate a number of ($d, p$) reactions with $l=1\mathrm{}$ on ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$, ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$, and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$. The results exhibit in general a rather good agreement with shell-model calculations by Cohen and Kurath.

A rotational band with $K^{\pi }=0^{+}$ with $I=0\mathrm{}$ and $I=2\mathrm{}$ at excitation energies of 1410.8 and 1438.5 keV, respectively, has been identified and carefully characterized in ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$. We conclude that these states are members of a two-phonon octupole vibrational band.

The combined data for the high-energy backward reactions $\pi N\to N\pi$, $\pi N\to N\rho$, and $\gamma N\to N\pi$ are analyzed in terms of the strong-cut Reggeized absorption model proposed by Henyey, Kane, Pumplin, and Ross. Only the $N$ and $\Delta$ trajectories and the associated Regge cuts are necessary to describe the data, including the dip structure. The analysis lends strong support to the model, in particular to the feature that the Regge pole amplitudes do not have zeros at nonsense wrong-signature points.

Current algebra and strong partial conservation of axial-vector current (PCAC) predict a good value for the slope of the decay $\eta \to {\pi }^{+}{\pi }^{-}{\pi }^0$ but also the (experimentally contradicted) approximate vanishing of the $\eta \to 3\pi$ rates. We show that weak PCAC provides a framework in which the good result remains valid, but the bad one does not. The only speculative step is the assignment of the most plausible quantum numbers of the $H\left(990\right)\mathrm{}$.

The interaction of a noble-gas atom with a paramagnetic atom is studied by the use of optimized configuration mixing. It is shown (with actual computation for the helium-hydrogen system) that the optimized mixing of the Hartree-Fock ground state with polarization states is adequate for reproducing the interaction over almost the entire range of the internuclear distance. The computed wave function is used to calculate the hyperfine pressure shift for hydrogen in the atmosphere of helium buffer gas atoms, with results in good agreement with experiment.