The fluorescence yield was determined for the Ar $L$ shell by measuring absolute cross sections for Ar $L$ x-ray and Auger-electron emission for 30- to 600-keV ${\mathrm{H}}^{+}$, $\mathrm{H}_2^{}{}_{}{}^{+}$, and ${\mathrm{He}}^{+}$ ions on Ar. When the Auger-electron spectrum was analyzed, the fluorescence yield for ${\mathrm{He}}^{+}$ was found to be an order of magnitude larger than existing theoretical estimates.

Mechanisms are discussed by which radiations can produce color changes in Fe-doped SrTi${\mathrm{O}}_3$. $\alpha$-particle and cosmic-ray ($\pi$-meson) absorption events have been detected by these crystals.

According to a phenomenological theory of collisionless superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, the velocity of high-frequency sound should show a transition from zero- to first-sound velocities as the superfluid fraction $\frac{{\rho }_s}{\rho }$ is increased. From the experimental observations of this behavior by Paulson, Johnson, and Wheatley, the order parameter $\frac{{\rho }_s}{\rho }$ can be determined for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ II.

It is shown that the anomalous zero-sound attenuation at the transition "$A$" observed recently in liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ at about 2.7 mK can be understood by postulating pairing in a state of odd relative angular momentum. The attenuation is found to depend strongly on the angular variation and orientation of the gap parameter, providing information on the precise nature of the pairing. It is concluded that (1) Balian-Werthamer $p$-wave pairing can be ruled out, and (2) Anderson-Morel $p$-wave pairing is possible.

It is shown experimentally that the thermoelectric power of ${\mathrm{La}}_{0.98}$${\mathrm{Tb}}_{0.02}$${\mathrm{Al}}_2$ has an anomalous peak at 2 K. This peak is due to inelastic scattering of the conduction electrons by the crystal-field—split energy levels of the Tb impurities. Our findings are in good quantitative agreement with recent calculations by Peschel and Fulde.

The simplified linear combination of muffin-tin orbitals method has been used to calculate the energy bands of Mo${\mathrm{S}}_2$ and Nb${\mathrm{S}}_2$. The calculated bands are in excellent agreement with photoemission data and provide a new interpretation of optical absorption spectra different from that of Wilson and Yoffe. The effect of the weak interlayer potential on the $d_{z^2}$ conduction band is shown explicitly.

Measurements of the $L_{2,3}\mathrm{VV}$ ($V=\mathrm{valence}$) Auger spectrum of aluminum and the $M_{4,5}\mathrm{VV}$ Auger spectrum of silver cannot be simply related to the valence-band density of states. The data for Al indicate a strong energy variation of the transition probability. For silver, the position and shape of the Auger spectrum are associated with multiplet splitting of localized double-$d$-hole final states.

We have measured the polarization parameter in neuton-proton charge-exchange scattering for incident neutron momenta of 2-12 $\frac{\mathrm{GeV}}{c}$ and $0.01<~\mathrm{}\left|t\right|\mathrm{}<~1.0 {\left(\frac{\mathrm{GeV}}{c}\right)}^2$. Results based on 300 000 events show a negative polarization whose magnitude increases monotonically with $\mathrm{}\left|t\right|\mathrm{}$ approaching 60% for $\mathrm{}\left|t\right|\mathrm{}\sim 0.6$ and which has little energy dependence.

The cross sections for single-arm inelastic electron-proton scattering were measured near the one-pion threshold for six values of $q^2$ between 0.23 and 1.84 Ge${\mathrm{V}}^2$. We determined the cross sections for nonresonant pion production and, using a particular formulation of soft-pion theory, extracted the normalized axial-vector form factor of the nucleon, $\frac{G_A\left(q^2\right)}{G_A\mathrm{}\left(0\right)\mathrm{}}$.

We have measured the total cross section for electron-positron annihilation into three or more hadrons, with at least two charged particles in the final state. The measurement was made at a center-of-mass energy of 4 GeV with a $2\pi -\mathrm{s}\mathrm{r}$ nonmagnetic detector. With 88 events detected, we obtain a model-independent lower limit on the hadron production cross section of 9.6 ± 1.4 nb; a calculation of detection efficiency based on invariant phase-space production of pions leads to a total cross section of 26 ± 6 nb. This cross section is 4.7 ± 1.1 times the theoretical total cross section for $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$. The average charged multiplicity is $\overline{n}=4.2\mathrm{}\pm 0.6$.

With optical resolution above ${10}^{10}$, we study hyperfine structure in the methane vibration-rotation line at 3.39 μm. Doppler-generated crossing resonances were observed in addition to the resolved $\Delta F=0\mathrm{}$ and - 1 lines. Splittings in both ground and excited states were determined. Differential saturation of such hyperfine structure will lead to an intensity-dependent shift in many molecularly stabilized lasers.

We have observed discrete resonances for fluorine nuclei near ${\mathrm{Yb}}^{3+}$ impurities in Ca${\mathrm{F}}_2$. Angular dependences are reported and some general features of the near-nuclei magnetic-resonance method are briefly discussed.

It is proposed that the paramagnon effects which enhance $T_c$ for triplet pairing in ${\mathrm{He}}^3$ are also important in selecting the particular component of the triplet $p$- wave state observed. It is found that the component favored is the original Anderson-Morel state.

The two-roton Raman spectra of superfluid solutions of ${\mathrm{He}}^3$ and ${\mathrm{He}}^4$ are measured at a temperature of 1.3 K for molar concentrations of ${\mathrm{He}}^3$ up to 31%. At 31% ${\mathrm{He}}^3$ concentration, the shift in the roton energy is inferred from these spectra to be + 0.3±0.5 K, in striking contrast to the -3.5-K shift inferred from previous measurements of normalfluid density. The width of the two-roton peak is resolved and is a measure of the ${\mathrm{He}}^3$-roton interaction.

Using Raman scattering from rotons in liquid ${\mathrm{He}}^3$-${\mathrm{He}}^4$ solutions for ${\mathrm{He}}^3$ concentrations $0<~X<~0.11$ at $T=0.60\mathrm{}$ °K, we have measured the two-roton energy and linewidth. Our measurements indicate no change in the single-roton energy as a function of concentration, whereas the single-roton linewidth increases nonlinearly with $X$.

Neutron emission from laser-produced plasmas is shown, experimentally, to be adequately explained by electron heating and electrostatic ion acceleration. The absence of anomalous ion-heating mechanisms is not proved, but these mechanisms, if they exist, may be unimportant in reported experiments. It is concluded that no neutrons of thermonuclear origin are necessary to explain the results obtained thus far.

We report measurements of the attenuation of negative-ion currents in turbulent counterflow, as a function of the heat current, $\dot{q}$, and temperature. The dependence of the attenuation on $\dot{q}$ is well explained by present models of the turbulent state. The magnitude of the effect is in reasonable agreement with Vinen's original model, but disagrees with a modified version recently introduced by Sitton and Moss.

The onset of superfluid flow in ${\mathrm{He}}^4$ films was measured between 1.37 and 2.13 K on substrates of NaF, Ca${\mathrm{F}}_2$, Si${\mathrm{O}}_2$, Si, and Grafoil. Values of the Van der Waals constant of 19, 26, and 65 K were obtained for NaF, Si${\mathrm{O}}_2$, and Grafoil, respectively. In addition, a precise measurement of the critical thickness of the liquid-helium film was obtained, taking into account a small correction for the influence of the substrate.

The specific heat of bcc ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ has been measured from 25 mK to near the melting curve, with particular attention given to the region of the low-temperature anomaly, $T\lesssim 500$ mK. Here we find that the specific heat has a term linear in $T$, in addition to the Debye $T^3$ term. From the specific heat at the lowest temperatures, for the larger—molar-volume samples, values of the exchange energy $J$ in agreement with previous results are found.

We have studied the transition from second sound to ballistic phonon flow in He II up to pressures of 24 bar. At saturated vapor pressure the phonon-phonon scattering rate $\tau _{\mathrm{pp}}^{}{}_{}{}^{-1\mathrm{}}\cong 1.7\times {10}^6{T}^3$ ${\sec }^{-1\mathrm{}}$ for $T<\mathrm{}0.6\mathrm{}$ K. At 24 bar, $\tau _{\mathrm{pp}}^{}{}_{}{}^{-1\mathrm{}}<8\mathrm{}\times {10}^4$ ${\sec }^{-1\mathrm{}}$ for $T<\mathrm{}0.7\mathrm{}$ K. The phonon-roton scattering rate $\tau _{\mathrm{pr}}^{}{}_{}{}^{-1\mathrm{}}$ is ∼ ${10}^6$ ${\sec }^{-1\mathrm{}}$ at 0.75 K and almost pressure independent. At 24 bar between 0.4 and 0.7 K, in addition to ballistic phonons, we observe a second pulse traveling at 16 m/sec, which we believe is the propagation of interacting rotons.