The two-body decays of the "old" and the "new" mesons are studied in a broken SU(4) scheme. The scheme succeeds in suppressing $\Gamma (\psi \to {\eta }_c\gamma )$. Sum rules among amplitudes are derived to support $\Gamma (\rho \to \pi \gamma )\simeq 75$ keV.

Evidence of systematic behavior in neutron-induced-fission cross sections has been observed in the actinide elements. Recently measured fission cross-section ratios show this behavior over the incident-neutron-energy range from 3 to 5 MeV.

Reanalysis of our experimental results on ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{N}$ provides shape factors that yield ${({a_{-}}^0-{a_{+}}^0)}_{\exp }=+(0.86\mathrm{}\pm 0.24)\%$ Me${\mathrm{V}}^{-1\mathrm{}}$, still in good agreement with the theoretical prediction of ${({a_{-}}^0-{a_{+}}^0)}_{\mathrm{theo}}=+0.86\%$ Me${\mathrm{V}}^{-1\mathrm{}}$. The experimental evidence for the conserved-vector-current theory as manifested in the mass-12 triad is on no less firm ground than it was at the time of our previous publication.

The multiphoton ionization of highly excited hydrogen ($45<~n<~57$) for frequencies $9.4<~\nu <~11.6$ GHz is of such high order $88<~k_0<~173$ that quantal tunneling may compete. Nevertheless, we observe resonances in the frequency dependence of the ionization rate caused by strong multiphoton transitions of order $3<~k^{\prime }<~7$ between adjacent energy levels. We show that these multiphoton transitions proceed at rates comparable to the overall ionization rate. These results rule out tunneling as the dominant intense-field ionization mechanism.

The impact-parameter dependence of the $2p\sigma -1s\sigma$ vacancy-sharing probability has been investigated in 35-MeV Cl on Ti and Cl on Ni collisions. A stronger impact-parameter depencence is observed with increasing asymmetry of the collision system. The impact-parameter dependence of the $K$-vacancy sharing is in good agreement with a simple analytical solution, derived by Briggs, of the two-state coupled-channel equations.

Total ionization cross sections for the highly stripped Mo ions by high-energy electron impact are estimated, including both the direct ionization of outer-shell electrons and the excitation of inner-shell electrons followed by an Auger emission. For highly stripped ions, the excitation to discrete states predominates and enhances the Auger contribution. For the ${\mathrm{Mo}}^{24+}$ ions, the Auger ionization of the $L$-shell electrons dominates over the direct $M$-shell ionization.

A steady-state model of a plasma slab, accelerated by interaction with laser radiation, determines temperature, velocity, and density profiles and boundaries consistent with laser intensity and wavelength and slab mass and acceleration. Density-profile modification is caused by laser pressure. Plasma flows subsonically into the critical surface, and supersonically out.

Mode conversion from the fast magnetosonic wave to a slow wave near the two-ion hybrid resonance is shown to explain recent experimental fast-wave damping results. A model for tunneling and mode conversion of the fast wave in the two-ion resonance zone incorporating $k_{\parallel }$ and plasma-density and magnetic-field profiles is used to explain the observations. The strong dependence of the absorption on $k_{\parallel }$ and the species concentration which is obtained has important consequences for major plasma-heating programs which are planned for tokamaks.

We present results which are encouraging for a multibeam approach to relativistic-electron-beam-induced pellet fusion. A self-pinched relativistic electron beam with nominal parameters of 1.1 MV, 200 kA, and 5-mm radius has been propagated at atmospheric pressure over distances of up to 1 m. Gross beam stability and reasonable energy transport efficiency have been achieved. A simple Alfvén-type calculation corroborates the propagation result, and a self-consistent particle simulation indicates the possibility of scaling to very high-$\frac{\nu }{\gamma }$ beams.

We present a new calculation of the critical exponents of the $n$-vector model through field-theoretical methods. The coefficients of the renormalization functions of the ${\left({\overrightarrow{\varphi }}^2\right)}^2$ theory are expanded in powers of the coupling constant. Asymptotic estimates of large order of perturbation series are used to transform the divergent perturbation series into a convergent one. As a consequence, new and more precise values of critical exponents are obtained.

An intinerant-electron model for ultrasonic propagation in a ferromagnetic metal, for both above and below the Curie temperature $T_C$, is developed within the mean-field approximation. The attenuation maxima of the longitudinal acoustic wave are shown to occur at slightly below $T_C$ in agreement with the experimental observation on Ni. In addition, new possibilities of magnetically driven structural instabilities in metals are pointed out.

We present experimental evidence for the identification of the deformed proton orbital ${\mathrm{½}}^{-}$- [521] in ${}_{}{}^{251}{}_{}{}^{}\mathrm{Es}$ and ${}_{}{}^{247}{}_{}{}^{}\mathrm{Bk}$. The implications of this finding with respect to the stability of superheavy elements in the vicinity of $Z\approx 114$ are discussed.

We have used the Stark-switching technique to observe two-photon optical free-induction decay in the visible using sodium vapor. Transients were observed with use of both a resonant and a nonresonant intermediate state for the two-photon transition.

It is shown that effective-photon theory is in serious conflict with established experimental results in two areas. A lower limit on the total photon-photon scattering cross section is derived which requires this cross section to be unacceptably large. The rate of beam degradation also is examined and shown to be too high by many orders of magnitude.

The $\alpha$-particle emission from laser-compressed, D-T-filled microshells has been imaged using a zone-plate-coded imaging technique. Nominal image resolution was 10 μm. Approximately 97% of the recorded $\alpha$ emission was found to originate within a thermonuclear burn region of diameter roughly $\frac{1}{3}$ that of the original target. The full width at half-maximum of the burn region had a diameter roughly $\frac{1}{6}$ that of the target.

We have obtained initial geometric-focusing results using a high-current (≳ 100 kA) magnetically insulated diode. At the line focus, current densities over 300 A/${\mathrm{cm}}^2$ have been obtained with a radial compression of about 10. Results for propagation of the intense beams are in excellent agreement with geometric single-particle predictions.

We have performed experiments on explosive instability of space-charge waves of the helical electron beam due to nonlinear wave-particle interaction. The fast and slow beam modes interact nonlinearly with the helical electron beam and grow simultaneously.

The small widths of high-lying resonances can be explained by a fragmentation of a quasimolecular shape resonance through coupling to at least two exit doorway states.

Ion heating by irradiation of rf fields in the ion-cyclotron range of frequencies is investigated using several diagnostic techniques. It is shown that substantial heating of the bulk of the ions can be achieved by this method.

An anomalous steep decrease in the Kapitza resistance between liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and a single crystal of Cu${\left(\mathrm{N}{\mathrm{H}}_3\right)}_4$S${\mathrm{O}}_4$ · ${\mathrm{H}}_2$O has been observed for the first time just below its magnetic—phase-transition temperature, $T_{\mathrm{N}}=0.43\mathrm{}$ K. The decrease can be enhanced by the application of a magnetic field. These phenomena occur because of the strong coupling between ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ spins and electron spins of the magnetic salt, as detected in the previous NMR measurement.