An exactly solvable modification of the planar Ising ferromagnet is proposed which has a roughening transition below the Curie temperature. The computation confirms the de Gennes-Fisher scaling theory of correlations with homogeneous surface fields, giving an exponent value ${\Delta }_1=\frac{1}{2}$.

The standard SU(2) ⊗ U(1) model is extended to include two $W$ and two $Z$ bosons without changing the structure of its low-energy phenomenology. The experimental implications of this model regarding the existence of a light $W$ and a light $Z$ are discussed.

The photoproduction of charmed particles by polarized photons is calculated in perturbative quantum chromodynamics. For vector gluons the resulting linearly polarized photon asymmetry is found to be large and negative, therefore providing a distinctive test of the proposed production mechanism. Predictions are also given for scalar and pseudoscalar gluons and the magnitude of the cross section is discussed.

The possibility of the charge-monopole systems with half-integer spin in the grand unified SU(5) model is investigated and found to occur.

Charge-exchange cross section for antiprotons on protons has been measured in closely spaced momentum intervals from 0.119 to 1.046 GeV/c. The regions of the reported resonances at 1936 and 2020 MeV were scanned in 10-MeV/c steps with a typical statistical error of ≈ 1% and an rms mass resolution of ± 1.5 MeV. No enhancements were observed.

Total and annihilation cross sections for $\overline{p}p$ and $\overline{p}d$ have been measured over the momentum range 355-1066 MeV/c at closely spaced momenta and with good energy resolution. No evidence is seen for the narrow structure reported by other experiments in the vicinity of 500 MeV/c. The present measurements indicate a broader enhancement in this region, which, if interpreted as a resonance, would have a height of ∼ 3 mb and a width of ∼ 20 MeV. This structure appears only in the $\overline{p}p$ data.

The data from measurements of the total-cross-section differences $\Delta {\sigma }_T$ and $\Delta {\sigma }_L$ for $p-p$ scattering and the spin-averaged total cross sections are analyzed to determine the singlet (${{\sigma }_s}^T$) and (${{\sigma }_t}^T$) cross sections. The structures observed in $\Delta {\sigma }_T$ and $\Delta {\sigma }_L$ near 1.3 GeV/c are found to result primarily from increases in ${{\sigma }_s}^T$ and ${{\sigma }_t}^T$. These increases are shown to be consistent with the Mandelstam model of pion production. No resonantlike behavior is required to describe the structures in $\Delta {\sigma }_T$ and $\Delta {\sigma }_L$.

Cross sections and analyzing powers have been measured for 800-MeV proton inelastic transitions to unnatural-parity states in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$. Data for the 15.11-MeV $1^{+}$, $T=1\mathrm{}$ state are well explained by a distorted-wave impulse-approximation calculation based on proton-neutron charge-exchange cross sections. Negative analyzing powers were observed for the first time at 800 MeV, for the 12.71-MeV $1^{+}$, $T=0\mathrm{}$ state. Values of $A_y$ appear to be characteristic of the isospin transfer, and support isospin assignments for states at 18.3 and 19.4 MeV.

Analyzing powers of the continuum energy spectra from the reactions ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$($p_{\mathrm{pol}}, p^{\prime }X$) and ($p_{\mathrm{pol}}, \mathrm{dX}$) at 65 MeV have been measured. The analyzing powers of the continuum spectra were found to be small at forward angles and to be very large and positive at backward angles. These features indicate the importance of the spin-dependent interaction in the understanding of the continuum spectra.

The deep-inelastic double-charge-exchange reaction ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}({\pi }^{+}, {\pi }^{-})$ has been measured at 50°, 85°, and 130° with 240-MeV incident pions. The doubly differential cross section is peaked at low outgoing pion energies, as is expected from a double-scattering process, and is nearly isotropic. The integrated cross section is 5.8±0.9 mb. The shape of the differential cross section suggests that the low-energy tail in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}({\pi }^{+}, {\pi }^{+\prime })$ scattering at the same energy also arises from double scattering.

Isomer fission in ${}_{}{}^{236m}{}_{}{}^{}\mathrm{U}$, $t_{\frac{1}{2}}=125\mathrm{}$ nsec, from ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}(d, pf)$ was compared with prompt fission ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}(n_{\mathrm{th}}, f)$, in twin experiments. Fine structure in the total kinetic energy, average total kinetic energy as a function of mass, and mass yield were observed in isomer fission of ${}_{}{}^{236m}{}_{}{}^{}\mathrm{U}$. This observation is compatible with a superfluid descent from saddle to scission points. Two peaks in the total-kinetic-energy distribution from isomer fission are observed near fragment mass 132, and this is interpreted as due to the proton-pairing effect at $Z=50\mathrm{}$.

Improved statistical-model calculations allow a search for the lower and upper limiting angular momenta of compound-nucleus formation that give best fits to evaporation-residue mass distributions. For the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$+${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ reaction in the energy range $E_{\mathrm{lab}}=35-80\mathrm{}$ MeV, optimal fits are obtained for low-$l$ cutoff 0, and maximum $l$ equal to $l_{\mathrm{cr}}$, obtained from total fusion cross sections.

The real and the imaginary parts of the nucleus-nucleus interaction potential have been calculated using a suitable complex effective interaction, derived from the Skyrme interaction. It is shown that the transition from light to heavy ions can be predicted on the basis of the saturating property of the Skyrme effective interaction—a free two-body complex interaction does not predict such a transition.

A quantum mechanical approach is used to calculate the cross sections and rate constants of $\mathrm{D}+{\mathrm{H}}_2(v_{\alpha }=1, 0)\to \mathrm{DH}(v_{\beta }=0, 1)+\mathrm{H}$. With $v_{\alpha }=0\mathrm{}$, present results are in agreement with classical calculation. With $v_{\alpha }=1\mathrm{}$, cross sections for the vibrational adiabatic transition ($v_{\alpha }=1\mathrm{}$ to $v_{\beta }=1\mathrm{}$) is an order of magnitude larger than that for the vibrational non-adiabatic transition ($v_{\alpha }=1\mathrm{}$ to $v_{\beta }=0\mathrm{}$). This result is in agreement with recent experiments but in disagreement with classical-trajectory calculations.

Numerical simulations of tokamak plasmas are presented which reproduce the basic observed behavior of disruptions. Details are given of the onset of the disruption-initiated in the simulations by the $m=2\mathrm{}$ island intersecting the limiter or cold-gas region—and of the mechanism of the final (total or partial) plasma loss.

This paper reports on the transient field reversal of the applied magnetic field with a proton pulse. The 400-500-kA (peak), 50-nsec-duration, 1.7-MeV peak-energy hollow proton pulse containing about 8×${10}^{16}$ protons is generated by an inverse reflex tetrode. After passing through a magnetic cusp, the pulse propagates in a 1.5-kG uniform field $B_0$ with a self-generated magnetic field $\Delta B_z\simeq 1.25B_0$.

A theoretical model is proposed for understanding the effect of H adsorption on the displacive transition of the W(001) surface. The coupling of the H adatoms to the substrate distortion leads to an enhancement of the displacive transition and a change in the overall symmetry. This is consistent with the features observed in low-energy electron diffraction for the H/W(001) chemisorption system.

Theoretical evidence is presented that for temperatures so low that $k_{\mathrm{B}}T$ is much less than the rest energy of a soliton, the mean square displacement of a diffusing particle of an infinite sine-Gordon chain behaves as $t^{\frac{1}{2}}$ for times much longer than microscopic times but much shorter than the soliton lifetime $\tau$. For times much greater than $\tau$, linear behavior is suggested. Finite-size effects are discussed in the context of recent computer simulation studies.

The pressure-volume relation for americium has been obtained without adjustable parameters from self-consistent, spin-polarized band calculations. Around 100 kbar we find a first-order transition to a state with low volume and no spin. This is consistent with preliminary high-pressure measurements.

Absorption spectra of ${\mathrm{Cr}}^{3+}$-doped glasses exhibit features which are interpreted as Fano antiresonances resulting from interaction of ${}_{}{}^2{}_{}{}^{}E$ and ${}_{}{}^2{}_{}{}^{}T_1^{}{}_{}{}^{}$ states with a vibrationally broadened ${}_{}{}^4{}_{}{}^{}T_2^{}{}_{}{}^{}$. Inhomogeneous line broadening in glass permits the observation of a shift of sharp levels due to interaction with the quasicontinuum.