A microscopic model, constructed within the framework of the Boltzmann equation, is formulated and used to calculate particle spectra from high-energy nucleus-nucleus collisions. Formation of composite particles is treated according to Hagedorn's statistical-thermodynamical approach of strong interactions. Inclusive proton, deuteron, triton, and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ cross sections from 400-MeV/nucleon ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$+${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ are calculated and found in good agreement with experiment.

A class of parity-favored electric dipole transitions are classed as "dynamically unfavored" with a photoparticle angular distribution parameter $\beta \sim -1\mathrm{}$. This deviation from the elementary-model value $\beta =2\mathrm{}$ results when the squared pseudoscalar operator ${\left({\overrightarrow{j}}_t·\hat{r}\right)}^2$ is nonzero. Herrick's SO(4) classification singles out doubly excited ${}_{}{}^1{}_{}{}^{}P_{}^{\circ }{}_{}{}^{}$. continuum eigenchannels of ${\mathrm{H}}^{-}$ and He with ${\left({\overrightarrow{j}}_t·\hat{r}\right)}^2\sim 0 or \sim 1$. Most of the photoelectrons should have ${\left({\overrightarrow{j}}_t·\hat{r}\right)}^2\sim 1$, i.e., $\beta \sim -1\mathrm{}$.

Level shifting has been observed in a two-level, two-isotope atomic system which is undergoing stimulated emission. The optical fields which produce the level shifts are generated by the same stimulated process.

The existence of novel random-field critical and multicritical behavior in antiferromagnetic GdAl${\mathrm{O}}_3$:2.75% La was verified. In the neighborhood of the bictritical point, the two second-order transition lines are described each by a different shift exponent, and a random-field crossover exponent ${\phi }_{\mathrm{RF}}=1.79\mathrm{}\pm 0.04$ is deduced. At the random-field critical points, the specific-heat exponent crosses over to a value $\alpha <-1\mathrm{}$, whereas at random-exchange critical points $\alpha$ remains close to 0.

A detailed study of the uniform magnetization of Fe${\mathrm{Cl}}_2$ in the vicinity of the tricritical point shows deviations from classical scaling behavior. The deviations are shown to be remedied by logarithmic corrections derived by graphical methods, but not by those from approximate recursion relations. This is the first observation of logarithmic corrections to tricritical scaling.

Bragg diffraction of visible and near-ultraviolet light in the blue phase of a cholesteric liquid crystal have been observed. It is found that there are two distinct blue phases: One is stable from about 0.5°C below the clearing point to about 0.2°C below it and has either a body-centered-cubic or simple-cubic structure. A second, clearly distinct phase appears in the 0.2°C range immediately below the clearing point. The nature of this phase is unclear at this time.

Raman spectra of fluid hydrogen at room temperature include rotational, $S_0\mathrm{}\left(J\right)\mathrm{}$, and vibrational bands, $Q_1\mathrm{}\left(J\right)\mathrm{}$. The rotational bands become diffuse between 0.2 and 55 kbar, the solidification point at 22°C. Between 55 and 630 kbar, only $Q_1\mathrm{}\left(J\right)\mathrm{}$ was resolved. This band increases in frequency to 360 kbar, but the frequency decreases between 360 and 630 kbar. These phenomena are consistent with the softening of the molecular bond at high pressure.

It is shown that three-dimensional continuous melting is possible in the graphite intercalation compounds ${\mathrm{C}}_6$Eu, ${\mathrm{C}}_6$Yb, and ${\mathrm{C}}_6$Ba. The critical behavior is that of the three-dimensional $\mathrm{XY}$ model. Diffraction experiments are suggested.

A strong upward curvature in $H_{c2\mathrm{}\parallel }$ and a temperature-dependent critical-field anisotropy are observed in $2H$-Ta${\mathrm{S}}_2$ intercalated with methylamine. This is characteristic of dimensional crossover in Josephson-coupled superconducting layers and is confirmed by a dramatic reduction of the coherence length perpendicular to the layers. Critical fields greater than 213 kG are observed.

Strong temperature dependence has been observed in angle-resolved x-ray photoelectron spectra from the tungstem valence bands, indicating the importance of phonon-assisted nondirect transitions in Brillouin-zone averaging. The spectral changes with direction at ambient temperature furthermore agree very well with the predictions of a directtransition model assuming free-electron final-state dispersion and constant matrix elements. The direct and nondirect components in the temperature-dependent spectra are also determined.

Photon echoes have been generated in a coaxial cable at frequencies between 1 and 2 GHz. The echoes originate in electric dipole transitions within the inhomogeneously broadened tunneling systems of the partially disordered polyethylene of the cable dielectric. The two-pulse photon echo has been observed in the temperature region between 0.01 and 1.0 K and exhibits a weak decay with time, $\tau$ as $\exp (-\alpha {\tau }^{\frac{1}{2}})$.

A slow-neutron interferometer system has been used to test a nonlinear variant of the Schrödinger equation $i\hslash \frac{\partial \psi (\overrightarrow{\mathrm{r}}, t)}{\partial t}=\left[\right(-\frac{{\hslash }^2}{2m}){\nabla }^2+U(\overrightarrow{\mathrm{r}}, t\left)\right]\psi -b\ln \left(a^3{\left|\psi \right|}^2\right)\psi$. If this equation were correct, then, as Shimony has suggested, repositioning an attenuating plate downstream in a neutron beam would produce a phase modification. No measurable phase shift beyond experimental uncertainty was found and an upper limit of 3.4×${10}^{-13\mathrm{}}$ eV for the energy constant $b$ was established.

Quark models of hadron production in the beam-fragmentation region are extended to production off nuclei by taking into account quark attenuation in nuclear matter. Simple expressions are derived for the $A$ dependence of the production of beam fragments. They reproduce well the experimental data on hadron-nucleus and virtual-photon-nucleus collisions.

It is suggested that dynamical (Bose-Fermi) supersymmetries may be present in the spectra of complex nuclei. A concrete example in which a supersymmetric structure is experimentally observed is shown. In this example the supersymmetry is generated by $L=0\mathrm{}$ and $L=2\mathrm{}$ bosons together with $j=\frac{3}{2}$ fermions.

For ${\mathrm{He}}^{+}$ beams neutralized in alkali vapors and reionized in ${\mathrm{O}}_2$ gas, information on the intermediate neutral states has been used for the first time to isolate the differential cross sections for ion-pair formation in a pair of reactions occurring simultaneously. The reactions of ${\mathrm{He}}^{*}\left(2\mathrm{}{}_{}{}^3{}_{}{}^{}S\right)$ and ${\mathrm{He}}^{*}\left(2\mathrm{}{}_{}{}^1{}_{}{}^{}S\right)$ with ${\mathrm{O}}_2$ are strongly coupled by a shared Coulombic product channel, and evidence exists for unique three-surface trajectories leading to ion-pair products ${\mathrm{He}}^{+}$ + ${\mathrm{O}}_2^{-}$.

The general formula which gives the current density generated by an electrostatic traveling wave in a collisionless magnetized plasma is derived within the framework of quasilinear theory. This formula shows that the ion response is indispensable to generating the current via wave-particle interaction. The current which is obtained by use of this formula in the case of lower hybrid waves is in agreement with the experimental values.

Writing thermodynamic quantities near a critical point as $f_i\sim A_i{\mathrm{}\left|t\right|\mathrm{}}^{-{\lambda }_i}(1+a_i{\mathrm{}\left|t\right|\mathrm{}}^{\Delta })$, where $t=\frac{(T-T_c)}{T_c}$, we show that to leading order in $\epsilon =4-d$ one has $\frac{a_i}{a_j}=\frac{({\lambda }_i-{{\lambda }_i}^0)}{({\lambda }_j-{{\lambda }_j}^0)}$, where ${{\lambda }_i}^0$ is the mean-field value of ${\lambda }_i$. This ratio is also equal to $\frac{({\lambda }_{i, \mathrm{eff}}-{\lambda }_i)}{({\lambda }_{j, \mathrm{eff}}-{\lambda }_j)}$, where ${\lambda }_{i, \mathrm{eff}}$ is derived from a fit of data with $f_i\sim {\mathrm{}\left|t\right|\mathrm{}}^{-{\lambda }_{i, \mathrm{eff}}}$. Various experiments are analyzed and compared to these predictions.

Correction-to-scaling amplitudes are calculated to second order in $\epsilon =4-d$ by renormalized perturbation theory. It is shown that ratio of any two such amplitudes is universal, and that thermodynamic scaling laws among effective exponents break down beyond zeroth order in $\epsilon$. Values found are $\frac{{a_{\xi }}^{+}}{{a_{\chi }}^{+}}=0.65\mathrm{} (n=1, d=3) \mathrm{and} 0.63 (n=2, d=3)$ in good agreement with high-temperature series, and $\frac{{a_m}^{-}}{{a_{\chi }}^{+}}=0.85\mathrm{} (n=1, d=3)$.

Magnetically ordered solid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, produced by compressional cooling to $T\approx 1$ mK, has been studied by high-resolution NMR at fields up to 2.98 T. In the ordered solid, at low fields $B_0<~410$, mT, peaks in the spectrum above and below $\frac{\gamma B_0}{2\pi }$ characteristic of antiferromagnetic ordering, are observed. For $B_0>~430$ mT, there is a temperature-dependent shift of the resonance to higher frequencies and a large rapid growth in magnetization, beginning at the ordering temperature.

Detailed measurements of the low-field antiferromagnetic resonance spectrum of spin-ordered bcc ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ exhibit large shifts from the Larmor frequency, with a zero-field resonant frequency near zero temperature of $\frac{{\Omega }_0}{2\pi }\simeq 825$ kHz. Analysis of the spectrum leads to stringent constraints on possible sublattice structures. The temperature dependence of ${\Omega }_0$ shows low-temperature behavior expected from spin-wave theory, and indicates a first-order transition at 1.03 mK.