A measurement of the relative yield of fission events associated with the highest—kinetic-energy fragments has been made for several resonances in ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$. The results show that this yield is strongly correlated with $K$, the fission-channel quantum number.

The spectroscopic factors for $d\to \mathrm{np}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}\to n^3$ He are studied using dispersion relations. It is found that the large distortions represented by the cuts, which have previously prevented dispersion relations from being a practical tool for nuclear physics, can be handled using the conformal mapping techniques of Cutkosky. The method could have general applicability for nuclear physics.

A relativistic many-body theory is used to evaluate the equation of state to lowest order in the weak coupling constant for a dense system of electrons and neutrinos interacting through the universal Fermi interaction. The asymptotic limit for the speed of sound $v_s<~\frac{c}{\sqrt{3}}$ is obtained; it is conjectured that a large class of relativistic interactions leads to the same limit.

Tests of the discrete symmetries $P$, $C$, $\mathrm{CP}$, and $T$ are obtained through comparison of the rare decays $K^{\pm }\to {\pi }^{+}{\pi }^{-}{e}^{\pm }{\nu }_e$ ($K_{e4\mathrm{}}$ decays). An important outgrowth of the experiment is a direct measurement of the low-energy pion-pion relative scattering phase, ${\delta }_0-{\delta }_1$.

From 2728 events of 205-GeV $\mathrm{pp}$ interactions found in 15 000 pictures taken with the 30-in. hydrogen bubble chamber at the National Accelerator Laboratory, a total cross section of 39.5±1.1 mb was measured. The mean charged-particle multiplicity for inelastic $\mathrm{pp}$ collisions was measured to be 7.65±0.17. The prong distribution from 2 to 22 prongs is broader than a Poisson distribution and has a width parameter $f_2^{}{}_{}{}^{-}=〈n_{-}(n_{-}-1)〉-{〈n_{-}〉}^2=0.95\mathrm{}\pm 0.21$.

We have measured the circular polarization of $\gamma$ rays from thermal neutron capture in ${}_{}{}^{113}{}_{}{}^{}\mathrm{Cd}$ and find a $P_{\gamma }=(6.0\mathrm{}\pm 1.5)\times {10}^{-4\mathrm{}}$ for the combined 8.51- and 9.04-MeV transitions. This value was measured using a transmission Compton polarimeter and pulse-counting technique. The value confirms the existence of parity-nonconserving terms in the internucleon force.

Two models are presented for which the full multiparticle $S$ matrix is unitary at high energies. The production mechanism is based on the multiperipheral model. It is shown that the elastic-scattering amplitude contains a new type of cut in the angular-momentum plane which is dynamical in origin. This unitarity cut plays a crucial role in enforcing the Froissart bound.

Relations between structure functions conventionally obtained from quark-parton or light-cone models are shown to follow from model-independent symmetry assumptions common in hadron scattering. Exotic $t$-channel exchanges are forbidden. No strong-interaction symmetry beyond isospin is assumed, and SU(3) is used only for vertices involving currents. Relations originally derived for nucleon targets hold for any isospin mirror pair and apply to complex targets appearing in the Mueller formalism for inclusive processes in the target fragmentation region. New relations are derived.

In this paper it is demonstrated that 30-MeV oxygen ions bombarded on Ca produces a $K\alpha$ spectrum consisting of hypersatellite lines. $K\alpha$ hypersatellites are $1s\to 2p$ transitions in an atom with two $1s$ electron vacancies in the initial state.

Transient nutation is observed in the time-resolved infrared-microwave double resonance of ammonia. This behavior is described by a Bloch equation for relaxation of the ammonia inversion levels, with an effective $T_2$ cross section of 400 ± 50 ${\mathrm{\AA }}^2$. A similar effect was produced by rapidly switching the Stark field applied to the molecules, which suddenly brings them into resonance with the cw microwave radiation.

In a modulated crossed-beam experiment we have elastically scattered unpolarized electrons of 3.3 eV energy from spin-polarized K atoms. A measurement of the polarization of the scattered electron yields $\frac{{\left|f\right(\theta \left)\right|}^2}{\sigma \left(\theta \right)}$. Our measured values of $\frac{{\mathrm{}\left|f\right|\mathrm{}}^2}{\sigma \left(\theta \right)}$ show a significant angular shift relative to the theoretical curve in forward-angle scattering ($\theta ={20}^{\circ }-40\mathrm{}$°). This shift is not apparent in measurements of the differential scattering cross section $\sigma \left(\theta \right)$ over the same angular range, which, however, do show a significant angular shift in the range $\theta ={50}^{\circ }-120\mathrm{}$°.

Linewidths of Rayleigh scattering from a binary liquid system of $n-\mathrm{h}\mathrm{e}\mathrm{x}\mathrm{a}\mathrm{n}\mathrm{e}\mathrm{p}\mathrm{l}\mathrm{u}\mathrm{s}\mathrm{n}\mathrm{i}\mathrm{t}\mathrm{r}\mathrm{o}\mathrm{b}\mathrm{e}\mathrm{n}\mathrm{z}\mathrm{e}\mathrm{n}\mathrm{e}$ have been measured at two fixed scattering angles over a temperature range such that $\epsilon \equiv \frac{(T-T_c)}{T_c}$ extends from ${10}^{-2\mathrm{}}$ to ${10}^{-6\mathrm{}}$. The ratio of the linewidths at two angles as a function of the correlation length $\xi$ have been compared with recent self-consistent mode-mode coupling calculations of Kawasaki and Lo. The theory takes into account the nonlocality of shear viscosity near the critical point, and the data clearly establish the predicted effect in the critical region.

A quasi—one-dimensional spectrum of ion waves excited by a slow-electron beam is investigated experimentally. The power spectrum in a region of spatial wave decay is found to fall off with increasing frequency as $f^{-2.3\pm 0.2}$. The result is compared with some nonlinear theories.

At low fluctuation levels the small changes in magnetic moment induced by resonant electrostatic modes are nonrandom and do not lead to particle loss.

NMR linewidth measurements have been made on ${\mathrm{He}}^3$ monolayer films adsorbed on graphite. A melting transition and transition to an ordered lattice gas are identified. Mobile, ideal-gas behavior above the transition temperature is observed with the gas phase persisting to low temperatures for coverages outside the transition regions. The present measurements indicate that helium films adsorbed on graphite provide a fruitful system for the study of NMR in two dimensions.

A central problem in the theory of phase transitions is the calculation of the order-parameter correlation function. Here we study the correlation function of an $n$-component order parameter whose configuration energy is determined by the usual Landau functional. Using a screening approximation, we obtain a simple closed form for the Fourier transform of the correlation function and examine its dependence on wave vector $\overrightarrow{\mathrm{k}}$ and the reciprocal correlation length $k$.

The behavior of superconducting Sn and Sn-In microbridges has been studied as a function of physical parameters of the evaporated films. For a proper choice of mean free path and bridge size, a regime of ideal Josephson-junction-like behavior appears just below $T_c$. The data are in good agreement with recent calculations by Baratoff, Blackburn, and Schwartz.

The nuclear heat capacity of praseodymium in fields from 0 to 18.6 kOe has been measured from 16 to 300 mK. In zero field the metal was found to be ordered with average magnetic moments of 0.62${\mathrm{\mu }}_{\mathrm{B}}$ and 0.05${\mathrm{\mu }}_{\mathrm{B}}$ on the two inequivalent lattice sites. Above 10 kOe the Van Vleck behavior dominates and an induced moment appears on both sites. The corresponding induced hyperfine field has been employed for nuclear cooling.

We show the equivalence of the side-jump model of the ferromagnetic Hall effect recently proposed by Berger and the anomalous velocity contribution obtained by Luttinger and others. Specifically, starting from the cited anomalous velocity expression, we give a derivation (to the lowest Born order) of the (vector) side jump which an electron undergoes during a collision with an impurity for a system of ferromagnetically polarized free electrons, each interacting with the impurity centers, together with the concomitant spin-orbit interaction. The side jump obtained is independent of the strength and form of the impurity potential and agrees with the result of Berger.

Coherent scattering regions of approximately 10-25 Å in size have been observed in a variety of amorphous solids. It has been suggested that these observations provide evidence for the microcrystalline model. In this note we show that the observations of coherently scattering regions are not incompatible with a random-network model.