Search

The state at 3.614-MeV in Cr 52 was found to have a spin of 5 by low temperature nuclear orientation techniques. It is thus reasonable to identify this state with the spin 5 seniority-four state predicted by Edmonds and Flowers for an ( f 7 2 ) 4 configuration. The angular distribution parameters for the 1.246-MeV γ-ray, connecting this state with the 4+ state at 2.369-MeV, require that the amplitude mixing ratio δ( E 2 M 1 ) be negative. It is probable that this transition is 3–23% quadrupole.

Protons scattered quasi-elastically with energy 315 Mev at 13 deg from a beryllium target in the Berkeley synchrocyclotron were brought out of the machine, slowed by absorbers, and scattered in helium at 765 psi absolute pressure. Scattering events at angles of 90 deg plus or minus 22.5 deg were detected in nuclear emulsions. Observed asymmetries in left versus right scattering of protons with energies below 14 Mev were used, in conjunction with phase shifts from pHe scattering data, to compute the direction of spin polarization. (auth)

Electron free precession and electron spin echoes have been detected for molecules in their excited triplet states in zero field by monitoring the microwave-induced modulation of the phosphorescence. The technique is capable of measuring as few as ${10}^{4}$ excited-state spins and should be applicable to a wide variety of problems.

We have observed spin polarization of photoelectrons emitted by solid alkali targets exposed to circularly polarized light. The polarization increases monotonically with increasing atomic number.

A finite temperature perturbation expansion is employed to obtain an approximate description of the thermodynamic behaviour of a Heisenberg antiferromagnet for spin half. The calculations are carried out using the drone-fermion representation, and contributions are classified with respect to a high density parameter 1/z, where z is the number of spins interacting with any given spin. This leads to the results of molecular field theory in lowest order (1/z)0. The spin fluctuation effects, which are absent in molecular field theory, are introduced in higher orders. Calculations of the sublattice magnetization, free energy, and internal energy are carried out up to and including (1/z)1. The results are valid provided the fluctuation effects are sufficiently small, which is the case for all temperatures below the Neel temperature TN and also for higher temperatures if there is a suitable applied magnetic field or anisotropy field acting on the system. In a low temperature approximation the results are found to be consistent with linear spin wave theory, including zero point effects.

The spin-orbit interaction for the $P$-state continuum of heavy alkali metals was investigated in a photoionization experiment using spin-polarized alkali atoms and circularly polarized light. From the asymmetry in ion-counting rates corresponding to the two photon helicities, Fano's spin-orbit perturbation parameter $x$ was determined over a range of several hundred angstroms for K, Rb, and Cs. The spin-orbit perturbation was found to increase from K to Rb to Cs as expected, and the nonlinear behavior of $x$ as a function of the photon energy $E$ was demonstrated for K. Knowledge of $x(E)$ was used to establish accurate values for the position of the Cooper minimum and to estimate the magnitude of the cross section at the minimum. In addition, the $x(E)$ data for Cs were used to gain information about the spin polarization of photoelectrons in a Fano-type polarized electron source. Finally, extrapolation of $x(E)$ for cesium into the discrete spectrum indicated the existence of a pole in the function $\ensuremath{\rho}(E)$ which corresponds to the doublet line-strength ratio $\ensuremath{\rho}({E}_{\mathrm{nP}})=\frac{S(n{P}_{\frac{3}{2}})}{S(n{P}_{\frac{1}{2}})}$ at the discrete energies ${E}_{\mathrm{nP}}$. According to our extrapolation, the pole lies in the region of $n=10 \mathrm{to} 15$, in agreement with the early spectroscopic work of Sambursky (1928) and Beutell (1939), whose measurements were discounted by later investigators.