Recent studies found huge disagreements (about 0.15 to 170) between the measured spin resonance strength εFS and the εBdl predicted by the widely used formulae. This resulted in theoretical disputes over: the correct factor of 2 in the εBdl equations for both rf solenoids and rf dipoles; and then between Gγ and (1 + Gγ) in the rf-dipole equation. Thus, we are systematically studying this problem at COSY. Our recent rf-dipole deuteron data strongly favor Gγ over the widely-used (1 + Gγ) factor for rf dipoles. This is further supported by the precise agreement of our new rfsolenoid deuteron data with the widely used rf-solenoid equation, indicating that our experiment is calibrated correctly. Moreover, these data firmly support the “BNL” factor of 2.

Results from a study of electrophysical and luminescent properties of zinc-germanium diphosphide single crystals, diffusion doped with copper, are presented. The nature of the dominant defects formed upon copper diffusion in ZnGeP2 is determined using a thermodynamic analysis of defect formation processes in ZnGeP2 and a ZnGeP2: Cu solid solution performed within the framework of the quasichemical analysis method. It is demonstrated that by choosing the copper diffusion method the hole concentration in the ZnGeP2 can be varied over the range 1012−1016 cm−3. A retrograde character was observed in copper solubility in ZnGeP2 compounds. Defect formation processes in ZnGeP2 upon copper diffusion depend on the degree of atomic ordering in the cation sublattice at the diffusion annealing temperature.

The temperature dependences of the density, mobility, and lifetime of electrons, and the photoconductivity and cathodoluminescence spectra of gallium arsenide with different electron densities doped with germanium when single crystals are grown by the Czochralski method are investigated. An analysis of the scattering mechanism is given, and the acceptor and donor densities are determined. The acceptor-type capture levels are found from the temperature dependence of the electron lifetime. The results of a study of the cathodoluminescence spectra indicate the presence in the specimens of complex radiational recombination centers similar to germanium-atom complexes with inherent lattice defects.

Investigations were made of the electrical properties, the cathodolumiescence and photoconductivity spectra, and the temperature dependence of the majority carrier lifetime in gallium arsenide with a high concentration of tin (n=2·1018 cm−3, 1.5·1017 cm−3) that was doped with copper under different diffusion regimes. Measurements of the Hall effect revealed centers with an ionization energy 0.175 ± 0.005 eV, their concentration depending on the rate of cooling of the samples. The cathodoluminescence and Hall effect data suggest that the cathodoluminescence band observed at 1.35 eV in GaAs∶Sn∶Cu is associated with radiative transitions of electrons to centers with ε a =Ev + 0.175 eV. The hole lifetime in GaAs∶Sn∶Cu has a complicated temperature dependence which can be explained qualitatively by the presence of two types of capture center.

The cathodoluminescence (CL) of doped and undoped layers of p-AlxGa1−xsb(0≤x≤0.8) grown by liquid-phase epitaxy has been investigated. Changing the composition of the solid solution resulted in emission bands having maxima between 0.77 and 1.58 eV at 77°K and between 0.72 and 1.55 eV at 300°K. It is shown that the following factors play a role in determining the luminescence intensity as a function of x: 1) the transfer of electrons to the L minimum in the conduction band; 2) a decrease in the hole concentration in the layers; 3) a decrease in the concentration of nonradiative recombination centers. The CL spectrum at 77°K contains a longwavelength band whose behavior is attributed to recombination through a level similar to the level known to be present in GaSb and believed to be caused by an intrinsic defect. The ionization energy of this level increases as x increases.

We recently studied the spin manipulation of 1.85 GeV/c vertically polarized deuterons stored in the COSY Cooler Synchrotron. We adiabatically swept an rf dipole's frequency through an rf- induced spin resonance and observed its effect on the deuterons' vector and tensor polarizations. After optimizing the resonance crossing rate and maximizing the rf dipole's voltage, we measured a spin-flip efficiency of 97 ± 1%. We confirmed at higher energy the striking behavior of the spin-1 tensor polarization recently found at IUCF.