Search Results (3 total)

A high-resolution photoabsorption spectrum of Ne has been measured in the energy range of the [1s2p]nℓn^′ℓ^′ doubly excited states, where square brackets indicate hole states, by means of photoion yield spectroscopy. The observed features have been interpreted by adopting a simple Rydberg formula. Energies as well as quantum defects for the members of the [1s2p](^3,1P)3pnp (3≤n≤5) series have been determined. We report observations of angle-resolved spectra of the resonant Auger (RA) transitions to the Ne⁺ [2p³]3p² states and to the Ne⁺ [2s2p²]3p² states from the [1s2p](^3,1P)3p² doubly excited states. These double-spectator-type transitions are confirmed by a good general agreement between the measured and theoretical RA spectra, where theoretical spectra are calculated based on the Hartree-Fock approximation. The measured anisotropy parameters are compared with theoretical predictions calculated using a pure LS coupling approach. We have made assignments for several levels with the aid of theoretical calculations.

A vertical coupled-bunch instability was observed for a positron beam at the Beijing Electron Positron Collider (BEPC). The experimental results show that the instability has similar characteristics as that observed in the Photon Factory of KEK several years ago. The instability at BEPC can be explained by the effect of an electron cloud which is produced in the beam chamber by synchrotron light hitting the wall.