Nick Jelley

Abstract:

The 33S1-33P0,1,2 transitions in helium-like oxygen have been observed in a foil-excited beam using a 'Doppler cancellation' light-enhancement technique applied to a grating spectrometer. The wavelengths of these transitions were measured at oxygen beam energies of 13.5, 18.0 and 23.5 MeV. The results are compared with calculations of the fine-structure splitting and with estimates of the Lamb shift of the 3 3S and 33P levels.

Abstract:

Radiation emitted from silicon beams at 35, 38 and 45 MeV excited by passage through thin carbon foils has been studied in the range 3-9 AA using a curved-crystal X-ray spectrometer. More than 100 lines have been observed, of which only one quarter had been observed or predicted from solar or laboratory plasma spectra. Most of the previously unobserved lines may be attributed to satellites of H- and He-like transitions arising in three- and four-electron Si ions. The lifetime of the Si XIII 23P1 state has been measured, and a preliminary experimental value of 6.5+or-1.3 ps obtained.

Abstract:

A simple and practical arrangement of coupling lenses for viewing a fast beam light source with a grating spectrometer is shown to provide very efficient light collection with good spectral and spatial resolution together with a simple procedure for calibrating spectra.

Abstract:

A laser resonance technique using Doppler tuning has been applied to measure transitions between highly excited states of highly ionized fluorine. Resonance transitions between n=9 and n=10 levels of 19F8+ with a mean wavelength of 4796.06±0.24 Å were observed. This wavelength is close to the calculated value of 4796.16 Å for the wavelength of the 92L17/2-102M19/2 transition.