M.L.A. Raphaelian

Lifetime of the 2 sup 3 S sub 1 state of heliumlike sup 79 Br sup 33

We report a measurement of the lifetime of the 2{sup 3}{ital S}{sub 1} level in heliumlike {sup 79}Br{sup 33+}. Our result is {tau}{sup exp}(2 {sup 3}{ital S}{sub 1})=224.1(7.1) ps. This agrees with the theoretical calculation of 230(2) ps and provides a test of {ital O}({ital Z}{sup 2}{alpha}{sup 2}) corrections to the lifetime. The experimental error is dominated by uncertainties in the correction required to account for long-lived cascades from highly excited states.

Doubly-excited levels in Al III☆

Abstract We have used the beam-foil technique to search for transitions between the doubly-excited quartet levels in Al III. These levels, due to excitation of an inner-shell 2p electron, lead to radiation in the range of 900 to 1500 A. Calculations using a multiconfigurational Dirac Fock code have enabled us to propose preliminary identification of a number of transitions in this wavelength region.

Atomic physics measurements using an ECR ion source located on a 350 kV high-voltage platform

Abstract We report on a new atomic physics facility at the Argonne PII ECR ion source which was built for the Uranium Upgrade of the ATLAS heavy-ion accelerator. An important feature of our ECR ion source is that it is on a high-voltage platform which provides beam energies of up to 350 q keV, where q is the charge of the ion. We discuss the experimental program in progress at this ion source which includes measurements of state-selective electron capture cross sections, photon and electron spectroscopy, studies of quasi-molecular collisions, and polarization studies using an optically pumped Na target.

Subshell selective electron capture (2-105 keV amu-1) studied by VUV spectroscopy in O6++He collisions

Photon emission cross sections have been measured between 100 and 600 AA in collisions of 2-105 keV amu-1 O6+ ions on helium. The results extend existing data at low energy (0.56-7.13 keV amu-1) to higher energy. The data are compared with the existing atomic orbital calculations for one-electron capture in (quasi-) two-electron systems.

Probing QED using microwave and X-ray spectroscopy in hydrogenic ions☆

Abstract We discuss the status of measurements of the 2s Lamb shift in singly-ionized helium (He+) and of the 1s Lamb shift in one-electron calcium or titanium ions. The He+ Lamb shift experiment, which is being done at Princeton University, utilizes the microwave-resonance method in a beam of metastable He+. The high-Z experiment involves measurement of the 1s-2p transition energies using precision X-ray spectroscopy. This experiment will be carried out at the Argonne tandem-Linac (ATLAS).

M1 decay of the 2 3S1 state of helium‐like bromine

We have measured the lifetime of the 2 3S1 level in helium‐like bromine with the result τexp (2 3S1=224.1 (7.1) ps, in agreement with theory. Our error is dominated by uncertainties in the correction for the effects of cascades from highly excited states.

Precision spectroscopic measurements in few-electron ions

We describe recent precision experiments in fewelectron ions including measurements of the lifetimes of two-photon-emitting levels in Ni26+ and Ni27+, a measurement of the lifetime of the 23S1 level in Br33+ and measurements of the 23S1 + 23P0,1,2 transition energies in B3+.

Lifetime of the 2 1 S 0 state of heliumlike Ni 2 6

We report the observation of the two-photon decay of the

Lifetimes of two-photon-emitting states in heliumlike and hydrogenlike nickel.

{2}^{1}