Multicomponent non-neutral ion plasmas in a Penning trap consisting of Be(+) and highly charged Xe ions, having different mass-to-charge ratios than Be(+), are cooled to form strongly coupled plasmas by applying a laser-based collisional cooling scheme. The temperature of the plasma was determined from a Doppler broadened transition in Be(+). For the Xe ions, which are centrifugally separated from the Be, the Coulomb coupling parameter was estimated to be approximately 1000. Molecular dynamics simulations of the ion mixture show ordered structures, indicating crystallization of the Xe.

The mean lifetimes r of the Ca + 4p 2 Pin and 2 P\n levels have been measured to ==0.3% precision using a variant of the collinear laser-beam-ion-beam spectroscopy technique. Like previously measured precision lifetimes of light alkali-metal-like systems, these data fall significantly higher than calculations by the most recent multiconfiguration Hartree-Fock and relativistic many-body perturbation theories. Discrepancies between experiment and theory for alkali-metal-like systems have implications for the interpretation of parity-violation research.PACS numbers: 32.70.Fw, 31.30Jv, 42.55.Px, 42.62.Fi There is a current demand for precision (better than 1%) measurements of the lifetimes of electric dipole transitions of atoms or ions with a single electron outside a closed electron shell [1]. This arises from persistent attempts to improve the accuracy of relativistic many-body perturbation theory (MBPT) and multiconfiguration Dirac-Fock (MCDF) or Hartree-Fock (MCHF) calculations to this level of precision and beyond. Theoretical accuracy in transition matrix elements is required in conjunction with experimental precision (currently at the 2% level) in interference in transition amplitudes, to obtain the weak coupling constants in the analysis of atomic physics measurements [2] of parity violation in heavy, many-electron alkali-metal atoms such as Cs.During the last decade, discrepancies at the 1% level have been noted between the most precise experimental lifetimes of electric dipole decays of levels of light alkali metals, and ab initio theoretical lifetime calculations [3]. The measurements fall higher than the theory typically by > 5 standard deviations ( 3/2 level is r (Ca + ,4p 2^3/2) =6.924(0.019) ns while the corresponding measurement for the 2 P\/2 level is r (Ca + , 4p 2 / > i/2> =7.098(0.020) ns. Our results agree with, but are 3 times more precise than, the crossed laser-ion-beam data of Gosselin, Pinnington, and Ansbacher [6]. Our lifetime data fall higher than all of the ab initio theoretical calculations by about 2% (6a) or more, and 0.75% (2.5cr) or more higher than all semiempirical calculations. The disagreement between the theoretical and experimental results for Ca + is in accord with the earlier trend [3] for the few-electron alkali-metal-like systems, possibly signaling fundamental problems.Lifetime determinations based on laser excitation of fast beam atoms or ions are known for their accuracy and precision, since a single level is excited by the laser, and particle velocities can be well establ...

Lifetimes of metastable levels in the ground term of Fe ions within the 3s 2 3p k , kϭ1-5, isoelectronic sequences have been measured. These measurements were performed utilizing ions that were selected by mass to charge ratio while transported from an electron cyclotron resonance ion source to a Kingdon ion trap, where they were captured and then confined for periods of up to 2.1 s. During this storage period, selected emission wavelengths of transitions from metastable levels in the visible or near-ultraviolet spectral regions were isolated using interference filters, and the time-dependent fluorescence intensities were measured using a photomultiplier tube. Measurement precisions on the order of 2% were achieved in favorable cases. The measured lifetimes are ͑Fe X, 3s 2 p 5 2 P 1/2)ϭ13.64Ϯ0.25 ms, ͑Fe XI, 3s 2 3p 4 1 D 2)ϭ9.86Ϯ0.22 ms, ͑Fe XII, 3s 2 3p 3 2 P 3/2)ϭ1.85Ϯ0.24 ms, ͑Fe XII, 3s 2 3p 3 2 P 1/2)ϭ4.38Ϯ0.42 ms, ͑Fe XII, 3s 2 3p 3 2 D 3/2)ϭ20.35 Ϯ1.24 ms, ͑Fe XIII, 3s 2 3p 2 1 D 2)ϭ6.93Ϯ0.18 ms, and ͑Fe XIV, 3s 2 3p 2 P 3/2)ϭ17.52Ϯ0.29 ms. These results are compared with existing and with new theoretical calculations, which have estimated uncertainties on the order of 10-25 %.

The lifetimes of the 1s 2 2s2p 3 P 2 level of Ar XV and 1s 2 2s 2 2p 2 P 3/2 of Ar XIV have been measured using metastable Ar 14ϩ and Ar 13ϩ ions produced by an electron cyclotron resonance ion source, which were subsequently separately captured into a Kingdon ion trap. The lifetime results are ͑Ar XV, 2s2p 3 P 2 ) ϭ13.4(7) ms and ͑Ar XIV,2 p 2 P 3/2 )ϭ9.12(18) ms. Transition rates derived from the measured lifetimes differ significantly from both relativistic and nonrelativistic calculations of the 2s2p 3 P 1 -3 P 2 M 1 transition rate of Ar XV, but are in reasonable agreement with calculations for the 2p 2 P 1/2 -2 P 3/2 M 1 rate of Ar XIV.

In a laboratory study, the lifetimes of the P levels producing the coronal transitions of Fe x and Fe xiv have 2 been measured. The fluorescence from the metastable levels, which were populated when the ions were produced in a source of multiply charged ions, was studied after the selected ions were injected into an electrostatic ion trap. The results are t(Fe x, 3s 3p) ϭ ms and t(Fe xiv, 3s 3p) ϭ ms. The 2 5 2 o 2 2 o P 13.64 ‫ע‬ 0.25 P 17.52 ‫ע‬ 0.29 1/2 3/2 data significantly reduce the uncertainty of the lifetimes when compared with existing theory.