[en] Accurate atomic lifetime data are useful for terrestrial and astrophysical plasma diagnostics. At accuracies higher than those required for these applications, lifetime measurements test atomic structure theory in ways complementary to spectroscopic energy determinations. At the highest level of accuracy, the question arises whether such tests reach the limits of modern theory, a combination of quantum mechanics and QED, adn possibly point to physics beyond the Standard Model. If high-precision atomic lifetime measurements, especially on multiply charged ions, have not quite reached this high accuracy yet, then what is necessary to attain this goal?

[en] In a historical review, the observations and the insight gained from polarization studies of fast ions interacting with solid targets are presented. These began with J. Macek's recognition of zero-field quantum beats in beam-foil spectroscopy as indicating alignment, and D.G. Ellis' density operator analysis that suggested the observability of orientation when using tilted foils. Lastly H. Winter's studies of the ion-beam surface interaction at grazing incidence yielded the means to produce a high degree of nuclear orientation in ion beams

[en] Although it may sound like a contradiction in terms, the electron beam ion trap (EBIT) works as an ion trap even when the electron beam is switched off. We present various experiments that exploit the ''magnetic trapping mode'' for investigations of ion confinement, charge exchange processes, atomic lifetime and ion mass measurements

[en] We present wavelength measurements of K-shell resonance lines of O V and O VI, using the University of California Lawrence Livermore National Laboratory EBIT-I electron beam ion trap. The wavelength accuracy of better than 140 ppm is sufficient to determine gas outflow velocities of warm absorbers associated with AGNs to within 40 km/s and better. Our measurements confirm that the outflow velocities associated with NGC 5548 and derived from O V and O VI lines are similar to those derived from the O VII lines. These kinematic measurements make for further evidence that the X-ray and UV absorbers in these systems are truly two manifestations of the same physical outflow

[en] We present high resolution laboratory spectra of K-shell X-ray lines from inner-shell excited and ionized ions of oxygen, obtained with a reflection grating spectrometer on the electron beam ion trap (EBIT-I) at the Lawrence Livermore National Laboratory. Only with a multi-ion model including all major atomic collisional and radiative processes, are we able to identify the observed K-shell transitions of oxygen ions from O III to O VI. The wavelengths and associated errors for some of the strongest transitions are given, taking into account both the experimental and modeling uncertainties. The present data should be useful in identifying the absorption features present in astrophysical sources, such as active galactic nuclei and X-ray binaries. They are also useful in providing benchmarks for the testing of theoretical atomic structure calculations

[en] Systematic variation of the electron-beam energy in an electron-beam ion trap has been employed to produce soft-X-ray spectra (20 to 60 A) of Au with well-defined maximum charge states ranging from Br- to Co-like ions. Guided by large-scale relativistic atomic structure calculations, the strongest Δn = 0 (n = 4 to n^' = 4) transitions in Rb- to Cu-like ions (Au⁴²⁺ - Au⁵⁰⁺) have been identified. (author)

[en] Measurements of the L-shell emission of highly charged gold ions were made under controlled laboratory conditions using the SuperEBIT electron beam ion trap, allowing detailed spectral observations of lines from ironlike Au⁵³⁺ through neonlike Au⁶⁹⁺. Using atomic data from the Flexible Atomic Code, we have identified strong 3d_5/2 → 2p_3/2 emission features that can be used to diagnose the charge state distribution in high energy density plasmas, such as those found in the laser entrance hole of hot hohlraum radiation sources. We provide collisional-radiative calculations of the average ion charge < Z> as a function of temperature and density, which can be used to relate charge state distributions inferred from 3d_5/2 → 2p_3/2 emission features to plasma conditions, and investigate the effects of plasma density on calculated L-shell Au emission spectra

[en] The line ratios of the 2p-3d transitions in the B-like spectra Ar XIV and Fe XXII have been measured using the electron beam ion traps at Livermore. Radiative-collisional model calculations show these line ratios to be sensitive to the electron density in the ranges ne = 10¹⁰ to 10¹² cm^-3 and ne = 10¹³ to 10¹⁵ cm^-3, respectively. In our experiment, the electron beam density of about 10¹¹ cm^-3 was varied by about a factor of 5. Our data show a density effect for the line doublet in Ar XIV, and good agreement with theory is found. The relative intensity of the Fe XXII doublet shows good agreement with our predicted low density limit. The N VI K-shell spectrum was used to infer the actual electron density in the overlap region of ion cloud and electron beam, and systematic measurements and calculations of this spectrum are presented as well. The Ar XIV and Fe XXII spectra promise to be reliable density diagnostics for stellar coronae, complementing the K-shell diagnostics of helium-like ions

[en] The Electron Beam Ion Trap Microcalorimeter Spectrometer (ECS) routinely surveys the K-shell x-ray spectra that fall into the energy range between 200 eV and 14,000 eV. The spectra serve as in situ energy references and include the K-shell emission from ions between boron at the low-energy end and krypton at the high end. Example spectra are presented of the n = 2 → n = 1 emission from heliumlike noble gas ions neon, argon, and krypton, from the heliumlike transition metals iron and nickel, as well as the heliumlike ions of boron, silicon, sulfur, and germanium.

[en] The extreme ultraviolet spectrum of foil-excited Li has been recorded at ion energies 100--300 keV with higher spectral resolution than before. Previously assigned decays of core-excited three-electron doublet states (some of which autoionize rapidly) are confirmed with higher wavelength precision