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in creator/contributor: "Trabert, E"  
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Forbidden line wavelengths and transition probabilities measured using an electron beam ion trap (EBIT)

Description: Several coronal lines posed a long-standing riddle to earth-bound spectroscopists, until - following up on a suggestion by Grotrian (1937) - B. Edlen (1942) confirmed that their wavenumbers indeed corresponded to fine structure intervals in the ground configurations of highly charged ions like Fe X and Fe XI. This in turn caused turmoil in solar physics, because the corona must be much hotter than the underlying chromosphere in order to produce such ions. X-ray and EUV spectra of the sun became… more
Date: September 10, 1998
Creator: Beiersdorfer, P.; Gillaspy, J. D.; Serpa, F. G.; Trabert, E. & Utter, S. B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Flat-Field Grating Spectrometer for High-Resolution Soft X-Ray and EUV Measurements on an Electron Beam Ion Trap

Description: A R = 44.3 m grazing-incidence grating spectrometer has been implemented on the Livermore electron beam ion traps for high-resolution measurements in the soft x-ray and extreme ultraviolet region spanning from below 10 Angstrom up to 50 Angstrom. The instrument uses a grating with variable line spacing (about 2400 l/mm) for a flat field of view. Spectra are recorded with a back-illuminated charge-coupled device detector. The new instrument greatly improves upon the resolution achieved with exis… more
Date: March 27, 2004
Creator: Beiersdorfer, P.; Magee, E.; Trabert, E.; Chen, H.; Lepson, J. K.; Gu, M. F. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Wavelengths of the 4s1/2 - 4p3/2 resonance lines in Cu- and Zn-like heavy ions

Description: Using an electron beam ion trap and a high-resolution flat-field spectrometer, the EUV resonance lines 4s{sub 1/2} - 4p{sub 3/2} of the Cu- and Zn-like ions of Os, Bi, Th, and U (Z = 76-92) have been observed and their wavelengths measured. Our experiments remove systematic errors from line blends encountered in earlier work. Our results on Cu-like ions are in good agreement with recent ab initio calculations for all ions that include QED. Our results for Zn-like ions corroborate and extend our… more
Date: March 1, 2004
Creator: Beiersdorfer, P; Chen, H & Trabert, E
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Measurement of the two-loop Lamb shift in lithiumlike U89+

Description: Using the SuperEBIT electron beam ion trap we have measured the 2s{sub 1/2}-2p{sub 1/2} transitions in U{sup 88+} and U{sup 89+}. The value of 280.645 {+-} 0.015 eV for Li-like U{sup 89+} improves the available precision by nearly an order of magnitude and establishes a new benchmark for testing QED, including higher-order contributions, within a fractional accuracy of better than 3 x 10{sup -4}. From our measurement, we infer a value for both the 2s and 1s two-loop Lamb shift, yielding excelle… more
Date: April 1, 2005
Creator: Beiersdorfer, P; Chen, H; Thorn, D B & Trabert, E
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Magnetic-Field Sensitive Line Ratios in EUV and Soft X-ray Spectra

Description: We discovered a class of lines that are sensitive to the strength of the ambient magnetic field, and present a measurement of such a line in Ar IX near 49 {angstrom}. Calculations show that the magnitude of field strengths that can be measured ranges from a few hundred gauss to several tens of kilogauss depending on the particular ion emitting the line.
Date: April 24, 2006
Creator: Beiersdorfer, P; Scofield, J; Brown, G V; Chen, H; Trabert, E & Lepson, J K
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Investigation of the 2p3/2-3d5/2 line emission of Au53+ -- Au69+ for diagnosing high energy density plasmas

Description: 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 Au{sup 53+} through neonlike Au{sup 69+}. Using atomic data from the Flexible Atomic Code, we have identified strong 3d{sub 5/2} {yields} 2p{sub 3/2} emission features that can be used to diagnose the charge state distribution in high energy density plasmas, such as those found… more
Date: January 29, 2008
Creator: Brown, G V; Hansen, S B; Trabert, E; Beiersdorfer, P; Widmann, K; Chen, H et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Experimental and theoretical evaluation of density sensitive N VII, Ar XIV and Fe XXII line ratios

Description: 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 = 10{sup 10} to 10{sup 12} cm{sup -3} and ne = 10{sup 13} to 10{sup 15} cm{sup -3}, respectively. In our experiment, the electron beam density of about 10{sup 11} cm{sup -3} was varied by about a factor of 5. Our data show a dens… more
Date: January 9, 2004
Creator: Chen, H; Beiersdorfer, P; Heeter, L A; Liedahl, D A; Naranjo-Rivera, K L; Trabert, E et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Laboratory Measurement and Theoretical Modeling of K-shell X-ray Lines from Inner-shell Excited and Ionized Ions of Oxygen

Description: 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 stron… more
Date: February 5, 2005
Creator: Gu, M.; Schmidt, M.; Beiersdorfer, P.; Chen, H.; Thorn, D. B.; Trabert, E. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Relativistic Multireference Many-body Perturbation Theory for Open-shell Ions with Multiple Valence Shell Electrons: the Transition Rates and Lifetimes of the Excited Levels in Chlorinelike Fe X

Description: A recently developed relatistic multireference many-body perturbation theory based on multireference configuration-interaction wavefunctions as zeroth order wavefunctions is outlined. The perturbation theory employs a general class of configuration-interaction wve functions as reference functions, and thus is applciable to multiple open valence shell systems with near degeneracy of a manifold of strongly interacting configurations. Multireference many-body perturbation calculations are reported… more
Date: September 30, 2009
Creator: Ishikawa, Y; Santana, J A & Trabert, E
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Spectroscopy of ions using fast beams and ion traps

Description: A knowledge of the spectra of ionized atoms is of importance in many fields. They can be studied in a wide variety of light sources. In recent years techniques coming under the broad heatings of fast beams and ion traps have been used extensively for such investigations. This article considers the advantages that various techniques have for particular applications.
Date: October 1, 2004
Creator: Pinnington, E. H. & Trabert, E.
Item Type: Refine your search to only Book
Partner: UNT Libraries Government Documents Department
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EBIT in the Magnetic Trapping Mode: Mass Spectrometry, Atomic Lifetime Measurements, and Charge Transfer Reactions of Highly Charged Atomic Ions

Description: 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.
Date: July 10, 2001
Creator: Schweikhard, L; Beiersdorfer, P & Trabert, E
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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In Pursuit of Highly Accurate Atomic Lifetime Measurements of Multiply Charged Ions

Description: 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… more
Date: June 1, 2009
Creator: Trabert, E
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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On the transition rates of the Fe X and Fe XIV corona lines

Description: Despite a considerable scatter of the theoretical predictions of the M1/E2 transition rate of the ''red iron line'' (FeX) in the solar corona, there is disagreement of all the results with the single measurement that used an electrostatic ion trap. Employing a heavy-ion storage ring for measuring the same transition in isoelectronic ions of Co, Ni, and Cu, the situation has been clarified, and a new data point for FeX can be determined by extrapolation. This result agrees with the basic atomic … more
Date: November 20, 2003
Creator: Trabert, E
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Polarization Studies in Fast-Ion Beam Spectroscopy

Description: 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 h… more
Date: December 20, 2001
Creator: Trabert, E
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Spectroscopy of Argon Excited in an Electron Beam Ion Trap

Description: Argon is one of the gases best investigated and most widely used in plasma discharge devices for a multitude of applications that range from wavelength reference standards to controlled fusion experiments. Reviewing atomic physics and spectroscopic problems in various ionization stages of Ar, the past use and future options of employing an electron beam ion trap (EBIT) for better and more complete Ar data in the x-ray, EUV and visible spectral ranges are discussed.
Date: April 18, 2005
Creator: Trabert, E
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Isoelectronic trends of line strength data in the Li and Be isoelectronic sequences

Description: The decays of the 2p J = 1/2 and J = 3/2 levels of Li-like ions and of the 2s2p {sup 1,3}P{sub 1}{sup 0} levels of Be-like ions can be used as simple-atom test beds for experimental lifetime measurements and for the development of accurate calculations of the transition rates. They have summarized and filtered the experimental data in order to obtain consistent data sets and isoelectronic trends that can be compared to theoretical predictions. The graphical presentation of line strength data en… more
Date: March 1, 2006
Creator: Trabert, E & Curtis, L J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Soft-X-ray spectra of highly charged Os, Bi, Th, and U ions in an electron beam ion trap

Description: Systematic variation of the electron-beam energy in an electron-beam ion trap has been employed to produce soft-X-ray spectra of Os, Bi, Th, and U with highest charge states ranging up to Ni-like ions. Guided by relativistic atomic structure calculations, the strongest lines have been identified with {Delta}n = 0 (n = 4 to n' = 4) transitions in Rb- to Cu-like ions. The rather weak 4p-4d transitions are much less affected by QED contributions than the dominant 4s-4p transitions. Our wavelength … more
Date: December 3, 2004
Creator: Trabert, E.; Beiersdorfer, P.; Fournier, K. B. & Chen, M. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Observation of hyperfine mixing in measurements of a magnetic octupole decay in isotopically pure nickel-like 129Xe and 132Xe ions

Description: We present measurements of high statistical significance of the rate of the magnetic octupole (M3) decay in nickel-like ions of isotopically pure {sup 129}Xe and {sup 132}Xe. On {sup 132}Xe, an isotope with zero nuclear spin and therefore without hyperfine structure, the lifetime of the metastable level was established as (15.06 {+-} 0.24) ms. On {sup 129}Xe, an additional fast (2.7 {+-} 0.1 ms) decay component was established that represents hyperfine mixing with a level that decays by electri… more
Date: December 21, 2006
Creator: Trabert, E; Beiersdorfer, P & Brown, G V
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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