Accurate calculation of the 4<i>p</i>lifetimes of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Ca</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>

Theodosiou, Constantine E.

doi:10.1103/physreva.39.4880

Cited by 62 publications

(53 citation statements)

References 25 publications

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“…3, to obtain the desired value γ P S . [8,16,26,27,28,29,30,31,32,33,34] Together with b this also yields γ P D = b 3 γ P S , and the radiative lifetime is given by 1/τ = γ P S (1 + b 3 ). Averaging over the data sets and taking into account the corrections discussed below, we obtain the resulting values: γ P S = 2π × 21.57 (8) Experimental imperfections and model approximations lead to uncertainties and corrections for the value of γ P S .…”

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confidence: 87%

Measurement of Dipole Matrix Elements with a Single Trapped Ion

et al. 2015

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We demonstrate a method to determine dipole matrix elements by comparing measurements of dispersive and absorptive light ion interactions. We measure the matrix element pertaining to the Ca II H line, i.e. the 4 2 S 1/2 ↔ 4 2 P 1/2 transition of 40 Ca + , for which we find the value 2.8928(43) ea0.Moreover, the method allows us to deduce the lifetime of the 4 2 P 1/2 state to be 6.904(26) ns, which is in agreement with predictions from recent theoretical calculations and resolves a longstanding discrepancy between calculated values and experimental results.PACS numbers: 37.10. Ty, 32.80.Qk, 03.67.Lx Methods for trapping and cooling single or few atoms, molecules or ions and manipulating them at the quantum level have opened up new avenues for precision laser spectroscopy. In particular, quantum logic techniques [1] have enabled a new accuracy regime of timekeeping with optical atomic clocks [2]. In contrast to atomic transition frequencies, dipole matrix elements and radiative lifetimes are still notoriously hard to determine at high accuracy, but are important for the quantification of black body radiation shifts of atomic clocks [3], interpretation of astrophysical spectra [4,5], novel approaches for the search for physics beyond standard model [6,7] and for testing the accuracy of atomic structure calculations [8].Regarding measurements of radiative lifetimes and transition matrix elements, established methods e.g. based on ion beams have been successfully complemented by novel techniques based on trapped particles. For 87 Rb, dipole matrix elements have been determined on the 10 −3 uncertainty level by diffraction in a condensate [9], while for the 6p 2 P o 1/2 state of 174 Yb + , the radiative lifetime has been measured by time-resolved counting of photons emitted from a single trapped ion [10]. A related technique was used for neutral 171 Yb in an optical lattice [11].The species Ca + is widely used in quantum optics experiments, and its II H line led to the discovery of the interstellar medium [12]. For 40 Ca + , branching ratios between different decay channels have been determined at uncertainties approaching the 10 −5 level [13,14], and lifetimes of metastable states have been accurately measured [15]. The radiative lifetime of the 4 2 P 1/2 excited state of 40 In this work, we determine the radiative decay rates and the lifetime of the 4 2 P 1/2 excited state of 40 Ca + together with the dipole matrix element of the 4 2 S 1/2 ↔ 4 2 P 1/2 transition. The cornerstone of our scheme is the comparison between the dispersive and absorptive interactions, which occur upon driving this transition with an off-resonant laser, see Fig. 1. As the method is based on the discrete discrimination of atomic states of a single trapped particle [17,18], it is robust against many systematic error sources which affect other existing methods.The off-resonant laser is characterized by its detuning ∆ from the 4 2 S 1/2 ↔ 4 2 P 1/2 transition, the Rabi frequency Ω and the relative amplitudes q , which characarXiv:1505.025...

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confidence: 87%

Measurement of Dipole Matrix Elements with a Single Trapped Ion

et al. 2015

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“…We compare with previous calculations by Vaeck et al (1992) where they use a multiconfiguration Hartree-Fock method with core polarization included variationally (SECP) using a model potential of the form described first by Baylis (1977) and then reviewed by Hibbert (1989). We also compare with Theodosiou (1989) who used a Hartree-Slater (HS) core potential with semiempirical corrections, Guet & Johnson (1991) who used relativistic many-body theory and Brage et al (1993) using an orthogonal Breit-Pauli MCHF method. We also compare with experimental values of Gallagher (1967) who used the Hanle-effect technique with optical excitation from the ion ground state.…”

Section: Model Potentialmentioning

confidence: 99%

“…Oscillator strengths for Ca ii. The oscillator strengths from previous calculations of Vaeck et al (1992), Theodosiou (1989), Guet & Johnson (1991) and Brage et al (1993), and experimental data from Gallagher (1967) are also given. Zeippen (1990), Ali & Kim (1988) and Vaeck et al (1992 correlation functions for the bound (e + ion) system, and A is the antisymetrization operator.…”

Section: Scattering Calculationsmentioning

confidence: 99%

Atomic data from the IRON project

Meléndez

Bautista²,

Badnell

2007

A&A

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Aims. This work reports radiative transition rates and electron impact excitation rate coefficients for levels of the n = 3, 4, 5, 6, 7, 8 configurations of Ca ii.Methods. The radiative data were computed using the Thomas-Fermi-Dirac central potential method in the frozen core approximation and includes the polarization interaction between the valence electron and the core using a model potential. This method allows for configuration interactions (CI) and relativistic effects in the Breit-Pauli formalism. Collision strengths in LS-coupling were calculated in the close coupling approximation with the R-matrix method. Then, fine structure collision strengths were obtained by means of the intermediate-coupling frame transformation (ICFT) method which accounts for spin-orbit coupling effects.Results. We present extensive comparisons with the most recent calculations and measurements for Ca ii as well as a comparison between the core polarization results and the "unpolarized" values. We find that core polarization affects the computed lifetimes by up to 20%. Our results are in very close agreement with recent measurements for the lifetimes of metastable levels. The present collision strengths were integrated over a Maxwellian distribution of electron energies and the resulting effective collision strengths are given for a wide range of temperatures. Our effective collision strengths for the resonance transitions are within ∼11% from previous values derived from experimental measurements, but disagree with later computations using the distorted wave approximation.

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“…with an oscillator strength of f lu = 0.3155 and radiative damping constant of γ rad = 1.42 × 10 8 s −1 , both from Theodosiou (1989). The coefficient Γ W = 1.33 × 10 −8 is calculated by Rouppe van der Voort (2002) from the broadening cross-section of Barklem & O'Mara (1998).…”

Section: Temperature and Depth Estimatesmentioning

confidence: 99%

Three-dimensional temperature mapping of solar photospheric fine structure using Ca ii H filtergrams

Henriques

2012

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Context. The wings of the Ca ii H and K lines provide excellent photospheric temperature diagnostics. At the Swedish 1-m Solar Telescope (SST), the blue wing of Ca ii H is scanned with a narrowband interference filter mounted on a rotation stage. This provides up to 0. 10 spatial resolution filtergrams at high cadence that are concurrent with other diagnostics at longer wavelengths. Aims. The aim is to develop observational techniques that provide photospheric temperature stratification at the highest spatial resolution possible and use them to compare simulations and observations at different heights.Methods. We use filtergrams in the Ca ii H blue wing that were obtained with a tiltable interference filter at the SST. Synthetic observations are produced from three-dimensional (3D) hydro and magneto-hydrodynamic numerical simulations and degraded to match the observations. The temperature structure obtained from applying the method to the synthetic data is compared with the known structure in the simulated atmospheres and with observations of an active region. Cross-correlation techniques using restored non-simultaneous continuum images are used to reduce high-altitude, small-scale seeing signal introduced from the non-simultaneity of the frames when differentiating data.Results. Temperature extraction using high-resolution filtergrams in the Ca ii H blue wing works reasonably well when tested with simulated 3D atmospheres. The cross-correlation technique successfully compensates for the problem of small-scale seeing differences and provides a measure of the spurious signal from this source in differentiated data. Synthesized data from the simulated atmospheres (including pores) match well the observations morphologically at different observed heights and in vertical temperature gradients.

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Accurate calculation of the 4plifetimes ofCa+

Cited by 62 publications

References 25 publications

Measurement of Dipole Matrix Elements with a Single Trapped Ion

Measurement of Dipole Matrix Elements with a Single Trapped Ion

Atomic data from the IRON project

Three-dimensional temperature mapping of solar photospheric fine structure using Ca ii H filtergrams

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