A high precision beam-foil meanlife measurement of the 1s 3p 1 P level in He I

Astner, G.; Curtis, L. J.; Liljeby, L.; Mannervik, S.; Martinson, I.

doi:10.1007/bf01409083

Cited by 56 publications

(13 citation statements)

References 23 publications

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“…Cascade repopulation affects the accurate determination of cross sections, therefore adding uncertainty in the comparison with theory, which eventually must also include the additional cascade contributions by performing a detailed cascade feeding analysis. Moreover, cascades have been an ever present limitation in the precise determination of lifetimes [17] using beam-foil spectroscopy [18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Radiative Cascade Repopulation of 1s2s2p 4P States Formed by Single Electron Capture in 2–18 MeV Collisions of C4+ (1s2s 3S) with He

Zouros

Nikolaou

Madesis

et al. 2020

Atoms

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This study focuses on the details of cascade repopulation of doubly excited triply open-shell C3+(1s2s2p)4P and 2P± states produced in 2–18 MeV collisions of C4+(1s2s3S) with He. Such cascade calculations are necessary for the correct determination of the ratio R of their cross sections, used as a measure of spin statistics [Madesis et al. PRL 124 (2020) 113401]. Here, we present the details of our cascade calculations within a new matrix formulation based on the well-known diagrammatic cascade approach [Curtis, Am. J. Phys. 36 (1968) 1123], extended to also include Auger depopulation. The initial populations of the 1s2snℓ4L and 1s2snℓ2L levels included in our analysis are obtained from the direct nℓ single electron capture (SEC) cross sections, calculated using the novel three-electron close-coupling (3eAOCC) approach. All relevant radiative branching ratios (RBR) for n≤4 were computed using the COWAN code. While doublet RBRs are found to be very small, quartet RBRs are found to be large, indicating cascade feeding to be important only for quartets, consistent with previous findings. Calculations including up to third order cascades, extended to n→∞ using an n−3 SEC model, showed a ∼60% increase of the 1s2s2p4P populations due to cascades, resulting, for the first time, in R values in good overall agreement with experiment.

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Section: Introductionmentioning

confidence: 99%

Radiative Cascade Repopulation of 1s2s2p 4P States Formed by Single Electron Capture in 2–18 MeV Collisions of C4+ (1s2s 3S) with He

Zouros

Nikolaou

Madesis

et al. 2020

Atoms

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“…The theory also predicts optical oscillator strengths for transitions among singlet levels [4][5][6] allowing the construction of the n 1 P lifetimes [7]. Many lifetime and optical oscillator strength measurements have been performed over the years using a variety of different techniques such as level crossing [8][9][10], self-absorption [11,12], beam-foil excitation [13,14,16,15], two-colour [17] and electron scattering [18]. Of these, only the last experimental technique has reached the 7 1 P state due to the various complicating effects which make reliable measurements difficult for n > 4 [19].…”

Section: Introductionmentioning

confidence: 99%

Emission of the³He—Xe—Cd mixture in the active zone of a nuclear reactor

Хасенов¹

2004

Quantum Electron.

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We have determined the lifetimes of helium n 1 P states, from the shortest 2 1 P (560 ± 14 ps), up to the 10 1 P (59.8 ± 1.5 ns). The experiment was performed by measuring the time dependence of UV fluorescence after the resonant excitation of states with pulsed synchrotron light. The apparent lifetimes have been extrapolated to the zero gas pressure limit for each n. Cascade decays of the initially prepared states and the effect of periodic target excitation have been also considered. The results are compared with our MCHF calculations and with other theoretical and experimental values.

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“…The spectra and decay curves were recorded as described earlier [8,9]. Spectral scans were taken at 210, 260 and 330 keV incoming ion energy while the lifetimes were determined using 160 and 230 keV energies.…”

Section: Methodsmentioning

confidence: 99%