| 1. |
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| 2. |
- Falster, Daniel, et al.
(författare)
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AusTraits, a curated plant trait database for the Australian flora
- 2021
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Ingår i: Scientific Data. - : Nature Portfolio. - 2052-4463. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- We introduce the AusTraits database - a compilation of values of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 448 traits across 28,640 taxa from field campaigns, published literature, taxonomic monographs, and individual taxon descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological attributes (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised individual- and species-level measurements coupled to, where available, contextual information on site properties and experimental conditions. This article provides information on version 3.0.2 of AusTraits which contains data for 997,808 trait-by-taxon combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data, which also provides a template for other national or regional initiatives globally to fill persistent gaps in trait knowledge.
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| 3. |
- Gao, Si, et al.
(författare)
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Drivers and reduction solutions of food waste in the Chinese food service business
- 2020
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Ingår i: Sustainable Production and Consumption. - : Elsevier BV. - 2352-5509. ; 26, s. 78-88
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Tidskriftsartikel (refereegranskat)abstract
- Food waste generated from the food service sector is associated with significant social, ecological and economic impacts. There is lack of knowledge on status quo, drives and solutions for food waste in food service sector despite its importance. In order to understand and identify key issues of food waste and find potential solutions for food waste minimization in food service business, both a questionnaire and a qualitative study were conducted using China as a case country. 228 questionnaires were collected and in a subsequent workshop 51 representatives from 19 enterprises and other organizations joined. The results show that more than half (57%) of the respondents pay no attention to food waste issue, while majority of the respondents (86%) pay attention to regulations and policy on waste issues, suggesting that these instruments would be efficient tools to take actions on reducing food waste. The workshop identified 21 drivers with division of different stages including pre-kitchen (upstream processing, procurement and storage), kitchen and post-kitchen (consumption & communication with consumers), which is then categorized according to the focus (including 13 internal drivers derived from foods service business itself and 8 external factors caused by other parties). 33 possible solutions were proposed for food waste mitigation and reduction, among which 25 were directly for Chinese food service business internal improvement such as food waste management system upgrading, staff capacity raising, innovative actions, more tasteful dishes and adjusted potion size from different angles or for the joint activities by food service business and other relevant stakeholders like consumers interaction, clear communicated procurement standards with upstream suppliers. This paper pinpointed some interesting findings under the Chinese context, such as lacking of food waste measurement, considerable amount of upstream processing waste resulted from combination of unclear standards and buyers’ privilege”, noticeable food waste from central kitchen and decoration/free snacks food waste etc.. This paper has not only identified the current status quo of the Chinese food service business food waste, but also summarized systematically the potential drivers from the business with specific division of different stages and gave out possible solutions, all directly from the staffs’ opinions. The findings would be referential to global food waste issues under similar situation.
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| 4. |
- Guo, Xueling, et al.
(författare)
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Energy levels and radiative data for Kr-like W38+ from MCDHF and RMBPT calculations
- 2016
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 49:13
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Tidskriftsartikel (refereegranskat)abstract
- Energies, transition rates, line strengths and lifetimes have been computed for all levels of the 4p 6 and 4p 54d configurations of W38+ by using the multi-configuration Dirac-Hartree-Fock (MCDHF) method as well as relativistic many-body perturbation theory. We investigate systematically correlation, relativistic and quantum electro-dynamical (QED) effects of different properties, including excitation energies and transition rates. We demonstrate that it is important to include the core-valence correlation of rather deep subshells (including 3d and 3p) to reach close to spectroscopic accuracy for the transition energies. We also show that high-multipole transitions (E3, M2) are important for the lifetime of some metastable levels of 4p 54d (). The present results are in good agreement with experiments and of considerably higher accuracy than those achieved in previous theoretical works.
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| 5. |
- Kristan, Matej, et al.
(författare)
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The Sixth Visual Object Tracking VOT2018 Challenge Results
- 2019
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Ingår i: Computer Vision – ECCV 2018 Workshops. - Cham : Springer Publishing Company. - 9783030110086 - 9783030110093 ; , s. 3-53
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2018 is the sixth annual tracker benchmarking activity organized by the VOT initiative. Results of over eighty trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis and a “real-time” experiment simulating a situation where a tracker processes images as if provided by a continuously running sensor. A long-term tracking subchallenge has been introduced to the set of standard VOT sub-challenges. The new subchallenge focuses on long-term tracking properties, namely coping with target disappearance and reappearance. A new dataset has been compiled and a performance evaluation methodology that focuses on long-term tracking capabilities has been adopted. The VOT toolkit has been updated to support both standard short-term and the new long-term tracking subchallenges. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website (http://votchallenge.net).
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| 6. |
- Li, Haimeng, et al.
(författare)
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Sleep microenvironment improvement for the acute plateau entry population through a novel nasal oxygen supply system
- 2024
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Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 256
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Tidskriftsartikel (refereegranskat)abstract
- Most people who have moved to high-altitude areas temporarily suffer from sleep disorders. Sleep deprivation negatively affects not only people's daytime activities but also their health. However, most of the existing nonpharmaceutical intervention methods have the problems of discomfort, restricted movement, or high cost. This study involved the use of an oxygen-rich flow of air in the breathing area during sleep to fight hypoxia and aid with altitude acclimatization when people first traveled to a highland plateau. The associated nasal breathing targeted oxygen supply system (NBTOSS) was designed and optimized by numerical simulation and full-scale experiments. Blood oxygen saturation (SaO2) and pulse rate (PR) monitoring experiments were conducted on subjects exposed to hypoxia at a high altitude (Lhasa, 3646.31 m) with or without assistance from the novel oxygen system and on a lowland plain (Xi'an, 397.5 m) as a comparison. The size of the affected area, concentration target value, and oxygen consumption were used as evaluation indices. Experiments have demonstrated the feasibility of creating an oxygen-enriched microenvironment in breathing area during sleep. The results of the testing showed that the oxygen supply area was uniformly covered and that the degree of hypoxia in subjects was effectively alleviated, with average SaO2 increasing to 95% ± 1%. Maintaining oxygen levels during sleep for temporary residents of high altitudes with less oxygen consumption and minimal oxygen supply costs is discussed to provide a healthy and comfortable oxygen-enriched environment.
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| 7. |
- Li, Yanting, et al.
(författare)
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Performance Tests and Improvements on the rmcdhf and rci Programs of GRASP
- 2023
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- The latest published version of GRASP (General-purpose Relativistic Atomic Structure Package), i.e., GRASP2018, retains a few suboptimal subroutines/algorithms, which reflect the limited memory and file storage of computers available in the 1980s. Here we show how the efficiency of the relativistic self-consistent-field (SCF) procedure of the multiconfiguration-Dirac-Hartree-Fock (MCDHF) method and the relativistic configuration-interaction (RCI) calculations can be improved significantly. Compared with the original GRASP codes, the present modified version reduces the CPU times by factors of a few tens or more. The MPI performances for all the original and modified codes are carefully analyzed. Except for diagonalization, all computational processes show good MPI scaling.
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| 8. |
- Li, Yan Ting, et al.
(författare)
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Reducing the computational load : atomic multiconfiguration calculations based on configuration state function generators
- 2023
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Ingår i: Computer Physics Communications. - : Elsevier. - 0010-4655 .- 1879-2944. ; 283, s. 108562-108562
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Tidskriftsartikel (refereegranskat)abstract
- In configuration interaction (CI) calculations the atomic wave functions are given as expansions over configuration state functions (CSFs) built on relativistic one-electron orbitals. The expansion coefficients of the configuration state functions are obtained by constructing and diagonalizing the Hamiltonian matrix. Here we show how a regrouping of the configuration state functions and the introduction of configuration state function generators (CSFGs) allow for a substantial reduction of the computational load in relativistic CI calculations. The computational methodology based on configuration state function generators, recently implemented in the General Relativistic Atomic Structure package (Grasp2018, Froese Fischer et al. (2019) [16]), is applied to a number of atomic systems and correlation models with increasing sets of one-electron orbitals. We demonstrate a reduction of the CPU time with factors between 10 and 14 for the largest CI calculations. The inclusion of the Breit interaction into the calculations is time consuming. By applying restrictions on the Breit integrals we show that it is possible to further reduce the CPU times with factors between 2 and 3, with negligible changes to the computed excitation energies. We also demonstrate that the introduction of configuration state function generators allows for efficient a priori condensation techniques, with reductions of the expansions sizes with factors between 1.5 and 2.5 and the CPU time with factors between 2.5 and 4.5, again with negligible changes to the excitation energies. In total we demonstrate reductions of the CPU time with factors up to 68 for CI calculations based on configuration state function generators, restrictions on the Breit integrals and with a priori condensed expansions compared to ordinary CI calculations without restrictions on the Breit integrals and with full expansions. Further perspectives of the new methodology based on configuration state function generators are given.
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| 9. |
- Liu, Wei, et al.
(författare)
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Arbitrarily rotating polarization direction and manipulating phases in linear and nonlinear ways using programmable metasurface
- 2024
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Ingår i: Light: Science and Applications. - 2095-5545 .- 2047-7538. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Independent controls of various properties of electromagnetic (EM) waves are crucially required in a wide range of applications. Programmable metasurface is a promising candidate to provide an advanced platform for manipulating EM waves. Here, we propose an approach that can arbitrarily control the polarization direction and phases of reflected waves in linear and nonlinear ways using a stacked programmable metasurface. Further, we extend the space-time-coding theory to incorporate the dimension of polarization, which provides an extra degree of freedom for manipulating EM waves. As proof-of-principle application examples, we consider polarization rotation, phase manipulation, and beam steering at linear and nonlinear frequencies. For validation, we design, fabricate, and measure a metasurface sample. The experimental results show good agreement with theoretical predictions and simulations. The proposed approach has a wide range of applications in various areas, such as imaging, data storage, and wireless communication.
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| 10. |
- Si, Ran, et al.
(författare)
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A First Spectroscopic Measurement of the Magnetic-field Strength for an Active Region of the Solar Corona
- 2020
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics (IOP). - 2041-8205 .- 2041-8213. ; 898:2
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Tidskriftsartikel (refereegranskat)abstract
- For all involved in astronomy, the importance of monitoring and determining astrophysical magnetic-field strengths is clear. It is also a well-known fact that the corona magnetic fields play an important part in the origin of solar flares and the variations of space weather. However, after many years of solar corona studies, there is still no direct and continuous way to measure and monitor the solar magnetic-field strength. We present here a scheme that allows such a measurement, based on a careful study of an exotic class of atomic transitions, known as magnetic induced transitions, in Fe9+. In this contribution we present a first application of this methodology and determine a value of the coronal field strength using the spectroscopic data from Hinode.
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| 11. |
- Si, Ran, et al.
(författare)
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Ab initio multiconfiguration Dirac-Hartree-Fock calculations of the in and Tl electron affinities and their isotope shifts
- 2021
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Ingår i: Physical Review A. - 2469-9926. ; 104:1
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Tidskriftsartikel (refereegranskat)abstract
- We report multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction calculations on the thallium (Tl) electron affinity, as well as on the excited energy levels arising from the ground configuration of Tl-. The results are compared with the available experimental values and further validated by extending the study to its homologous, lighter element, indium (In), belonging to group 13 (III.A) of the Periodic Table. The calculated electron affinities of In and Tl, 383.4 and 322.8 meV, agree with the latest measurements by within 1%. Three bound states 3P0,1,2 are confirmed in the 5s25p2 configuration of In-, while only the ground state 3P0 is bound in the 6s26p2 configuration of Tl-. The isotope shifts on the In and Tl electron affinities are also estimated. The E2 and M1 intraconfiguration radiative transition rates within 5s25p2 3P0,1,2 of In- are used to calculate the radiative lifetimes of the metastable 3P1,2 levels.
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| 12. |
- Si, Ran, et al.
(författare)
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EXTENDED CALCULATIONS WITH SPECTROSCOPIC ACCURACY : ENERGY LEVELS AND TRANSITION PROPERTIES FOR THE FLUORINE-LIKE ISOELECTRONIC SEQUENCE WITH Z = 24–30
- 2016
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 227:2
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Tidskriftsartikel (refereegranskat)abstract
- We have performed extensive multiconfiguration Dirac–Hartree–Fock calculations and second-order many-body perturbation calculations for F-like ions with Z = 24–30. Energy levels and transition rates for electric dipole (E1), electric-quadrupole (E2), electricoctupole (E3), magnetic dipole (M1), and magnetic-quadrupole (M2) transitions, as well as radiative lifetimes, are provided for the lowest 200 levels belonging to the 1s22s22p5, 1s22s2p6, 1s22s22p43l, 1s22s2p53l, 1s22p63l, and 1s22s22p44l configurations of each ion. The results from the two sets of calculations are in excellent agreement. Extensive comparisons are also made with other theoretical results and observed data from the CHIANTI and NIST databases. The present energies and wavelengths are believed to be accurate enough to aid line identifications involving the n = 3 and n = 4 configurations, for which observations are largely missing. The calculated wavelengths and transition data will be useful in the modeling and diagnostics of astrophysical and fusion plasmas.
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| 13. |
- Si, Ran, et al.
(författare)
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Proposal for observation of transitions induced by external magnetic fields mixing in the lower states : with an example from Fe X
- 2020
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Ingår i: Journal of Physics B. - : Institute of Physics (IOP). - 0953-4075 .- 1361-6455. ; 53:9
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Tidskriftsartikel (refereegranskat)abstract
- It is normally assumed that induced transitions, by e.g. hyperfine, magnetic field or spin interaction, arise due to mixing in the upper levels. In this paper we discuss an example when mixing in the lower levels through an externally applied magnetic field gives rise to a magnetic field induced transition. We discuss the theory for such a transition and give an example from Fe X, which is relevant for the determination of the magnetic field of the solar corona. To make this possible, it is important to determine the energy difference between the 3p(4)3d D-4(5/2) and D-4(7/2), which are accidentally very close in energy in Fe X. The splitting of these levels is expected to be around 3.5 cm(-1) whereas their excitation energies are about 388 709 cm(-1). We discuss how this fine structure can be determined, by observing transitions from levels that decay into this pair which have a longer wavelength than the resonance transition. Finally we discuss an experimental scenario based on an electron beam ion trap and a Fabry-Perot interferometer, to perform the measurement of this interval.
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| 14. |
- Su, Yangluojia, et al.
(författare)
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The structure and radiative lifetimes of negative ions homologous to N-
- 2019
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 52:12, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Negative ions homologous to N- are interesting systems, since there are several bound terms within the ground configuration. The forbidden transitions between them, often dominated by the magnetic dipole contributions, are affected by term mixing - a relativistic effect. When increasing the nuclear charge in the homologous sequence of negative ions, this effect increases. In this paper we use systematic multiconfiguration Dirac-Hartree-Fock calculations to study these effects and predict affinities, level splittings and transition rates between bound states of N-, P-, As-, Sb- and Bi-. By monitoring the line strengths we are able to predict the deviation from the non-relativistic LS-coupled values for transitions between levels of the lowest 3P term. For Sb- the 1D term is also bound, and the prediction for the rates of its transition to the 3P-levels is a challenge for theory. For Bi- less is known experimentally and we analyze its structure and the relativistic contributions to it.
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| 15. |
- Tang, Rulin, et al.
(författare)
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Candidate for Laser Cooling of a Negative Ion : High-Resolution Photoelectron Imaging of Th
- 2019
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Ingår i: Physical Review Letters. - 0031-9007. ; 123:20
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Tidskriftsartikel (refereegranskat)abstract
- Laser cooling is a well-established technique for the creation of ensembles of ultracold neutral atoms or positive ions. This ability has opened many exciting new research fields over the past 40 years. However, no negatively charged ions have been directly laser cooled because a cycling transition is very rare in atomic anions. Efforts of more than a decade currently have La- as the most promising candidate. We report on experimental and theoretical studies supporting Th- as a new promising candidate for laser cooling. The measured and calculated electron affinities of Th are, respectively, 4901.35(48) cm-1 and 4832 cm-1, or 0.607 690(60) and 0.599 eV, almost a factor of 2 larger than the previous theoretical value of 0.368 eV. The ground state of Th- is determined to be 6d37s2 F43/2e rather than 6d27s27p G45/2o. The consequence of this is that there are several strong electric dipole transitions between the bound levels arising from configurations 6d37s2 and 6d27s27p in Th-. The potential laser-cooling transition is S1/2o2↔F43/2e with a wavelength of 2.6 μm. The zero nuclear spin and hence lack of hyperfine structure in Th- reduces the potential complications in laser cooling as encountered in La-, making Th- a new and exciting candidate for laser cooling.
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| 16. |
- Tang, Rulin, et al.
(författare)
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Observation of electric-dipole transitions in the laser-cooling candidate Th- And its application for cooling antiprotons
- 2021
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Ingår i: Physical Review A. - 2469-9926. ; 103:4
-
Tidskriftsartikel (refereegranskat)abstract
- Despite the fact that the laser-cooling method is a well-established technique to obtain ultracold neutral atoms and atomic cations, it has rarely if ever been applied to atomic anions due to the lack of suitable electric-dipole transitions. Efforts of more than a decade have until recently only resulted in La- as a promising anion candidate for laser cooling, but our previous work [Tang et al., Phys. Rev. Lett. 123, 203002 (2019)10.1103/PhysRevLett.123.203002] showed that Th- is also a potential candidate. Here we report on a combination of experimental and theoretical studies to determine the frequencies and rates, as well as branching ratios, for the relevant transitions in Th-. The resonant frequency of the laser-cooling transition is determined to be ν=123.455(30) THz [λ=2428.4(6)nm]. The transition rate is calculated as A=1.17×104s-1. Since the branching fraction to dark states is negligible, 1.47×10-10, this represents an ideal closed cycle in Th- for laser cooling. Furthermore, the zero nuclear spin of Th232 makes the cooling process possible in a Penning trap, which can be used to confine both antiprotons and Th- ions. The presented ion dynamics simulations show that the laser-cooled Th- anions can effectively cool antiprotons to a temperature around 10 mK.
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| 17. |
- Wang, Kai, et al.
(författare)
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Benchmarking Atomic Data for Astrophysics : Be-like Ions between B II and Ne VII
- 2018
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Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics (IOP). - 0067-0049 .- 1538-4365. ; 234:2
-
Tidskriftsartikel (refereegranskat)abstract
- Large-scale self-consistent multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction calculations are reported for the n <= 6 levels in Be-like ions from B II to Ne VII. Effects from electron correlation are taken into account by means of large expansions in terms of a basis of configuration state functions, and a complete and accurate data set of excitation energies; lifetimes; wavelengths; electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole line strengths; transition rates; and oscillator strengths for these levels is provided for each ion. Comparisons are made with available experimental and theoretical results. The uncertainty of excitation energies is assessed to be 0.01% on average, which makes it possible to find and rule out misidentifications and aid new line identifications involving high-lying levels in astrophysical spectra. The complete data set is also useful for modeling and diagnosing astrophysical plasmas.
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| 18. |
- Wang, Kai, et al.
(författare)
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Calculations with spectroscopic accuracy : Energies and transition rates in the nitrogen isoelectronic sequence from Ar XII to Zn XXIV
- 2016
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 223:1
-
Tidskriftsartikel (refereegranskat)abstract
- Combined relativistic configuration interaction and many-body perturbation calculations are performed for the 359 fine-structure levels of the 2s2 2p3, 2 s2p4, 2p5, 2s2 2p2 3l, 2 s2p3 3l, 2p4 3l, and 2s2 2p2 4l configurations in N-like ions from Ar XII to Zn XXIV. Complete and consistent data sets of energies, wavelengths, radiative rates, oscillator strengths, and line strengths for all possible electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among the 359 levels are given for each ion. The present work significantly increases the amount of accurate data for ions in the nitrogen-like sequence, and the accuracy of the energy levels is high enough to enable the identification and interpretation of observed spectra involving the n=3, 4 levels, for which experimental values are largely scarce. Meanwhile, the results should be of great help for modeling and diagnosing astrophysical and fusion plasmas.
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| 19. |
- Wang, Kai, et al.
(författare)
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Calculations with spectroscopic accuracy for energies, transition rates, hyperfine interaction constants, and Landé gJ-factors in nitrogen-like Kr XXX
- 2017
-
Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier. - 0022-4073 .- 1879-1352. ; 187, s. 375-402
-
Tidskriftsartikel (refereegranskat)abstract
- Extensive self-consistent multi-configuration Dirac-Fock(MCDF) calculations and second-order many- body perturbation theory (MBPT) calculations are performed for the lowest 272 states belonging to the 2s22p3, 2s2p4, 2p5, 2s22p23l, and2s2p33l (l¼s, p, d) configurations of N-like KrXXX.Complete and consistent datasets of level energies,wavelengths,line strengths, oscillator strengths,lifetimes, AJ, BJ hyperfine interaction constants,Landé gJ-factors, and electric dipole(E1),magnetic dipole(M1),electric quadrupole(E2),magnetic quadrupole(M2) transition rates among all these levels are given.The present MCDF and MBPTresults are compared with each other and with other available experimental and theoretical results.The mean relative difference between our two sets of level energies is only about 0.003% for these 272 levels.The accuracy of the present calculations are high enough to facilitate identification of many observed spectral lines.These accurate data can be served as benchmark for other calculations and can be useful for fusion plasma research and astrophysical applications.
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| 20. |
- Wang, Kai, et al.
(författare)
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EXTENDED RELATIVISTIC CONFIGURATION INTERACTION AND MANY-BODY PERTURBATION CALCULATIONS OF SPECTROSCOPIC DATA FOR THE N 6 CONFIGURATIONS IN Ne-LIKE IONS BETWEEN Cr XV AND Kr XXVII
- 2016
-
Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 226:2
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Tidskriftsartikel (refereegranskat)abstract
- Level energies, wavelengths, electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transition rates, oscillator strengths, and line strengths from combined relativistic con guration interaction and many-body perturbation calculations are reported for the 201 ne-structure states of the 2s22p6, 2s22p53l, 2s2p63l, 2s22p54l, 2s2p64l, 2s22p55l, and 2s22p56l con gurations in all Ne-like ions between Cr XV and Kr XXVII. Calculated level energies and transition data are compared with experiments from the National Institute of Standards and Technology (NIST) and CHIANTI databases, and other recent benchmark calculations. The mean energy difference with the NIST experiments is only 0.05%. The present calculations signi cantly increase the amount of accurate spectroscopic data for the n > 3 states in a number of Ne-like ions of astrophysical interest. A complete data set should be helpful for analyzing new observations from solar and other astrophysical sources, and is also likely to be useful for modeling and diagnosing a variety of plasmas, including astronomical and fusion plasma.
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| 21. |
- Wang, Kai, et al.
(författare)
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Large-scale Multiconfiguration Dirac-Hartree-Fock and Relativistic Configuration Interaction Calculations of Transition Data for B-like S XII
- 2018
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 864:2
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Tidskriftsartikel (refereegranskat)abstract
- Excitation energies and lifetimes for the 213 lowest states of the n <= 5 configurations in B-like S XII are calculated using highly correlated wave functions, optimized with the fully relativistic multiconfiguration Dirac-Hartree-Fock method. Multipole transition rates and associated radiative data (line strengths and oscillator strengths) for transitions connecting these levels are also reported. The theoretical excitation energies are systematically compared with the NIST Atomic Spectra Database in which misidentifications are pointed out. After eliminating the latter, a mean energy difference with the standard deviation between computed and observed energies of 12 +/- 341 cm(-1) is obtained for the n >= 3 high-lying states. This level of accuracy confirms that elaborate ab initio calculations can assist in the identification of new emission lines in the solar and other astrophysical spectra. The present work provides atomic data of high accuracy for an ion of astrophysical interest, B-like S XII, for which experimental data are scarce.
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| 22. |
- Zhang, Chun Yu, et al.
(författare)
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Benchmarking calculations of wavelengths and transition rates with spectroscopic accuracy for W XLVIII through W LVI tungsten ions
- 2022
-
Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 105:2
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Tidskriftsartikel (refereegranskat)abstract
- Atomic properties of n = 3 levels for W47+ - W55+ ions (Z = 74) are systematically calculated using two different and independent methods, namely, the second-order many-body perturbation theory and the multi-configuration Dirac-Hartree-Fock method combined with the relativistic configuration interaction approach. Wavelengths and transition rates for electric-and magnetic-dipole transitions involving the n = 3 levels of W47+ - W55+ are calculated. In addition, we discuss in detail the importance of the valence and core-valence electron correlations, the Breit interaction, the higher-order frequency-dependent retardation correction, and the leading quantum electrodynamical corrections for transition wavelengths. Spectroscopic accuracy is achieved for the present calculated wavelengths, and most of them agree with experimental values within 0.05%. Our calculated wavelengths, combined with collisional radiative model simulations, are used to identify the yet unidentified 25 observed lines in the extremely complex spectrum between 27 angstrom and 34 angstrom measured by Lennartsson et al. [Phys. Rev. A 87, 062505 (2013)]. We provide additional data for 472 strong electric-dipole transitions in the wavelength range of 17-50 angstrom, and 185 strong magnetic-dipole transitions between 36 angstrom and 4384 angstrom, with a line intensity greater than 1 photon/s. These can provide benchmark data for future experiments and theoretical calculations.
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| 23. |
- Zhang, Chun Yu, et al.
(författare)
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Benchmarking calculations with spectroscopic accuracy of excitation energies and wavelengths in sulfur-like tungsten
- 2020
-
Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 101:3
-
Tidskriftsartikel (refereegranskat)abstract
- Atomic properties of S-like W are evaluated through a state-of-the-art method, namely, the multiconfiguration Dirac-Hartree-Fock method combined with the relativistic configuration-interaction approach. The level energies, wavelengths, and transition parameters involving the 88 lowest levels of W58+ (W LIX) are calculated. We discuss in detail the relative importance of the valence- and core-valence electron correlation effects, the Breit interaction, the higher-order retardation correction beyond the Breit interaction through the transverse photon interaction, and the quantum electrodynamical corrections. The present level energies are highly accurate, with uncertainties close to what can be achieved from spectroscopy. As such, they provide benchmark tests for other theoretical calculations of S-like W and should assist the spectroscopists in their assignment and identification of observed lines in complex spectra.
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