Correlation and Quantum Electrodynamic Effects on the Radiative Lifetime and Relativistic Nuclear Recoil in Ar¹³⁺ and Ar¹⁴⁺ Ions

The radiative lifetime and mass isotope shift of the 1s22s22p 2P3/2 - 2P1/2 M1 transition in Ar13+ ions have been determined with high accuracies using the Heidelberg electron beam ion trap. This fundamentally relativistic transition provides unique possibilities for performing precise studies of correlation and quantum electrodynamic effects in many-electron systems. The lifetime corresponding to the transition has been measured with an accuracy of the order of one per thousand. Theoretical calculations predict a lifetime that is in significant disagreement with this high-precision experimental value. Our mass shift calculations, based on a fully relativistic formulation of the nuclear recoil operator, are in excellent agreement with the experimental results and cofirm the absolute necessity to include relativistic recoil corrections when evaluating mass shift contributions even in medium-Z ions

Relativistic calculations of isotope shifts in highly charged ions

The isotope shifts of forbidden transitions in Be- and B-like argon ions are calculated. It is shown that only using the relativistic recoil operator can provide a proper evaluation of the mass isotope shift, which strongly dominates over the field isotope shift for the ions under consideration. Comparing the isotope shifts calculated with the current experimental uncertainties indicates very good perspectives for a first test of the relativistic theory of the recoil effect in middle-Z ions

Progress at the Heidelberg EBIT

Two years after the relocation of the Heidelberg EBIT, several experiments are already in operation. Spectroscopic measurements in the optical region have delivered the most precise reported wavelengths for highly charged ions, in the case of the forbidden transitions of Ar XIV and Ar XV. The lifetimes of the metastable levels involved in those transitions has been determined with an error of less than 0.2%. A new, fully automatized x-ray crystal spectrometer allows systematic measurements with very high precision and reproducibility. Absolute measurements of the Lyman series of H-like ions are currently underway. Dielectronic recombination studies have yielded information on rare processes, as two-electron-one photon transitions in Ar16+, or the interference effects between dielectronic and radiative recombination in Hg77+. The apparatus can now operate at electron beam currents of more than 500 mA, and energies up to 100 keV. A further beam energy increase is planned in the near future. Ions can be extracted from the trap and transported to external experiments. Up to 4 x 107 Ar16+ ions per second can be delivered to a 1 cm diameter target at 10 m distance. Charge-exchange experiments with U64+ colliding with a cold He atomic beam have been carried out, as well as experiments aiming at the optimization of the charge state distribution of the extracted via dielectronic recombination. Two new EBITs, currently in advanced state of construction in Heidelberg, will be used for experiments at the VUV free electron laser at TESLA (Hamburg) and for the charge breeding of short-lived radioactive isotopes at the TRIUMF ISAC facility

Benchmarking High-Field Few-Electron Correlation and QED Contributions in Hg⁷⁵⁺ to Hg⁷⁸⁺ Ions. I. Experiment

The photorecombination of highly charged few-electron mercury ions Hg75+ to Hg78+ has been explored with the Heidelberg electron beam ion trap. By monitoring the emitted x rays (65-76 keV) and scanning the electron beam energy (45-54 keV) over the KLL dielectronic recombination (DR) region, the energies of state-selected DR resonances were determined to within ±4 eV (relative) and ±14 eV (absolute). At this level of experimental accuracy, it becomes possible to make a detailed comparison to various theoretical approaches and methods, all of which include quantum electrodynamic (QED) effects and finite nuclear size contributions (for a 1s electron, these effects can be as large as 160 and 50 eV, respectively). In He-like Hg78+, a good agreement between the experimental results and the calculations has been found. However, for the capture into Li-, Be-, and B-like ions, significant discrepancies have been observed for specific levels. The discrepancies suggest the need for further theoretical and experimental studies with other heavy ions along these isoelectronic sequences

Relativistic Electron Correlation, Quantum Electrodynamics, and the Lifetime of the 1s²2s²2p²P\u3csup\u3eo\u3c/sup\u3e\u3csub\u3e3/2\u3c/sub\u3e Level in Boronlike Argon

The lifetime of the Ar13+ 1s22s22p2Po3/2 metastable level was determined at the Heidelberg Electron Beam Ion Trap to be 9.573(4)(5)ms(stat)(syst). The accuracy level of one per thousand makes this measurement sensitive to quantum electrodynamic effects like the electron anomalous magnetic moment (EAMM) and to relativistic electron-electron correlation effects like the frequency-dependent Breit interaction. Theoretical predictions, adjusted for the EAMM, cluster about a lifetime that is approximately 3σ shorter than our experimental result

The Heidelberg EBIT: Present results and future perspectives

The Heidelberg electron beam ion trap (EBIT) is one of the three high energy EBITs worldwide presently in operation. In this contribution, selected recent experimental results on precision spectroscopy measurements of trapped ions in the visible and x-ray wavelength regimes, respectively, will reviewed. Moreover, interference between radiative and dielectronic recombination pathways is demonstrated for Hg75+...78+ ions and state selected electron transfer reactions in collisions of U64+ with He is reported. Future perspectives with two new EBITs coming into operation in 2005 for the investigation of radioactive ions as well as the interaction of highly charged ions with intense photon beams from the free electron laser at DESY in Hamburg will be highlighted

Emission spectroscopy of highly charged ions in plasma of an electron beam ion trap

The results of experimental study of magnetic dipole (M1) transitions in highly charged ions of argon (Ar9+, Ar10+, Ar13+ and Ar14+) and krypton (Kr18+ and Kr22+) are presented. The forbidden transitions of the highly charged ions in the visible and near UV range of the photon emission spectra have been measured with accuracy better than 1 ppm. Our measurements for the ``coronal lines'' are the most accurate yet reported using an EBIT as a spectroscopic source of highly charged ions. These precise wavelength determinations provide a useful test and challenge for atomic structure calculations of many-electron systems

Motivation autodéterminée et perceptions de conflit et d'instrumentalité liées au rôle de pratiquant sportif (relations et influence sur l'engagement et le désengagement sportif)

Le conflit d'intérêt ou le manque de temps font partie des explications les plus souvent avancées par les adolescents ou les adultes afin de justifier l'arrêt de la pratique d'une activité sportive ou l'absence d'activité physique régulière. Ce travail doctoral vise à enrichir un modèle motivationnel de l'engagement sportif basé sur la théorie de l'autodétermination (Ryan & Deci, 2002), en y intégrant les perceptions de conflit et d'instrumentalité liées au rôle de pratiquant. Un programme de recherche articulé autour de 5 études et impliquant plus de 2500 participants a été conduit. L'étude 1, qui a comparé des jeunes pratiquants et d'anciens sportifs, a confirmé le lien entre les conflits perçus par rapport à la pratique sportive et le comportement d'abandon, et la relation négative entre les conflits et la motivation autodéterminée sportive. Les études 2 à 4 ont adopté un devis longitudinal sur une durée allant de 6 mois à 3 ans, afin d'étudier de façon approfondie les antécédents des perceptions de conflit et d'instrumentalité liées au rôle de pratiquant, et leur impact sur les comportements d'engagement sportif. Les résultats indiquent que le degré de motivation autodéterminée contextuelle prédit généralement négativement les conflits perçus, et positivement l'instrumentalité de la pratique sportive. Des niveaux élevés de conflit et faibles d'instrumentalité liés au rôle de sportif, semblent néfastes au maintien de l'engagement sportif dans le temps. Enfin, le devis expérimental de l'étude 5 a examiné le sens de la relation entre la motivation autodéterminée et conflit, soutenant l'hypothèse d'un rôle causal de la motivation.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF