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We have performed a detailed experimental study of resistive cooling of large ensembles of highly charged ions such as Ar$^{13+}$ in a cryogenic Penning trap. Different from the measurements reported in [M. Vogel et al., Phys. Rev. A, 043412 (2014)], we observe purely exponential cooling behavior when conditions are chosen to allow collisional thermalization of the ions. We provide evidence that in this situation, resistive cooling time constants and final temperatures are independent of the initial ion energy, and that the cooling time constant of a thermalized ion ensemble is identical to the single-ion cooling time constant. For sufficiently high ion number densities, our measurements show discontinuities in the spectra of motional resonances which indicate a transition of the ion ensemble to a fluid-like state when cooled to temperatures below approximately 14 K. With the final ion temperature presently being 7.5 K, ions of the highest charge states are expected to form ion crystals by mere resistive cooling, in particular not requiring the use of laser cooling.
A low-energy, compact and superconducting electron beam ion trap (the Shanghai-Wuhan EBIT or SW-EBIT) for extraction of highly charged ions is presented. The magnetic field in the central drift tube of the SW-EBIT is approximately 0.21 T produced by
Relativistic calculations of the isotope shifts of energy levels in highly charged Li-like ions are performed. The nuclear recoil (mass shift) contributions are calculated by merging the perturbative and large-scale configuration-interaction Dirac-Fo
An overview and status report of the new trapping facility for highly charged ions at the Gesellschaft fuer Schwerionenforschung is presented. The construction of this facility started in 2005 and is expected to be completed in 2008. Once operational
The most precise to-date evaluation of the nuclear recoil effect on the $n=1$ and $n=2$ energy levels of He-like ions is presented in the range $Z=12-100$. The one-electron recoil contribution is calculated within the framework of the rigorous QED ap
The current status of bound state quantum electrodynamics calculations of transition energies for few-electron ions is reviewed. Evaluation of one and two body QED correction is presented, as well as methods to evaluate many-body effects that cannot