QED Effects in Cu-Like Pb Recombination Resonances Near Threshold

Abstract

In an electron-ion recombination study with Pb53+ dielectronic recombination resonances are found for as low as approximately 10(-3)-10(-4) eV relative energy. The resonances have been calculated by relativistic many-body perturbation theory and through comparison with experiment the Pb53+(4p(1/2)-4s(1/2)) energy splitting of approximately 118 eV is determined with an accuracy comparable to the position of the first few resonances, i.e., approximately 10(-3) eV. Such a precision provides a test of QED in a many-body environment at a level which can still not be reached in calculations.

S-matrix calculations of energy levels of the lithium isoelectronic sequence

“…On the latter side, the achievement of sub-0.1 eV precision requires extraordinary care, and issues of fitting resonance curves and controlling systematics make getting another order of magnitude problematical. The very high precision achieved for copperlike tungsten [6], however, suggests that this problem may be overcome. If so, the challenge to theory is considerable.…”

“…While this approach is successful in accounting for the spectra of the above mentioned sequences at the few tenths of an eV level, subtle effects relating to retardation and negative energy states begin to be important when levels under 0.1 eV are reached in modern experiments for high-Z ions [5][6][7]. It is rather complicated to restore the effect of negative energy states, which are usually omitted from Hamiltonian treatments in order to avoid the continuum dissolution problem [8], and in addition the treatment of retardation is problematical [9].…”

Electron–ion merged-beam experiments at heavy-ion storage rings

“…2). Recent related experiments (see also Schippers 2009b) comprise the determination of hyperfine-structure splittings (Lindroth et al 2001, Lestinsky et al 2008) and nuclear charge radii ) in heavy few electron systems, the quantitative investigation of the influence of the Breit interaction on recombination resonance strength in H-like uranium , and the spectroscopy of ions with in-flight produced unstable nuclei (Brandau et al 2013). Such spectroscopy studies will greatly benefit from the installation of Cryring at the international FAIR facility in Darmstadt, Germany.…”

Level-resolved quantum statistical theory of electron capture into many-electron compound resonances in highly charged ions

“…Experimentally, much progress has been made due to the use of ion storage rings and electron-beam ion traps (EBITs) [21][22][23]. On the theory side, a number of computational approaches have been used successfully to describe DR for many simpler ions and to produce data for plasma modelling (see [24][25][26][27][28][29][30][31][32][33][34] and references therein). For more complex targets such as Au 25+ , U 28+ , or W 20+ considered in this work, conventional DR calculations underestimate the measured recombination rates, particularly at low incident-electron energy [17,35].…”