Sprecher
Beschreibung
Electron-ion collision spectroscopy is a very successful approach for studying the properties of highly charged ions [1-3], in particular if low-energy dielectronic recombination (DR) resonances are scrutinized. The heavy-ion storage ring CRYRING@ESR of the international FAIR facility in Darmstadt,Germany, is particularly attractive for DR studies, since it is equipped with an electron cooler that provides an ultra-cold electron beam promising highest experimental resolving power and precision. Due to its high precision, DR spectroscopy at the CRYRING will allow us to sensitively probe higher-order contributions to state-of-the-art quantum-electrodynamical (QED) calculations of binding energies in strong fields.
At the FAIRNESS, we will report on the results from an DR experiment with highly charged gold ions, which were injected into CRYRING@ESR from the full chain of GSI accelerators consisting of the linear accelerator UNILAC, the heavy-ion synchrotron SIS18, and the high-energy storage ring ESR. The Be-like gold ions (Au75+) were produced by stripping at an energy of about 12 GeV and injected into ESR, where they were cooled and decelerated to an energy of 12 MeV/u. Finally, an average of 5×106 ions per cycle were injected into the CRYRING where the beam lifetime was about 30 s, mainly limited by collisions with residual gas particles.
DR spectra in the collision-energy range 0 – 300 eV were measured, where among others the 2s2p (3P1) 19l, 2s2p (3P1) 26l and 2s2p (3P1) 32l resonances occur that are associated with 2s2 1S0 →2s2p 3P1 excitations of the Be-like ion core. The analysis of the data is currently in progress. We will present preliminary comparisons of our experimental DR spectra with corresponding theoretical results.
References:
[1] S. Schippers, Nucl. Instrum. Methods Phys. Res B 350, 61 (2015)
(DOI:10.1016/j.nimb.2014.12.050).
[2] C. Brandau, C. Kozhuharov, M. Lestinsky, A. Müller, S. Schippers, and T. Stöhlker, Phys. Scr. T166,
014022 (2015) (DOI : 10.1088/0031-8949/2015/T166/014022).
[3] A. Müller, Adv. At. Mol. Opt. Phys. 55, 293 (2008) (DOI: 10.1016/S1049-250X(07)55006-8).
