Dielectronic Recombination Experiments at CRYRING@ESRHYBRID

The James Webb Space Telescope (JWST) has discovered a surprising population of bright galaxies in the very early universe (≲ 500 Myrs after the Big Bang). These observations test our understanding of galaxy formation in the early universe and the physical properties remain to be fully understood. [1] Spectral analysis of these objects has identified a number of charge states of elements which were synthesized in the very first stars. To interpret these emission lines accurately, photoionization models must include precise dielectronic recombination (DR) rates for low charged ions.

Experiments at CRYRING can provide quantitative input for improving these models — especially in the regime of low-temperature plasma. Dielectronic recombination (DR) is the dominant electron - ion recombination process and thus, modifies the charge state distributions in plasmas. While theoretical prediction of DR rates are quite reliable for higher energies, notable discrepancies have been shown in the region of a few eV and below [2]. Accurate recombination rates for a light ion species in low charge states can provide valuable data for modelling cold plasma environments (such as planetary nebulae).

The experiments were conducted at the CRYRING@ESR, storage ring at GSI in Darmstadt, where beams of specific elements and charge states can be stored, cooled, and merged with a monoenergetic electron beam for DR measurements [3]. The ultra-cold electron beam enables high-resolution DR rate measurements at low collision energies [4]. Recombined ions were detected by particle detectors placed in the section following the electron cooler, where the product beam is well separated from the stored beam.

Detailed analysis of the data is currently ongoing and this talk discusses our experimental method, our recent results, and discusses their relevance in the astrophysical context.

[1] Jorge A. Zavalla et al., Nature Astronomy 9, 155–164 (2025)

[2] N. R. Badnell et al., Astrophys. J. 804, 100 (2015).

[3] M. Lestinsky et al., Phys. Rev. Let. 100, 033001 (2008).

[4] M. Lestinsky et al., Eur. Phys. J Special Topics 225, 797–882 (2016).

https://gsi-fair.zoom.us/j/63856816325
Meeting-ID: 638 5681 6325
Passcode: AP_Seminar
dial by phone
+496938079884,,63856816325#,,,,*8527227260# Deutschland
+496950500951,,63856816325#,,,,*8527227260# Deutschland