Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relativistic, QED and nuclear effects in highly charged ions revealed by
  resonant electron-ion recombination in storage rings   Dielectronic recombination (DR) of few-electron ions has evolved into a
sensitive spectroscopic tool for highly charged ions. This is due to
technological advances in electron-beam preparation and ion-beam cooling
techniques at heavy-ion storage rings. Recent experiments prove unambiguously
that DR collision spectroscopy has become sensitive to 2nd order QED and to
nuclear effects. This review discusses the most recent developments in
high-resolution spectroscopy of low-energy DR resonances, experimental studies
of KLL DR of very heavy hydrogenlike ions, isotope shift measurements of DR
resonances, and the experimental determination of hyperfine induced decay rates
in divalent ions utilizing DR.

24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
18
The categories of this paper are: econ