Measurement of the lifetime and the proportion of 12 C 3+ ions in stored relativistic ion beams as a preparation for laser cooling experiments at the CSRe H.B. Wang a,b , W.Q. Wen a , Z.K. Huang a,b , D.C. Zhang a , B. Hai a,b , X.L. Zhu a , D.M. Zhao a , J. Yang a , J. Li a , X.N. Li a , L.J. Mao a , R.S. Mao a , J.X. Wu a , J.C. Yang a , Y.J. Yuan a , L. Eidam c , D. Winters c , T. Beck d , D. Kiefer d , B. Rein d , Th. Walther d , M. Loeser e , U. Schramm e , M. Siebold e , M. Bussmann e , X. Ma a,⇑ a Institute of Modern Physics, Chinese Academy of Sciences, 730000 Lanzhou, China b University of Chinese Academy of Sciences, 100049 Beijing, China c GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany d Institut für Angewandte Physik, Technische Universität Darmstadt, 64289 Darmstadt, Germany e Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany article info Article history: Received 19 November 2016 Received in revised form 28 February 2017 Accepted 16 March 2017 Available online xxxx Keywords: Storage ring Laser cooling Electron cooling Schottky pick-up abstract We report on an experiment that was conducted in preparation of laser cooling experiments at the heavy-ion storage ring CSRe. The lifetimes of ion beams made up of 12 C 3+ and 16 O 4+ ions stored at an energy of 122 MeV/u in the CSRe were determined by two independent methods, firstly via a DC current transformer (DCCT) and secondly via a Schottky resonator. Using electron-cooling, the signals of the 12 C 3+ and 16 O 4+ ions could be separated and clearly observed in the Schottky spectrum. The obtained individual lifetimes of the 12 C 3+ and 16 O 4+ components were 23.6 s and 17.8 s, respectively. The proportion of 12 C 3+ ions in the stored ion beam was measured to be more than 70% at the beginning of the injection and increasing as a function of time. In addition to these measurements, the operation and remote control of a pulsed laser system placed directly next to the storage ring was tested in a setup similar to the one envisaged for future laser experiments. Ó 2017 Elsevier B.V. All rights reserved. 1. Introduction Laser cooling is one of the most promising techniques to reach high phase-space densities for relativistic heavy ion beams at stor- age rings [1]. Compared with the established cooling schemes at storage rings, such as stochastic cooling [2] and electron cooling [3], the cooling rate for laser cooling of relativistic heavy ion beams is expected to be much higher [4,5] and laser-cooled ion beams could reach ultra-low temperatures (mK). Laser cooling is regarded as one of the most promising methods to realize crys- talline beams in heavy ion storage rings [6], and in addition, preci- sion laser spectroscopy of relevant transitions in highly charged ions can be performed simultaneously during the laser cooling experiments [7]. First laser cooling of heavy ion beams was achieved for 7 Li + ions at the storage ring TSR [8] in Heidelberg and ASTRID [9] in Aarhus. Later on, laser cooling of 24 Mg + ion beams has been investigated at the S-LSR [10–12] in Kyoto, and laser cooling of relativistic 12 C 3+ ion beams has been realized at the ESR [7,13–15] in Darmstadt. However, there are still many challenges for laser cooling of rela- tivistic ion beams at large-scale storage rings. At these rings, the properties of laser-cooled ion beams were not investigated system- atically and the strong coupling regime and phase-transition of laser-cooled highly charged ion beams to the crystalline state could not be realized. Furthermore, all-optical methods to investi- gate the dynamics of ultra-cold ion beams [7], which might provide additional data complementary to standard beam diagnostics, still need to be explored. At the experimental Cooler Storage Ring (CSRe) in Lanzhou, progress has been made to prepare for laser cooling and laser spectroscopy of relativistic 12 C 3+ and 16 O 5+ ion beams [16,17]. Studies of laser cooling at the CSRe and the ESR are directly relevant to laser cooling and precision laser spec- troscopy of highly charged and relativistic heavy ions at the future large facilities, such as the High Intensity heavy ion Accelerator Facility (HIAF) [18] in China and the Facility for Antiproton and Ion Research (FAIR) [19] in Germany. At these facilities, such exper- http://dx.doi.org/10.1016/j.nimb.2017.03.096 0168-583X/Ó 2017 Elsevier B.V. All rights reserved. ⇑ Corresponding author. E-mail address: x.ma@impcas.ac.cn (X. Ma). Nuclear Instruments and Methods in Physics Research B xxx (2017) xxx–xxx Contents lists available at ScienceDirect Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb Please cite this article in press as: H.B. Wang et al., Measurement of the lifetime and the proportion of 12 C 3+ ions in stored relativistic ion beams as a prepa- ration for laser cooling experiments at the CSRe, Nucl. Instr. Meth. B (2017), http://dx.doi.org/10.1016/j.nimb.2017.03.096