Birkl, G.

Boine-Frankenheim, O.

Bussmann, M.

Eidam, L.

Hai, B.

Huang, Z. K.

Li, J.

Loeser, M.

Ma, X.

Mao, L. J.

Rein, B.

Schramm, U.

Siebold, M.

Walther, T.

Wang, H. B.

Wen, W. Q.

Winters, Danyal

Yang, J. C.

Yuan, Y. J.

Zhang, D. C.

Zhu, J. F.

Zhu, X. L.

GSI Repository

Progress of laser cooling of relativistic Li-like C3+ ion beams at the CSRe* W. Q. Wen1, H. B. Wang 1, Z. K. Huang1, D. C. Zhang1, B. Hai1, X. L. Zhu1, J. Li1,  L. J. Mao1, R. S. Mao1,J. W. Xia1, J. C. Yang1, Y. J. Yuan1, M. Loeser2, M. Siebold2,  U. Schramm2, O. Boine-Frankenheim3, L. Eidam3, D. F. A Winters3, G. Birkl4,  B. Rein4, Th. Walther4, J.F. Zhu5, M. Bussmann2 and X. Ma1# 1IMP, China; 2HZDR, Germany; 3GSI Germany;  4TU Darmstadt, Germany;  5Xidian University, ChinaLaser cooling is one of the most promising techniques to reach high phase-space densities for relativistic heavy ion beams. Realizing a crystalline ion beam is one of the ultimate goals of laser cooling of heavy ion beams at stor-age rings [1]. Preparations for laser cooling of relativistic lithium-like C3+ are being made at the experimental cooler storage ring (CSRe) in Lanzhou, China [2].  In September 2014 a test experiment was performed with 12C3+ ion beams at an energy of 122 MeV/u on the CSRe with a pulsed laser system. A schematic view of the experimental setup is shown in figure 1. In the experiment 12C3+ ions were produced by an Electron Cyclotron Reso-nance  ion source (ECR). In the ECR, a significant frac-tion of 16O4+ was produced alongside. Then the ions were accelerated by a Sector Focused Cyclotron (SFC), and injected into the main Cooler Storage Ring (CSRm). After accumulation and acceleration in the CSRm, the ion beams were extracted and injected into the CSRe at the energy of 122 MeV/u (at a velocity of 47% of the speed of light). Since the circumference of the CSRe is 128.8 m, this beam energy lead to the revolution frequency of 1.087 MHz. A pulsed UV laser system from HZDR was employed for this test laser cooling experiment. The closed 2s1/2―2p1/2 optical transition at a wavelength of0 155.07   nm of the Li-like carbon ions was Doppler-shifted to be resonant with the UV-laser at the wavelength 257.3laser   nm in the experiment ( 0(1 )laser     ).  A Schottky spectrum of an electron-cooled coasting ion beam is shown in figure 2, in which the Schottky signals of 12C3+ and 16O4+ ions were separated by electron-cooling. Stable operation of the CSRe was observed over several days, including rf-bunching and diagnostic sys-tems. The injected number of C3+ (~5×108) was suffi-cient for testing laser cooling. The dynamics of the elec-tron-cooled and RF-bunched ion beams were investigated systematically. However, first results did not yet indicate a strongly interaction of the laser with the ions. The fluo-rescence from the ions, measured using UV-CPM and UV-PMT detectors, is thereby of great interest since it reflects the interaction between laser and ion beam. Since two ion species were stored simultaneous-ly, there is also the possibility that the laser-cooled 12C3+ ions sympathetically cool the 16O4+ ions. Further data analysis is currently in progress. Laser cooling experiment at the storage ring of the CSRe and ESR are directly relevant for laser cooling and precision laser spectroscopy of highly charged and relativistic heavy ions at the future large facilities such as HIAF in China and FAIR in Germany. At these facilities, laser interaction with highly charged ions (HCIs) will open a new field of atomic physics and nuclear physics [3].  Figure 1: Schematic view of the experimental setup for laser cooling experiments at the CSRe. The locations of the resonant Schottky pick-up, RF-buncher, UV-PMT and the UV-CPM are shown.  Figure 2: Schottky spectrum of the electron-cooled inject-ed 12C3+ and 16O4+ at the CSRe. References [1] U. Schramm and D. Habs, Prog. Part. Nucl. Phys. 35 (2004) 583-677. [2] W.Q. Wen et al., Nucl. Instrum. Meth. A 736 (2014) 75-80  [3] H. Backe, Hyperfine Interact 171 (2007) 93-1  ___________________________________________  * Work supported by NSFC No.11221064, GJHZ1305 and BMBF # x.ma@impcas.ac.cn APPA-MML-AP-19 GSI SCIENTIFIC REPORT 2014234 DOI:10.15120/GR-2015-1-APPA-MML-AP-19

Progress of laser cooling of relativistic Li-like C$^{3+}$ ion beams at the CSRe

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Progress of laser cooling of relativistic Li-like C $^{3+}$ ion beams at the CSRe

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Progress of laser cooling of relativistic Li-like C3+^{3+}3+ ion beams at the CSRe

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Progress of laser cooling of relativistic Li-like C $^{3+}$ ion beams at the CSRe