Appel, S.

El Hayek, Y.

Gerhard, P.

Groening, Lars

Maier, M.

Mickat, S.

Seibel, A.

Vormann, H.

Vossberg, M.

Xiao, C.

GSI Repository

Results of the experiments on emittance transfer EMTEX M. Maier, S. Appel, Y. El Hayek, P. Gerhard, L. Groening, S. Mickat, A. Seibel, H. Vormann, M. Vossberg, C. Xiao GSI, Darmstadt, Germany Introduction EMTEX is an experimental setup to proof the principle of transverse emittance partitioning on an ion beam. Accord-ing to simulations it is possible to transfer emittance by changing only the magnetic field of a solenoid with a charge state changing stripper inside. The change of charge state in the solenoid changes the set of eigen-emittances and the skew quadrupoles serve to remove inter-plane correlations. The field strength of the solenoid determines the amount of transfer between the eigen-emittances. A detailed description of the concept and the beam line itself is given in [1]. Experimental setup Besides some matching quadrupoles, the setup shown in Figure 1 consists of a stripping foil inside a magnetic so-lenoid field to couple the transverse planes and for the emittance transfer. Behind the solenoid a skew quadru-pole triplet rotated by 45° is used to remove the coupling.  Figure 1: Beam line of EMTEX (Emittance Transfer Experiment) in the transfer channel of GSI. Results For the experiment a low intensity beam of 14N3+ at 11.4 MeV/u was fully stripped to 14N7+ in a 200µg C-foil placed at the centre of the solenoid. For each solenoid setting full transmission was preserved and the emittances were measured for both planes.   Figure 2: Vertical (upper) and horizontal (lower) phase space distribution measured behind EMTEX for varied solenoid field strength. The black ellipses represent  the 4*rms emittances.    Figure 2 shows the measured emittances behind EMTEX for different solenoid field strengths. All other magnet settings were kept constant and the Twiss parameters re-mained constant. Yet for these solenoid field settings the emittance partitioning changes and, as shown in Figure 3, matches the simulation results [2] very well. For this rea-son the multi turn injection efficiency into SIS18 has been investigated using this technique [3]. As expected, the reduced horizontal emittance directly translates into in-creased multi turn injection efficiency shown in Figure 4.   Figure 3: Measured transverse emittances behind EMTEX for different solenoid field strength com-pared to the simulations.  Figure 4: Improved multi turn injection efficiency us-ing EMTEX. Outlook To quantify the possible gain factor of this technique the limits should be investigated. This could be achieved by increasing the macro pulse length and thus the injection time above the regularly used 150µs. References [1] C. Xiao, et al. PRSTAB 16, 044201 (2013). [2] L. Groening et al., PRL 113, 264802 (2014). [3] S. Appel, GSI Report 2013-03 (2013). FG-UNILAC-19 GSI SCIENTIFIC REPORT 2014414 DOI:10.15120/GR-2015-1-FG-UNILAC-19

Results of the experiments on emittance transfer EMTEX

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Results of the experiments on emittance transfer EMTEX

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