Dolinskii, A.

Kovalenko, O.

Litvinov, Yury

Stöhlker, T.

GSI Repository

Ion Optics of the High Energy Storage Ring for Operation With Heavy Ions∗O. Kovalenko1,2, A. Dolinskii1, Yu.A. Litvinov1,2, T. Sto¨hlker1,3,4, and the SPARC Collaboration11GSI Helmholtz Center; 2Ruprecht-Karls University Heidelberg; 3Helmholtz Institute Jena; 4Friedrich-SchillerUniversity JenaIntroductionIn this report we show the latest improvements of theoptical properties of the High Energy Storage Ring (HESR)for the operation with heavy ions.Modified ion optics of the HESRThe ion optical lattice with γtr = 6.2 [1], which is thestandard optics for the PANDA experiment, was taken asa starting point. This lattice has low-beta insertions in thePANDA straight section. Apart from their main function(strongly focus the beam in the interaction region) it drivesthe amplitude functions to high values around the interac-tion point. In the case of the SPARC experimental pro-gram such amplitudes are not needed. Thus, by varying thestrengths of the quadrupoles in the zero-dispersion straightsections a more relaxed behaviour of the beta-functionscould be achieved. More precisely, the maximum beta am-plitudes (βx, βy) = (222 m, 172 m) were decreased to (172m, 153 m), respectively (see Fig. 1, around s = 510 m).This results in a smaller beam size and in an enhanced ac-ceptance for operation with ions. Consequently, the calcu-lations showed an increased dynamic aperture. A workingpoint for the new optics is currently at (7.63, 7.60).Figure 1: Optics for heavy ionsThe beta function amplitudes at the waist of the beamat the PANDA target remained virtually unchanged. Thismeans that the radius of the beam at the PANDA target lo-cation stays the same. An expected intensity of the heavyions during the SPARC experiment is about 3 orders ofmagnitude less that the antiproton intensity in the PANDAexperiment (108 vs. 1011). Therefore, even for the bareuranium ions with charge 92+, the beam current for ions is∗Work supported in part by the Helmholtz-CAS Joint Research GroupHCJRG-108 and Helmholtz Institute Jenaroughly 10 times smaller than for antiprotons. Hence thereare no harmful effects expected to the sensitive equipmentof the PANDA detector due to intensive heavy ion beamand the SPARC experiments will not necessarily require thedisassembling of the PANDA setup. Potential risks validfor both, the antiproton and ion, beams due to injection intothe HESR still has to be studied.Closed orbit bump at internal target locationIn order to have the best possible beam-target overlap afeasibility of a closed orbit bump at the SPARC internal tar-get location in the arc was investigated. With a present setof corrector magnets [2], only 3 correctors in the vicinityof the SPARC setup can be used for creating a bump. Itallowed for varying the amplitude of the closed orbit at thegiven point. We proved that a ±5 mm bump is possible (upto 8 mm if needed). In order to additionally vary the angleof the closed orbit, one extra corrector close to the SPARCtarget needs to be installed.Closed orbit correctionA closed orbit correction was simulated. On the statisticsof 500 seeds it was verified (see Fig. 2) that the maximumvalues of the closed orbit deviation are as high as 20 mmin a horizontal and 35 mm in a vertical planes. The closedorbit could be corrected down to 2 mm and 4 mm in thehorizontal and the vertical planes, respectively.Figure 2: Both corrected (up) and uncorrected (bottom) inhorizontal (blue) and vertical (green) planesFruitful discussions with colleagues from FZ Ju¨lich andPANDA collaboration are greatly acknowledged.References[1] R. Maier. Proc. IPAC 2011, New York, USA (2011)[2] B. Lorentz, Ju¨lich, private communicationGSI SCIENTIFIC REPORT 2013 FG-ESR-01doi:10.15120/GR-2014-1-FG-ESR-01 FAIR@GSI 357 FG-ESR-01 GSI SCIENTIFIC REPORT 2013358 doi:10.15120/GR-2014-1-FG-ESR-01

Ion Optics of the High Energy Storage Ring for Operation With Heavy Ions

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Ion Optics of the High Energy Storage Ring for Operation With Heavy Ions

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