Kleffner, C.

Litvinov, S.

Nolden, F.

Steck, M.

Winters, D.

GSI Repository

A novel scheme for fast extraction of low energy beams from the ESR to theCRYRINGS. Litvinov1, C. Kleffner1, F. Nolden1, M. Steck1, and D. Winters11GSI, Darmstadt, GermanyThe CRYRING@ESR facility [1] will provide theunique possibility for studying properties of low energycooled heavy beams in the field of atomic and nuclear re-search within the FAIR project [2]. Heavy ion beams willbe stored, cooled and decelerated to the energy of about 4MeV/u in the ESR and then delivered to the CRYRING.Presently, there is no special kicker magnet which could beused for the fast extraction towards the CRYRING. How-ever, a special distorted closed orbit has been suggested,applying it to the stored beam one can perform the fast ex-traction with the existing injection kicker magnet.CalculationThe beam from SIS18 is usually injected into the ESRon the orbit of ∆p/p ≈ +1%, and then stored and cooled(solid black curve in Fig. 1). In order to keep the beam par-allel to the electron beam in the cooler section, 4 horizontalcorrectors in 2 neighboring main dipole magnets are used.The ESR is equipped with one injection and two extractionseptum magnets. The horizontal width of the beam pipearound the septums is 104 mm and in addition, there is thenarrow knife of 17 mm width of each septum (see Fig. 1).The injection kicker magnet is placed after the first dipoledownstream. The beam goes after the kick either to thenorthern extraction septum (towards the HITRAP) or to thewall (dotted black curve in Fig. 1). In order to extract thebeam to the CRYRING, it is necessary to change the tra-path length [m]Injection orbit( p/p=+1%)D Bumped orbitExtraction Orbit(to HITRAP)Extraction Orbit(to CRYRING)Injection KickerInj. SeptumNorth. ExtractionSeptumSouth. Extract.SeptumE-Cooler0 80 1006020 408010012014060-40-6040-20200x [mm]Figure 1: Calculated beam trajectories for one turn in theESR. The injected stored orbit of ∆p/p = +1% is indi-cated by the solid black curve. Its kicked orbit (extractionto HITRAP) is shown by the black dotted curve. The dis-torted bumped orbit is marked by the dashed black curveand its kicked orbit (extraction to CRYRING) is shown bythe dotted-dashed red curve.x [mm]510-10-2020-5-15-20 2010-10 0015y [mm]Figure 2: The extracted 100 MeV/u 58Ni26+ beam directlyafter the extraction septum.jectory of the kicked beam, such that it avoids the knives ofthe septa but reaches the southern extraction septum. Thisorbit distortion has been performed with a special bumpedclosed orbit, which has been calculated using 8 horizontalcorrectors in 4 main dipoles (dashed black curve in Fig. 1).Applying the kick on the distorted orbit the beam can freelybe extracted to the CRYRING (dotted-dashed red curve inFig. 1).ExperimentIn August 2014, the calculations could be proven byexperiments at the ESR. Firstly, the proposed extractionscheme was verified with 100-400 MeV/u proton and58Ni26+ beams. The extracted beam was measured directlyafter the septum using a fluorescent screen (see Fig. 2).Later, a 14N7+ beam at 30 MeV/u was injected, storedand stepwise decelerated iteratively to the final energy of4 MeV/u (Bρ = 0.58 Tm), the lowest possible magneticrigidity from the ESR to the CRYRING. At each energy,the beam was successfully extracted, changing only thekick angle of the injection kicker by several tenths of a mil-liradian. The distortion orbit was unchanged. Despite thelack of experimental time, it could be managed to trans-port the extracted 4 MeV/u ion beam over a length of 20 mtowards the CRYRING for the first time.References[1] CRYRING@ESR, A study group reporthttps://www.gsi.de/fileadmin/SPARC/documents/Cryring/ReportCryring 40ESR.PDF[2] http://www.fair-center.eu/GSI SCIENTIFIC REPORT 2014 FG-GENERAL-15DOI:10.15120/GR-2015-1-FG-GENERAL-15 433

A novel scheme for fast extraction of low energy beams from the ESR to the CRYRING

http://repository.gsi.de/record/184148/files/FG-GENERAL-15.pdf

A novel scheme for fast extraction of low energy beams from the ESR to the CRYRING

Abstract

Similar works

Full text

Available Versions

GSI Repository