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Frank Zimmermann, CLIC “Away Day” 28 March 2006 x * Limitations and Improvements Paths Damping Rings Maxim Korostelev, Frank Zimmermann

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 ATF single-bunch emittances: x ~3.5-4.3 m (CLIC: ~0.5 m) y ~13-18 nm (CLIC: 3 nm) z ~8640 eVm (CLIC: <5400 eVm) 6D phase-space density in CLIC ~70 times higher how can we go further? ? ATF CLIC new CLIC?

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 2004: CLIC-NLC comparison for ITRP “Wise Men” NLC DRCLIC DR energy1.98 GeV2.42 GeV* circumference~299 m364 m arc cell length~6 m1.8 m hor. phase advance/arc cell*108 o 210 o #arc TME cells*~30-40?100 total wiggler length*44 m152 m wiggler period*27 cm10 cm bunch population7.6-15.2x10 9 4.2x10 9 longit. emittance, s 10.6 keVm5.5 keVm transv. emittances x, y ~3000 nm, 30 nm660 nm, 3.3 nm damping times x,y, s 3.63, 4.08 ms, 2.18 ms2.64 ms,1.32 ms *smaller emittance due to smaller bend angle / arc cell, less emittance detuning, more damping, smaller H x in wiggler *higher energy reduces intrabeam-scattering effect

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 further progress in 2005 Wiggler 1 permanent magnet Wiggler 3 Nb 3 Sn superconductor BwBw 1.7 T2.5 T w 10 cm4.5 cm x 550 nm (133 nm w/o IBS) 354-375 nm (79 nm w/o IBS) y 3.3 nm (0.8 nm w/o IBS) 2.9-2.3 nm (0.5 nm w/o IBS) z 4724 eVm (2551 eVm w/o IBS) 4817-4997 eVm (3433 eVm w/o IBS) also: less charge per bunch

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 possible approaches for achieving even smaller emittance 1) larger damping-ring circumference (weaker arcs & longer wigglers) + increased beam energy 2) damping in linac 3) laser wiggler?

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 1) larger circumference + higher energy not self-consistent, artificially kept longitudinal emittance at constant value (4500 eVm), opening-angle effect not included w/o IBS horizontal emittance is 100 nm w/o IBS at 3.74 GeV MAD-X calculation

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 analytical equations including IBS (Bane approx.) & opening angle H. Braun, M. Korostelev, F. Zimmermann, CLIC Note 594, 2004 dispersive terms opening angle IBS

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 result of my analytical calculation includes opening angle Karl Bane’s IBS approximation almost self- consistent ( z fixed = 1 mm) for case 2x circumference, I find large discrepancy in z (w/o IBS) between analytical formula and MAD-X!?

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 exact calculation by Maxim “nominal”2x arc 2x straights E2.42 GeV3.74 GeV C365 m529 m704 m530 m x 375 nm (79 nm) 421 nm (73 nm) 340 nm (66 nm) 315 nm (135 nm) y 2.3 nm (0.5 nm) 2.65 nm (0.5 nm) 2.14 nm (0.415 nm) 1.98 nm (0.862 nm) z 4997 eVm (3433 eVm) 5030 eVm (4100eVm) 4975 eVm (4221 eVm) 5020 eVm (4480 eVm) best

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 exact calculation by Maxim cont’d “nominal”2x arc 2x straights Q’ x -102-187-200-114 Q’ y -135-254-266-148 SF [10 3 m -3 ] 7.8514.115.08.76 SD [10 3 m -3 ] -9.99-18.219.3-11.06 >10% larger sextupole strength implies >10% smaller dynamic aperture

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 new ring parameters? presentoption circumference357 m530 m energy2.424 GeV3.746 GeV rf frequency1.875 GHz rf voltage2.39 MV20.5 MV energy loss/ turn2.19 MeV18.93 MeV total wiggler length 152 m304 m synchr. radiation power 0.3 MW1.9 MW

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 2) damping in linac H. Braun, M. Korostelev, F. Zimmermann, CLIC Note 594, 2004 damping factor 2 beam energy34 GeV addt’l linac length640 m / side (~1/B w ) addt’l voltage48 GV (~1/B w ) wiggler peak field B w 10 T wiggler period w 1.5 cm x,y 1.5 m, 8 m final x 272 nm (~ x w 2 B w 3 ) final y 3.5 nm (~ y B w ) wiggler parameters quite challenging

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 3) laser wiggler naturally small period assume laser parameters of Snowmass Posipol Proposal (CLIC note 639) laser wiggler equivalence: typeYAG A laser 592mJ w 0.53 m x,y 5 m zz 0.9 mm I laser 5x10 20 W/m 2 BwBw 4090 T undulator regime! ~6% transverse emittance reduction per laser collision! however →50%!

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 conclusions laser wiggler → unacceptable energy spread superconducting wiggler in linac beyond present state of the art double wiggler length & increase beam energy to 3.74 GeV→15% reduction in x & y ; but expect impact on dynamic aperture ~20-30% & 6x increased heat load

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 spare slide

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Frank Zimmermann, CLIC “Away Day” 28 March 2006 DR equilibrium emittance without IBS & w/o 1/ present design: above can also be written as

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