sx* Limitations and Improvements Paths Damping Rings Maxim Korostelev, Frank Zimmermann Frank Zimmermann, CLIC “Away Day” 26 March 2006

Frank Zimmermann, CLIC “Away Day” 26 March 2006 ATF single-bunch emittances: gex~3.5-4.3 mm (CLIC: ~0.5 mm) gey~13-18 nm (CLIC: 3 nm) gez~8640 eVm (CLIC: <5400 eVm) 6D phase-space density in CLIC ~70 times higher how can we go further? ATF CLIC ? new CLIC? Frank Zimmermann, CLIC “Away Day” 26 March 2006

Frank Zimmermann, CLIC “Away Day” 26 March 2006 2004: CLIC-NLC comparison for ITRP “Wise Men” NLC DR CLIC DR energy 1.98 GeV 2.42 GeV* circumference ~299 m 364 m arc cell length ~6 m 1.8 m hor. phase advance/arc cell* 108o 210 o #arc TME cells* ~30-40? 100 total wiggler length* 44 m 152 m wiggler period* 27 cm 10 cm bunch population 7.6-15.2x109 4.2x109 longit. emittance , ges 10.6 keVm 5.5 keVm transv. emittances gex, gey ~3000 nm, 30 nm 660 nm, 3.3 nm damping times tx,y, ts 3.63, 4.08 ms, 2.18 ms 2.64 ms,1.32 ms *smaller emittance due to smaller bend angle / arc cell, less emittance detuning, more damping, smaller Hx in wiggler *higher energy reduces intrabeam-scattering effect Frank Zimmermann, CLIC “Away Day” 26 March 2006

Frank Zimmermann, CLIC “Away Day” 26 March 2006 further progress in 2005 Wiggler 1 permanent magnet Wiggler 3 Nb3Sn superconductor Bw 1.7 T 2.5 T lw 10 cm 4.5 cm gex 550 nm (133 nm w/o IBS) 354-375 nm (79 nm w/o IBS) gey 3.3 nm (0.8 nm w/o IBS) 2.9-2.3 nm (0.5 nm w/o IBS) gez 4724 eVm (2551 eVm w/o IBS) 4817-4997 eVm (3433 eVm w/o IBS) also: less charge per bunch Frank Zimmermann, CLIC “Away Day” 26 March 2006

possible approaches for achieving even smaller emittance larger damping-ring circumference (weaker arcs & longer wigglers) + increased beam energy 2) damping in linac 3) laser wiggler? Frank Zimmermann, CLIC “Away Day” 26 March 2006

larger circumference + higher energy MAD-X calculation 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 Frank Zimmermann, CLIC “Away Day” 26 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 Frank Zimmermann, CLIC “Away Day” 26 March 2006

result of my analytical calculation includes opening angle Karl Bane’s IBS approximation almost self-consistent (sz fixed = 1 mm) for case 2x circumference, I find large discrepancy in ez (w/o IBS) between analytical formula and MAD-X!? Frank Zimmermann, CLIC “Away Day” 26 March 2006

exact calculation by Maxim “nominal” 2x arc 2x straights E 2.42 GeV 3.74 GeV C 365 m 529 m 704 m 530 m gex 375 nm (79 nm) 421 nm (73 nm) 340 nm (66 nm) 315 nm (135 nm) gey 2.3 nm (0.5 nm) 2.65 nm 2.14 nm (0.415 nm) 1.98 nm (0.862 nm) gez 4997 eVm (3433 eVm) 5030 eVm (4100eVm) 4975 eVm (4221 eVm) 5020 eVm (4480 eVm) best Frank Zimmermann, CLIC “Away Day” 26 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 [103 m-3] 7.85 14.1 15.0 8.76 SD -9.99 -18.2 19.3 -11.06 >10% larger sextupole strength implies >10% smaller dynamic aperture Frank Zimmermann, CLIC “Away Day” 26 March 2006

Frank Zimmermann, CLIC “Away Day” 26 March 2006 new ring parameters? present option circumference 357 m 530 m energy 2.424 GeV 3.746 GeV rf frequency 1.875 GHz rf voltage 2.39 MV 20.5 MV energy loss/ turn 2.19 MeV 18.93 MeV total wiggler length 152 m 304 m synchr. radiation power 0.3 MW 1.9 MW Frank Zimmermann, CLIC “Away Day” 26 March 2006

Frank Zimmermann, CLIC “Away Day” 26 March 2006 2) damping in linac H. Braun, M. Korostelev, F. Zimmermann, CLIC Note 594, 2004 e damping factor 2 beam energy 34 GeV addt’l linac length 640 m / side (~1/Bw) addt’l voltage 48 GV (~1/Bw) wiggler peak field Bw 10 T wiggler period lw 1.5 cm bx,y 1.5 m, 8 m final gex 272 nm (~bx lw2 Bw3) final gey 3.5 nm (~by Bw ) wiggler parameters quite challenging Frank Zimmermann, CLIC “Away Day” 26 March 2006

Frank Zimmermann, CLIC “Away Day” 26 March 2006 3) laser wiggler naturally small period assume laser parameters of Snowmass Posipol Proposal (CLIC note 639) laser wiggler equivalence: type YAG Alaser 592mJ lw 0.53 mm sx,y 5 mm sz 0.9 mm Ilaser 5x1020 W/m2 Bw 4090 T undulator regime! ~6% transverse emittance reduction per laser collision! however sd→50%! Frank Zimmermann, CLIC “Away Day” 26 March 2006

Frank Zimmermann, CLIC “Away Day” 26 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 gex & gey; but expect impact on dynamic aperture ~10% & 6x increased heat load Frank Zimmermann, CLIC “Away Day” 26 March 2006

Frank Zimmermann, CLIC “Away Day” 26 March 2006 spare slide Frank Zimmermann, CLIC “Away Day” 26 March 2006

Frank Zimmermann, CLIC “Away Day” 26 March 2006 DR equilibrium emittance without IBS & w/o 1/g present design: above can also be written as Frank Zimmermann, CLIC “Away Day” 26 March 2006