DA Study for the CEPC Partial Double Ring
DA Study for the CEPC Partial Double Ring Scheme Yiwei Wang, Feng Su, Dou Wang, Yuan Zhang, Huiping Geng, Jie Gao 8 April 2016, CEPC workshop
Outline • CEPC parameters • Lattice design – arc, interaction region, partial double ring • Dynamic aperture study • Summary
CEPC primary parameter (wangdou 20160325) Number of IPs Energy (Ge. V) Circumference (km) SR loss/turn (Ge. V) Half crossing angle (mrad) Piwinski angle Ne/bunch (1011) Bunch number Beam current (m. A) SR power /beam (MW) Bending radius (km) Momentum compaction (10 -5) IP x/y (m) Emittance x/y (nm) Transverse IP (um) x/IP y/IP VRF (GV) f RF (MHz) Nature z (mm) Total z (mm) HOM power/cavity (kw) Energy spread (%) Energy acceptance by RF (%) n Life time due to beamstrahlung_cal (minute) F (hour glass) Lmax/IP (1034 cm-2 s-1) Pre-CDR H-high lumi. H-low power W Z 2 120 54 3. 1 0 0 3. 79 50 16. 6 51. 7 6. 1 3. 4 0. 8/0. 0012 6. 12/0. 018 69. 97/0. 15 0. 118 0. 083 6. 87 650 2. 14 2. 65 3. 6 0. 13 2 6 0. 23 47 2 120 54 2. 96 15 2. 85 67 16. 9 50 6. 2 2. 5 0. 25/0. 00136 2. 45/0. 0074 24. 8/0. 1 0. 03 0. 11 3. 62 650 3. 1 4. 1 2. 2 0. 13 2 2. 2 0. 47 36 2 120 54 2. 96 15 2. 67 44 10. 5 31. 2 6. 2 2. 2 0. 268 /0. 00124 2. 06 /0. 0062 23. 5/0. 088 0. 032 0. 11 3. 53 650 3. 0 4. 0 1. 3 0. 13 2 2. 1 0. 47 32 2 80 54 0. 59 15 5 0. 74 400 26. 2 15. 6 6. 1 2. 4 0. 1/0. 001 1. 02/0. 003 10. 1/0. 056 0. 008 0. 074 0. 81 650 3. 25 3. 35 0. 99 0. 09 2 45. 5 54 0. 062 15 7. 6 0. 46 1100 45. 4 2. 8 6. 1 3. 5 0. 1/0. 001 0. 62/0. 0028 7. 9/0. 053 0. 006 0. 073 0. 12 650 3. 9 4. 0 0. 99 0. 05 1. 7 0. 3 1. 1 0. 24 0. 68 2. 04 0. 82 2. 96 0. 81 2. 01 0. 92 3. 09 0. 95 3. 09
ARC lattice • 60 /60 FODO cell – n=6 – All 3 rd RDT due to sextupoles cancelled – All 4 th RDT except 2 Qx-2 Qy due to sextupoles cancelled • 90 /60 FODO cell – n=12 – All 3 rd RDT due to sextupoles cancelled – All 4 th RDT except 4 Qx due to sextupoles cancelled • 90 /90 FODO cell – – n=4 All 3 rd RDT due to sextupoles cancelled 4 th RDT except 4 Qx, 2 Qx+2 Qy, 4 Qy, 2 Qx-2 Qy due to sextupoles cancelled Should be non-interleaved sextupole scheme
ARC lattice • 60/60 degree FODO cell – 156=26*6 cells in each section to make resonance driving terms cancellation • Length of ARC: 55 km
RDT in ARC • Resonance driving terms (RDT) of ARC lattice • With 2 families of sextupoles in 6 cells – All 3 rd RDT due to sextupoles cancelled – All 4 th RDT except 2 Qx-2 Qy due to sextupoles cancelled – Amplitude-dependent tune shift d. Qx/d. Jx, d. Qy/d. Jy, d. Qx/d. Jy accumulated in FODO cells which can be further optimized 3 rd RDT 4 th RDT d. Qx/d. Jx, d. Qy/d. Jy, d. Qx/d. Jy 2 Qx-2 Qy
Tune shift • tune vs. d. P/P – Second order chromaticity arise due to stronger focusing 2 families in ARC
IR lattice • IR lattice design with local chromaticity correction • Additional sextupole for 3 rd order chromaticity MT CCY L*= 1. 5 m x*= 0. 22 mm y*= 1 mm GQD 0= -200 T/m GQF 1= 200 T/m LQD 0=1. 69 m LQF 1=0. 90 m CCX FT IP
Chromaticity correction 3 rd order vertical chromaticity 3 rd order vertical and horizontal chromaticity Preliminary result to be further optimized with whole ring
Check chromaticity with ARC+IR ARC 6. 28 nm 3 rd order vertical chromaticity ARC 2. 9 nm 3 rd order vertical and horizontal chromaticity 4 families in IR 2 families in ARC Preliminary result to be further optimized with whole ring
Partial double ring • Separator: 12*62. 5 urad=0. 75 mrad • Septum: 4. 25 mrad • Exit of septum X=0. 028875 m
Whole ring • Circumference=61 km, Emittance 3. 19 nm • High order chromaticity correction with whole ring is under going. To get a ring around 54 km, the PDR should be included into the ARC
Dynamic aperture • • • W/O error of the magnets Synchrotron motion and radiation damping included Tracking with 240 turns Coupling factor =0. 003 for y Preliminary result of dynamic aperture for on momentum: (13 x, 90 y) – High order chromaticity correction and other aberration analysis is under going
Summary • A preliminary lattice designed for CEPC partial double ring scheme – ARC: 60/60 degree FODO cell – IR: L*=1. 5 m, y*= 1 mm, c=15 mrad – PDR: 3 km • Local chromaticity correction for IR • Preliminary result of dynamic aperture – on momentum – High order chromaticity correction and other aberration analysis with whole ring is under going
PDR lattice • The bending angle in PDR is small compare with its length – If scale bending angle with (6 km/54 km)*2 /4=175 mrad – Actually: Left PDR 0. 75 mrad+14. 25 mrad-15 mrad – Actually: Right PDR +15 mrad-14. 25 mrad-0. 75 mrad • Present PDR almost doesn’t contribute to the emittance • The PDR should be included into the ARC, otherwise the total length will be 55 km+6 km
- Slides: 15