Dou Wang Jie Gao Feng Su Yuan Zhang Ming Xiao Yiwei Wang Bai Sha Tianjian Bian Zhe Duan CEPC AP meeting 20151127 Machine constraints given parameters Energy ID: 440198
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Slide1
Parameter study and IR design for CEPC local double ring scheme
Dou Wang, Jie Gao, Feng Su, Yuan Zhang, Ming Xiao, Yiwei Wang, Bai Sha, Tianjian Bian, Zhe Duan
CEPC AP meeting,
20151127Slide2
Machine constraints / given parameters
Energy E0Circumference C0NIP
Beam power
P
0y*R=y/xEmittance coupling factor Bending radius Piwinski angle luminosity enhancement by crab waist Fl ~1.5Energy acceptance (DA)Phase advance per cell (FODO)A=0/BS (A>~3)Slide3
Pre-CDR
crab waist
-high
lumi.crab waist-low power
Number of IPs
222Energy (GeV)120120120Circumference (km)545454SR loss/turn (GeV)3.12.962.96Half crossing angle (mrad)014.511.5Piwinski angle022Ne/bunch (1011)3.793.792.81Bunch number505040Beam current (mA)16.616.910.1SR power /beam (MW)51.75030Bending radius (km)6.16.26.2Momentum compaction (10-5)3.43.02.6IP x/y (m)0.8/0.00120.306/0.00120.22/0.001Emittance x/y (nm)6.12/0.0183.34/0.012.67/0.008Transverse IP (um)69.97/0.1532/0.1124.3/0.09x/IP0.1180.040.04y/IP0.0830.110.11VRF (GV)6.873.73.6f RF (MHz)650650650Nature z (mm)2.143.32.6Total z (mm)2.654.44.2Energy spread (%)0.130.130.13Energy acceptance (%)222Energy acceptance by RF (%)62.22.2n0.230.490.47Life time due to beamstrahlung_cal (minute)475341F (hour glass)0.680.730.69Lmax/IP (1034cm-2s-1)2.042.972.03
Primary parameter designSlide4
Combine with local double ring lattice
Choice 1
Choice 2Slide5
Double ring FFS design with crab sextupoles
Ec=100 keVBetax=0.8mBetay=0.003m
IP
Crab
sextupole
L*=1.5m
L(DQ0)=0.91m, G(DQ0)=-300T/mL(DF1)=0.74m, G(DF1)=106T/mL0=4mAs Oide said, the second FFS sextupoles of the CCS-Y section can work as the crab sextupoles, if their strengths and phases to the IP are properly chosen.Slide6
Crab
sextupole strengthThe crab
sextupole
should be placed on both sides of the IP in phase with the IP in the horizontal plane and at π/2 in the vertical one.
x=2, y=2.5Slide7
Chromaticity correctionSlide8
summary
CEPC partial double ring parameters for high luminosity mode has been adjusted to enlarge the energy acceptance of RF system.Based on crab waist scheme, we can get higher luminosity (2.97*1034
cm
-2
s-1) keeping head-on beam power or to reduce the beam power (30 MW) keeping same luminosity. New FFS with crab sextupoles has been designed. DA optimization of the whole ring is undergoing.For next step, arc lattice should be redesigned as soon as possible to get smaller emittance for crab waist scheme.