Preliminary Result on L*=1.5m CEPC Interaction Region Yiwei Wang, Dou Wang, Sha Bai Yingshun Zhu, Teng Yue CEPC acc. meeting, 5 September 2014

IR optics with L*=1.5m betx*=0.8m, bety*=1.2mm, L*=1.5m IPFTCCYCCXMT FT: final telescopic transformer CCY: chromatic correction section y CCX: chromatic correction section x MT: matching telescopic transformer

with total 4 sextupoles in the chromatic correction – For the first try of chromatic correction, zero length of sextupoles are used to neglect the finite length effect. Chromatic Correction

Optics of whole ring IR+ARC

Dynamic Aperture L*=1.5m L*=2.5m

Final Doublet Beam stay-clear(L*=2.5m) – beam_clear_x=5*sigmax_inj, beam_clear_y=10*sigmax_inj – emitx_inj=21.8nm, emity_inj=2.2nm (10% coupling for injection beam) – emitx_inj=22.9nm, emity_inj=1.1nm (5% coupling for injection beam) IP L*=2.5m Q1: L=0.56m, R=0.7cm, G=-516T/m D2=1.14m Q2: L=0.58m, R=1.5cm, G=364T/m

Final Doublet Beam stay-clear (L*=1.5m) – beam_clear_x=5*sigmax_inj, beam_clear_y=10*sigmax_inj – emitx_inj=21.8nm, emity_inj=2.2nm (10% coupling for injection beam) – emitx_inj=22.9nm, emity_inj=1.1nm (5% coupling for injection beam) L*=1.5m Q1: L=0.76m, R=0.55cm, G=-400T/m D2=2.45m Q2: L=0.42m, R=1.85cm, G=283T/m IP

Summary Preliminary design for L*=1.5m IR optics Chromaticity from final doublet reduced as expected DA for off momentum particles still very small Optimization on IR linear lattice (include the final doublet) and chromatic correction need to be done

reseverd

Final Doublet Beam stay-clear – beam_clear_x=20*sigmax, beam_clear_y=20*sigmay – emitx=6.9nm, emity=0.021nm (0.3% coupling for beam in main ring) L*=1.5m Q1: L=0.76m, R=0.55cm, G=-400T/m D2=2.45m Q2: L=0.42m, R=1.85cm, G=283T/m IP (m) IP L*=2.5m Q1: L=0.56m, R=0.7cm, G=-516T/m D2=1.14m Q2: L=0.58m, R=1.5cm, G=364T/m

Final Doublet Beam trajectories: beamx=20*sigmax, beamy=20*sigmay Inner radius of beam pipe Distance between final doublet could be reduced L*=1.5m Q1: L=0.76m, R=0.55cm, G=-400T/m D2=2.45m Q2: L=0.42m, R=1.85cm, G=283T/m IPQ1Q2 (m) IP Q1Q2 L*=2.5m Q1: L=0.56m, R=0.7cm, G=-516T/m D2=1.14m Q2: L=0.58m, R=1.5cm, G=364T/m

with total 4 sextupoles in the chromatic correction – For the first try of chromatic correction, zero length of sextupoles are used to neglect the finite length effect. Chromatic Correction

MDI consider 1 ring consider no crossing angle – We can separate e+ and e- far away from IP as large bunch separation. What we need to do on MDI? – space and angle allowed for the machine outer aperture of FD (contact with detector and magnet people) – effect of detector solenoid field(3~4T) on the beam (need to compensate) – force of detector solenoid on the FD (add supports for FD) – background requirements (contact with Teng YUE) Beam loss, synchrotron radiation… – need collimator in IR – High voltage of detector have to be turned on when injection? – When back ground is too high, we have to dump the beam. CEPC should need such a mechanism.

Review of colliders MDI SuperKEKB and ILC BEPCII LEPII

SuperKEKB 7GeV 4GeV

SuperKEKB