Narrow Results

In order to avoid the pretzel orbit, CEPC is proposed to use partial double ring scheme in CDR. In this paper, a general method of how to make an consistent machine parameter design of CEPC with crab-waist by using analytical expression of maximum beam–beam tune shift and beamstrahlung beam lifetime started from given IP vertical beta, beam power and other technical limitations were developed. FFS with crab sextupoles will be developed and the arc lattice will be redesigned to acheive the lower emittance for crab-waist scheme.

In this paper, a consistent calculation method for the CEPC parameter choice with a crab waist scheme is reported. A crosscheck of luminosity with beam–beam simulations has been done. With this new scheme, a higher Higgs luminosity (+170%) can be reached while keeping Pre-CDR beam power or the beam power (19 MW) can be reduced while keeping the same Pre-CDR luminosity. CEPC is compatible with W and Z experiment. The luminosity for Z is at the level of $10^{35}{\mathrm{\text{cm}}}^{-2}{\mathrm{\text{s}}}^{-1}$. Requirement for energy acceptance of Higgs has been reduced to 1.5% by enlarging the ring to 100 km. The arc optics and the Final Focus System (FFS) with crab sextupoles have been designed, and also some primary Dynamic Aperture (DA) results were introduced.

The CEPC booster needs to provide electron and positron beams to the collider at different energy with required injection speed. A 10 GeV linac is adopted as the injector for CDR. Then the beam energy is accelerated to specific energy according to three modes of operation of the CEPC collider ring ($H$, $W$ and $Z$). The geometry of the booster is designed carefully in order to share the same tunnel with the collider. The design status of the booster with the CDR lattice including parameters, optics and dynamic aperture is discussed in this paper.

In order to avoid the pretzel orbit, CEPC is proposed to use partial double ring scheme in CDR. In this paper, a general method of how to make an consistent machine parameter design of CEPC with crab-waist by using analytical expression of maximum beam–beam tune shift and beamstrahlung beam lifetime started from given IP vertical beta, beam power and other technical limitations were developed. FFS with crab sextupoles will be developed and the arc lattice will be redesigned to acheive the lower emittance for crab-waist scheme.