CEPC/SppC and FCC Collaboration J. Gao On behalf of CEPC+SppC Group IHEP, CAS, China Pre-FCC ICB Meeting Sept. 9-10, 2014

Lepton and Hadron Colliders’ History and China Accelerator based High Energy Physics Development in the Future 2 BEPC II LC BEPC History of BEPC and BEPC II CEPC+SppC CEPC: Ecm=240GeV e+e- Circular Collider SppC: Ecm=50-100TeV pp Collider HIEPAF : High Intensity Electron Positron Accelerator Facility Old picture! CEPC+SppC will be constructed with international collaboration and participation

Strategy on Future High Energy Colliders of China 1) On “The 464 th Fragrant Hill Meeting”, Chinese High Energy Physics Community arrived at the following consensus: a) China supports ILC and will participate to ILC construction with in-kind contributions and requests R&D fund from government b) After the discovery of Higgs, as next collider after BEPCII in China, a circular e+e- Higgs factory （ CEPC ） and a Super proton- proton Collier (SppC) afterwards in the same tunnel is an important option and historical opportunity. 2) During the meeting of Chinese High Energy Physics Association on “China High Energy Physics based on Particle Accelerators”, Feb. 28, 2014, it was concluded that:“Circular e+e- Circular Higgs Factory(CEPC) +Super pp Collider (SppC) is the first choice for China’s future high energy physics accelerator. It is considered that CEPC (250GeV upper limit) is supplementary to ILC in terms of its energy range down to W and Z boson and to the number of detectors from both machines International collaboration and participation are necessary

Preliminary Conceptual Design Report of CEPC-SppC

Writing assigned for Pre-CDR 4CEPC - accelerator physics 4.1Main parameters Guo Yuanyuan, Geng Huiping, Wang Dou, Xiao Ming, Gao Jie 4.2Lattice Geng Huiping, Wang Dou, Guo Yuanyuan, Wang Na, Wang Yiwei, Xiao Ming, Peng Yuemei, Bai Sha, Su Feng, Xu Gang, Duan Zhe, Gao Jie 4.3IR and MDI Wang Dou, Geng Huiping, Wang Yiwei, Bai Sha,, Gao Jie 4.4Beam instabilityWang Na, Wang Yiwei 4.5Beam-beam effects Zhang Yuan, Guo Yuanyuan, Wang Dou, Xiao Ming, Gao Jie 4.6Synchrotron radiationMa Zhongjian, Geng Huiping 4.7Injection and beam dumpCui Xiaohao, Su Feng, Xu Gang 4.8BackgroundYue Teng 4.9PolarizationDuan Zhe  Visitors from other labs in the world participate the Pre-CDR joint works

CEPC Layout LTB : Linac to Booster BTC : Booster to Collider Ring BTC IP1 IP2 e+e- e+ e- Linac (240m) LTB CEPC Collider Ring(50Km) Booster(50Km) BTC

SppC Layout Medium Energy Booster(4.5Km) Low Energy Booster(0.4Km) IP4 IP3 SppC Collider Ring(50Km) Proton Linac (100m) High Energy Booster(7.2Km)

CEPC/SppC Layout LTB : Linac to Booster BTC : Booster to Collider Ring BTC IP1 IP2 e+e- e+ e- Linac (240m) LTB CEPC Collider Ring(50Km ) Booster(50Km ) BTC Medium Energy Booster(4.5Km) Low Energy Booster(0.4Km) IP4 IP3 SppC Collider Ring(50Km) Proton Linac (100m) High Energy Booster(7.2Km)

Possible site (example) 300 km from Beijing 3 h by car 1 h by train 9/45 Beijing Qinhuangdao Tianjing Beidaihe

ParameterUnitValueParameterUnitValue Beam energy [E]GeV120Circumference [C]km53.6 Number of IP[N IP ] 2SR loss/turn [U 0 ]GeV3 Bunch number/beam[n B ] 50Bunch population [Ne] 3.71E+11 SR power/beam [P]MW50Beam current [I]mA16.6 Bending radius [  ] m6094 momentum compaction factor [  p ] 4.15E-05 Revolution period [T 0 ]s1.79E-04Revolution frequency [f 0 ]Hz emittance (x/y)nm 6.79/  IP (x/y) mm800/1.2 Transverse size (x/y) mm 73.7/0.16  x,y /IP 0.1/0.074 Beam length SR [  s.SR ] mm2.35 Beam length total [  s.tot ] mm2.66 Lifetime due to Beamstrahlung min80 lifetime due to radiative Bhabha scattering [  L ] min56 RF voltage [V rf ]GV6.87RF frequency [f rf ]MHz650 Harmonic number [h] Synchrotron oscillation tune [ s ] Energy acceptance RF [h]%5.56 Damping partition number [J  ] 2 Energy spread SR [  .SR ] %0.13 Energy spread BS [  .BS ] %0.07 Energy spread total [  .tot ] %0.15nn 0.22 Transverse damping time [n x ] turns81 Longitudinal damping time [n  ] turns40 Hourglass factorFh0.679Luminosity /IP[L]cm -2 s E+34 Main parameters for CEPC

ParameterValueUnit Circumference52km Beam energy35TeV Dipole field20T Injection energy2.1TeV Number of IPs2 (4) Peak luminosity per IP1.2E+35cm -2 s -1 Beta function at collision0.75m Circulating beam current1.0A Max beam-beam tune shift per IP0.006 Bunch separation25ns Bunch population2.0E+11 SR heat dipole (per aperture)56W/m SppC main parameters

Beam-beam tune shift limit analytical calculations For lepton collider: For hadron collider: where SppC (actual parameter list) FCC (pp) (theory and FCC design) Formulae from private note of J. Gao r_e is electron radius γ= is normalized energy R is the dipole bending radius N_IP is number of interaction points r_p is proton radius J. Gao, Nuclear Instruments and Methods in Physics Research A 533 (2004) 270–274 J. Gao, Nuclear Instruments and Methods in Physics Research A 463 (2001) 50–61

CEPC lattice with FFS In current design: Circumference: 52.1 km 16*arcs: 2.64 km (60 FODO) 12*short straight: 352m (8 FODO) 4*long straight: ~700 m Bending radius: 5.7 km U0: 3.77GeV Nature emittance: 7.67 nm Nature energy spread: 0.19% Nature bunch length : 2.82mm Momentum compaction: 3.3E-5 (FFS)

 Use 2 pairs of electrostatic separators  Beam separated at horizontal plane with orbit offset of 5  x  Maximum bunch number: 96 Pretzel scheme

Half Quad of dispersion suppressor IP FFS entrance condition: DX=DPX=0  x=  y=0 betax=75.6m betaY=25.6m IR optics with L*=2.5m betaX*=0.8m betaY*=0.0012m L*=2.5m We use the same method as Yunhai’s example to make a new design of CEPC FFS. 15 Total length: 170 m

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 The key issue of pre-CDR is to have a working FFS in CEPC with enough off- momentum dynamic apertures Key collaboration issue now, for example

SRF parameters of CEPC unitsMain RingBooster fRFMHz U0 ( single beam )GeV33 Beam current of e-&e+mA2*16=320.9 Total beam power (SR)MW total RF voltageGV76 EaccMV/m8.815 cavity cells59 cavity numbers Input power per cavitykW13920 Total RF powerMW LLRF station numbers Cryo module numbers180 (4cav/ module) 40 Another key R&D collaboration item is on CEPC SRF systems, both for main ring and for booster

SppC Technical challenges and R&D plan (Possible collaboration items) High field magnets: both dipoles (20 T) and quadrupoles (pole tip field: T) are technically challenging, key technology to be solved in the coming two decades by a strong R&D program (see the next slide) Beam screen and vacuum: the key issue to solve the problem with very high synchrotron radiation power inside the cold vacuum. Need to develop an effective structure and working temperature to guide out the high heat load when minimizing Second-Electron-Yield, heat leakage to cold mass, impedance in the fast ramping field, vacuum instability etc. Both design and R&D efforts in the coming decade are needed to solve this critical problem. Collimation system: requiring unprecedentedly high efficiency, may need some collimators in cold sections. Perhaps need new method and structure. R&D efforts are needed.

R&D plan of the 20 T accelerator magnets : Development of a 12 T operational field Nb 3 Sn twin-aperture dipole with common coil configuration and field quality; Fabrication and test of 2~3 T HTS (Bi-2212 or YBCO) coils in a 12 T background field and basic research on tape superconductors for accelerator magnets (field quality, fabrication method, quench protection) : Development of a 15 T Nb 3 Sn twin-aperture dipole and quadrupole with field uniformity; Fabrication and test of 4~5 T HTS (Bi-2212 or YBCO) coils in a 15 T background field : 15 T Nb 3 Sn coils + HTS coils (or all-HTS) to realize the 20 T dipole and quadrupole with field uniformity; Development of the prototype SppC dipoles and quadrupoles and infrastructure build-up. (Very Preliminary) 19

Timeline in 2014 CEPC Workshop in Shanghai Jiaotong University, Sept , 2014 ICFA Advanced Beam Dynamics Workshop on High Luminosity Circular e+e- Colliders - Higgs Factory, October 8-11, 2014, Beijing Pre-CDR review: November 2014 Pre-CDR v1.0: by the end of the year 2014

CEPC/SppC long term Schedule (Preliminary) BEPC II will stop in ~2020 CPEC – Pre-study, R&D and preparation work Pre-study:  Pre-CDR by 2014 R&D: Engineering Design: – Construction: – Data taking: SPPC – Pre-study, R&D and preparation work Pre-study: R&D: Engineering Design: – Construction: – Data taking:

Collaboration Issues (1) (Common and different points) FCC is similar to CEPC/SppC in machine and particle types However, there are two main differences: (1) FCC’s priority is focusing on pp, CEPC/SppC’s priority is focusing on e+e- (2) FCC’s CDR is due in 2018, and CEPC/SppC ‘s CDR is due in 2015 (3) CERN is running LHC (pp) with LHC upgrades following and IHEP is running BEPCII (e+e-) with CEPC/SppC following

Collaboration Issues (2) (Feature of relation between FCC and CEPC/SppC) FCC and CEPC/SppC represent the landscape of future super circular accelerator centers in addition to Linear one, ILC FCC and CEPC/SppC is complementary in particle type priority and program schedules FCC and CEPC/SppC is complementary in their advantages, i.e. technologies, human resources, economical potential, etc… In short, FCC and CEPC/SppC is of collaborative relation instead of others, which is vital for both programs

Collaboration Issues (3) (The possible mode of collaboration between FCC and CEPC/SppC) 1)Exchange visitors (Ph.D students also) 2)Visitors working on both projects ( with comparisons, cross- checks, new ideas, training students, etc., design works in the first phase) 3)Joint meetings (with web-meetings), workshops, and schools, etc… 4)Help each other by taking into account of differences in time and particle type priorities… 5)Key technical parameter be better same such as rf frequency 6)Common design of key components, such as SCRF system… 7)Joint R&D on key bottle –neck design and technology development (IR FFS design ， SRF systems, High field SC magnets, Prezel technology, for examples)

Summary (1) FCC and CEPC+SppC are very exciting and important in parallel to ILC, as future high energy accelerator programs High energy physics committee is booming with these projects and programs, especially for young generations who will continue to live and enrich the extraordinary high energy physics culture in 21th century Circular colliders’ beam dynamics and technologies are arrived at a good time to boom together with linear colliders, both are great heritages of high energy physics community, which are worthwhile to be preserve and to be developed

Summary (2) Future large collider projects are all of the nature international collaborations, both in design/construction and operation, and are for the community and by the community Each country, region, and the community’s efforts to probe and bridging economical resources are positive and vital to the sustainable development of the community Collaborations between institutions, programs and projects are vital for all, especially FCC, CEPC/SppC, and ILC. China HEP is open to the world for the participation and joint development

Thank you for your attention