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+SppCCEPC: Ecm=240GeV e+e- Circular ColliderSppC: 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 China1) On “The 464th 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

4 CEPC - accelerator physics

4.1 Main parameters Guo Yuanyuan, Geng Huiping, Wang Dou, Xiao Ming, Gao Jie

4.2 LatticeGeng Huiping, Wang Dou, Guo Yuanyuan, Wang Na, WangYiwei, Xiao Ming, Peng Yuemei, Bai Sha, Su Feng, Xu Gang, Duan Zhe, Gao Jie

4.3 IR and MDIWang Dou, Geng Huiping, Wang Yiwei, Bai Sha, , Gao Jie

4.4 Beam instability Wang Na, Wang Yiwei

4.5 Beam-beam effectsZhang Yuan, Guo Yuanyuan, Wang Dou, Xiao Ming, Gao Jie

4.6 Synchrotron radiation Ma Zhongjian, Geng Huiping4.7 Injection and beam dump Cui Xiaohao, Su Feng, Xu Gang4.8 Background Yue Teng4.9 Polarization Duan 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)

BTCMedium 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

BeijingQinhuangdao

Tianjing

Beidaihe

Parameter Unit Value Parameter Unit ValueBeam energy [E] GeV 120 Circumference [C] km 53.6Number of IP[NIP] 　 2 SR loss/turn [U0] GeV 3Bunch number/beam[nB]　 50 Bunch population [Ne] 　 3.71E+11SR power/beam [P] MW 50 Beam current [I] mA 16.6

Bending radius [] m 6094momentum compaction factor [p]

　 4.15E-05

Revolution period [T0] s 1.79E-04 Revolution frequency [f0] Hz 5991.66

emittance (x/y) nm 6.79/0.021

IP(x/y) mm 800/1.2

Transverse size (x/y) m 73.7/0.16 x,y/IP 　 0.1/0.074Beam length SR [s.SR] mm 2.35 Beam length total [s.tot] mm 2.66Lifetime due to Beamstrahlung min 80

lifetime due to radiative Bhabha scattering [L]

min 56

RF voltage [Vrf] GV 6.87 RF frequency [frf] MHz 650

Harmonic number [h] 　 116244Synchrotron oscillation tune [s]

　 0.199

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]

% 0.15 n 　 0.22

Transverse damping time [nx]

turns 81Longitudinal damping time [n]

turns 40

Hourglass factor Fh 0.679 Luminosity /IP[L] cm-2s-1 1.8E+34

Main parameters for CEPC

Parameter Value Unit

Circumference 52 km

Beam energy 35 TeV

Dipole field 20 T

Injection energy 2.1 TeV

Number of IPs 2 (4)

Peak luminosity per IP 1.2E+35 cm-2s-1

Beta function at collision 0.75 m

Circulating beam current 1.0 A

Max beam-beam tune shift per IP 0.006

Bunch separation 25 ns

Bunch population 2.0E+11

SR heat load @arc dipole (per aperture) 56 W/m

SppC main parameters

Beam-beam tune shift limit analytical calculations

max

2845

6p

IP

r

f x RN

dtt

xfx

0

2

)2

exp(2

21)(

IPpIP NrRxf

Nxf

x

6

2845)(4)(4 2

max

2

03656.2x

0417.0)( xf

0064.0max

For lepton collider:

For hadron collider:

where SppC (actual parameter list)

FCC (pp) 0.005 (theory and FCC design)Formulae from private note of J. Gao

)(072.01

28456maxy, CEPC

IP

e

RNr

r_e is electron radiusγ= is normalized energyR is the dipole bending radiusN_IP is number of interaction points

r_p is proton radius

)(11.02 max,maxx, CEPCy

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)

(FFS)

Use 2 pairs of electrostatic separators Beam separated at horizontal plane with orbit offset of 5x

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*=0.8mbetaY*=0.0012mL*=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*=1.5mIP FT CCY CCX MT

FT: final telescopic transformer

CCY: chromatic correction section y

CCX: chromatic correction section x

MT: matching telescopic transformer

The key issue of pre-CDRis to have a working FFS in CEPC with enough off-momentum dynamic apertures

Key collaboration issue now, for example

SRF parameters of CEPC

units Main Ring Booster

fRF MHz 650 1300

U0 ( single beam ) GeV 3 3

Beam current of e-&e+ mA 2*16=32 0.9

Total beam power (SR) MW 100 2.7

total RF voltage GV 7 6

Eacc MV/m 8.8 15

cavity cells 5 9

cavity numbers 720 320

Input power per cavity kW 139 20

Total RF power MW 100 6.4

LLRF station numbers 720 320

Cryo module numbers 180 (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: 14-20 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

• 2015-2020: Development of a 12 T operational field Nb3Sn twin-aperture dipole with common coil configuration and 10-4 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).

• 2020-2025: Development of a 15 T Nb3Sn twin-aperture dipole and quadrupole with 10-4 field uniformity; Fabrication and test of 4~5 T HTS (Bi-2212 or YBCO) coils in a 15 T background field.

• 2025-2030: 15 T Nb3Sn coils + HTS coils (or all-HTS) to realize the 20 T dipole and quadrupole with 10-4 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. 12-13, 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: 2013-15 Pre-CDR by 2014 • R&D: 2016-2020 • Engineering Design: 2015-2020

– Construction: 2021-2027– Data taking: 2030-2036

• SPPC– Pre-study, R&D and preparation work

• Pre-study: 2013-2020• R&D: 2020-2030 • Engineering Design: 2030-2035

– Construction: 2036-2042– Data taking: 2042 -

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 frequency6) 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