The Vision of CEPC-SppC
Yifang Wang
Institute of High Energy Physics, Beijing
NTU, Dec. 8, 2015
Where Are We Going ?
• After the Higgs, game is over ?
• Shall we wait for results from LHC/HL-LHC ?
• ILC ?
– If yes, enough ？Next ？ – If no, then ?
• What is the future of our
field ?
Standard Model Is not Complete
• From neutrinos to top quark, masses differs by a factor 1013, why ？
• Fine tuning of Higgs mass(naturalness)：
• Masses of Higgs and top quark are in the meta-stable region, why ?
Fundamental reason ?
• Many of the free parameters in the SM are related to Higgs. A deeper theory ?
Fundamental reason(s) beyond SM ?!
For L(new physics) at the Planck scale ~ 1016 TeV：
A coincidence of 10-34 ? Never before even at 10-4
Evidence Beyond the Standard Model
• Unification at a high energy ?
• No dark matter particles in the SM, Needed ? Where ?
• No CP in the SM to explain Matter-antimatter asymmetry, why ?
• How to describe neutrinos in the SM ?
• SUSY can provide solutions to many of these problems, incident ？
New Tasks after the Higgs Discovery
• Open questions about Higgs
– Consistent with SM ?
– Composite or elementary ? – Other Higgs ？
– New properties ？
– Responsible for CP violation？
– What type of potential ?
• New type of interactions concerning only the Higgs:
– Yukawa coupling through Higgs with spin 0:
– hττ, hbb, htt coupling constant，~10% @ LHC
– Self-coupling h3 & h4:
• ~ 50% @ LHC
Higgs is the only elementary particle with spin 0 !
Never seen point-like scalars !
Need a factor of ~10 improvement over LHC !
• Yes, there are new physics, and also “standard”
physics to be learned
• ILC is not enough, even if it can be built soon
• High energy frontier is still the center of particle physics
What to do ?
Our Proposal: CEPC+SppC
• Thanks to the low mass Higgs, we can build a Circular Higgs Factory(CEPC), followed by a proton collider(SppC) in the same tunnel
• A natural continuation of BEPCBEPCIICEPCSppC
BTC
IP1
IP2
e+ e-
e+ e- Linac (240m)
LTB
BTC Medium Energy Booster(4.5Km)
Low Energy Booster(0.4Km)
IP4 IP3
Proton Linac (100m) High Energy Booster(7.2Km)
A 50-70 km tunnel is relatively easier NOW in China
In Europe, TLEP FCC
Science
• Electron-positron collider(90, 250, 350 GeV)
– Higgs Factory: Precision study of Higgs(mH, JPC, couplings)
• Similar & complementary to ILC
• Looking for hints of new physics
– Z & W factory: precision test of SM
• Deviation from SM ? Rare decays ?
– Flavor factory: b, c, t and QCD studies
• Proton-proton collider(~100 TeV)
– Directly search for new physics beyond SM – Precision test of SM
• e.g., h3 & h4 couplings
Precision measurement + searches:
Complementary with each other !
Design Goal of CEPC/FCC-ee
• Limit SR power to 50 MW per beam
• CEPC: single ring, head-on collision, up to 250 GeV
• FCC-ee: double ring, large crossing angle, up to 350 GeV
CEPC:
106 Higgs 1010 Z FCC-ee:
107 Higgs 1012-13 Z
Design Goal of SPPC/FCC-pp
• Technology to bend the proton beam is limited by the field strength of the dipole magnet.
Currently we can only imagine up to 20 T.
• Hence, ~ 100 km ring and ~ 100 TeV is a generic desire
May 5, 2015
New Physics for Sure ?
• If no new physics at LHC
– L~ 1 TeV 10-2 fine tuning
• If no new physics at 100 TeV
– L~ 10 TeV 10-4 fine tuning – Never before
Three pillars of future circular colliders
EW phase transition Dark Matter
Naturalness
For L(new physics) at the Planck scale ~ 1016 TeV：
If naturalness does not work, then ?
Shall We Wait for Results from LHC ?
• If LHC finds nothing, we should go to higher energies
– An e+e- Higgs factory can give us a first indication
– go directly to 100 TeV pp collider is also a viable option
• If LHC finds something, it is a new era
– Beyond SM new energy scale, new spectrum, LHC can not complete it
– A higher energy pp collider is needed immediately
• To access the spectra of higher masses
• To have more statistics since Event No. E~5CM
– An e+e- Higgs factory can give us time to develop technologies for 16-20 T magnet and SC cables
Why in China ？
• Timing (after BEPCII)
• Technological feasibility (experience at BEPC/BEPCII)
• Economy new funding to the community
• Large & young population new blood to the community
• Affordable tunnel & infrastructure still cheap in China now
• Money will be taken by somebody anyway It is a pity if we miss it
• Too expensive ?
– BEPC cost/4 y/GDP of China in 1984 0.0001 – SSC cost/10y/GDP of US in 1992 0.0001
– LEP cost/8y/GDP of EU in 1984 0.0002 – LHC cost/10y/GDP of EU in 2004 0.0003 – ILC cost/8y/GDP of Japan in 2018 0.0002 – CEPC cost/6y/GDP of China in 2020 0.0001
– SPPC cost/10y/GDP of China in 2036 0.0001- 0.0002
Physics wise，
CEPC+SPPC is ideal
CEPC ? ILC ? SPPC ? FCC ?
• CEPC is our main goal now. SPPC is very attractive but at the distant future
• CEPC design has to maintain the possibility for SPPC, but there is no need now to firmly prove the feasibility of SPPC,
scientifically or technologically
• We can work together for the future pp machine, SPPC or FCC
• CEPC & ILC are complementary, and can happen at the same time
– As a fraction of GDP, we are not asking more than what we obtained in 50-90’s.
– HEP after the cold war: need new argument. WWW ?
– CEPC+ILC: Two machines & two detectors, no push-pull option for ILC
• Some level of competition can only help our case
– Each continent has a major project
– ILC approach for selecting SPPC/FCC ?
Current Status
• Initiated a global effort for the Conceptual design
• Pre-CDR completed
– No show-stoppers
– Technical challenges identified R&D issues – Preliminary cost estimate
• R&D issues identified and funding request underway
– Seed money from IHEP available: 12 M RMB/3 years – MOST: ~ 100 M / 5yr, hopefully next year
– NCDR: ~1 B RMB / 5 yr, maybe 2017
• Working towards CDR by 2016
– A working machine on paper
• Site selection
• Internationalization & organization
Timeline (dream)
• CPEC
– Pre-study, R&D and preparation work
• Pre-study: 2013-15
– Pre-CDR for R&D funding request
• R&D: 2016-2020
• Engineering Design: 2015-2020
– Construction: 2021-2027 – Data taking: 2028-2035
• SppC
– Pre-study, R&D and preparation work
• Pre-study: 2013-2020
• R&D: 2020-2030
• Engineering Design: 2030-2035
– Construction: 2035-2042 – Data taking: 2042 -
March 30, 2015
Can be downloaded from
http://cepc.ihep.ac.cn/preCDR/volume.html
403 pages, 480 authors 328 pages, 300 authors
International Review of Pre-CDR
March 30, 2015
CEPC Accelerator
Linac Booster
Collision ring
Electron
Positron
6~10 GeV
45/120 GeV
3 machines in one tunnel
CEPC & booster
SppC
Main choice of CEPC:
One ring machine
Head-on collision
Energy Ramp 10 ->120GeV
Compatibility: a Complicated Issue
CEPC Injector
SPPC injector
Beam pipe detour for detectors
CEPC booster avoid storage ring
CEPC avoid SPPC detectors
SPPC avoid CEPC detectors
SR beamlines
Predict what SPPC needs
Collimators
Straight sections
Tunnel dimensions
Access tunnel
….
To be fully understood in the next 5 years
CEPC Design
Critical parameters:
• SR power: 51.7 MW/beam
• 8*arcs, 2*IPs
• 8 RF cavity sections (distributed)
• RF Frequency: 650 MHz
• Filling factor of the ring: ~70%
Parameter Unit Value Parameter Unit Value
Beam energy [E] GeV 120 Circumference [C] m 54752 Number of IP[NIP] 2 SR loss/turn [U0] GeV 3.11 Bunch number/beam[nB] 50 Energy acceptance RF [h] % 5.99 SR power/beam [P] MW 51.7 Beam current [I] mA 16.6 emittance (x/y) nm 6.12/0.018 bIP(x/y) mm 800/1.2 Transverse size (x/y) mm 69.97/0.15 Luminosity /IP[L] cm-2s-1 2.04E+34
Main Challenges
• Beam physics: dynamic aperture, momentum acceptance, electron cloud, pretzel scheme, …
• Superconducting cavity: High-Q cavity, HOM dumping, mass production, power consumption,…
• Total power consumption: ~ 500 MW ! need a green machine
– Reuse the thermal power, ~ 200 MW
• Heating of houses close to a big city, summer ?
• Gasifying liquified natural gas close to a harbor
• Agricultural greenhouse summer ?
– Increase the efficiency of the RF power supply to more than 70%, even 80%
– ICFA established a panel this summer for this issue
– Partial double ring for reduced power and higher luminosity ?
Partial Double-Ring Machine ?
• ~ 10% double-ring
• Large crossing
angle &
Crabwaist
& small
by• O(1000) bunches
• Luminosity close to double-ring
machine ?
• Issues
– Electrostatic separators – RF systems – Electron Cloud
Issues M. Koratzinos, talk given at HF2014, Beijing M. Koratzinos & F. Zimmermann, this Conf.
J. Gao, IHEP-AC-LC-Note2013-012
SppC Design
• Proton-proton collider luminosity
• Main constraint: high-field superconducting dipole magnets
– 50 km: Bmax = 12 T, E = 50 TeV
– 50 km: Bmax = 20 T, E = 70 TeV
– 70 km: Bmax = 20 T, E = 90 TeV
2 2
0
,
( 1 )
4 2
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n IP x IP
N N f
L F F
b
x = Nprp
4pen £0.004
min
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B C
SppC General design
• 8 arcs (5.9 km) and long straight sections
(850m*4+1038.4m*4) 26
Parameter Value
Circumference 54.36 km
Beam energy 35.3 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) 56.9 W/m
Challenges
• High field magnets: both dipoles (20 T) and quadrupoles (pole tip field: 14-20 T).
• Beam screen and vacuum: very high synchrotron radiation power inside the cold vacuum:
• Collimation system: high efficiency collimators in cold sections: new method and structure ?
• ……
A R&D plan is developed.
Main focus is the magnet
A Conceptual design of 20-T Nb3Sn + HTS common coil dipole magnet from IHEP 27
HTS ?
• Cost per meter decreased by ~ 2.5 times per 10 years
• Current limit per unit area increased by ~3 times per 10 years
• Unit price per (Ameter) can improve by ~50 times over 20 years, if past data can be used for prediction !
• 20T Full HTS magnet ???
Let’s KEEP OPTIMISTIC !!!
29
Superconductor Price Comparison
Steve Gourlay – Superconductor price paid by LBNL to the US companies some years ago :
Superconductor price quoted by the Chinese companies now:
• Bi-2223: RMB 15,000/kg USD 2,400/kg
• YBCO: RMB 20,000/kg USD 3,300/kg
By Weiren Chou
CEPC Detector
ILD-like detector but (incomplete):
Shorter L* (1.5m) → constraints on space for the Si/TPC tracker
No power-pulsing → cooling issues Limited CoM (up to 250 GeV) → calorimeters of reduced size
Lower radiation background → vertex detector closer to IP
…
• Similar performance requirements to ILC detectors
– Momentum: ← recoiled Higgs mass
– Impact parameter: ← flavor tagging, BR
– Jet energy: ← W/Z di-jet mass separation
• Beneficial from 20 years of ILC study
-1 5
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m ) sin /(
10
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3 m
r p
% 4 3 E
E
CEPC Detector R&D
Device:
• Vertex
• Tracking device
• EM calorimeter
• Hadorn calorimeter
• SC magnet
• Muon Chamber
• Readout, trigger, DAQ
• Physics & software
Technology:
• Silicon pixel
• Silicon strips
• Silicon pads
• Scintillator pads
• RPC
Simulation and Physics
Z mm recoil Z ee recoil Z qq recoil
A Candidate Site
Beijing
Qinhuangdao
Tianjing
Beidaihe
• 300 km from Beijing
• 3 h by car
• 1 h by train
Good Thing About This Site
Best beach & cleanest air Summer capital of China
Starting point of the Great Wall
Wine yard
Good geology:
granite ~ few meters underground seismic intensity < 0.1g
extremely small earth vibration Good environment
for living, international science city,…
Strong support from local government
Civil Construction
• A credible design with cost estimate
• The key to keep the cost low
– Find a site geologically the best(granite) – Optimize of the design
– Choose the right designer &
construction contractor – Management
Surface and Underground Construction
Tunnel
• Concrete/Steel is not needed in granite for the stability of the structure
• Water leaks are mainly cured by Concrete + water proof material
• Concrete/Steel could bear more than half of the tunnel cost
• Solution: steel plate ~ 50% cost saving
Organization and Activities
• International workshops
– ICFA Higgs factory workshop, Oct. 2014
– Workshop on CEPC organized by IAS HKUST, Jan. 2015 – ICFA workshop on SC Magnet, June 2015
– IHEP-DOE CEPC physics workshop in Aug. 10-12, 2015 – Beijing-Chicago workshop on CEPC in Sep. 2015
– More in 2016
• Training & professional development
• Communication, education & Outreach
International Collaboration
• Why we need international collaboration ?
– Not only because we need technical help
– But also for financial & political support in China
• A way to integrate China better to the international community
• A way to modernize China’s research system(“open door” policy)
• A machine for the community
• Right now the pre-CDR is mainly Chinese efforts with international help
– An excise for us
– Build confidence for the Chinese HEP community
International Collaboration(con’t)
• A new scheme of international collaboration to be explored:
– Not the same as ITER, ILC, CERN, …
– A new institution, a consortium, or just a new project ?
• An international advisory board is formed to discuss in particular this issue, together with others
– Working groups – Workshops
– Preliminary organizations next year
– …
