Download - Status and Prospect of sKEKB
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May 30, 2008
Yutaka Ushiroda (KEK)Flavour as a Window to New Physics at the LHC
Focus Week “B@LHC”
Status and Prospect of sKEKB
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Outline
• Introduction
• Accelerator status and prospect
• Detector status and prospect
• Political situation
• Summary
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KEK and KEKB
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KEK and KEKB
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KEK and KEKB
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~1 km in diameter
Mt. Tsukuba
KEKBBelle
KEK and KEKB
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3.5 GeV e X 8.0 GeV e
crossing angle = 11 mrad.
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The Luminosity Frontier
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Main results from Belle
Evidence for direct CP violation in B K+
Evidence for direct CP violation in B K+
Evidence for B Evidence for B
Observation of b dObservation of b d
Observation of B K(*)llObservation of B K(*)ll
Observation of CP violation in B meson system
Observation of CP violation in B meson system
Measurements ofCP violation in B Ks, ’Ks etc.
Measurements ofCP violation in B Ks, ’Ks etc.
Discovery of X(3872)
Discovery of X(3872)
Evidence for D0 mixingEvidence for D0 mixing
Observation of direct CP violation in B
Observation of direct CP violation in B
Observation of Bs Observation of Bs
L>830/fb
DCP in B0 vs. B+
DCP in B0 vs. B+
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M. Nakao @ BPAC/KEK, 2008
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Jan. 24, 2008
SuperKEKB Physics Reach @ 50 ab−1 BNM200810
S.Nishida (KEK)
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BK*(KS) TCPV
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Ks track
IP profile
B vertex
B vertex recon by a KS
0 *0 0SB K K
535fb
10ab
SM
NP
sB X
ds
t
db
W
The decay is almost flavor specificbecause photon is highly polarized
L
R
b s
b s
1
2sin 2 0.04s
b
m
m S
SM prediction
AGS [Phys.Rev.Lett. 79, 185 (1997)]AGHS [Phys. Rev. D 71, 076003 (2005)]
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talk by M. Misiak
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Crab cavities will be installed and tested with beam in 2006.
The superconducting cavities will be upgraded to absorb more higher-order mode power up to 50 kW.
The beam pipes and all vacuum components will be replaced with higher-current-proof design.
The state-of-art ARES copper cavities will be upgraded with higher energy storage ratio to support higher current.
SuperKEKBe+ 4.1 A
e- 9.4 A
β*y = σz = 3 mm
will reach 8 × 1035 cm-2s-1.
L 2ere
1 y
*
x*
Iy
βy*
RL
Ry
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Machine parameters
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LER HER
Energy E 3.5 8.0 GeV
Current Ib 9.4 4.1 A
#particles/bunch N 1.18x1011 5.13x1010
#bunches nb 5018
Emittance x 12 nm
Coupling y/x 0.5 %
Beta at IP βx* 20 cm
βy* 3 mm
Bunch length (0A) z 3 mm
Crossing angle x 30→0 (crab crossing) mrad
Bean-beam x 0.272
y 0.295
Luminosity reduction
RL 0.86
Beam-beam Rx 0.98
reduction Ry 1.11
Luminosity L 5.5x1035 cm-2s-1
Slide from Y. Ohnishi
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Improve Luminosity
KEKBPEPIIKEKBPEPII
•Increase beam current•Squeeze beam size (a little)
sKEKB
SuperB
•Squeeze beam size
Brute force, but adiabatic and steady
New sophisticated approach
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Improve Gas Mileage
Hybrid Plug-in HybridTOYOTA Prius
HydrogenFIAT Panda Hydrogen
GasolineCar
GasolineCar
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operation time : 240 days/year
Target forroadmap
Target forroadmap
Inte
grat
e lu
min
osity
(a
b-1)
Peak
lum
inos
ity (c
m-2
s-1)
Year
3 yearsshutdown
DampingRing
RF upgrade
KEKroadmap
Peak
cur
rent
(A)
KEK roadmap includes RF/DR (after 3 years shutdown)
Projected Luminosity (preliminary)
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Slide from Y. Ohnishi
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Beam Background (extrapolation)
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Prepare against 20xPrepare against 20x
Ideas to reduce background: Neutron shield for KLM Improve vacuum Cu chamber near IR Careful IR design
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Against high background (1)
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Hit rate per cell can be reduced
Large cellOccupancy = 6/12 = 50%Hits overlap
Small cellOccupancy = 7/48 = 14.5%Hits separated
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t
Against high background (2)
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t
t
Even when we cannot shorten the peaking time, waveform sampling will help to discriminate two signals
Short signals are separated
Long-tailed signals overlap each other
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“effective” backgroundwith new hardware
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How to cope with Reduction factor bkg
SVD Shorter tp 50/800 = 1/16 0 ~ 1
CDC Smaller cell <2/3 4 ~ 13 (*)
PID Brand new device Good enough 0 ~ 1
B-ECL Waveform fitting 1/7 1 ~ 2
E-ECL Pure CsI (shorter ) 1/200 0 ~ 1
KLM Faster detector, finer segment Under control 0 ~ 1
(*) Software efforts needed for CDC
We know how to deal with high backgroundWe know how to deal with high background
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sKEKB: Baseline Design
Belle
sBelle
SVD: 4 lyr 6 lyr DSSD (option: pixel, striplet)CDC: small cell, long lever armACC+TOF TOP+A-RICHECL: waveform sampling, pure CsI for end-capsKLM: RPC Scintillator +SiPM (end-caps)
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To be improved
• Larger radial size of vertex detector to accept more KS
• Innermost sensor closer to the IP to improve z resolution
• More hermetic detector to help reconstruction of invisible modes (w/ )
• Better Particle Identification
• Better KL reconstruction
• …
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End-cap PID (A-RICH)Test beam result
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March 2008 at KEK Fuji electron beam linepe = 2 GeV/c
Clear ring image observed ! ~ 12mrad, Np.e. ~ 4
6 HAPDs
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External Reviews
Belle PAC, Feb. 25,26, 2008
KEK Roadmap Review Committee, Mar. 9,10, 2008
and one more Belle review in July by Japanese key figures
http://belle.kek.jp/hot/Review_report-bis.pdf
KEKB Review, Nov.-Dec., 2007
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Necessary approvals to starta new big project at KEK
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We’re here!
KEK = an inter-university research
institute corporation
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Tight Schedule Toward Upgrade
Detector Study Report
TDR
Design Decision
Open meetings for the proto-collaboration (next Jul. 3,4)
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Summary
• We plan to upgrade KEKB/Belle in a sure and steady method.
• We have ideas to make the accelerator and the detector, and continuing R&Ds.
• We will make a budget request to the government soon.
• Hopefully, we will start the operation in late 2012 and accumulate 10-50ab1 by 202x depending on the budget.
• Hope you will put this talk not in the ‘Long-term future’ session from the next time.
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KEK’s 5 year Roadmap• Official 20 page report released on January 4, 2008 by
director A. Suzuki and KEK management
• KEKB’s upgrade to 2x1035 /cm2/sec in 3+x years is the central element in particle physics. (Funding limited: Final goal is 8 x 1035 and an integrated luminosity of 50 ab-1)– Will be finalized after recommendations by the Roadmap
Review Committee (March 9-10).• Membership: Young Kee Kim, John Ellis, Rolf Heuer, Andrew
Hutton, Jon Rosner and reviewers from other fields
Super-Belle (and Super KEKB) is an open international project that covers the next two orders of magnitudes at the luminosity frontier. A special opportunity for high impact international collaboration
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Three factors to determine the luminosity:
L 2ere
1 y
*
x*
Iy
βy*
RL
Ry
Stored current:
1.7 / 1.4 A (e+/ e- KEKB)
→ 9.4 /4.1 A (SuperKEKB)
Beam-beam parameter:
0.059 (KEKB)
→ >0.24 (SuperKEKB)
Vertical β at the IP:
6.5/5.9 mm (KEKB)
→ 3.0/3.0 mm (SuperKEKB)
Lorentz factor
Classical electron radius Beam size ratio
Geometrical repipeion factors due to crossing angle and hour-glass effect
Luminosity:
0.17 ×1035 cm-2s-1 (KEKB)
8×1035 cm-2s-1 (SuperKEKB)
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Costs & EffectsItem Object
Oku-yen = 1.0 M$
Luminosity
New beam pipes
Enable high currentReduce e-cloud
178(incl. BPM,
magnets, etc.)x1.5
New IR Small β* 31 x2
e+ Damping Ring
Allow injection with smallincrease e+ capture
40 incl. linac upgrade
if not, x0.75
More RF and cooling systems
High current179
(incl. facilities)x3
Crab Cavities Higher beam-beam param. 15 x2 - x4
Preliminary
Items are interrelated.
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Time schedule is restricted.
Baseline is “HIGH current scheme”.
Alternative is low beta+low emittance+crab waist scheme
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Luminosity upgradeLuminosity gain and upgrade items (preliminary)
Item Gain Purpose
beam pipe x 1.5high current, short bunch, electron cloud
IR(β*x/y=20cm/3 mm) x 1.5 small beam size at IP
low emittance(12 nm)x → 0.5
x 1.3mitigate nonlinear effects with beam-beam
crab crossing x 2mitigate nonlinear effects with beam-beam
RF/infrastructure x 3 high current
DR/e+ source x 1.5low β* injection, improve e+ injection
charge switch x ? electron cloud, lower e+ current
3 ye
ars
shut
dow
n
35
KEK
road
map
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Machine parameters
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LER HER
Energy E 3.5 8.0 GeV
Current Ib 9.4 4.1 A
#particles/bunch N 1.18x1011 5.13x1010
#bunches nb 5018
Emittance x 12 nm
Coupling y/x 0.5 %
Beta at IP βx* 20 cm
βy* 3 mm
Bunch length (0A) z 3 mm
Crossing angle x 30→0 (crab crossing) mrad
Bean-beam x 0.272
y 0.295
Luminosity reduction
RL 0.86
Beam-beam Rx 0.98
reduction Ry 1.11
Luminosity L 5.5x1035 cm-2s-1
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sKEKB: Accelerator Luminosity is funding-limited
Assume a construction project starting in 2009 with luminosity in 2012 (i.e. a 3 year accelerator and detector construction shutdown.)
Slide from K. Oide
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Luminosity Gas mileage
Hybrid Plug-in Hybrid
EV
Girasole = Street2008
TOYOTA PriusMAZDA RX8
Hydrogen
Hydrogen
FIAT Panda