Prospects of Super KEKB and Belle II Experiment
Transcript of Prospects of Super KEKB and Belle II Experiment
Gagan Mohanty
Prospects of Super KEKB andBelle II Experiment
Tata Institute (TIFR), India
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Talk outline
28-09-2009
• Physics case
• Accelerator Super KEKB in Japan
• Detector upgrade Belle → Belle II
• Current status of the project Timeline, collaboration, funding
• Closing remarks
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Threefold Way
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Energy (Tevatron, LHC)
Today, breakthroughs in elementary particle physics are made possiblethrough the advances in three complementary directions
I shall concentrate on the right-most corner, i.e., luminosity frontier
Now: 10 years after the B factories
Discovery of CPV in B decaysDiscovery of CPV in B decays
Precision test of KM paradigmPrecision test of KM paradigm
Look for new physics (NP) signatureLook for new physics (NP) signature
Step1
Step2
Step3
2001 summer !
2008
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Kobayashi, Maskawa, PTP 49 (1973) 2
Need more than 50 times the data (50 ab−1) we have at present to decipherNP effects
What is so special about 50?
50 ab−1
Lu~
CKM UT triangleNow
New CP phaseNP effect
B K(*)l+l-: AFB
Theory error50 ab−1
50 ab−1
Flipped C7
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Xu et al., PRD 74 (2006) 114019
Is that all?
1, 2, 3s @ 50 ab−1
D0D0 mixingτ LFV decays X(3872)
Z+(4430)
Super B factories are really super flavor factories
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LFV in tau decays, CPV in D-mixing would be unambiguous signatures ofNP – beam polarization, operating @ threshold further benefit the cause
Good detector, huge data in a clean environment Rest assured
In fact a “treasure chest”
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Would be possible with a good amount data taken at ϒ(5S)
Complementary with the LHC
S.Stone
Bs
Com
mon
No IPg,n
50ab−1
NP flavor couplings
Diagonal: Energy frontier(LHC – ATLAS, CMS)
Off-diagonal: Lumi frontier(super flavor factory, LHCb)
• Settle NP models• Look for higher scale NP
Super flavor factory vs LHCb
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What about worst-case scenario?
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• Imagine the possibility, where NP follows the SM patternof flavor and CP violation (minimal flavor violation)
• Even in this most unfavorable scenario, super flavor factoriesare still sensitive up to NP mass range of 600-1000 GeV
D’Ambrosio et al., NPB 645 (2002) 155
• The model predicts all NP flavor couplings are zero – naturemay not be so much unkind to us!
• Going little up, in the next-to-minimal flavor violation, the to-beexploratory scale goes beyond 10 TeV LHC domain
• For generic flavor violation scenario, super flavor factoriesare sensitive up to ~1000 TeV
Explore luminosity frontier
2.1×1034
1.2×1034
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KEKB/Belle (Japan)
Super KEKB (Japan)
PEP II/BaBar (US)
SuperB (Italy)Peak luminosity ~1036 cm−2s−1
One eqn. – many ways to play around
L
2ere1
y*
x*
Iy
y*
RL
Ry
• Raise the beam current, I• Larger beam-beam par, xy
• Smaller b*y
× ~5~5
~1/2
~50
High current approach
< 1/20+ low emittance
Nano-beam approach
Brute forceRealizable
New schemeRisk?
Baseline:
(short bunch) (long bunch)
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Super KEKB (Japan) SuperB (Italy)
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Crab cavities installed andundergoing testing in beam
Superconducting cavities willbe upgraded to absorb morehigher-order mode power upto 50 kW
The beam pipes and allvacuum components willbe replaced with higher-current design
Super KEKB
e− 4.1 A
e+ 9.4 A
High-current option (baseline)
L
2ere1
y*
x*
Iy
y*
RL
Ry
Damping ring
New IR: Belle II
Crab crossing
+ Linac upgrade
8 GeV
3.5 GeV
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Higher currentMore RFNew vacuum system
The state-of-art ARES coppercavities will be upgraded withhigher energy storage ratio tosupport higher current
Crab crossing and its impact
Crossing angle 22 mrad
Head-on (crab)
(Simulation: K. Ohmi)
2222 mradmradcrossingcrossing
crab crossingcrab crossing
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2007
2009Crab ON
2008
Crab OFF
Crabbing: successful!
L = 2.11×1034 (17 July)higher than without crab(new skew sextupoles)
Specific luminosityhas increased ~30%
Nano-beam scheme
Present KEKB
SuperB
L NN f
4 x* y
*RL
L
2ere
1 y
*
x*
I y
y*
R L
R y
5mm
1mm
100mm
(w/o crab)L
Hourglass condition:β*
y >~ L=sx/f
Half crossingangle: f
1mm
5mm100mm
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Replace long TRISTANdipoles with shorter ones
Tin coated beam pipeswith antechambers Nano-beam option
e− 2.1 A
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Low emittanceelectrons to inject
Low emittancepositrons to inject
New positron targetand capture section
Add/modify RF systems
New superconducting /permanent final focussing quads
New IR: Belle II
e+ 3.7 A
Super KEKB
Comparison of parameters
High-current option includes crab crossing and travelling focusNano-beam option does not include crab waist
KEKBdesign
KEKB achieved(with crab)
Super KEKBhigh-current
option
Super KEKBnano-beam
option
by* (mm)(LER/HER) 10/10
6.5/5.9(5.9/5.9)
3/6 0.24/0.37
ex (nm) 18/18 18(15)/24 24/18 2.8/2.0
sy (mm) 1.9 1.1 (0.84) 0.85/0.73 0.084/0.072
xy 0.0520.108/0.056
(0.101/0.096)0.30/0.51 0.09/0.09
sz (mm) 4 ~ 7 5(LER)/3(HER) 5
Ibeam (A) 2.6/1.11.80/1.45
(1.62/1.15)9.4/4.1 3.6/2.1
Nbunches 5000 1387 (1585) 5000 2119
Luminosity(1034 cm−2 s−1)
1 1.76 (2.11) 53 80
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Luminosity projection
3-year shutdownfor the upgrade
L~2×1035
L~8×1035
50ab−1 by ~2020
~10ab−1 by 2016
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Requirements for the detector
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• Will be built by upgrading the current Belle spectrometertaking the following points into account
1) Higher background
2) Higher event rates
3) New requirements
− Radiation damage, higher occupancy
− Higher DAQ rate
− Improved hermiticity for LFV searches and study of final states involving neutrinos
Super KEKB baseline detector
Belle
Belle II
SVD: 4 layers g 2 DEPFET + 4 DSSD layersCDC: small cell and long lever armPID: ACC+TOF g TOP+A-RICHECL: waveform sampling, pure CsI for endcapKLM: RPC g Scintillator+SiPM (endcap)
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Progress and planJun 2004: LoI for Super KEKBJan 2008: KEK Roadmap
Super KEKB is identified as high priorityDec 2008: New collaboration (Belle II) officially formed
13 countries, 43 institutesElection of the spokesperson
Mar 2009: BPAC (Chair: T.Nakada) endorsement
Mar 2009: FY2008/9 supplemental budget:~5M$ for the Belle upgrade
May 2009:~27M$ for KEKB upgrade R&DJuly 2009: 3rd Open Belle II collaboration meeting
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Current organizational setup
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Closing Remarks
• Super KEKB in Japan is one of the candidates Baseline design (high-current option) is finalized, work
in progress for the nano-beam option Belle II collaboration is formed Partial funding is already secured
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• Both the B factories – Belle and BaBar – have performedexceptionally well, beyond their original design
• CKM paradigm has been established as the only source ofCP violation in the SM
• Proposal for two super flavor factories with raison d’être toprobe NP effects (complementary to LHC)
Your active support and participation are most welcome