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Toru IijimaToru IijimaNagoya University

October 29, 2008ICFA seminar @ SLAC

Talk Outline

KEKB & BelleSuper KEKB & Belle– Physics target– KEKB upgrade – Belle upgrade

Plan / New CollaborationSummary

Special Thanks to;J.Flanagan, K. Oide, Y. Sakai, Y. Ushiroda, M. Yamauchi

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KEKB & Belle

e+ source

Ares RF cavity

Belle detectorSCC RF(HER)

ARES(LER)

Peak luminosity1.71 x 1034 cm-2s-1 !

e- (8.0GeV) × e+ (3.5GeV)

⇒Υ(4S) →BB

⇒Lorentz boost: βγ = 0.425

Finite crossing angle

- 11mrad ×2

Operation since 1999.

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4

KEKB PerformanceLuminosity Records;

L peak = 1.71x1034cm-2s-1 70% higher than the designL day = 1232pb-1/day double the designL int = 855 fb-1 as of Oct.28, 2008

The best day > 1.2 /fb1034

The power of Continuous Injection

KEKB/Belle:

709.9 fb-1

Υ(4S): 620.6 fb-

1 Υ(5S): 21.2 fb-1

Υ(3S): 2.9 fb-1

Off-peak: 58.9 fb-

1

Total:853 fb-1

Υ(4S): ~740 fb-1

Υ(5S): 23.6 fb-1

Υ(3S)/Υ(1S) 2.9 / 5.7fb-

Off-peak: ~85 fb-1

Lum / day

Achievement of the B Factories

Quantitative confirmation of the KM model

Af ~ 0Sf = 0.652±0.039±0.020

Violation of CP symmetry !

B0 J/ψKS

B0 J/ψKS

Belle, July 05

Belle, July 05

Discovery of CP violation in BB systemDiscovery of CP violation in BB system

Confirmation of Kobayashi-Maskawa modelConfirmation of Kobayashi-Maskawa model

WA, PDG08

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Achievement of the B Factories

Quantitative confirmation of the KM model

Af ~ 0Sf = 0.652±0.039±0.020

Violation of CP symmetry !

B0 J/ψKS

B0 J/ψKS

Belle, July 05

Belle, July 05

Discovery of CP violation in BB systemDiscovery of CP violation in BB system

Confirmation of Kobayashi-Maskawa modelConfirmation of Kobayashi-Maskawa model

WA, PDG08

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Press release from the Academy“As late as 2001, the two particle detectors BaBar at Stanford, USA and Belle at Tsukuba, Japan, both detected broken symmetries independently of each other. The results were exactly as Kobayashi and Maskawa had predicted almost three decades earlier. “

The next challenge is to find what KM cannot explain !

It requires >1010 B and τ pairs !

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Physics Reach at Super-KEKB/BelleBelle’06(~0.5ab-1)

5ab-1 50ab-1

ΔS(φK0) 0.22 0.073 0.029

ΔS(η’K0) 0.11 0.038 0.020

ΔS(KSKSKS) 0.33 0.105 0.037

ΔS(KSπ0γ) 0.32 0.10 0.03

Br(Xsγ) 13%

ACP(Xsγ) 0.058 0.01 0.005

C9 [AFB(K*ll)] --- 11% 4%

C10 [AFB(K*ll)] --- 13% 4%

Br(B+ → K+νν) <9Br(SM) 33ab-1 for 5σ discovery

Br(B+ →τν) 3.5σ 10% 3%

Br(B+ →μν) <2.4Br(SM) 4.3ab-1 for 5σ discovery

Br(B+ → Dτν) --- 7.9% 2.5%

Br(τ →μγ) <45 <30 <8

Br(τ →μη) <65 <20 <4

Br(τ → 3μ) <209 <10 <1

Δsin2φ1 0.026 0.016 0.012

ΔΦ2 (ρπ) 68°ー95° 3° 1°

ΔΦ3( Dalitz) 20° 7° 2.5°

ΔVub (incl.) 7.3% 6.6% 6.1%

0.01

0.1

0.3

0.03

Dev

iatio

n fro

m S

M

1 10 100Integ. luminosity (ab-1)

Presentexp. limits

5ab-1

50ab-1

CP asymmetry in B→KKK, φK and η’K

■ ● ★

(3σ discovery lim.)

Physics at Super B Factory (hep-ex/0406071) being updated.

X10-9

Search for H± in B→τν

50ab-1 assume5σ discovery

Integ. Lum.（ ab-1 ）Reach of B factories

Upgraded KEKB

Upper limits

CKM at 50ab-1

SuperSuper‐‐KEKB StrategyKEKB Strategy

L = γ±2ere

1+σ y*

σ x*

⎛

⎝ ⎜

⎞

⎠ ⎟ I±ξ± y

βy*RLRy

⎛

⎝ ⎜

⎞

⎠ ⎟

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 ratioGeometrical reduction factors due to crossing angle and hour-glass effect

Luminosity:0.17 ×1035 cm-2s-1 (KEKB)5×1035 cm-2s-1 (SuperKEKB)

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Three factors that determine luminosityThree factors that determine luminosity

Crab cavities installed and undergoing testing in beam

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 design.

The state-of-art ARES copper cavities will be upgraded with higher energy storage ratio to support higher current.

SuperKEKB

e- 4.1 A

e+ 9.4 A

will reach 8 × 1035 cm-2s-1

L = γ±2ere

1+σ y*

σ x*

⎛

⎝ ⎜

⎞

⎠ ⎟ I±ξ±y

βy*RLRy

⎛

⎝ ⎜

⎞

⎠ ⎟

Dampiing ring

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New IRβ*y = σz = 3 mm

Higher currentMore RFNew vacuum system

Crab crossing

+ Linac upgrade

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Item 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 current 179(incl. facilities)

x3

Crab Cavities Higher beam‐beam param. 15 x2 ‐ x4

Items are interrelated.Tunnel already exists.Most of the components (magnets, klystrons, etc.) 

will be re‐used.

High currents (9.4/4.1A)  & short bunch (σz=3mm) lead to;– Intense SR power

Max. power density of 28kW/m (40W/mm2) even at half aperture.– High Photon density

~1x1019 photons/m/s in average.– Intense HOM power

For a loss factor of 1V/pC, loss power is ~200kW.

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Copper beam duct w/ ante‐chamberTiN coating on inner surface 

• to decrease secondary electron yield (SEY); max.SEY~0.9

Clearing electrode• A possible measure even inside 

of magnets

BeamSR

Pump

φ 90 mm

Adopt the same RF frequency as KEKB and use the existing RF system as much as possible, with improvements as necessary to meet the requirements for SuperKEKB.

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Construction cost is greatly reduced.

Technical uncertainties are relatively small.

Normal-conducting ARES cavity: LER + HERPassive stabilization with huge stored energy.T. Kageyama et al.

Superconducting cavity: HERS. Mitsunobu et al.

ARES Normal conducting cavity Superconducting cavity

Normal Conducting cavities (ARES):– Upgrade of ARES with higher energy storage ratio. (left)– High power rf input couplers.– SiC dummy load with higher power capability (right).

Superconducting cavities:– The expected power load to the HOM absorber is 50 kW/cavity at 4.1 A,  (even) with a larger beam pipe of 220 mmφ.

– HOM damper upgrade may be needed.13

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SuperKEKB

KEKB

θ=17°θ=150°

EFC

QCSL QCSRESR-1ESR-2ESL-1 ESL-2

ESL ESRQCSL QCSR

Move final focus quad. closer to IP for lower beta functions at IP.Preserve current machine‐detector boundary.Rotate LER 8 mrad.Crossing angle: 22‐> 30 mrad

QCS and solenoid compensation magnets overlap in SuperKEKB.

Achieved KEKB design SuperKEKB unit

Beta (hor.) at IP βx* ~60 33 20 mm

Beta (ver.) at IP βy* ~6.5 10 3 mm

Bunch length σz ~7 5 3 mm

Crossing angle θx* ±11 ±11 ±15 mrad

Issues CausesPhysical aperture around IP Lower β at IPDynamic aperture Lower β at IPDetector background Higher beam currentHeating of IP components Higher beam current & shorter bunch length

Damping Ring

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Pulse beam kicker for quick beam switching (50 Hz).

Start testing this Fall

Intensity Upgradese+: stronger focusing field in capture section after target.e-: increase bunch current from pre-injector

Energy Upgrade (Positrons)Replace S-band (2856 MHz) withC-band (5712 MHz) RF system to double field gradient in downstream section of linac.C-band linac:

completed a single section in the linac with 4 structures

Performance was satisfactory with beam.

Damping RingDamping RingPositron emittance needs to be damped, to pass reduced aperture of C‐Band section and to meet IR dynamic aperture restrictions.

– Electron DR may also be considered later to reduce injection backgrounds in physics detector, but for now only positron DR considered.

Damping ring located downstream of positron target, before C‐Band accelerating section.

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e+ Damping Ring

e+ productionJ-ARC

BTe- gun

Crab Crossing at KEKB Crab Crossing at KEKB Crab Crossing can boost the beam‐beam parameter > 0.15 .

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Crossing angle 22 mrad

Head-on (crab)

(Simulation：K. Ohmi)

22 mrad.22 mrad.crossingcrossing

crab crossingcrab crossing

Crab Cavity & Coaxial Crab Cavity & Coaxial Coupler in CryomoduleCoupler in CryomoduleK. Hosoyama et al.K. Hosoyama et al.

The squashed cell shape cavity studied by K. Akai in 1991 and 1992 under KEK-Cornell collaboration.

Test of Crab CrossingTest of Crab CrossingTwo crab cavities were installed in KEKB in January 2007.

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Beams have been indeed tilted !

one for each ringHER(8GeV e-) LER(3.5GeV e+)

LER HER

long

itudi

nal

horizontal

inside of the rings

outside of the rings

Observation with streak cameras (H. Ikeda et al, PAC07 FRPMN035)

Specific Luminosity With Crab CrossingSpecific Luminosity With Crab Crossing

A number of measurements indicate effective head-on collision.The vertical tune shift went from 0.055 to 0.088.The specific luminosity/bunch improved by more than just the geometrical gain, by about 15%.Need more time to achieve the goal (X2 specific luminosity).

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22 mrad crossing

3.06 bucket spacing

before crab, tune shift was 0.055

Simulation22 mrad

Simulationhead-on

Crab Crossing•49 sp. βx*=80, 84cm

the highest vertical beam-beam tune shift was about 0.088.

10 cm

BELLE

Super-Belle Strategy

10 cm

BELLE

- low p μ identification sμμ recon. eff.- hermeticity ν “reconstruction”

- radiation damage and occupancy- fake hits and pile-up noise in the EM

- higher rate trigger, DAQ and computing

IssuesHigher background ( ×20)

Higher event rate ( ×10)

Require special features

Possible solution:Replace inner layers of the vertex detectorwith a silicon striplet/pixel detector.Replace inner part of the central trackerwith a silicon strip detector.Better particle identification deviceReplace endcap calorimeter by pure CsI.Faster readout electronics and computingsystem.

Possible solution:Replace inner layers of the vertex detectorwith a silicon striplet/pixel detector.Replace inner part of the central trackerwith a silicon strip detector.Better particle identification deviceReplace endcap calorimeter by pure CsI.Faster readout electronics and computingsystem.

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Super-Belle (Baseline)

New Dead time free readout and high speed

computing systems

ECLWave sampling + pure

CsI crystal(endcap) PIDThreshold Aerogel + TOF→ TOP + Aerogel-RICH

SVD4-lyr DSSD → 6lyr DSSD(option: striplet / pixel )

CDCSuper small cellLonger lever arm

KL/μ detectionRPC → Scintillator

+SiPM(endcap)

Background EffectsEffective background with new hardwares

How Reduction factor Effective bkgSVD Shorter tp 50/800=1/16≈1/12.5 0 ~ 1CDC Smaller cell <2/3 4 ~ 13 (*)PID Brand new device Good enough 0 ~ 1B-ECL Waveform fitting 1/7 1 ~ 2E-ECL Pure CsI (shorter t) 1/200 0 ~ 1KLM Faster detector, finer segment Under control 0 ~ 1

(*) Software efforts needed for CDCBackground effects on trackingGain in reconstruction efficiency of B D*D*(D*→Dπs, D→K3π)

We know how to handle the background.

“sBelle Detector Study Report”posted as arXiv: 0810.4084

New

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KEK RoadmapKEK RoadmapKEK’s 5‐year roadmap.3‐year shutdown for KEKB upgrade

– 0.5‐1 year delay, KEKB will run in FY2009KEK management in close contact with MEXT.

– “Investigation money” requested in FY2008.

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HopePositive effects from  the Nobel Prize …

Luminosity ProspectLuminosity Prospect

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3year shutdown for upgrade

10ab-1

(10x present)

Results from LHC(b)Situation of LC…

L~8x1035 cm-2s-1

50ab-1 by ~2020X50 present

New collaborationSuper-Belle will be a new international collab.– Two proto-collaboration meetings in Mar&Jul, 2008

• Participation of new people from Germany, India, U.S., Japan,… .– Kick-off of the new collaboration: Dec.10-12, 2008.

• Still many sessions will be open.

Near-term plan (preliminary)– Detector study report has been completed.– Detector proposals (by summer 2009).– The final detector design by Dec. 2009.

Detector proposals Internal review

TDR

Actions to invite new collaborators

Kick-off meeting(Dec 08)

20094 71 2 103 5 8 9 11 126

200810 11 12

20101 2 3

KEKB operation

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Super-Belle webpagehttp://superb.kek.jp/ML subscription is available.

SummarySummaryKEKB/Belle has been running successfully, and brought important scientific and technical achievements, together with PEP II/BaBar.Next generation e+e− B factory with L~1036 will be very useful to study the new sources of flavor mixing and CP violation.Super‐KEKB: the target luminosity is 8 x 1035cm‐2s‐1, based on existing or tested technologies (mostly), which enables us to accumulate 10ab‐1 by 2016, and 50ab‐1 by 2020. Super‐Belle: detector upgrade studies are in progress, and will be finalized in 2009. New proposals are still welcomed. New collaboration is being formed; the kick‐off meeting on Dec.10‐12 at KEK (many sessions will be open).  

26We are trying to get ready soon. We are trying to get ready soon.  Stay Tuned !Stay Tuned !

Backup

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Belle Detector

4 lyr DSSD

Belle CollaborationBelle CollaborationBINPChennaiChiba U.Hanyang U.U. of CincinnatiFu-Jen U.Giessen U.Gyeongsang Nat’l U.U. of HawaiiHiroshima Tech.HEPHY, ViennaIHEP, ProtvinoIHEP, BeijingINFN, TorinoITEPKanagawa U.KarlsruheKEKKorea U.

Krakow Inst. of Nucl. Phys.Kyoto U.Kyungpook National U.U. of LausanneJozef Stefan Inst.MPI, MunichU. of MelbourneNagoya U.Nara Women’s U.National Central U.National United U.National Taiwan U.Nihon Dental CollegeNiigata U.Nova Gorica U.Osaka U.Osaka City U.Panjab U.Peking U.Princeton U.

Illinois U. - RikenSaga U.USTCSeoul National U.Shinshu U.Sungkyunkwan U.U. of SydneyTata InstituteToho U.Tohoku U.Tohuku Gakuin U.U. of TokyoTokyo Inst. of Tech.Tokyo Metropolitan U.Tokyo U. of A and T.Toyama Nat’l CollegeU. of TsukubaVPIYonsei U.

About 360 collaborators from 59inst./Univ.from 14 regions.

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Other Highlights

SMBelle, 2005

D0-D0 mixing

AFB in B K*l+l−

X(3872)

Many new resonances

b dγ transition

and more…

0

50

100

150

200

250

300

350

400

0 0.25 0.5 0.75 1EECL (GeV)

Eve

nts

/ 0.0

5 G

eV

0

20

40

60

80

100

120

140

160

0

Eve

nts

/ 0.0

5 G

eV

0

20

40

60

80

100

120

140

160

0 0.25 0.5 0.75 1EECL (GeV)

Eve

nts

/ 0.0

5 G

eV

0

10

20

30

40

50

60

70

0

Eve

nts

/ 0.0

5 G

eV

Evidence for B τν

Z(4430)Signal

B D*τν

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What is next with flavour physics?

LHC will start soon to explore the TeV region, which is the scale of the electroweak symmetry breaking, and most probably related to the “New Physics” scale.– It is natural to assume that the NP

effects are seen in B/D/τ decays.– Flavour structure of new physics?– CP violation in new physics?– These studies will be useful to

identify mechanism of SUSY breaking, if NP=SUSY.

Otherwise…– Search for deviations from SM in

flavor physics will be one of the best ways to find new physics. Search for New Physics in precision meas.

In order for the flavor physics to be useful in the coming LHC era, the precision of variousflavor measurements must be significantly improved, both in terms of experimental reachand understanding of theoretical uncertainty.

In order for the flavor physics to be useful in the coming LHC era, the precision of variousflavor measurements must be significantly improved, both in terms of experimental reachand understanding of theoretical uncertainty.

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Present upperlimits

Measurementsat upgraded KEKB

（ ab-1 ）

Reach of presentB factories

Reach of upgradedKEKB

Dev

iatio

n fro

m S

M

Deviation from SMDeviation from SM

Relevant to baryogenesis?

Relevant to baryogenesis?

New source of CP violation

New source of CP violation

CP asymmetries of penguin dominated B decays

Searches for new sources of quark mixing and CP violation

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Precise measurements of τ decays

LF violating τ decay?

Integ. Lum.（ ab-1 ）Reach of B factories

Upgraded KEKB

Upper limits

τ−>μγ

μ->eγ

τ−>eγ

T.Goto et al., 200733

Comparison with LHCb

e+e− is advantageous in… LHCb is advantageous in…

CPV in B→φKS, η’KS,…

CPV in B→KSπ0γ

B→Kνν, τν, D(*)τν

Inclusive b→sμμ, see

τ→μγ and other LFV

D0D0 mixing

CPV in B→J/ψKS

Time dependent measurements of BS

Bc and bottomed baryons

Most of B decays not including ν or γ

B(s,d)→μμ

These are complementary to each other !!

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Lattice DesignNew IR(design,magnets,vacuum pipes…)Components for higher currents

– Vacuum components (pipes/bellows…)– Modification of the monitors (BPMs,SRMs…)– Longitudinal bunch‐by‐bunch FB system– More RF cavities and klystrons– Modifications of the RF systems for higher currents– Crab cavities for SuperKEKB

Some magnets/power supplies need to be newly fabricated.Damping ringLinac upgradeFacilities upgrade

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R&D’s for all components in progress.Crab cavities are tested in beam.

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symbol LER HER unit

Beam Energy E 3.5 8.0 GeV

Beam current I 9.4 4.1 A

Circumference C 3016 m

Number of bunches nb 5018

Number of particles N/bunch 11.8 5.1 x1010

Emittance εx 9 nm

Emittance ratio εy/εx 0.5 %

Beta (hor.) at IP βx* 200 mm

Beta (ver.) at IP βy* 3 mm

Bunch length σz 3 mm

Crossing angle θx* 30 to 0 mrad

Beam‐Beam (hor.) ξx 0.36

Beam‐Beam (ver.) ξy 0.43

RF AC plug power PAC 73 MW

Luminosity L 8.0 x1035 cm‐2s‐1

Why the specific luminosity drops faster than Why the specific luminosity drops faster than expected ?expected ?

SpeculationsLifetime may be limited by the dynamic‐β and dynamic emittance caused by beam‐beam.To save the lifetime, two beams have been collided with horizontal offset by about 50 μm, which violates the perfect horizontal symmetric collision.The single beam vertical emittance may not be sufficiently smallElectron Cloud in the LER: Luminosity becomes better for longer bunch spacing.The SPOOABS nature in the optimum condition of the collision: Too many parameters.Synchrotron‐betatron resonance near the 1/2 integer tune... and more ..

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Lattice Design: the arc sectionLattice Design: the arc section

The beam-opticalparameters can be adjustedto SuperKEKB withoutchanging the latticein the arc section.

KEKB lattice:2.5π cell and non-interleaved chromaticity correction scheme.

→Wide tunability of horizontal emittance, momentum compactionfactor.

→Principle nonlinearities in sextupole pairs cancelled out to give large dynamic aperture

38

Comb-type RF shield

Features (compared to finger type):

Low beam impedanceHigh thermal strengthApplicable to complex apertureLittle flexibility (offset)

Effect of RF shielding wasdemonstrated in KEKB.Finger-type as an option

If more flexibility is required.39

Without cooling fan

Comb-type RF-shield

Temperature of bellows

Big impedance sources in the ringPlanning to use “stealth” type (Ver.6)

Low beam impedancePresent Ver.4 ~ 1V/pC (φ 90 mm) 200 kW power loss

Loss factor decreases to ~1/10 (φ 90 mm).Manageable by conventional HOM absorber

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Loss factor

Bunch length [mm]

Loss

fact

or [V

/pC

] Ver.4

Ver.6

Ver.4

Ver.6

(1) 12 cured double pan-cake coils.(2) Curing process of 6 layer coils. This process is

necessary for improving the field quality in the magnet straight section (magnet body).

(1)

(2)

N. Ohuchi

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Beam Background

1st layer

Rad-Bhabha mask around QCS magnetand IR chamber being designed

Results based on GEANT sims validated by Belle/KEKB experience.

Conservative & robust detector should handle up to 20 x more background 42

(GeV)LERE3 3.2 3.4 3.6 3.8 4

Ld

t∫

Rat

io o

f

0.8

0.9

1

1.1

1.2

1.3

January 25, 2008 BNM2008@Atami 43

sKEKB: Beam Energy Asymmetry

− J/ψK0 tCPV− φK0 tCPV− B τν BF

better

worse

• Toy MC results considering Δt resolution and geometrical acceptance.

• Geometrical acceptance is assumed to be same as the current Belle detector.

KEKB

ELER = 3.5 GeV looks good

43

Very Forward Detector

44

Challenges:Very high backgroundMagnetic field

F-CAL for ILC?

44