Prospects and Status of Belle II Prospects and Status of Belle II experimentexperiment

Yoshiyuki Yoshiyuki OnukiOnuki

High Energy Physics groupHigh Energy Physics group

1The 3rd Tohoku University GCOE

International Symposium

OutlineOutline

•• KEKB and Belle experimentKEKB and Belle experiment

•• Physics motivation for Belle2 experimentPhysics motivation for Belle2 experiment

•• SuperKEKBSuperKEKB accelerator accelerator

•• Belle2 detectorBelle2 detector

•• Contributions from Tohoku UniversityContributions from Tohoku University

•• Construction schedule Construction schedule

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Quark transition coupling constant in SM

VCKM: Cabibbo-Kobayashi-

Maskawa Matrix

VCKMVCKM† =1

f3

f2

f1(0,0)(1,0)

(r,h)

|VudVub*|

|VcdVcb*|

|VtdVtb*|

|VcdVcb*|

f3≡argVudVub

*

VcdVcb*

B-meson system is the best place to measure the matrix elements since the three sides of the bottom related triangle is same order of magnitude.3

u

d

c t

s b

~1 km in diameter

Mt. Tsukuba

KEKB

Belle

Lpeak = 2.1 x 1034 sec-1cm-2

KEKB e+e− collider and Belle detector

>Twice of the design Luminosity !

Producing enormous BB pairs copiously

→ called B-factory

Detecting the produced particles and

reconstruct the interaction by Belle

on resonance of Y(4S)~10.58GeV

8 GeV e- and 3.5 GeV e+ collided

Y(4S) consists of bounding stateof bottom and unti-bottom quarkand almost all Y(4S) decay into B-meson and anti B-meson pair.

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15countries,63 institutes,429people

First physics run on June 2, 1999Last physics run on June 30, 2010Lpeak = 2.1x1034/cm2/sL > 1ab-1

The last beam abort of KEKB on June 30, 2010

Corresponds to 1.1 Billion BB pairs! 5

Physics outputs from Belle •Established the mixing-induced time-dependent CP violation(TCPV)with B0→J/yKS and related decays in 2002. This provides sin2f1 .

•Measured TCPV of B0→fKS and related penguin-dominated decays

•Discovered a new resonance named X(3872) and exotic hadrons. The studies cotributes nuclear physics.

•Measured f3, an angle of CKM unitary triangle, with various methods

No.55 Yutaro Sato「Study of B-pi tagging method at the Y(5S) resonance for

the measurement of CP-violation parameter sin2f1 」

No.53 Yasuyuki Horii「First Evidence of the Suppressed B Meson Decay B- → DK-, D→K+p- 」No.5 Kennosuke Itagaki「Study of the B→D*pi decay for CP violation measurement」No.23 Zenmei Suzuki「Study of decay B->DK,D->KsKpi for the measurement of the CP-violating angle phi3 」

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Motivation for upgrade

To observe beyond the Standard Model phenomena,

New physics contribution via “Tunnel effect” using penguin-dominant decays

• b→sss transition

• b→sg,sll transition

• B→tn decay…

• At the same time, well constrained CKM unitary triangle works as the Standard Model “reference”

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b→sss transition

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SJ/yKs=sin2f1

DSfKs ≡SfKs-SJ/yKs

In SM,

DSfKs ~0DSfKs ≠0 indicates NP

Experimental determination of DSfKs can constraint

flavor violation in SUSY model under the some approximation.

b→sg&sll transition• Model independent new physics search

• Both mode can compare SM model prediction with experimental measurements.

For example: Forward backward asymmetry in B→K*l+l-

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arXiv:0810.0335 Belle collaboration I.Adachi et al. 657 million BB pairs

The solid (dashed) curve shows the SM (C7 = −CSM7 ) prediction.

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KEKB and Belle upgrade planKEKB and Belle upgrade plan

Next generation

B-factories

KEKB to SuperKEKB

40 times higher luminosity

E.Kikutani / M. Masuzawa

1036

KEKB

SuperKEKB

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(1) Smaller by*

(2) Increase beam currents

(3) Increase xy

Strategies for increasing Luminosity

Collision with very small spot-size beams

“Nano-Beam” scheme

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e- 7GeV 2.6 A

e+ 4GeV 3.6 A

Target: L = 8x1035/cm2/s

SuperKEKB

Colliding

bunches

Damping ring

Low emittance gun

Positron source

New beam pipe& bellows

Belle II

New IR

TiN-coated beam pipe with antechambers

Redesign the lattices of HER & LER to squeeze the emittance

Add / modify RF systems for higher beam current

New positron target / capture section

New superconducting /permanent final focusing quads near the IP

Low emittance electrons to inject

Low emittance positrons to inject

Replace short dipoles with longer ones (LER)

SuperKEKB collider

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Reconstruction of charged particleDetermination of the momentum

Extrapolate tracks from outer to inner detectorParticle identification、Energy measurement

Insert tracks to the SiliconVertex Detector

Determine energy and momentum and vertex in each particle

CDC

SVDKLMECL

PID

How to reconstruct B-meson：B0J/yKS

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Belle to Belle II upgrade

SVD: 4 DSSD lyrsg 2 DEPFET lyrs + 4 DSSD lyrsCDC: small cell, long lever armACC+TOF gTOP+A-RICHECL: waveform sampling (+pure CsI for end-caps)KLM: RPC g Scintillator +MPPC(end-caps) 15

DEPFET pixel detector(PXD)DEPFET pixel detector:Baseline for innermost pixel

Radiation length 0.16%/layer

Hit occupancy 1-2%(layer1)

>10MRadRadiation tolerance17°＜θ＜150°Acceptance

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DEPFET(DEPleted Field Effect Transistor)

Full depleted Bulk CMOS.Electron-hole pairs generated by charged Particle accumulates in the “Internal gate”.

Electric field generates between Gate−”Internal gate”→The situation is as same as applying Gate voltage in the MOSFET. Drain－Souce current Ids is flowing.

Instead of readout electron-hole pair, readout DIds of MOSFET

A full depleted MOSFET with Internal gateacts like a pixel detector(50mm×56mm×50mm)

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Silicon strip vertex detector(SVD)

17°＜θ＜150°30MRad

Acceptance

Radiation tolerance

6”DSSD 187 DSSDs

Radiation length ~0.58%/layer

Hit occupancy 6.7%(layer3)

Double SidedStrip Detector(DSSD) 1D+1D strip sensor acts as 2D detector

e

h

e

h

rf- strips

z- strips

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Origami module

DSSD

Rohacell

Bonding wire

APV25

Flexible print circuit board

Flexible print circuit board

Bonding wires

rf- strip

z- strip

R/O chipsin both side

•Conventional readout scheme(Belle)

•Origami readout scheme(Belle2)

Doesn’t work in Belle2@40 times Lum. of Belle

- Replacing fast R/O chip: VA1TA→APV25- Adapting “chip on sensor method” for S/N- Realizing one side readout to extract the other side readout wrapping DSSD with Flex PCB.

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longer lever arm

improve resolution of momentum and dE/dx

Belle Belle II

inner most sense wire r=88mm r=168mm

outer most sense wire r=863mm r=1111.4mm

Number of layers 50 56

Total sense wires 8400 14336

Gas He:C2H6 He:C2H6

sense wire W(Φ30μm) W(Φ30μm)

field wire Al(Φ120μm) Al(Φ120μm)

Central Drift Chamber

normal cell

10~20 mm

18 mm10 mm

6~8 mm

small cell

Belle

Belle II

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Aerogel radiator

Hamamatsu HAPD

+ new ASIC

200mm

n~1.05

200mm

Particle Identification(PID) DetectorThreshold type Cherenkov PID(Belle)

Aerogel Ring image Cherenkov(ARICH)

Quartz RICH PID for barrel Aerogel RICH type PID for endcap

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RICH with Time measurementTTS~40ps

Time of Projection chamber(TOP)

Contributions from Tohoku University group

• Beam BG study in beam interaction region• SVD vertex detector construction• SOI(Silicon On Insulator) pixel detector for future

PXD option

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Beam BG study by K.Nakano&H.Yamamoto

SOI radiation tolerance study by Y.OnoSVD development by me & Y.Himori

SOI beam test study by H.Katsurayama

InstallationInstallation

FY2009 FY2010 FY2011 FY2012 FY2013 FY2014

Tunnel construction Tunnel construction

Building construction Building construction

RF-gun & laser system

e+ new matching & L-band acc.

R&D R&D Construction Construction

Design studyDesign studyCommissioning at test standCommissioning at test stand

Damping Ring

Linac

Main Ring

Belle II Detector

InstallationInstallation

Cosmic Ray Test

R&D Mass ProductionMass Production

Construction

Mass FabricationMass FabricationInstallationInstallation

Building construction Building construction

Mass FabricationMass Fabrication

R&D, DesignR&D, Design

R&D, DesignR&D, Design

Construction Schedule of SuperKEKB/Belle II

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Luminosity upgrade projection

Shutdown

for upgrade

Inte

gra

ted L

um

inosity

(ab

-1)

Peak L

um

inosity

(cm

-2s

-1)

Milestone of SuperKEKB

FY

9 month/year

20 days/month

Commissioning starts

mid of 2014

We will reach 50 ab-1

in 2020~2021.

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Summary

• KEKB&Belle upgrade project was approved

• The target is 40 times luminosity of KEKB and 50 times data of Belle.

• The motivation is to observe beyond standard model in particle physics.

• Tohoku group contributes beam BG study in IR, SVD and SOI pixel detector for future upgrade option.

• The experiment will start in 2014

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• 10 billion yen funded by Very Advanced Research Support Program of MEXT(Ministry of Education, Culture, Sports, Science and Technology) in FY2010-2012

Funding Status

KEKB upgrade has been approved.Construction had started. 26

SOI pixel detector for PXD option

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Silicon On Insulator(SOI) pixel detector- Next generation pixel detectorR/O electronics and sensor in single wafer=>Monolithic detector.-Able to implement sophisticated functions in Front End Electronics. e.g. counter, memory-Developed by KEK and Tohoku Univ etc.-Manufacturer is OKI-Semiconductor Miyagi

e+ beam test@Tohoku LNS

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