super kekb project

Super KEKB project

WIN03Oct 9th, 2003

Nobu KatayamaKEK

Octl 9th, 2003Octl 9th, 2003 Nobu KatayamaNobu Katayama 22

Outline

§ Belle/KEKB status§ Super KEKB plan

– Physics– Detector study– Accelerator study


KEKB status1999/102003/7/1

> 50 fb1 in years 2002, 2003

LER~1.55AHER~1.1AWith SRF

1.0571034

cm-2s-1

158.7fb-1


Best day (May 12th, 2003) 579.1 pb-1/day recorded


SVD 1 SVD 2

6+12+18+18=54 ladders

8+10+14=32 ladders

SVD1 SVD2

RBP 1.5 cmRBP

2.0cm

RL1

3.0cm

RL1

2.0cm

Rout

6.0cm

Rout

8.8cm


SVD 1.6 SVD2.0RBP / RL1 / Rout 20/30/60 mm 15/20/90 mm

Acceptance 23º<<139º 17º<<150º

# of layer/# of ladders

3 / 32 4 / 54

Max. length (mm) 220 460

Orthogonal readout Built in double metal layer

Flexible printed circuit

Isolation of detector bias

Integrated capacitor on DSSD

Optical isolator in a buffer circuit

Fast trigger No Yes

Shaping time ~1s ~0.5s

z (90deg.,p=2GeV/c) ~35m ~25m

Measured Signal to Noise ratio

~20 25(lyr4)~36(lyr1)

Radiation tolerance ~2Mrad ~20Mrad

How much improved?

We have just started!

More and more Bs

Super KEKB


Mission 1: 300 fb1

Precision test of KM unitarity

Search for new physics in B and decays

Identify SUSY breaking mechanism

Bread’nd butterfor B factories

See quantum effect in penguin and box

loop

Very important if New physics =

SUSY

Mission 2: 3,000 fb1

Mission 3: 30,000 fb1

Mission of Super B Factory(ies)


In which processes can we find New Physics?

§ Rare decays– B Xs,– B K*

§ CP violations– B KS and ’KS

– B Xs,§ b c emitting charged Higgs§ Forbidden decays by SM§ Forbidden/rare decays of


CPV in penguin decays

Belle (August 2003)ACP(KS)=0.96±0.50

ACP(’KS)=0.43±0.27

ACP(J/KS)=0.731±0.057

Prove ACP(KS, ’KS)≠ACP(J/KS)In SM,

New phase in penguin loop may change this relation

KEKBPEP-II

Next B factory

5 discoveryKS

K+K-KS

’KS

ACP


Atmospheric Neutrinos Can Make Beauty Strange?

§ Leptogenesis models inspired by the naïve SO(10) unification exist where the near-maximal mixture of and results in large mixing of RH super-b and super-s, giving O(1) effects on bs transitions such as– Asymmetry in B Ks (effect is in first order)– Bs mixing– b s(effect is of the order of |Cg(NP)|2)

§ Ref. R. Harnik, D. Larson, H. Murayama and A. Pierce (hep-ph/0212180), D. Chang, A. Masiero and H. Murayama (hep-ph/0205111)

§ Many other GUT inspired models are coming up!


Dominant Right-Right Mixing case


SUSY effect in B K*

§ These measurements are excellent probe to search for SUSY§ Inclusive decay, bsll, is much less model dependent. An e+e B fact

ory provides a unique opportunity to measure this by pseudo reconstruction technique

A.Ali

m()2 distribution

F/B asymmetry

SM

SUSY models with various parameters set


Rare decays of


Charged Higgs in tree decay

BD(*)vsD

- Large branching fraction: ~1%- Uncertainty in form factor cancels in the ratio (BgD)/(BgD).- polarization is more sensitive to H±.

M.Tanaka


Comparison with an LHC experiment

(BD)/(BD)at B factory with5,000 fb-1

B factories don’t really do tree diagrams of new particles with the exception of charged Higgs…But together with LHC measurements, we can determine tan!


What can we do?

Compilation at the 5th High Luminosity WS


KEKB upgrade strategy

Present KEKB L=1034

2002

03 04 05 080706 09 10 11

L=103

5

L~1036

dt =500fb1

One year shutdown to: replace vacuum chambers double RF power upgrade inj. linac g C-band

larger beam currentsmaller y*long bunch optioncrab crossing

ILER=1.5A2.6A

ILER=9.4A

ILER=20A

Constraint:8GeV x 3.5GeVwall plug pwr.<100MWcrossing angle<30mrad

dt =3000fb1

beforeLHC!!


Detector upgrade

§ Higher luminosity collider will lead to:– Higher background

§ radiation damage and occupancy in the vtx. detector§ fake hits in the EM calorimeter§ radiation problem in the tracker and KL detector

– Higher event rate§ higher rate trigger, DAQ and computing

§ Require special features to the detector– low p identification for s reconstruction eff.– hermeticity for “reconstruction”


/ KL detection 14/15 lyr. RPC+Fe

Tracking + dE/dx small cell + He/C2H5

CsI(Tl) 16X0

Aerogel Cherenkov counter + TOF counter

Si vtx. det. 3 lyr. DSSD

SC solenoid1.5T

8GeV e

3.5GeV e

Detector upgrade: an example

2 pixel lyrs. + 3 lyr. DSSD tile scintillator

pure CsI (endcap)

remove inner lyrs.

“TOP” + RICH

New readout and computing systems


SVD occupancy and CDC hit rate

§ Current most inner layer of SVD’s occupancy is 3~5%

§ Current most inner layer of CDC’s occupancy is 2~3%

§ With 1035 luminosity, two layers of pixel + silicon (~15cm R) + CDC survives

§ With 1036 luminosity, Pixel + Silicon a la super BaBar design?

Radius = 15cm

Cathode

Inner

Main


Does CDC work with L>1035 ?

§ Smaller cell§ Faster gas§ Larger starting

diameter

Yes !!


Small Cell Chamber (with SVD2)

~20cm


XT curve for small cell measured

Small cellNormal cell


New PID detector

Present Belle: Aerogel Cherenkov counter both for barrel and endcap.

TOP counter for barrel &Aerogel RICH for endcap

Requirements: - Thin detector with high rate immunity - >3/K separation up to 4GeV/c - low p / separation


Time of propagation (TOP) counter

20mm

time & X sensitive PMTs Fused silica(n=1.47)

Reflection mirror 200mm

A few meters

photon hits


Aerogel RICH for endcap

§ Single event display§ Hit distribution

Super KEKBAccelerator upgrades


What’s impressive about KEKB

§ KEKB and PEP-II have achieved the highest luminosities in history of particle accelerator/collider

§ KEK and PEP-II have recorded more than 140 fb1 of data and continue to accumulate Thanks to tremendous efforts by and ingenuity of the commissioning and operation groups


Features of KEKB

§ Super conducting RF cavities and ARES cavities– Holds more than 1A of beam current with

SRF

§ IR region– 3m100m: the smallest beam size

among the storage rings– Finite crossing angle

§ Solenoids for positron ring– Suppress photo-electron clouds

§ Flexible Optics– Real time monitor and correction system


Challenges with Super KEKB

§ High beam currents (LER 9.4A+HER4.1A)– Heating, breakdown will occur– Ultra high vacuum, beam lifetimes– Power consumption (80~100MW)– Stability of the beam/photo electron clouds– Injection– Noise/Background to detector

§ Beam-beam effect (tune shift of 0.05 assumed for 1035)– Beam-beam tune shift; unknown– For a double ring machine, more than 50 parameters must

be optimized simultaneously– Hard to maintain the optimum beam conditions due to

disturbances§ Optics with very small focusing depth (3mm)

– KEKB vertical beta is <6mm (world record)– Shorter bunch length:=more peak current gives more

power dissipation, shorter lifetime


Towards Super KEKB

§ LER 9.4A + HER 4.1A (4~6 times as now)– Rewind solenoids– Double RF systems– Replace vacuum chambers of the both rungs– Cooling system

§ More focusing and shorter bunch (half as now)– New IR

§ Charge switch and better/faster injection– 8GeV positron injection with a C-band linac– Damping ring– New positron production target

§ Crab crossing


Accelerator Upgrades for Super KEKB

K. Oide @ Izu 2003

§Crab cavities

§More RF sources

§More cavities

§Super Belle§New IR§New beam pipe

& bellows

§Damping ring

§Positron source

§Charge switch by C-band


Machine parameters

x = 20 cm x = 15 cm

L 2ere

Iyy*


Crab cavity developments

crossing angle 22 mrad

Head-on(crab)

◊

◊◊

◊◊

y

(Strong-weak simulation)

(Strong-strong simulation)

lCrab crossing may boost the beam-beam parameter up to 0.2!

lSuperconducting crab cavities are under development, will be installed in KEKB in 2005.

I.R. 20

I.R. 90

I.D. 188

I.D. 120

I.D. 30

I.D. 240

Input Coupler

Monitor Port

I.R.241.5

483

866Coaxial Coupler

scale (cm)

0 50 100 150

K. Ohmi

K. Hosoyama, et al


(Each building for 4〜 6 RF units.)

D8 D7

D4

D1

0D

11

new newn

ew

new

new

D1 D2D

5LER-RF(ARES)

HER-RF(ARES)HER-RF

(SCC)

5 buildings should be added.

50% more RF cavitiesDouble # of Klystrons

#RF/#SRF30/8

44/12

#Kly/ACPW(MW)23/45

56/73


Energy exchange(HER : e+/LER : e)

§ Advantages :– Effect of photoelectron cloud can be reduced.

■ Positron energy increases.– Injection time can be reduced.

■ Intensity of injector : e- > e+

■ Beam current : e- > e+ § Unknowns :

– Multipactering occurs in e+ at HER or not ?■ Height of vacuum chamber is smaller than LER.

– Is fast ion instability safe for e- in LER ?■ Electron energy decreases.

§ Major upgrade of injector linac is needed.– Energy upgrade : C-band scheme


Linac upgrades for 8 GeV e+

AB

HER1 2 3 4 5C

e- Gun

DampingRing1.7-GeV

J-arc for e–

LER

e+ target

E(e–)=3.5 GeV, Q(e–)=10 nC to targetQ(e–)=5 nC for Injection

E(e+)=1.0 GeV

E(e–)=3.5GeV, Q(e–)=5 nC

E(e+)=8.0 GeV, Q(e+)=1.2 nC

Q(e+)=1.2nC

New C-band units

2-Bunches for Simultaneous Injection 1-st bunch -> e- Injection 2-nd bunch -> e+ production

S-band accl. units are replacedwith C-band units.Accl. Field 21 -> 41 MV/m

e+ Damping Ring for loweremittance

Achieved

40 MW (0.5ms, 50pps),

> 40 MV/m (1m structure)

Goal:

40 MW

40 MV/m


Summary§ Belle and KEKB have achieved 1.06×1034 c

m2s1 and 158 fb1

§ We have installed SVD2, two more RF cavities and come back online in 2 wks

§ We are hoping to upgrade KEKB and Belle to reach 1035 luminosity and to accumulate 3000fb1 before 2010 when LHC starts producing results– Simulation tells us that we may reach 51035 wi

th head-on collision with crossing angles using the crab cavities

super kekb project

Documents