Super KEKB project
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Transcript of Super KEKB project
Super KEKB project
WIN03Oct 9th, 2003
Nobu KatayamaKEK
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Outline
§ Belle/KEKB status§ Super KEKB plan
– Physics– Detector study– Accelerator study
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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
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Best day (May 12th, 2003) 579.1 pb-1/day recorded
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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
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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
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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)
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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
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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
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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!
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Dominant Right-Right Mixing case
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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
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Rare decays of
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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
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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!
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What can we do?
Compilation at the 5th High Luminosity WS
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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!!
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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”
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/ 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
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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
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Does CDC work with L>1035 ?
§ Smaller cell§ Faster gas§ Larger starting
diameter
Yes !!
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Small Cell Chamber (with SVD2)
~20cm
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XT curve for small cell measured
Small cellNormal cell
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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
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Time of propagation (TOP) counter
20mm
time & X sensitive PMTs Fused silica(n=1.47)
Reflection mirror 200mm
A few meters
photon hits
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Aerogel RICH for endcap
§ Single event display§ Hit distribution
Super KEKBAccelerator upgrades
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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
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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
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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
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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
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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
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Machine parameters
x = 20 cm x = 15 cm
L 2ere
Iyy*
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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
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(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
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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
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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
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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