Super KEKB project

1
Super KEKB project

• WIN03
• Oct 9th, 2003
• Nobu Katayama
• KEK

2
Outline

• Belle/KEKB status
• Super KEKB plan
• Physics
• Detector study
• Accelerator study

3
KEKB status1999/10-2003/7/1
1.057?1034 cm-2s-1
gt 50 fb-1 in years 2002, 2003
LER1.55A HER1.1A With SRF
158.7fb-1
4
Best day (May 12th, 2003) 579.1
pb-1/day recorded
5
SVD 1 ? SVD 2
RBP 1.5 cm
RBP 2.0cm
RL1 2.0cm
RL1 3.0cm
Rout 8.8cm
Rout 6.0cm
81014 32 ladders
6121818 54 ladders
SVD1
SVD2
6
How much improved?
7
We have just started!

• More and more Bs
• ?
• Super KEKB

8
Mission of Super B Factory(ies)
Breadnd butter for B factories
Mission 1 300 fb-1
Precision test of KM unitarity
See quantum effect in penguin and box loop
Mission 2 3,000 fb-1
Search for new physics in B and t decays
Mission 3 30,000 fb-1
Identify SUSY breaking mechanism
Very important if New physics SUSY
9
In which processes can we find New Physics?

• Rare decays
• B ? Xsg ,rg
• B ? Kmm
• CP violations
• B ? fKS and hKS
• B ? Xsg , rg
• b ? c emitting charged Higgs
• Forbidden decays by SM
• Forbidden/rare decays of t

10
CPV in penguin decays
Prove ACP(fKS, hKS)?ACP(J/yKS)
In SM,
5s discovery
fKS KK-KS hKS
?ACP
New phase in penguin loop may change this
relation
Belle (August 2003)
ACP(fKS)-0.960.50 ACP(hKS)0.430.27
KEKB PEP-II
Next B factory
ACP(J/yKS)0.7310.057
11
Atmospheric Neutrinos Can Make Beauty Strange?

• Leptogenesis models inspired by the naïve SO(10)
  unification exist where the near-maximal mixture
  of nt and nm results in large mixing of RH
  super-b and super-s, giving O(1) effects on b?s
  transitions such as
• Asymmetry in B ? fKs (effect is in first order)
• Bs mixing
• b ? sg (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!

12
Dominant Right-Right Mixing case
13
SUSY effect in B ? Kmm
F/B asymmetry
m(mm)2 distribution
A.Ali
SUSY models with various parameters set
SM

• These measurements are excellent probe to search
  for SUSY
• Inclusive decay, b?sll, is much less model
  dependent. An ee- B factory provides a unique
  opportunity to measure this by pseudo
  reconstruction technique

14
Rare decays of t
15
Charged Higgs in tree decay

• Large branching fraction 1
• Uncertainty in form factor cancels
• in the ratio G(BgDtn)/G(BgDmn).
• t polarization is more sensitive to H.

B?D()tn vs. D()mn
M.Tanaka
/-
16
Comparison with an LHC experiment
G(B?Dtn)/G(B?Dmn) at B factory with 5,000 fb-1
B factories dont really do tree diagrams of new
particles with the exception of charged
Higgs But together with LHC measurements, we can
determine tanb!
17
What can we do?
Compilation at the 5th High Luminosity WS
18
KEKB upgrade strategy
larger beam current smaller by long bunch
option crab crossing
L1036
ILER20A
Constraint 8GeV x 3.5GeV wall plug
pwr.lt100MW crossing anglelt30mrad
?dt 3000fb-1
L1035
before LHC!!
ILER9.4A
One year shutdown to replace vacuum chambers
double RF power upgrade inj. linac g C-band
Present KEKB L1034
ILER1.5A?2.6A
?dt 500fb-1
2002
03
04
05
08
07
06
09
10
11
19
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 KLm detector
• Higher event rate
• higher rate trigger, DAQ and computing
• Require special features to the detector
• low p m identification for smm reconstruction
  eff.
• hermeticity for n reconstruction

20
Detector upgrade an example
Aerogel Cherenkov counter TOF counter
SC solenoid1.5T
?TOP RICH
3.5GeV e
CsI(Tl) 16X0
? pure CsI (endcap)
8GeV e-
Tracking dE/dx small cell He/C2H5
? remove inner lyrs.
New readout and computing systems
Si vtx. det. 3 lyr. DSSD
m / KL detection 14/15 lyr. RPCFe
? 2 pixel lyrs. 3 lyr. DSSD
? tile scintillator
21
SVD occupancy and CDC hit rate

• Current most inner layer of SVDs occupancy is
  35
• Current most inner layer of CDCs occupancy is
  23
• With 1035 luminosity, two layers of pixel
  silicon (15cm R) CDC survives
• With 1036 luminosity, Pixel Silicon a la super
  BaBar design?

Cathode
Inner
Main
Radius 15cm
22
Does CDC work with Lgt1035 ?

• Smaller cell
• Faster gas
• Larger starting diameter

Yes !!
23
Small Cell Chamber (with SVD2)
20cm
24
XT curve for small cell measured
Normal cell
Small cell
25
New PID detector
Requirements - Thin detector with high rate
immunity - gt3s p/K separation up to 4GeV/c
- low p p/m separation
TOP counter for barrel Aerogel RICH
for endcap
Present Belle Aerogel Cherenkov counter both
for barrel and endcap.
26
Time of propagation (TOP) counter
Reflection mirror
200mm
20mm
A few meters
Fused silica(n1.47)
time X sensitive PMTs
27
Aerogel RICH for endcap

• Single event display

• Hit distribution

28
Super KEKBAccelerator upgrades
29
Whats 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 fb-1
  of data and continue to accumulate
• Thanks to tremendous efforts by and ingenuity of
  the commissioning and operation groups

30
Features of KEKB

• Super conducting RF cavities and ARES cavities
• Holds more than 1A of beam current with SRF
• IR region
• 3?m?100?m 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

31
Challenges with Super KEKB

• High beam currents (LER 9.4AHER4.1A)
• Heating, breakdown will occur
• Ultra high vacuum, beam lifetimes
• Power consumption (80100MW)
• 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 lt6mm (world record)
• Shorter bunch lengthmore peak current gives
  more power dissipation, shorter lifetime

32
Towards Super KEKB

• LER 9.4A HER 4.1A (46 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

33
Accelerator Upgrades for Super KEKB

• Crab cavities

• Super Belle

• New beam pipe bellows

• New IR

• More RF sources

• More cavities

• Damping ring

• Charge switch by C-band

• Positron source

K. Oide _at_ Izu 2003
34
Machine parameters
bx 20 cm bx 15 cm
35
Crab cavity developments

• Crab crossing may boost the beam-beam parameter
  up to 0.2!

(Strong-weak simulation)
K. Ohmi
Head-on(crab)
(Strong-strong simulation)
crossing angle 22 mrad

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

K. Hosoyama, et al
36
50 more RF cavities Double of Klystrons
D1
D2
5 buildings should be added.
(Each building for 4?6 RF units.)
RF/SRF 30/8 ? 44/12
HER-RF (ARES)
D4
D11
new
new
HER-RF (SCC)
LER-RF (ARES)
D10
new
D5
Kly/ACPW(MW) 23/45 ? 56/73
new
new
D8
D7
37
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- gt e
• Beam current e- gt 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

38
Linac upgrades for 8 GeV e
S-band accl. units are replaced with C-band
units. Accl. Field 21 -gt 41 MV/m
2-Bunches for Simultaneous Injection 1-st
bunch -gt e- Injection 2-nd bunch -gt e
production
e Damping Ring for lower emittance

• Achieved
• 40 MW (0.5ms, 50pps),
• gt 40 MV/m (1m structure)

Goal 40 MW 40 MV/m
39
Summary

• Belle and KEKB have achieved 1.061034 cm-2s-1
  and 158 fb-1
• 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 3000fb-1 before
  2010 when LHC starts producing results
• Simulation tells us that we may reach 5?1035 with
  head-on collision with crossing angles using the
  crab cavities