SuperBfactory Detector plan Recent status

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SuperBfactory Detector planRecent status

• Junji Haba

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Since the LoI writing in 2004

• The LoI detector was designed to work (anyhow)
  under 20 times harsher beam background.
• Optimization through physics case studies,
  supposed to make intensively after LoI, have not
  yet been advanced well.
• Beam background study itself made a good progress
  with BBB (Belle Babar Background) Task force by
  Hawaii WS in 2005. BaBar-ians now seem to make
  more realistic detector design based on the
  outcomes.

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EMC Background Projections
Radiation Damage Projections
Degradation of light output with luminosity
EMC lifetime limit about 20 ab-1
D. MacFarlane (SLAC)
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Scenario 4 Detector Upgrades

• Replace inner layers of present SVT with
  segmented strips
• Should be viable to about 5 x 1035
• Develop thin pixels and replace inner SVT at an
  appropriate time to go higher in luminosity
• Replace DCH with all silicon tracker
• Replace DRC SOB and bar boxes due to smaller
  radius for EMC
• Not at all clear that DRC will work at these
  luminosities
• Replace EMC with either
• radiation hard crystals or
  liquid xenon
• Replace IFR forward endcap

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A potential upgrade path from BABAR to SuperBABAR
DIRC
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Options for Beyond 2x1035

• Basic configuration is
• Leave SVT geometry unchanged replace DCH with
  4-layer silicon tracker with lampshade modules.
  Remove support tube
• Radii of barrel part of SVT modules 3.3, 4.0,
  5.9, 12.2, 14.0 cm
• Radii of barrel part of CST modules 25,35,45,60
  cm

Current detector
All silicon tracker
60 cm
F.Forti
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Average Vacuum 5x10-7 Pa
Super-KEKB design at Now!!
KEKB
1st layer
2005 Hawaii Tajima
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SuperBelle 2004
Barrel
BWD EndCap
FWD EndCap
Realistic design based on discussion with QCS
group
VertexSi striplet (MAPS later) inner-most and Si
strip tracker TrackerDrift chamber rgt15cm PID
w/TOP and AC-RICH (endcap) ECALCsI (Tl) wave
from (barrel) pure CsIPMT (endcap) m
Scintillator SiPM
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The baseline is
Babar-ians move to Italy Nov. 2006

• As much of the BaBar detector as makes sense
• Upgrades to the BaBar detector that are necessary
  to cope with higher luminosity
• Optional upgrades have to be
• Not too expensive
• Not interfering with another sub-system
• Justified by the physics

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Beam pipe
F. Raffaelli

• 1.0 cm inner radius
• Be inner wall
• 4um inside Au coating
• 8 water cooled channels (0.3mm thick)
• Power 1kW
• Peek outer wall
• Outer radius 1.2cm
• Thermal simulation shows max T 55C
• Issues
• Connection to rest of b.p.
• Be corrosion
• Outer wall may be required to be thermally
  conductive to cool pixels

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SVT

• Baseline use an SVT similar to the Babar one,
  complemented by one or two inner layers.
• Question on whether it would possible/economical
  to add a layer between SVT and DCH, or move L5 to
  larger radius
• Cannot reuse because of radiation damage
• Beam pipe radius is paramount
• inner radius 1.0cm,
• layer0 radius 1.2cm,
• thickness 0.5 X0

N.Neri/G.Calderini
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SVT Layer 0
7.7 cm
1.35 cm

• Depends critically on background level
• Striplet solution (baseline)
• Basically already available technology but more
  sensitive to background. OK for 1MHz/cm2
• Some margin to improve background sensitivity
• Monolithic Active Pixel Solution solution
  (option)
• RD is still ongoing but giving a big safety
  margin in terms of performance and occupancy
• Cooling and mechanical issues need to be
  addressed

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Particle ID
B. Ratcliff/D. Leith

• Barrel DIRC baseline
• Quartz bars are OK and can be reused
• Almost irreplaceable
• PMTs are aging and need to be replaced
• Keep mechanical support
• Barrel Options
• Faster PMTs
• Focusing readout
• Different radiator
• Extra tracking device outside DIRC

No Change !?
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EMC
S. Playfer/S. Robertson

• Barrel CsI(Tl) crystals
• Has worked fine in BaBar and Belle
• No problems with radiation damage of CsI(Tl)
  crystals so far
• Pileup can be handled by feature extraction of
  waveform digitisations
• Need to upgrade readout electronics
• Forward Endcap EMC
• BaBar crystal are damaged by radiation and need
  to be replaced
• Occupancy at low angle makes CsI(Tl) too slow
• No doubt we need a forward calorimeter
• Backward EMC option
• Because of material in front will have a degraded
  performance
• Maybe just a VETO device for rare channels such
  as B?tn.
• Physics impact needs to be quantitatively
  assessed
• DIRC bars are necessarily in the middle
• DCH electronics relocation is critical for the
  perfomance

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Forward EMC crystals

• Both pure CsI and LSO could be used in the
  forward EMC
• LSO more expensive, but more light, more compact,
  and more radiation hard
• Now LSO is available industrially
• Cost difference still significant, but not
  overwhelming.
• Use LSO as baseline
• Gives better performance
• Leaves PID option open
• CsI option still open
• in case of cost/availability issues

Backward calorimeter

• Keep as an option
• Backward endcap
• Barrel extension
• Could be less performant
• Benchmark physics gain

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IFR and steel
G. Cavoto/M. Negrini

• BaBar configuration has too little iron for m ID
• gt 6.5 lI required 4-5 available in barrel
• Fine segmentation overdid KL efficiency
  optimization
• Focus on m ID fewer layers and more iron
• ? Is it possible to use the IFR in KL veto mode ?

• Baseline
• Fill gaps in Babar IFR with more iron
• Leave 7-8 detectionlayers
• Need to verify structural issues
• LST in barrel
• Avalanche RPC in EC for rate

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Detector Layout
BASELINE
OPTION
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What we can learn?

• Now at last, two detectors look alike more than
  before.
• 1cm Be beam pipe
• Striplet (MAP later) 5 layer Si strip
• Drift chamber tracker for rgt15cm
• PID with DIRC principle optional FWD PID
• Ecal with CsI(Tl)(barrel reuse) pure CsI (or
  LSO)
• Several important points to note
• Energy asymmetry/vertex resolution
• KLM?m detector
• APD for CsI endcap
• Consideration for backward EC
• Minor differences are worth investgation.

Certificate reasonable design
Many stimulating and useful discussions !
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What looks different?

• Beam pipe radius Chosen sizes are same, strategy
  is largely different.
• DC cell No change from the present assuming no
  worse BKG other than luminosity proportional ones
  like radiated Bhabha which should be able to
  shield
• PID and backward endcap calorimeter.
• Hermeticity argument.
• Maybe just a VETO device for rare channels such
  as B?tn.

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Better vertex and a small radius (or super flat)
beam pipe
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Luminosity vs Dz resolution for J/yKS
BGM Tajima
Current resolution
H.Ozaki BN111 (1996)
Energy asymmetry will be discussed in the
Tsuboyamas talk tomorrow.
Super Flat Beampipe(?)
Can be improvemed w/ better vtx resolution ½ s ?
20 gain of luminosity
Cf. Gain of S.F. for dSpp(dApp) 22(11)
with considering continuum BG (by K.
Sumisawa 2003?)
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What is Super Flat (SF) BP?
Extreme case for a small radius beam pipe.
Y. Unno _at_ HL06
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qq suppression vs Dz (Super Flat BP case)
BGM Tajima
Y. Unno _at_ HL06

• Assuming no correlation between current qq
  method and vertex
• Cut on Dz distributions after applying a cut on
  current qq method
• Use F.O.M S/sqr(SN) to estimate the
  performance

Currently, advantage is small ex. 23 gain for
b?dg (by S.Nishida) eff. gain w/ keeping
same S/N
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No more armchair plan. Should be demonstrated in
simulations under realistic occupancy.
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Backgrounds
Background we have Not investigated !
E. Paoloni

• Dominated by QED cross section
• Low currents / high luminosity
• Beam-gas are not a problem
• SR fan can be shielded

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Low B or smaller beam pipe !
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Beam background so small as assumed by Italian
Babar-ians ?

• How far the present DCH can survive?
• Beam-Gas background can be small.
• Luminosity term can be suppressed.
• There may be another beam background source other
  than the above mentioned.

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CDC Hit rate
DCH cell size
Belle Case study
Scale adjusted
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Another possible sourceTouschek

• Data taken 28-June-2003 12301300
• LER single beam
• Vertical beam size changed by size bump
• Beam life time expected to follow
• Background could depend on

Beam current
Vertical beam size sy
Beam life t
1/t
k might be different for different processes
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300 min
300 min.
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kvac
kTouschek
CDC2 leak current /i
CDC0 leak current /i
1/t
1/t
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Background from vacuum and Touschek
If 1/t(Tauchek)/1t(Vac) 60, background from
Tacuchek may be 15 times higher than that from
Vac !
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Particle ID and ..

• Babar DIRC is very successful. Good target for
  long to Belle PID group.
• Another feature of BB DIRC is its penetrating
  readout bars and SOB.
• Not consistent with backward EC or any hermetic
  detector.

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B?tn Analysis
Calorimeter Hermeticity

• Extra neutral energy in calorimeter EECL
• Most powerful variable for separating signal and
  background
• Total calorimeter energy from the neutral
  clusters which are not associated with the tag B

• Minimum energy threshold
• Barrel 50 MeV
• For(Back)ward endcap 100(150) MeV

Zero or small value of EECL arising only
from beam background
Higher EECL due to additional neutral clusters
MC includes overlay of random trigger data to
reproduce beam backgrounds.
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B? ? ????
CP, Rare decays, CKM V Browder (Belle) Sekula
(BaBar)

• Identify possible ? in common decay mode
• Look at extra calorimeter energy
• (validate with for Dln)

H?
Extra E(GeV)
Extra E(GeV)
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Good Pid, hermeticity or both?

• If hermeticity is a key feature of the SuperB
  detector, DIRC without projection (SOB) like TOP
  or Focusing DIRC is an essential technology.
• The practical system (a 50 psec precision photon
  sensor with matching electronicics) is not yet
  demonstarted to be available soon.

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TOP (Time Of Propagation) counter
N.Sato 2005 Hawaii
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To make the LoI model more realistic

• Only physics case study can justify/finalize the
  key concepts/parameters
• BP radius/IP resolution
• Outer radius of vertex
• Hermeticity/resolution for back EC
• Ebeam asymmetry (not only economy)
• Pid requirement (perfoamance, coverage)
• B field
• Status of RD for the ambitious components should
  be reviewed to assess their availability in view
  of the construction schedule.