Interaction Region: a terse summary

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Interaction Region a terse summary
Conveners K. Trabelsi, W. Kozanecki
A very lively productive interchange between
BEPC BES experts!

• Accelerator issues
• Parameter comparison with PEP-II/KEKB
• IR layout
• Particle-loss mechanisms
• Thermal issues
• Detector issues
• Machine background predictions
• Detector radiation-protection beam-abort
• Luminosity monitor
• Subdetector-specific issues (DCH, trigger, TOF)
• Summary the most critical/urgent studies

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• Introduction
• Experience in PEP-II BaBar Iimportance of an
  integrated approach to
• Solving layout problems
• Predicting (now) understanding (later) machine
  backgrounds
• IR heating issues (SR, HOM)
• Machine operation (injection, abort,...)
• Accelerator issues
• Parameter comparison BEPCII vs B-factories
• Same beam-current L regime
• The joys the pains of 2-ring machines
• Some issues harder, a few easier
• IR layout
• orbits, BSCs, aperture constraints,

T WK
T Xu Gang
Major implications for machine SR backgrounds
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• Accelerator issues (ctd)
• IR layout (contd)
• Mechanical vacuum interfaces
• Significant enginering challenge in
  accomodating necessary mechanical/vacuum
  interfaces in the heart of BESIII

T HUANG Nan
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• Accelerator issues (ctd)
• IR layout (contd)
• Mechanical vacuum interfaces
• support tube approach (BaBar) impractical bec.
  of DCH conical shape

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• Accelerator issues (ctd)
• Particle-loss mechanisms
• Injection
• Injected e- prob. OK
• Injected e e inj/stored 10 gt x-baam size
  x 3-4, gt (present) clearance 1 sinjected
• If confirmed, ? !!
• Need better understanding of injected beam specs
  (AD)
• may need to collimate (shave off) tails in
  linac, before injection
• Beam abort gap needed
• Touscheck need background calculation (AD
  Turtle!)
• Beam-beam brems (aka radiative Bhabhas) where do
  the debris go? (Turtle!)

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• Accelerator issues (ctd)
• Thermal issues IR very sensitive
• Synchrotron radiation
• HOM losses

BaBar luminosity presently limited by heating here
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• Detector issues
• Machine background predictions
• Radiation tolerance of BES subdetectors
• Most sensitive to injection calorimeter
• Most sensitive to stored beam DCH
• Numbers criteria/specs needed!
• Occupancy issues in BES subdetectors (esp.
  trigger)
• Numbers criteria/specs needed!
• Background simulations
• Belle experience
• Early BES beam-gas SR studies

T K. Trabelsi
TJin Dapeng
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Detector issues (ct d) Machine background
predictions (ct d) Background simulations
(ct d) Early BES beam-gas SR studies
TJin Dapeng
Total power
Total photon flux
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• Detector issues (ct d)
• Detector radiation-protection beam-abort
  consensus it is absolutely needed

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• Detector issues (ct d)
• Luminosity monitor
• Absolute large- and/or medium angle BhaBhas
• Relative 0-BhaBhas (e e- g)
• Water Cerenkov referred (Belle), 1/side
• essential for
• Machine optimization
• Beam-beam centering (feedback)
• b-b vertical (y-z) alignment
• IP beam size measurements
• Bunch train diagnostics
• Machine vs detector operation
• Trigger must accommodate easily arbitrary bunch
  patterns
• TOF consider separate timing signal from trigger
  (phase drift along train)

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Summary the top of the list.

• IR layout trade-offs between
• Orbits
• Backgrounds
• Engineering
• Injection !!
• Abort gap gt kicker RD
• Background simulations
• SR
• Beam-gas
• Touscheck