Low Q option of ILC

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Low Q option of ILC

• 2005.June 8
• Y. Sugimoto, T. Fujikawa

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Main MDI Issues

• Crossing angle
• L
• Beam parameters
• Ne/bunch
• s
• Timing
• etc.

• BCAL
• All sub-det.
• Solenoid, TPC
• BCAL
• All sub-det.

• Minimum veto angle
• n, e/e- back scattering
• Anti-solenoid
• DID
• Event overlap
• Background in BCAL
• Readout timing

MDI issues are Physics/Detector issues!
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Parameter sets by Tor Raubenheimer
peak luminosity

• TESLA
• USSC
• Nominal
• Low Q (Low charge)
• Large Y (Large Emittance)
• Low P
• High Lum

3?1034
parameterspace
2?1034
Nick Walker (LCWS2005)
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Proposed Machine Parameters
TESLA Nominal Low Q
ECM (GeV) 500 500 500
Ne/bunch 2.0e10 2.0e10 1.0e10
Nb/train 2820 2820 5640
Tsep (ns) 335.9 307.7 153.8
bx (m) 1.5e-2 2.1e-2 1.2e-2
by (m) 4.0e-4 4.0e-4 2.0e-4
sx (m) 5.54e-7 6.55e-7 4.95e-7
sy (m) 5.0e-9 5.7e-9 3.5e-9
sz (m) 3.0e-4 3.0e-4 1.5e-4
PBeamstrahlung (W) 3.35e5 2.48e5 2.05e5
L (cm-2 s-1) 2.94e34 2.03e34 2.01e34
Incoherent pair/BX 4.14e5 2.59e5 0.84e5
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Advantages of Low Q option

• Same Luminosity but less bunch Luminosity (1/2 of
  nominal option)
• Less possibility of event overlap (2-g events)
• Less beamstrahlung power
• Less incoherent pair background
• Per BX 1/5 of TESLA design, 1/3 of nominal
  option
• Less b.g. hits in the Beam Calorimeter ? Better
  veto efficiency
• Per Train 2/5 of TESLA design, 2/3 of nominal
  option
• Less b.g. hits in the Vertex Detector

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Disadvantages(?) of LowQ option

• Smaller beta functions and beam size
• Compatible with large l ?
• Smaller bunch spacing of 154 ns
• Hard job of the Damping Ring
• No problem for FPCCD
• How about other detector components?

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Simulation Study

• Pair background hit rate on the 1st layer of the
  Vertex Detector (R24mm)
• Simulation using CAIN and JUPITER
• Hit rate of the Low Q option is 1/3 of the
  nominal option, as expected

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Summary

• New ILC parameter sets are different from that of
  TESLA design
• LowQ option is attractive from the view point of
  the detector
• It has been confirmed by simulation study using
  CAIN and JUPITER that the LowQ option makes less
  background hits on the vertex detector than the
  nominal option