GLD IR optimization and background study

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GLD IR optimization and background study

• H.Fujishima, Saga-U
• ILCWS2007, Beijin
• 5 February 2007

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Motivation

• Geant4 based full simulation (Jupiter)
• Anti-DID optimization in GLD
• Background hits in GLD detector with 3T solenoid
  field added anti-DID.
• IR optimization (FCAL inner radius)

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IR Design
Hole radius
FCAL inner radius
Beam crossing angle 14mrad
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Anti-DID Field
Solenoid with anti-DID Bz 3T, Bx_serpentine
Andreis anti-DID data (z,Bz,Br,Bx_serpentine)
Br_x r/dBrcos(theta) Br_y
r/dBrsin(theta) d ztheta
Solenoid with anti-DID, X-Z plane
Anti-DID field
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Anti-DID Optimization
1.2 times Andreis data is the best pass
efficiency. Pair background cluster exits
extraction hole.

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Background hits with anti-DID
CAIN is used to generate pair background. Beam
parameter is nominal at center of mass energy 500
GeV. Plain solenoid 10 bunches Solenoid with
anti-DID 8 bunches Background hits are
monitored by VTX and TPC. They are simply
digitized.
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Hits in VTX
VTX in GLD has 6 layers. It consists of the 5
micron pixel charge coupled device. The signal of
each 1 train is read, and 1 incident particle
sound 4 pads on the average. So tolerance (1
occupancy) is 1.0104 hits/cm2/train.
tolerance
Hits of solenoid field added anti-DID became half
compared with it of plain solenoid. Do VTX hits
include much backscatter? I have to study the
origin of VTX hits.
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Hits in TPC
1 hit in TPC consists of 5 pads (1mm6mm) 5
buckets (50nsec). Tolerance of TPC (0.5
occupancy) is 5105 hits/50micro second. Hits of
solenoid field added anti-DID is about 1/3
compared with it of plain solenoid. It is because
backscatter decreased.
tolerance
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IR Optimization
FCAL inner radius for TPC background hits. Hole
radius of extraction to decrease
backscattering. Radius of beam pipe _at_VTX
Hole radius
FCAL inner radius
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FCAL Inner Radius Optimization
The purpose is to optimize forward calorimeter
(FCAL) inner radius to decrease TPC
background. Default value of FCAL inner radius
was determined by simple head on geometry. But
we have to verify it by full simulation.
FCAL
CH2Mask
BCAL
Support Tube
FCAL Inner Radius
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Treatment of TPC hits
There are continuous hits in the z
direction. These are made by 1 incident
particle. Estimation by the number of incidence
particle. About 3 bunches are used.
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Preliminary Result
Results are written by 4 kinds of radiuses. 82 mm
is standard. No dependency is seen. Statistics
is not enough because of necessity a lot of time.
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Summary

• Anti-DID field is optimized.? Background hits
  are reduced.
• IR optimization has been started.FCAL inner
  radius is under study now.