GlueX Simulations

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GlueX Simulations
GlueX Collaboration Meeting, Newport News,
January 10-12, 2008

• Status Report on CD3 geometry
• Richard Jones

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Detector subsystems

• Target - unchanged
• Start Counter - updated
• Central Drift Chamber - updated
• Forward Drift Chamber - updated
• Barrel Calorimeter - updated
• Upstream Calorimeter/Veto removed
• Gas Cerenkov - updated
• Time-of-Flight counter - unchanged
• Forward Calorimeter - unchanged
• Solenoid / magnetic field updates in progress

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Target- unchanged

• liquid hydrogen volume
• diameter 3 cm
• length 30 cm
• kapton walls 150 mm thick
• vacuum chamber walls
• 1 cm of high-density (0.11 g/cm3) ROHACELL
• exterior diameter 8 cm
• vacuum entrance, exit windows
• 70 mm of aluminum

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Start Counter - updated

• layer structure
• high density ROHACELL r6.95 - 7.48 cm
• scintillator 2.15 mm thick
• low density ROHACELL r7.69 8.68 cm
• cellulose wrapping tape 0.5 mm thick
• forward tapered section
• first conical section 22.5 taper
• second conical segment 45 taper
• all layers constant thickness
• innermost diameter 4.58 cm

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Central Drift Chamber - updated

• active length shortened to 150 cm
• two options for stereo layer sequence
• option 1
• stereo layers 4-7 and 13-16
• sequence -,-,, in each
• option 2
• stereo layers 4-6, 12-14, 20-22
• sequences -,-,- ,, -,-,-
• trade-off issues
• polar angle resolution
• track finding / pattern recognition

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Forward Drift Chamber - updated

• changed package positions
• compressed in z
• last package in stronger field region
• different dead region in each package
• 2.3 cm, 3.2 cm, 3.9 cm, 4.6 cm
• important reduction in outer radius of active
  region
• now r48.5 cm
• allows space for HV coupling capacitors
• detailed sandwich repeating structure for frames
• important new materials at r60cm for cooling
• 0.5 mm copper cylinder around frame periphery
• 0.7 mm aluinum cylinder between packages

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Barrel Calorimeter - updated

• overall dimensions unchanged
• new readout segmentation scheme
• innermost 12 cm covered by 4 (phi) x 6 (depth)
  2 x 2 cm2 cells with Winston cones and SiPMs.
• outermost 10.48 cm covered by 2 x 2 5.23 x 5.04
  cm2 cells with light collectors, light pipes
• readout scheme specifies coupling with Winston
  cones of uniform 2 x 2 cm2 collection area
• large gaps appear in phi at outer layers
• coverage ranges from 92.6 (layer 1) to 80.4
  (layer 6) for inner layers, 96.7 - 90.7 outer
  layers
• may affect energy resolution, should be studied
• only energy in readout cells is seen in simulation

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Barrel Calorimeter - updated

• total channel count settled
• 2304 SiPM channels (upstream downstream
• 384 outer channels (several per Planacon?)
• routing of light pipes not shown, probably
  doesnt matter because outside acceptance

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Upstream Veto removed

• commented out

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Gas Cerenkov
Stand-alone Monte Carlo toy model of Cerenkov
optics, Eugene Chudakov
This mirror geometry is now in HDGeant. Optical
properties by E. Chudakov
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Time-of-Flight counter - unchanged

• two layers
• 2.54 cm thick
• square area 255 cm on a side
• square beam hole 12 cm on a side
• unwrapped in simulation, probably ok

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Forward Calorimeter - unchanged

• quasi circular, radius 29 x 4 cm
• beam hole 3 x 3 blocks
• nothing special for beam-hole region
• energy deposition response model

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Solenoid / magnetic field

• uniform field in azimuth
• map coverage from 4 cm to 254 cm
• linear extrapolation outside mapped region
• probably inaccurate in downstream region
• update underway to new larger map
• new map dimensions ??
• CD3 studies should use the new map

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