Calorimeter Parameters and Choices

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Calorimeter Parameters and Choices

• Peter Nemethy
• MECO Collaboration Meeting
• Irvine - February 6-7, 2005

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Present Configuration (new) REF DESIGN

• 135cm LONG (down fr.150cm)
• LEAD TUNGSTATE
• At Temp 24deg C
• 4 VANES of
• 8 x 36 288 crystals
• Total 1152 CRYSTALS
• PWO crystal size
• 3.75 x 3.75 x 12 cm3 13.5 RL
• 2 APD/Crystal 13 x 13 mm2
• Preamps at Detector
• Shaper Amps outside.

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PRESENT COST (k) CONTING () COST w CONT
CRYSTALS 1,215 26 1,530
APDs 1,800 32 2,376
PREAMP SHAPER SYST 288 20 345
POWER SUPPLY 480 20 576
CABLES w CONN 211 20 253
CALIB MON 55 25 69
MECH HOUSING 80 20 96
COOLING 40 20 48
TOTAL 4,168 27 5,292 (102)
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PARAMETERS and CHOICES

• LENGTH in Z (Scales ALL , exc. Mech. and
  cooling)?
• gt ACCEPTANCE, EDGE EFFECTS.
• CALORIMETER DEPTH (Scales XTAL Volume )?
• gt ACCEPTANCE, RESOL, EDGE EFFECTS,
  PUNCHTHRU
• HV POWER SUPPLY GANGING (scales HV )?
• CRYSTAL Transverse Dimension(?) used
• APD choice ?
• 2 APD / Crystal to 1 (?) N.

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ACCEPANCE vs CAL LENGTH

• For 2 different
  Crystal depths

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COST (w. CONT) vs ACCEPTANCE

• Previous 150cm -gt 135cm Lose 2 Acceptance
• 12 cm deep, 135cm -gt 120cm
• LOSE 3 ACCEPTANCEsave 572K
• 12 cm deep, 135cm -gt 112.5cm
• LOSE 8 ACCEPTANCEsave 858K
• 12 cm deep, 135cm -gt 105cm
• LOSE 13 ACCEPTANCEsave 1144K
• 10 cm deep, 135cm -gt 120cm
• LOSE 7 ACCEPANCEsave 799K

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Calorimeter Depth 12cm to 10cm

• Save 225K. Edge, Punchthru and APD Nuclear
  Counter worse.
• Ratio of FWHH(10cm)/FWHH(12cm) 5.6MeV / 3.1MeV
  1.8
• Punchthru and Nuclear Counter Effect needs
  detailed sim.

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(more) CHOICES

• GANGING HV 2 APDs per CHANNEL. save 240K
• Hardship and convenience
• gain balancing harder Level-0 trigger?
• 5V gt 20 Gain Change (at 1700V)
• CRYSTAL TRANSVERSE SIZE CHANGE
• Scaled already (3.75cm -gt 3.0cm) Channels
  scaled by 1.5
• Matches manufacturing capability and Moliere
  radius 2cm
• Light Collection Loss under study.

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(no more) CHOICES

• APD CHOICE and smaller AREA DEGRADE S/N and
  resolution.
• Complicated, studies and info needed, if
• vs area scaling? 3 sources. need budgetary
  quotes.
• Physics gtresolution now est. 7.9
  (5.6) trigger rate?
• Elec noise scales with light coll,
  photostatistics w. sqrt of.
• Light Collection scales w. area (or somewhat
  better),
• Measuring at NYU now.
• Detector Capacitance varies widely, not area
  scaling
• ex. Hamamatsu 1x1cm 300puff -- RMD
  1.3x1.3cm 150puff.
• 2 APD/ XTAL to 1 ? DONT! Of course big save
  900K.
• But lose control of APD nuclear counter
  effect (NCE).
• No trustable reconstructed energy (infinite
  tail)
• Increased trigger rate, NCE probab/event low
  
• but base is all gt50MeV DIO showers, much
  higher rate.
• Needs detailed MC study

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CONCLUSIONS for DISCUSSION

• SHORTER CALORIMETER yes. and physics scaling
• understood. 120cm for sure, 112.5cm maybe,
  105cm hurts.
• Depth Change 12cm to 10cm, not as favorable as
  shorter cal.
• HV ganging doable though not convenient.
• APD choices prefer not to degrade. No offer on
  BLing timescale.
• 1 APD/CRYSTAL dont.