hadron calorimeter hcal-j gep electron calorimeter bigcal hadron calorimeter 1 g. franklin, carnegie...
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Hadron Calorimeter HCAL-J
GEp Electron CalorimeterBigCal
Hadron Calorimeter
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G. Franklin, Carnegie Mellon University
10/13/2011
• Requirements for the SBS experiments:
• Match acceptance of SBS magnet/polarimeter• Run with high threshold
while maintaining high trigger efficiency • Linear energy response• 0.5 ns time resolution• 5 mrad angular resolution
Hadron Calorimeter
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• 40 iron/scintillator layers (~ 5 ¸nucl)• 2.0 cm iron plates• 0.5 cm scintillator plates• 14.2 cm x 14.6 cm
• 120 cm long wave-shifter readout along 1 side• 6 photo-electrons for min-ionizing thru one scintillator
PMT
COMPASS HCAL1 Module Design
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HCAL-J Design
Each module:15 cm x 15 cmLayered scintillator and iron
288 modules for JLab HCALExisting HCAL1 in COMPASS
HCAL-J based on COMPASS HCAL1
Replicatewith smalldesign modifications
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Mod
ules
(36
0cm
)
12 Modules (180 cm
)
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5
40 layers 20 mm iron / 5 mm scintillator
Integral WLS/ Light guide Acrylic with Coumarin-7 impregnated surface5 mm thick
Novel light guide for 1 in PMTS
Steel casing
JINR (DUBNA) produced 9 HCAL modules of COMPASS designFunded by CMU
Hole in downstream light guide
HCAL-C Module shown on its side (WLS and side cover removed)
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COMPASS
Light Guide /WLS
Geant4 Energy Resolution Studies
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Energy 2.5 GeV 5.0 GeV 7.5 GeV 10.0 GeV
Resolution: ¾/E 48% 31% 27% 22%
Efficiency at ¼ mean signal: Neutrons
97.3% 99.2% 99.1% 99.1%
Efficiency at ¼ mean signal: Protons
98.8% 99.6% 99.4% 99.0%
¼ signal thresh.
½ signal thresh.
Geant4 Spatial Resolution Results
Achieves required angular resolution with HCAL positioned 17 m from target:
5 cm / 17 m ! 3 mrad resolution
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Agreement with COMPASS data
JLab kinematics
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Geant4 Timing Simulations
FWHM = 1.12 ns
¾ = 0.48 ns
FWHM = 2.1 ns
¾ = 0.9 ns
Waveshifter decay time 8 ns ! 3.5 ns
PMT rise time 10 ns ! 2.5 ns
Maximize Npe
0.5 ! 1.0 cm scint.Simulation using COMPASS parameters
Agrees with published COMPASS HCAL performance
Simulation using faster waveshifter dye and PMTs
Meets SBS requirements
To be confirmed with prototype HCAL module
Trigger Time (ns) Trigger Time (ns)
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Use commercial WLS with fast decay time
Need light guides
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EJ-299-27
Can’t be excited with “typical” PPO / POPOP scintillator
scintillator
WLS
PPO/POPOP Scintillator emission not matched to WLS absorption
BC-484Possible Fast WLS Solutions
EJ-299-27 WLSDecay time 1.5 ns
Or
BC-484 WLSDecay time 3 ns
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Possible Solutions for Scintillator
BC-420 $ 1,140k
Alternative PPO scintillator < $ 100kJINR ProductionFNAL Extrusion + CMU Machining
Issues• Short attenuation length at short wavelength• Delays in initiating production of PPO-only samples at JINR• 15 cm too wide for FNAL extrusion
Two problems solved with design change• Design with WLS down center of each module• 7.5 cm scintillator on each side• Double # iron plates (increases cost by 20%)
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GEANT4 Optical Monte Carlo Light Pipe Design Studies(Vahe Mamyan)
For offset WLS For centered WLSDesign 1
For centered WLSDesign 2
No foil 65.0% 61.1% 64.6%
Foil wrapped 75.4% 73.9% 77.6%
Results for simulated light transmissionAssumed 90% reflective
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Light Guide Production
• Found company (ICOMold) that can injection mold large pieces with optical-quality surface
• $10k tooling for mold• $12.59/piece cost • For 300 pieces: $10k + $ 3.8k = $ 13.8k
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Recent Developments• Vincenzo Bellini group (INFN/Catania) has joined
(with funding)• New WLS quote from Saint Gobain
• Pending• Sample WLS delivery from Saint Gobain• Sample scintillator from JINR (delivery unclear)• Sample scintillators from FNAL, PPO concentration
from 0.5% to 3%, (November)• Sample molded object from ICOMold for reflectivity
tests
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Scintillator (extruded 7cm x 1 cm) 2,400 kg $ 72 k FNAL estimateChop and Diamond Mill 24,000 pc 30 k CMU studentsIron, 14 cm x 7.5 x 0.5 cm 48,000 pc 72 k quoteLight Pipes (injection molded) 300 pc 14 k quoteWavelength Shifter (Eljen)(St. Gobain Quote: $ 52.5 k)
300 pc 63 k quote
Metal Cans, ribs, end-caps 300 pc 40 k ?PMT base adapters 300 pc 2 kOther (shipping etc.) ?
TOTAL $ 293 k
Cost estimate ~300 modules
• FY12 Prototype Module TestingCosmic ray uniformity testsBackground measurementsTest scintillator and waveguides options
Design Finalization• Jan 2013 Order scintillator
Order WLS, Light PipesStart end-plate and box construction
Order Iron• April 2013 Start scintillator chop and mill
Module assembly 9 to 12 months• April 2014 Complete modules
HCAL-J Project Timeline
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