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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