Hadron Calorimeter HCAL-J GEp Electron Calorimeter BigCal Hadron Calorimeter 1 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 2

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 3

HCAL-J Design Each module: 15 cm x 15 cm Layered scintillator and iron 288 modules for JLab HCALExisting HCAL1 in COMPASS HCAL-J based on COMPASS HCAL1 Replicate with small design modifications 24 Modules (360cm) 12 Modules (180 cm) 4

40 layers 20 mm iron / 5 mm scintillator Integral WLS/ Light guide Acrylic with Coumarin-7 impregnated surface 5 mm thick Novel light guide for 1 in PMTS Steel casing JINR (DUBNA) produced 9 HCAL modules of COMPASS design Funded by CMU Hole in downstream light guide HCAL-C Module shown on its side (WLS and side cover removed) 5

6 COMPASS Light Guide /WLS

Geant4 Energy Resolution Studies 7 Energy2.5 GeV5.0 GeV7.5 GeV10.0 GeV Resolution: ¾ /E48%31%27%22% Efficiency at ¼ mean signal: Neutrons 97.3%99.2%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 8 Agreement with COMPASS data JLab kinematics

9 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 N pe 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)

Use commercial WLS with fast decay time Need light guides 10

11 EJ Can’t be excited with “typical” PPO / POPOP scintillator scintillator WLS PPO/POPOP Scintillator emission not matched to WLS absorption BC-484 Possible Fast WLS Solutions EJ WLS Decay time 1.5 ns Or BC-484 WLS Decay time 3 ns

12 Possible Solutions for Scintillator BC-420$ 1,140k Alternative PPO scintillator< $ 100k JINR Production FNAL 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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14 GEANT4 Optical Monte Carlo Light Pipe Design Studies (Vahe Mamyan) For offset WLSFor centered WLS Design 1 For centered WLS Design 2 No foil65.0%61.1%64.6% Foil wrapped75.4%73.9%77.6% Results for simulated light transmission Assumed 90% reflective

15 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

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 16

17 Scintillator (extruded 7cm x 1 cm)2,400 kg$ 72 kFNAL estimate Chop and Diamond Mill24,000 pc30 kCMU students Iron, 14 cm x 7.5 x 0.5 cm48,000 pc72 kquote Light Pipes (injection molded)300 pc14 kquote Wavelength Shifter (Eljen) (St. Gobain Quote: $ 52.5 k) 300 pc63 kquote Metal Cans, ribs, end-caps300 pc40 k? PMT base adapters300 pc2 k Other (shipping etc.)? TOTAL$ 293 k Cost estimate ~300 modules

FY12Prototype Module Testing Cosmic ray uniformity tests Background measurements Test scintillator and waveguides options Design Finalization Jan 2013Order scintillator Order WLS, Light Pipes Start end-plate and box construction Order Iron April 2013Start scintillator chop and mill Module assembly 9 to 12 months April 2014Complete modules HCAL-J Project Timeline 18