Hadron Calorimeter G Franklin Carnegie Mellon University Hadron

Hadron Calorimeter G. Franklin, Carnegie Mellon University Hadron Calorimeter HCAL-J GEp Electron Calorimeter Big. Cal 10/13/2011 1

Hadron Calorimeter • 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 2

COMPASS HCAL 1 Module Design • 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 3

HCAL-J Design 24 Modules (360 cm) HCAL-J based on COMPASS HCAL 1 Each module: 15 cm x 15 cm Layered scintillator and iron 12 Replicate with small design modifications es ul od M 80 (1 ) cm Existing HCAL 1 in COMPASS 288 modules for JLab HCAL 4

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

COMPASS Light Guide /WLS 6

Geant 4 Energy Resolution Studies ¼ signal thresh. ½ signal thresh. Energy 2. 5 Ge. V 5. 0 Ge. V 7. 5 Ge. V 10. 0 Ge. V Resolution: ¾/E 48% 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% 7

Geant 4 Spatial Resolution Results JLab kinematics Agreement with COMPASS data Achieves required angular resolution with HCAL positioned 17 m from target: 5 cm / 17 m ! 3 mrad resolution 8

Geant 4 Timing Simulations FWHM = 2. 1 ns ¾= 0. 9 ns FWHM = 1. 12 ns ¾= 0. 48 ns Waveshifter decay time 8 ns ! 3. 5 ns Trigger Time (ns) Simulation using COMPASS parameters Agrees with published COMPASS HCAL performance PMT rise time 10 ns ! 2. 5 ns Trigger Time (ns) Maximize Npe 0. 5 ! 1. 0 cm scint. Simulation using faster waveshifter dye and PMTs Meets SBS requirements To be confirmed with prototype HCAL module 9

Use commercial WLS with fast decay time Need light guides 10

Possible Fast WLS Solutions EJ-299 -27 BC-484 EJ-299 -27 WLS Decay time 1. 5 ns Or BC-484 WLS Decay time 3 ns Can’t be excited with “typical” PPO / POPOP scintillator LS t lla i int W sc or PPO/POPOP Scintillator emission not matched to WLS absorption 11

Possible Solutions for Scintillator BC-420 $ 1, 140 k Alternative PPO scintillator < $ 100 k 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%) 12

13

GEANT 4 Optical Monte Carlo Light Pipe Design Studies (Vahe Mamyan) For offset WLS For centered WLS Design 1 For centered WLS Design 2 No foil 65. 0% 61. 1% 64. 6% Foil wrapped 75. 4% 73. 9% 77. 6% Results for simulated light transmission Assum ed 90 % refl ective 14

Light Guide Production • Found company (ICOMold) that can injection mold large pieces with opticalquality surface • $10 k tooling for mold • $12. 59/piece cost • For 300 pieces: $10 k + $ 3. 8 k = $ 13. 8 k 15

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

Cost estimate ~300 modules Scintillator (extruded 7 cm x 1 cm) 2, 400 kg $ 72 k FNAL estimate Chop and Diamond Mill 24, 000 pc 30 k CMU students Iron, 14 cm x 7. 5 x 0. 5 cm 48, 000 pc 72 k quote Light Pipes (injection molded) 300 pc 14 k quote Wavelength 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 Other (shipping etc. ) TOTAL 2 k ? $ 293 k 17

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