Hadron Calorimeter for Hall A (HCAL-J)

Transcription

1 Hadron Calorimeter for Hall A (HCAL-J) Status report 7/11/12 G.B. Franklin, Carnegie Mellon JLAB/ CMU/ JINR/INFN-CT Collaboration Based on JINR design used at COMPASS 1

2 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 Funky 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) 2

3 Funky Light Guide 3

4 HCAL-J Design Criteria (from CMU Statement of Work document) Size: Usable active area 160 cm x 330 cm Energy Resolution: Need 95% efficiency with trigger set at 25% of average signal Time Resolution: (driven by GEn experiment: E ) Minimum: 1.0 ns σ (trigger would be only 80% efficient) Desired: closer to 0.6 ns σ Angular Resolution 5 mrad Requires 8 cm σ spatial resolution 4

5 COMPASS HCAL-C Module Studies Cosmic Rays thru vertical module (JLab w/bogdan, JINR visitors) Cosmic Rays thru horizontal module (CMU) Extensive Monte Carlo Simulation with optical photon tracking (CMU-Vahe) + (INFN/CT-Francesco Mammoliti from July 2012) Experiments with Coumarin application to acrylic WLS Transmission studies (CMU) + (INFN/CT in 2013) HCAL-C WLS <<100% conversion efficiency 5

6 SOME CONCLUSIONS OF HCAL-C TESTS and SIMULATIONS ~100 photo-electrons for muons thru 20 cm of scintillator (2.4 pe / MeV deposited) Factor of 20 smaller than initial expectations JINR scintillator plate light output varies by factor of two Large light loss along WLS and light guide Coumarin-7 thickness much less than expected Measured time resolution agrees with simulations Coumarin-7 decay time approx. 2.7 ns COMPASS design would not meet timing requirements Achieved σ=0.9 ns at higher energies Should use high-quality PMTs (available from BigHand) Faster WLS Need to increase photo electron yield 6

7 HCAL-J Design Geometry (based on Vahe s Monte Carlo-based optimization report) 40 layers ~15 mm iron (instead of 20 mm) 10 mm scintillator (instead of 5 mm) Material Eljen EJ WLS 1.5 ns decay time instead of ~2.7 ns decay time ( proposed INFN funding in 2013 budget) Eljen EJ232 Scintillator? Spectrum matches WLS 1.4 ns decay time BUT EXPENSIVE compared to JINR production Separate WLS requires separate light guide 7

8 Studies with Eljen WLS and Scintillators Eljen provided small EJ-232 scintillator disks and 5 mm x 5 mm EJ WLS bars Initial studies showed marginal light output Large light loss along WLS bars. (2% loss per bounce) CMU purchased full-size WLS bars from Eljen 5 pieces: 5 mm x 142 mm x 800 mm Reflection and transmission tests with lasers Cosmic-ray test with WLS and small Eljen scintillator disks INFN-CT joins such an activity 8

9 Foil with small hole for single pe spectrum 9

10 Photo-electrons from cosmics: Preliminary results For COMPASS modules: ~100 photo-electrons for muons thru 20 cm of scintillator 2.4 pe / MeV deposited For Eljen WLS/ Scintillator 16 pe for 1 cm scintillator (no light guide on WLS) 16 pe x (14.2 cm/5cm) x (66% light guide efficiency) = 30 pe/cm 14 pe / MeV deposited 1200 pe thru 40 cm of scintillator 10

11 Light guide design and manufacturing JINR integrated WLS and light guide original est. $25 each! Eljen WLS ~ $216 each Adiabatic light guides $100 to $200 each? CMU machinist? Injection molding ($15 k for mold is probably OK) Casting ( Crystal-Clear urethane?) 11

12 Design Initiated CMU Mechanical Engineering Student Glenn Philon Eng. Francesco Noto (INFN-CT) joins from July 2012 Possible light guide design utilizing over-size guide with lip to facilitate stronger joint 12

13 3D Printed Version of a light-guide design Demonstrates the mechanical engineers have neat toys Unfortunately, opaque ABS plastic Useful for geometry check May be useful as a mold 13

14 Joint Agreements, Addendums, Joint Agreement Status Report, Statement of Work Continual progress Seems to be a delay on JINR end holding up Stage II Monte Carlo Design Study Report soon to be released INFN-CT Group (Vincenzo Bellini et al) joins the HCAL-J Workgroup from July

15 Budget Items Scintillator Plates $ 62.2 k *JINR??? Iron Plates 57.3 k Pittsburgh Company (Quote) Light Pipes 30.0 k **injection molded or machined? Metal Can 22.0 k CMU? Wavelength Shifter 62.2 k Eljen (Quoted for INFN-CT 2013 budget) PMT Housing adapter 2.0 k Stock item Other (Shipping, etc.)??? TOTAL $ k * Scintillator cost based on original JINR estimate with materials doubled and 20% added for inflation. Also exploring FNAL extrusion, and Eljen production, or finding existing scintillator. Non-JINR production likely to be much costlier. ** Injection molding or casting may be significantly less. 15