ActivitiesAtUTokyo - PDF Free Download

AHCAL Activities at Tokyo W. Ootani ICEPP, University of Tokyo AHCAL main meeting, Dec. 16th, 2016, DESY

AHCAL Activities at Tokyo On-going activities Scintillator material study Study on new readout scheme of AHCAL tile ( Four corner readout ) New activities Cosmic-ray test stand for HBU Study on mega-tile design 2

Study on Scintillator Material Base scintillator material candidates Poly-vinyl toluene (PVT) High light yield Production (casting+machining) is cumbersome. Polystyrene (PS), Estyrene-MS (MS) Moderate light yield Production (injection moulding) is easier. Performance of PS-based scintillator is being optimised. Test sample Scintillator base: Polystyrene (PS) Cut out from large 3mm-thick plate produced by injection molding. Machined only at edges. 1st fluor: p-terphenyl 2nd fluor: POPOP Reference sample Poly-vinyl toluene (PVT): EJ-212 (ELJEN) 3

Results Relative light yield w.r.t PVT(EJ-212) Averaged over repeated measurements with three samples Reproducibility of light yield measurement 5% Less affected by misalignment btw MPPC and tile using optical grease Best light yield reaching up to ~75% of PVT Not totally saturated for higher concentrations light yield ratio to EJ212 [%] p-terphenyl vs. light yield 85 80 75 POPOP 70 0.05% 65 0.07% 60 0.1% 55 50 1.5 1.75 2 2.25 2.5 2.75 3 3.25 p-terphenyl concentration [%] light yield ratio to EJ212 [%] 85 80 75 70 65 60 55 POPOP vs. light yield 50 0.04 0.06 0.08 0.1 0.12 pterphenyl 1.75% 2.0% 2.5% 3.0% POPOP concentration [%] 4

Results Position dependence No significant difference between PVT and PS with different fluor concentrations No difference in attenuation and surface condition within AHCAL tile size Sample-by-sample variation ~8% All three samples come from the same injection Sample-by-sample variation seems smaller for PVT Normalized light collection Need to be controlled for large scale production 1.8 1.6 1.4 1.2 1 0.8 0.6 0 10 20 30 Position [mm] EJ212 (1.75,0.05) (1.75,0.07) (1.75,0.10) (2.0,0.05) (2.0,0.07) (2.0,0.10) (2.5,0.05) (2.5,0.07) (2.5,0.1) (3.0,0.05) (3.0,0.07) (3.0,0.10) Light yield ratio to EJ212 [%] 90 85 80 75 70 65 60 55 50 0 5 10 15 Scintillator Number 5

Next Steps Even higher fluor concentrations will be tested to further improve light yield. Other fluor such as PPO and b-pbd as 1st fluor will also be tried. Best light yield for (PPO+POPOP) was reported in NIMA 835(2016)136. 6

Cosmic-ray Test Stand Test of assembled HBU with cosmic ray (MIP) HBU boards for next prototype detector HBU boards with new tile design (mega-tile, four corner, ) Test of multiple HBU boards in parallel for future mass assembly Mainz CR test stand Scintillators on top and bottom of SMD HBU board to trigger cosmics Strip design for cost reduction Each strip 36,5 x 3,015 cm² Components: 24 PMTs 24 ch. HV 24 ch. VME discriminator Dark box (1,8x1,3x0,8 m³) FPGA for trigger logic, event validation, time stamping of triggered events 7

Possible Design of Cosmic-ray Test Stand @Tokyo Two possibilities of trigger counter design under consideration Design1: Large scintillator plate with WLS fibre+sipm readout WLS fibres embedded in grooves Position resolution groove interval (~5mm) Grooves on both top and bottom surfaces in x-y orientations Design2: Scintillating fibre layer + SiPM readout Two layer with (square) scintillating fibres with x-y configuration Position resolution 1mm (fibre thickness) maybe too much? Design 2 Better performance, but even lower cost anticipated with multiple fibres readout (see later slide) X Y Design 1 X Y Position reconstruction 8

Scintillator Plate with WLS Fibre Readout Scintillator plate Size: ~42 42cm 2 slightly larger than HBU to minimise edge effect Thickness: 5-10mm Groove interval: ~5mm position resolution 5mm (to be tested) 83 grooves on each surface Base material: PVT Two scintillator plates (top and bottom) WLS fibre Kuraray Y11(200) 1mm-φ SiPM MPPC 3 3mm 2 Multiple fibres readout (see next slide) Scintillator plate with grooves for WLS fibre (grooves on top side only) 9

Previous Studies by Other Groups Kyoto University Source Dark Matter Particle Explorer @China 10mm 8cm T1 T2 5cm 3.5cm 5.5cm Anti-Coincidence Detector(ACD) 80cm ACD is composed of a 80x80x1cm plastic scintillator and two layer WLS fiber arranged in the x and y direction embed in grooves on two surface of the scintillator. Read out device is SiPM or Multi-Anode PMT. T3 1cm Fiber interval 1.2cm The scheme seems possible. N.B. Scintillator strip with WLS fibre readout is always possible if it doesn t work. 10

SiPM Readout Multiple fibres readout by single SiPM to reduce # of readout channels Multiple fibres with an interval of a few tiles (3 tiles interval ~18 fibres) are bundled and readout by single SiPM 5 fibres readout by single SiPM # of readout ch reduced by a factor of 5 # of readout ch: 32(X) + 32(Y) (double side readout, each plate) Fibre hit defined on grid ambiguity can be solved by looking at tile hit Multiple fibres readout can also be applied to scintillator fibre layer design No pileup for cosmic-ray event no ghost hit due to pileup SiPM Real hit Fake hit Tile hit 11

Readout Electronics EASIROC-based SiPM readout module Each module can drive 64 MPPCs Synchronisation with CCC was already successfully demonstrated at strip-cal test beam experiments by Shinshu group We have two of them, which can cover all ch for CR test stand. DAQ setup for test beam by Shinshu group Easiroc EasiRoc Mod. Easiroc EasiRoc Mod. 12

Discussion and Plan Measurement of inside tile response with σ~5mm @CR test stand Useful for new tile design, especially mega-tile design A few days data-taking for ~500events @5 5mm 2 (~20k events over single tile) Better angle determination better correction for path length within tile Plan Prototype tests and simulation studies to optimise design parameters WLS fibre groove interval position resolution Scintillator plate thickness Interval for fibre bundle Construct full-size setup Help from Mainz group would be welcome for setting-up and commissioning of the test stand. 13