Systematic Studies of Small Scintillators for New Sampling Calorimeter E.P.Jacosalem, S.Iba, N.Nakajima, H.Ono, A.L.Sanchez, A.M.Bacala & H.Miyata GLD Calorimeter Group LCWS06 (Linear Collider Workshop 2006) Indian Institute of Science, Bangalore, India March , 2006

2 Outline: Introduction Calorimeter design Motivation Bench Test Set-up Results Summary Future plans Acknowledgment

3 Previous Calorimeter Designs 10x200x2mm Strip-array EM Calorimeter 40x40mm Tile Calorimeter Module Beam experiments at KEK: T517 in 2002 & T454 in 2004

4 Proposed Calorimeter Designs (GLD DOD Draft) EMCAL Scintillator Design Motivation : To come up with the optimal size of small strip type scintillator and appropriate wrapping reflector that will have the best light collection efficiency HCAL Scintillator Design MPPC

5 Bench Test set-up Sensor PMT HV 90 Sr WLS fiber Collimator HV Black Box Trigger Discri- minator Octal Pulse Amp Gate Gen 1 Gate Gen 2 Gate Gen 3 ADC Int. Reg. Cable 15m (75ns delay) PC Veto Gate CH7 Logic Circuit

6 WLS fiber 16 Ch PMT Trigger scint Collimator & source sensor Photograph of the Bench test set-up

7 Strip Type Scintillator White Paint wrapping reflector (1.7mm groove for 1.6mm WLS fiber) 10x40x2mm scintillator (1.4mm groove for 1mm fiber) 10x160x2mm 10x80x2mm 10x40x2mm 3M Radiant Mirror Film Teflon Black tape White Paint + Teflon Gold Coat White Paint Aluminum Coat 10x120x2mm WLS fiber dia: 1.0mm ;1.6mm 10x10mm teflon-wrapped scintillator 8mm thick 6mm thick 5mm thick 4mm thick 2mm thick Block Type Scintillator

8  Plotted the pulse height (ADC Counts) vs. sensor’s length with different wrapping reflectors  Measured and plotted the position dependence across and along the strip scintillator  Determined the number of photoelectrons SignalPulse Height pedestal signal fitted pulse height 1.0cm 2.5 mm Top view Strip-type Sensor Source point

9 Pulse height slightly increases except for white paint and black tape wrapped scintillator Greatest pulse height : 3M reflective mirror film and teflon Systematic error: 3M : ± 17 ; Teflon : ± 15 Teflon Whitepaint + Teflon Aluminum coat Black tape Whitepaint 3M radiant mirror film

10 Greatest light yield: 3M reflective mirror film wrapped scint. Systematic error: 3M : ± 5.4 ; Teflon : ± 10 Teflon Whitepaint + Teflon Aluminum coat Black tape Whitepaint 3M radiant mirror film

11 PMT 1.6mmΦ WLS_3Mmirror film 1.0mmΦ WLS_3Mmirror film 1.6mmΦ WLS_ Teflon 1.0mmΦ WLS_ Teflon  Position dependence along the strip scintillator showed the uniformity of light transmission from the sensor to PMT. Keyhole WLS fiber measurement along the strip measurement across the strip

12 small peaks Fiber diameter 1.6mm 1mm  ‘dip’ at the center  small peaks near the fiber (1.6mmΦ fiber)  no significant difference on PH values at 2 different locations  light yield increases 100% as fiber diameter increase for 3M radiant mirror film. r = 20mm r = 30mm r = 20mm r = 30mm r = source distance from the edge

13 3M radiant mirror film Teflon Top view 5.0mm 2.5mm Block-type Sensor Source point  No trigger is observed at 8mm thick.  Pulse height directly proportional with scint thickness.  Pulse height about the same level as strip scintillator.

14  Comparison of simulation and bench test results on PH dependence on sensors length and wrapping reflector.  Simulation results is in good agreement with the bench test results. simulation results (by Sayaka Iba) 3M radiant mirror film Whitepaint Black tape

15 Bench test result  simulation results show a drop at fiber location is ~50%; no drop at both sides; narrow opening drop).  bench test ~ 40% ; with drop at both sides; wider opening Comparison of Bench Test & Simulation results on Position Dependence across the 10x40x2m 3M radiant film covered scintillation Simulation result (by: Sayaka Iba)

16  Ave. light yield is 9.2 photoelectrons in a 10x40x2mm 3M radiant mirror film wrapped scintillator PH=13.8 ADC PH = ADC

17 Summary 3M radiant mirror film covered scintillator has the greatest light yield for both WLS fiber diameters (1.0 & 1.6mm). Light yield increases by 100% as WLS fiber diameter increases from 1.0mm to 1.6mm for 3M radiant mirror film wrapped scintillator Block type scintillator’s pulse height is proportional to its thickness.

18 Summary cont.. Position dependence along the strip scintillator shows the uniformity of light transmission of the WLS fiber from scintillator to PMT. Dip at the center of the strip scintillator is dependent on the size of fiber groove. Simulation results for the PH dependence on sensor’s length and wrapping reflector in good agreement with the bench test results.

19 Future plans Do simulations for other type of scintillators. Test the best light yield scintillator using photon sensor or MPPC as read out through WLS fiber.

20 Acknowledgment MSU-IIT, Philippines CHED – COE, Philippines Department of Physics, Niigata University, Japan Japan Student Services Organization (JASSO) Short-Term Student Exchange Promotion Program Dr. T. Takeshita ACFA, Prof. S. Kurokawa LCWS06 Organizers

Simulation conditions: Scintillator: x: width : 10mm; Y: length: 40,80, 120mm Fiber : diameter: 1.0mm ; length: 20cm Attenuation length of scintillator: 400mm ; fiber : 3500mm Refractive index scintillator : 1.50 ; fiber : 1.49 Density of fiber (dye of fiber) : ppm Absorption rate of fiber : Wrapping reflector reflectivity: – 3M mirror film: top and bottom 95%; side 80%; total reflection – white paint: top and bottom 95%; side 90%; random reflection –Black tape: top and bottom 30%; side 20%; scint & air 90%; total reflection

Flow of simulation: by S. Iba