R&D of Strip/Block Scintillators E.P.Jacosalem, S.Iba, N.Nakajima, H.Ono, A.L.Sanchez, A.M.Bacala & H.Miyata GLD Calorimeter Group 8 th ACFA Workshop on Physics and Detector at the Linear Collider EXCO, Daegu, Korea July 12, 2005

Contents: Introduction Research Design and Methodology Scintillator’s length and surface covering dependence on Pulse Height (Strip type) Position dependence (Strip type) Scintillator’s thickness dependence (Block type) Results Summary Future plan

Motivation R&D for new calorimeters Needs fine segmentation Small scintillators Calorimeter Designs (GLD) Past and Existing Layers of strip type plastic scintillators (10x200x2mm) Layers of tile type scintillators (40x40x1mm) PMT as read out WLS Fiber Under construction  Stack of Z-layer + X-layer strip scintillators (10x200x2mm) + Tile-layer (40x40x1mm)  Absorber placed in between layers  SiPM/MPC (Multi pixels Photon Counter) as read out  WLS fiber Introduction

Calorimeter Design under construction New design ?  smaller scintillators  strip type for EM and hadron analog calorimeter  block type for digital hadron calorimeter  best light collection efficiency  WLS fiber  Photon Sensor Photon sensor This study focuses  small strip and block type sensors  different surface coverings  different lengths  thickness

Sensor : Strip type scintillator ( length: 4,8,12, 16cm) Block type scintillator (thickness: 2, 4, 5, 6 and 8mm) Trigger : Scintillator (about 1cmx8cmx5mm ) directly connected to PMT Source : 90Sr (beta-ray) WLS fiber diameter: 1.0mm ; 1.6mm (length: 20 cm) PMT (sensor) : 16 Ch MAPMT H , HV : -950V PMT (trigger) : H3164, HV : -900V Setup Research Design & Methodology

3M Radiant Mirror Film Teflon Black Sheet White Paint with Teflon Gold Coat White Paint Aluminum Evaporation White Paint Surface Covering (1.7mm groove for 1.6mm WLS fiber) 10x60x2mm Strip Type Scintillator 10x40x2mm scintillator (1.4mm groove for 1mm fiber) 10x160x2mm 10x80x2mm 10x40x2mm 10x120x2mm Research Design & Methodology cont..  Compared each type using ADC system  Used WLS fiber with diameter of 1.0mm and 1.6mm  Determined the systematic error

Research Design & Methodology cont.. Block Type Scintillator 10x10mm teflon-wrapped scintillator 8mm thick 6mm thick 5mm thick 4mm thick 2mm thick  fiber hole of 1.1mmΦ at the center  fiber not pass through the other end (1.0mm distance)  measured the thickness dependence on pulse height. sketch of block scintillator

Signal Pulse Height pedestal signal Source point location  Plotted the pulse height (ADC Counts) vs. sensors length with different surface covering  Measured and plotted the position dependence across and along the strip scintillator Research Design and Methodology cont.. fitted pulse height 10mm 2.5 mm Top view Strip-type Sensor Source point To PMT Top view 5.0mm 2.5mm Block-type Sensor Source point To PMT

Results:  3M radiant mirror film has the greatest pulse height.  There is a trend that pulse height slightly increases with sensor’s length for 3M radiant mirror film and Teflon. Syst error 3M radiant mirror film Teflon White paint with teflon White paint Aluminum evaporation Black sheet Gold 3M radiant mirror film Teflon White paint with teflon White paint Aluminum evaporation Black sheet Gold

 3M radiant mirror film has greatest pulse height.  3M radiant mirror film and teflon wrapped scintillators showed that good total reflection occurred when thin air gap is present between reflector and scintillator. Results cont.. syst error 3M radiant mirror film Teflon White paint with teflon White paint Aluminum evaporation Black sheet

Results cont.. 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 measurement along the strip WLS fiber measurement across the strip Position Dependence along the Strip Scintillator (2.5 mm from the center)

small peaks Position Dependence across the Strip Scint (3M radiant film) Results cont..  ‘dip’ is 40% corresponds to scint. thickness(300microns) f0r 1.6mmΦ fiber  small peaks near the fiber (1.6mmΦ fiber)  no significant difference on pulse height values across the strip at 2 different locations (20mm and 10 mm from end)  light yield increases about 100% as fiber diameter is increased from 1.0mm to 1.6mm for 3M radiant mirror film. Fiber diameter 1.6mm 1mm 1.6mmΦ WLS ; source 10 (bl) and 20mm (gr) from the far end 1mmΦ WLS ; source 10mm (bl) and 20mm (r) from the far end

Results cont.. 3M radiant mirror film Teflon  No peak observed at 8mm thick.  Pulse height almost proportional with scint thickness for 3M radiant mirror film.  Light output at 6mm is larger than that of strip scint (10x40x2mm) then the block scint is enough for digital hadron calorimeter. Thickness Dependence of Block Type Scintillator for Digital Hadron Calorimeter

Summary 1. 3M radiant mirror film covered scintillator found to have the greatest pulse height for both WLS fiber diameters (1.0 & 1.6mm). 2. There is a trend that pulse height slightly increases with sensor’s length for 3M radiant mirror film and Teflon. 3. 3M radiant mirror film covered scintillators using 1.6mm Φ WLS fiber had about 100% greater pulse height compared to scintillators with 1.0mmΦ fiber.

Summary cont.. 4. Position dependence along the strip scintillator showed the uniformity of light transmission from the sensor to PMT for 3M radiant mirror film and teflon wrapped scintillators. 5. ‘dip’ is 40% corresponds to scint. thickness(300microns) for 1.6mmΦ fiber 6. Block type scintillator’s pulse height is almost proportional to its thickness

Future plans Do simulation for light transmission for the strip and block type scintillator. Test the best light yield scintillator using photon sensor (MPC/SiPM) as read out through WLS fiber.