The Status of the Scintillator-based Calorimetry R & D Activities in Korea

1. The Status of the Scintillator-based Calorimetry R & D Activities in Korea DongHee Kim Kyungpook National University LCWS05 (SLAC) March 20, 2005

2. Collaborators Donghee Kim, Kihyun Cho, Jun suhk Suh, Youngdo Oh, Daejung Kong, Jieun Kim, Yuchul Yang, Sunghyun Chang, Kukhee Han, Shabeer Ahmad, Khan Adil Kyungpook National University Soobong Kim, Kyungkwang Ju, Eunjoo Jun, Hyunsoo Kim, Youngjang Lee, Byungsoo Yang, Jieun Jung, Seoul National University Intae Yu, Jaeseung Lee, Ilsung Cho SungKyunKwan University

3. Contents • - Basic Configurations • Current R&D status • Scintillator • SiPM • Simulation • Time schedule • - Future plan

4. Tungsten Scintillator Basic Configuration • Prototype for EM Calorimeter One Layer : Tungsten 20cm X 20cm X 0.3cm (example) Scintillator 1cm X 20cm X 0.2cm X 20 strips  Total : 30 Layers (~ 26 Xo) • The R&D of prototype includes scintillator, SiPM and DAQ system

5. Current R&D Status • Survey almost done for the last several months • Scintillator, W/W-Ni(or other alloy), SiPM, • Scintillator:R&D with Misung Chemical Company Ltd. • Tungsten: • R&D with TaeguTek Ltd • SiPM: • R&D with ETRI • SiPM/Tile R&D has been just started • Simulation is going on

6. Scintillator • The 1st scintillator bars(or strips) for R&D purpose expect • to be produced during this semester • Make sure proper chemical processes • Compare light yield with commercially available scintillators • Design of scintillator strip for LC prototype will be underway • Cost • Cast - $40-60 / kg • Extrusion - $3.5-7 / kg

7. Low cost plastic Scintillator • Extruded plastic scintillator materials - low cost : • Polymer pellets or powder must be used • - Commercial polystyrene pellets are available and cheap • - Component: Polystyrene pellets + Dopants(primary & secondary) • - Primary dopants : PT, PPO -> 1-1.5% concentration • - Secondary dopants: POPOP, bis-MSB ->0.01-0.03% concentration • - The extrusion process can manufacture any shape • Some disadvantage • - Poor optical quality because of • the high particulate matter content in the polystyrene pellets • The rapid cool-down cycle leaves the final material stressed. • → This stress can lead to non-absorptive optical distortions in the material that degrade the attenuation length • We need more R&D

8. Extrusion Process(conventional)

9. Extrusion Process All the work is done at one facility → reduces costs By removing its exposure to another high temperature cycle → reduces hits history of the product → eliminates an additional chance for scintillator degradation

10. Example of the Extruder Scintillator Extruder

11. Photo sensor – SiPM(Silicon Photomultiplier) • Current status for fabrication • Preparation design and process during this semester • - simulation of electric field in Geiger and drift region • - wafer and mask • - fabracation process R&D • Try to make sensor chip using FAB facility at ETRI. • ETRI : Electronics and Telecommunications Research Institute • Process R&D • To get parameters : geometrical and chemical parameter s • Simulation using TCAD • R&D  FAB : 5 ~6 times / year • Packaging , attaching with WLS fiber

12. DAQ system • The proto type has 30 layers(~26 Xo), one layer consists of 20 scintillator bars and tungsten plate  the prototype needs 600 read out channels • We have to think of how to manage these channels  Probably, VME or CAMAC system are not good solution for beam test for 600 channels. • So, the design of electronics and interface with computer is required. • We are considering R&D of electronics for QDC, TDC and USB2 for interface with computer.  need cowork with other group

13. Simulation • 4 cpu (43GHz) and 1.2TB RAID storage allocated. • Mokka and susygen 3.0 installed • SUSY simulation under Mokka • neutralino pair production from e+e- collision • Simulation of prototype started Tungsten-Scintillator Calorimeter using Geant 4

14. Simulation of TiCAL prototype • Structure Absorber : 200mm * 200mm * 3mm Scintillator : 200mm * 200mm * 2mm (We simulated plate, not strip yet)  30 layers ( ~26 X0 ) • Absorber pure W ( density = 19.3g/cm3) : simulaion done alloy W-Ni (W:Ni = 95:5) (density=18.7g/cm3) : simulation done alloy W-Pb (W:Pb = 90:10) (density=18.5g/ cm3) : simulation done • Effective Molier Radius from Simulation W : ~18.9mm W-Ni : ~19mm W-Pb : ~19mm : almost the same

15. % % W-Ni W Energy(GeV) Energy(GeV) Energy Resolution • Electron energy = 1, 5, 10, 20, 50, 80, 100, 200 GeV • Cut range : 0.001 mm W : (15.2  0.3)/sqrt(E) + (0.13  0.12) W-Ni : (13.4  0.7)/sqrt(E) + (0.16  0.29) W-Ni’s energy resolution is compatible with W’s

16. What to do and Future plan • Producing Extruded scintillator • Fabricating sample of SiPM • How to manage DAQ system for prototype • Simulation for the thickness of scintillaor = 25 , 30mm Simulation for alloy with different ratio for W:Pb and W:Ni  Optimize the ratio of thickness for Absorber and Scin and absorber material. • Simulation for scintillator strip • Jupiter and Physics simulation Possible target for physics simulation is SUSY - scan the SUSY parameter space - producing generator data in format of HEPEVT • Prepare for beam test next year