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 3rd ILC Workshop(Konkuk U.) Apr 1, 2005

2. Collaboration KOREA Kyungpook National University Seoul National University SungKyunKwan University JAPAN Kobe University Shin-Su University Niigata University Tsukuba University RUSSIA Dubna

3. Collaborators(Korea) DongHee Kim, Kihyeon Cho, Jun Suhk Suh, Youngdo Oh, Daejung Kong, Hongjoo Kim, Jieun Kim, Yuchul Yang, Sunghyun Chang, Kukhee Han, Shabeer Mian, Adil Khan Kyungpook National University Soo Bong Kim, Kyungkwang Ju, Eunjoo Jun, Hyunsoo Kim, Youngjang Lee, Byungsoo Yang, Jieun Jung Seoul National University Intae Yu, Jaeseung Lee, Ilsung Cho SungKyunKwan University

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

5. 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

6. Current R&D Status • Survey almost done for the last several months • Scintillator, W/W-Ni(or other alloy), SiPM, • Closely collaborate with Japan group • 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

7. Scintillator • The 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

8. 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

9. Extrusion Process(conventional)

10. 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

11. Example of the Extruder Scintillator Extruder

12. Sample scintillator strip • Sample scintillator • 10 MINOS tiles will be used for comparison with our scintillator strips which will be produced by the company. • 10cmX4.1cmX1cm • For improving light yield • Cosmic ray and 90Sr will be used

13. Profile of Scintillator Strip Misung Chemical Company will produce this type of tile at first. • All kinds of R&D will be going on while productions.

14. What is SiPM ? • SiPM – Silicon Photo Multiplier • SiPM is a Russian invention, reported by Boris Dolgoshein and colleagues at Moscow Engineering and Physics Institute, Lebedev Physical Institute, and Pulsar Enterprise (Moscow). • Ref: NIM A 504 (2003) 48 - 52; NIM A 442 (2000) 187-192 • SiPM consists of ~10**3 micropixels, size ~30microns, with very thin (0.75 micron) high field depletion layer.

15. How does SiPM work ? • Pixels are resistively isolated, each working in limited Geiger mode as “binary” devices. The pixels signals are ganged together by aluminum strips and the summed signal is effectively analog, with dynamic range limited by the number of pixels • Gain ~10**6 Bias voltage ~25V ~ 70V QE < 20% • Sees single pe, and resolves adjacent many-pe peaks with low noise • Works In high magnetic fields • Time resolution ~30ps for 10 pe

16. View of SiPM • Fabricated at Russia • Dimension : 1mm x 1mm , ~1000 pixels

17. View of SiPM Anode Pixels Kathode

18. SiPM – measured parameters Pixel Gain • Conditions • Yellow LED(595nm) • Wave guide • LED t impulse = 10ns • ADC : LeCroy 2249A • Gate = 80ns • Temperature = + 20 ℃ Efficiency Dark rate Provided by Prof. K. Kawagoe

19. SiPM test setup at KNU

20. 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

21. 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 Japan group

22. Simulation • Start simulation with different passive absorber configurations • Mokka and susygen 3.0 • SUSY simulation under Mokka • neutralino pair production from e+e- collision • Simulation of prototype started Tungsten-Scintillator Calorimeter using Geant 4

23. 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) : alloy W-Ni (W:Ni = 95:5) (density=18.7g/cm3) : alloy W-Pb (W:Pb = 90:10) (density=18.5g/ cm3) : alloy W-Pb (W:Pb = 75:25) (density=18.2g/ cm3) : • Effective Molier Radius from Simulation W : ~18.9mm W-Ni : ~19mm W-Pb : ~19mm : almost the same

24. % % 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 : (15.14  0.24)/sqrt(E) + (0.217  0.099) W/Ni (Ni 5%) : (15.39  0.20)/sqrt(E) + (0.070  0.084) W/Pb(Pb 10%) : (15.13  0.19)/sqrt(E) + (0.086  0.079) W/Pb(Pb 25%) : (14.89  0.09)/sqrt(E) + (0.149  0.038) W, W-Alloy or even W-Pb(25%) may be compatible of.

25. What to do and Future plan • Producing Extruded scintillator -> 1st prototype in April • 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

26. 검출기 산업체(검출기) • 모든 것이 내수가 가능하다고 사료되며 내수로 돼야 한다는 철학. •  R & D를 통하여 시제품 제작 및 시험을 통한 제작공정을 확립 • Scintillator - 압출형 섬광판 – 미성화학 (플라스틱회사) • 텅스텐 – TaeguTeK(전 대한중석) • Silicon PM, Wafer – 경북대반도체연구소, 서울대반도체공동연구소, 센스㈜, ETRI Mask 제작 – PKL, 두퐁, 에스와이테크, 메디오피아인터네셔널 • -본딩, PCB, signal cable • Readout board (ASIC 포함) - Addone 회사