1. 서준석, KPS, 2005.10.22 1 R&D of Extruded Plastic Scintillator 서 준석 김 동희, 양 유철, 오 영도, 장 성현, 조 기현, KHAN Adil, MIAN Shabeer Ahmad ( 경북대학교 )

2. 서준석, KPS, 2005.10.22 2 1.Motivation 2.Extruded Plastic Scintillator 3.Current R&D Status 4.Summary and plan Contents

3. 서준석, KPS, 2005.10.22 3  Probably the most commonly used organic scintillator in nuclear & high energy physics  Advantage  Fast response time (≤3ns)  Ease of manufacture  Versatile: plates, fibers, tiles, blocs  But Plastic Scintillator

4. 서준석, KPS, 2005.10.22 4 Machining of raw tileCovering with reflector $25/tile → $80/kg ~$300/sheet

5. 서준석, KPS, 2005.10.22 5  Disadvantage  High cost :  $ 40/kg-$60/kg (2000)  $ 80/kg (2004)  $ 100/kg (2005 ?) → $??/kg (2006)  Machining of the raw sheets → significantly add to the final detector cost & time  Not for very large detector like MINOS detector (300,000 kg scintillator) Plastic Scintillator

6. 서준석, KPS, 2005.10.22 6 To lower costs ⇒ Extruded Scintillator ☺  Advantages:  Use commercial polystyrene pellets → cheap  Processing flexibility → Manufacture of essentially any shape with reflector  Experimental applications:  MINOS for two detectors: 300 ton of scintillator strips  D0 for two preshower detectors  Star for a shower max. detector in the em. end-cap calorimeter  MINERVA for an active target  ILC calorimeter  And more … maybe for your future detector

7. 서준석, KPS, 2005.10.22 7  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) Basic Configuration of a ILC Calorimeter Tungsten Scintillator

8. 서준석, KPS, 2005.10.22 8  Component: Polystyrene pellets + Dopants (primary & secondary)  Dopants Primary dopants (UV-emitting) PPO(2,5-biphenyloxazole), PT(p-Teraphenyl) 1-1.5% (by weight) concentration Secondary dopants (blue-emitting) POPOP(1,4-bis(5-Phenyloxazole-2-yl)benzene), bis-MSB(4-bis(2-Methylstyryl)benzene) 0.01-0.03% (by weight) concentration Extruded Plastic Scintillator

9. 서준석, KPS, 2005.10.22 9 Plastic Scintillator – how does it work ? Excitation of base plastic by radiation Faster energy transfer Emit UV ~340nm Absorb UV photon Emit blue ~400nm 10 -8 m 10 -4 m photon Detector (PMT, photo diode …. ) Base plastic PPO (~1%) POPOP(~0.05%) Use WLS fibers as readout

10. 서준석, KPS, 2005.10.22 10 Die and Materials  Die profile  Mixture of dopants Polystyrene : 6 kg PPO : from 1.0 % POPOP : from 0.03% This was originally for MINOS tile We start to produce this tile for a reference produce and compare the light yield with reference tile

11. 서준석, KPS, 2005.10.22 11 Extrusion Process Produced at MiSung Chem. co. In Korea

12. 서준석, KPS, 2005.10.22 12 Current R&D Status  At first, the pure polystyrene bar was produced without PPO, POPOP  The mechanical process has been established  At second, PPO and POPOP were mixed up with polystyrene  The 1 st scintillator had been produced.  Many scintillator strips have been produced with different situations since then.  different amount of PPO and POPOP, nitrogen and/or vacuum, various mix-up methods etc.

13. 서준석, KPS, 2005.10.22 13 Mechanical establishment of tile  Produce polystyrene bar without PPO & POPOP for mechanical establishment  TiO 2 was co-extruded to make reflector for test.  Excellent bars were produced  assure mechanically  Then, 1 st batch came with PPO and POPOP. Progress

14. 서준석, KPS, 2005.10.22 14 Production of Scintillator bar

15. 서준석, KPS, 2005.10.22 15 Comparison of transparency Reference samples Polystyrene (only) bar 1 st batch Oxidation made the sample opaque because of production in air. Recent batch Progress

16. 서준석, KPS, 2005.10.22 16 Pulse Height (1 st batch) Our scintillator bars (5 samples) = 225.9  24.9 Reference scintillator bars(5 samples) = 534.8  56.9 Relative Light Yield of the first samples shows 42.3% of reference samples Our sample(1 st batch) Reference sample ADC counts

17. 서준석, KPS, 2005.10.22 17 Light Yield Progress Reference tile to be 100% light yield Relative Light Yield Progress

18. 서준석, KPS, 2005.10.22 18 Light Yield (currently the best one) Reference Sample New Sample Relative Light Yield of new samples shows (93±8)% of reference samples’ one.

19. 서준석, KPS, 2005.10.22 19 Position Scan Scan across the fiber

20. 서준석, KPS, 2005.10.22 20 Summary and Plan  First Polystyrene bar produced with PPO and POPOP  The mechanical process has been established  Light yield measured for new and reference samples  Currently the best samples show (93±8) % light yield of the reference sample  We will change the die to produce “thin” scintillator for Tile/W calorimeter  thickness : 2-3 mm, width : 1-2 cm hole : 1.2 mm for WLS fiber

21. 서준석, KPS, 2005.10.22 21 backup

22. 서준석, KPS, 2005.10.22 22 Preparation of test samples WLS fiber

23. 서준석, KPS, 2005.10.22 23 Scintillator test setup Typical cosmic ray From reference sample + WLS FAN IN-OUT Logic unit Gate Generator 100 ns Delay VME readout Disc  5 reference samples and new samples with the same geometrical shape and size were used to compare the light yield