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

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

서준석, KPS,  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

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

서준석, KPS,  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

서준석, KPS, 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

서준석, KPS,  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

서준석, KPS,  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) % (by weight) concentration Extruded Plastic Scintillator

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

서준석, KPS, 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

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

서준석, KPS, 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.

서준석, KPS, 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

서준석, KPS, Production of Scintillator bar

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

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

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

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

서준석, KPS, Position Scan Scan across the fiber

서준석, KPS, 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

서준석, KPS, backup

서준석, KPS, Preparation of test samples WLS fiber

서준석, KPS, 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