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 )

서준석, KPS, 2005.10.22 2

1. Motivation

2. Extruded Plastic Scintillator

3. Current R&D Status

4. Summary and plan

Contents

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

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Machining of raw tile Covering with reflector

$25/tile → $80/kg ~$300/sheet

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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

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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

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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

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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

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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

photon

Detector (PMT, photo diode …. )

Base plastic

PPO (~1%)

POPOP(~0.05%)

Use WLS fibers as readout

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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

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Extrusion Process

Produced at MiSung Chem. co. In Korea

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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 1st 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.

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Mechanical establishment of tile Produce polystyrene bar without PPO & POPOP for mechanical establishment TiO2 was co-extruded to make reflector for test. Excellent bars were produced assure mechanically Then, 1st batch came with PPO and POPOP.

Progress

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Production of Scintillator bar

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Comparison of transparency

Referencesamples

Polystyrene(only) bar 1st batch

Oxidation made the sample opaquebecause of production in air.

Recent batch

Progress

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Pulse Height (1st batch)

Our scintillator bars (5 samples)<ADC counts> = 225.9 24.9

Reference scintillator bars(5 samples)<ADC counts> = 534.8 56.9

Relative Light Yield of the first samplesshows 42.3% of reference samples

Our sample(1st batch)

Reference sample

ADC counts

ADC counts

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Light Yield

0

1

2

3

4

5

6

7

0 2 4 6

Sample #

Curr

ent[

μA]

MINOS507075080750809A50809B50810A50810B50813A50817A

Progress

0%

20%

40%

60%

80%

100%

0 2 4 6

Sample #

Relat

ive L

Y

507075080750809A50809B50810A50810B50813A50817A

Reference tile to be 100% light yield

Relative Light Yield

Progress

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Light Yield (currently the best one)

Reference Sample

New Sample

Relative Light Yield of new samples shows

(93±8)% of reference samples’ one.

0

1

2

3

4

5

6

7

0 2 4 6

Sample #

Cur

rent

[μA

]

50817AMinos5.76 5.35

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Position Scan

0

1

2

3

4

5

6

7

- 40 - 20 0 20 40

Distance [mm]

Curr

ent[

μA

]

Minos 1

Minos 3

Minos 6

Minos 6

Minos 9

K 1

K 3

K 4

K 5

K 6

Scan across the fiber

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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 mmfor WLS fiber

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backup

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Preparation of test samples

WLS fiber

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Scintillator test setup

Typical cosmic ray From reference sample + WLS

FAN IN-OUT

Logicunit

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