detector with plastic scintillators

International Workshop on a Far Detector in Korea for theJ-PARC Neutrino Beam, KIAS, Nov 18-19, ‘05

Detector with Plastic Scintillators

DongHee Kim

Kyungpook National University


1. Extruded Plastic Scintillator

2. Current R&D Status

3. Summary of R & D so far

4. Application to Far Detector

5. Summary & Conclusion

Contents


Extruded Scintillator • Comparing with Casting method:

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 K2K – SciBar detector And more …many applications for your future detectors


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


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


Die and Materials Die profile

Mixture of dopants Polystyrene : 100% 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


Extrusion Process

Produced at MiSung Chem. co. In Korea


Current R&D Status

The pure polystyrene bar was produced (w/o PPO, POPOP) The mechanical process has been established and choose the best

polystyrene

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.


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


Production of Scintillator bar


Comparison of transparency

Referencesamples

Polystyrene(only) bar 1st batch

Oxidation made the sample opaquebecause of production in air.

Recent batch

Progress


Preparation of test samples

WLS fiber


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


products of LG and Dongbu chemical company

totally about 10 polystyrenes tested

chose LG 25 E (the best attenuation length etc..)

Polystyrene only

Attenuation Length

0.00

5.00

10.00

15.00

20.00

25.00

4 8 12 16 20

[cm]

Curre

nt[μ

A]

DongbuLG 25 ILG 20 HLG 25 E


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


Light Yield

0

1

2

3

4

5

6

7

0 2 4 6

Sample #

Curr

ent[

μA]

MINOS507075080750809A50809B50810A50810B50813A50817AProgress

0%

20%

40%

60%

80%

100%

0 2 4 6

Sample #

Relat

ive L

Y

507075080750809A50809B50810A50810B50813A50817A

Reference tile to be 100% light yieldRelative Light Yield

Progress


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


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


Summary of R & D so far

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 course, need much more R & D in the future improving attenuation length, light yield, uniformity and radiation hardness etc.. Fiber(WLS and clear) will be also R & Ded in the Misung company

We can apply this to the detectors The LHC and LC … calorimeters Neutrino LB Experiments Reactor experiments etc….


Application to the Far Detector

• For appearance experiment

Totally active is appropriate

• Nova already chose liquid scintillator option

• Here we consider the plastic scintillator option

• Reference from Nova proposal – Thanks for them!

• Nova adopted Liquid scintillator option

e



Total Plastic Scintillator Calorimeter

• all active absorber• 300 X0 depth• ~ 2000 Layers• each layer : 15m x 15m • 27kT plastic scintillator• one bar : 6cm x 6cm x 15m• 250 bars/layer• x-y positioning every other layer• Total ~ 500k channels

120m

15m

15m

6cm

6cm


Scintillator Bar

• Polystyrene + PPO + POPOP

• 2mm WLS Fiber embedded in the bar

• Light Reflector(TiO2)

• readout both ends by APD(or SiPM??)

• need about 1M APDs

• Ensure enough light yields

• with 2mm WLS fiber (4time better light collection compared with 1mm fiber) and Both end readout


Cost Estimates

itemtotal weight

(kg)cost($)

Polystyrene 26721900 43554391

PPO 270000 38830297

POPOP 8100 5280920

TiO2 and fiber etc

sum ~ 27kT ~ 87M

1. Scintillator & Fiber : $ 87M

2. Electronics and DAQ : $ 8M

3. Building & outfitting etc.. : $20M

4. Total cost : ~ $114M

Scintillator costs• Very rough estimates• Need more studies


will start R & D for this far detector

Plastic scintillator option may also be feasible

scintillator R & D will go on as it scheduled

Summary


Backup



Option B :Sampling Calorimeter

• Scintillator/Fe Sandwitch• 300 X0 depth• ~ 230 Layers• each layer : 15m x 15m • Iron 15m x 15m x 2cm • Iron 2cm = 1.14 X0 • 8kT iron • 3.1kT plastic scintillator• one strip: 6cm x 6cm x 15m• 250 strips/layer• x-y positioning every other layer

~20m

15m

15mScintillator Bar

2cm thick Fe

detector with plastic scintillators

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