r&d status of scintillator
DESCRIPTION
R&D status of Scintillator. 8 th ACFA Workshop Daegu, Korea. Youngdo Oh Kyungpook National University. Junsuk Suh, Youngdo Oh, Kihyun Cho, Donghee Kim : Kyungpook National University Intae Yu : SungKyunKwan Univesity Soobong Kim : Seoul National University. Current R&D Status. - PowerPoint PPT PresentationTRANSCRIPT
R&D status of Scintillator
Youngdo OhKyungpook National University
Junsuk Suh, Youngdo Oh, Kihyun Cho, Donghee Kim : Kyungpook National UniversityIntae Yu : SungKyunKwan Univesity
Soobong Kim : Seoul National University
8th ACFA WorkshopDaegu, Korea
Current R&D Status
1. At first, the pure polystyrene bar was produced without PPO, POPOP
The mechanical process is established
2. At second, PPO and POPOP were mixed up with polystyrene The 1st scintillator was produced.
3. Light yield was measured and compared with reference scintillator
Component: Polystyrene pellets + Dopants (primary & secondary)
Dopants
• Primary dopants (blue-emitting) PT(p-Teraphenyl), PPO(2,5-biphenyloxazole) 1-1.5% (by weight) concentration
• Secondary dopants (green-emitting) POPOP(1,4-bis(5-Phenyloxazole-2-yl)benzene), bis-MSB(4-bis(2-Methylstyryl)benzene)
0.01-0.03% (by weight) concentration
Production : Extrusion extrusion is easy to make thin scintillator
Plastic Scintillator
Plastic Scintillator – how does it work ?
Excitation of bas plastic by radiation
Foster energy transfer ( resonant dipole-dipole interaction)
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%)
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
Die and Materials
4cm
1cm2mm1.2 mm
Die profile
Mixture of dopants
Polystyrene : 3 kg PPO : 1.3 % POPOP : 0.03%
First Batch from Misung chemical At first, We try to produce polystyrene bar without PPO and POPOP to make sure the chemical and mechanical process. TiO2 was coextruded to make reflector.
At 2005/5/17 , Misung launched extrusion for scintillator The first product had big groove die had minor problem At 2005/6/9 , the excellent bars were produced. At 2005/7/7, the 2nd bacth has PPO, POPOP.
Evolution
2nd Production PPO and POPOP were mixed up 110 cm bars were produced We produced this batch in air
Comparision of transparency
Referencesamples
Polysyrenebar
New samples
Oxidation made the sample opaquebecause of production in air.
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 light yield
Preparation of test samples
Light Yield MeasurementTrigger : threshold = 100mV , Gate=150ns
New scintillator bars (5 samples)<ADC counts> = 236.8 25.1
Reference scintillator bars(5samples)<ADC counts> = 590.6 76.9
Relative Light Yield of new samplesshows 40.1% of reference samples
Reference sample
New sample
ADC counts
ADC counts
Light Yield MeasurementTrigger : random trigger (1000Hz) , Gate=150ns (amplifier used : x100 )
New 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 new samplesshows 42.3% of reference samples
New sample
Reference sample
ADC counts
ADC counts
Trigger : random trigger (1000Hz) , Gate = 2 s (amplifier not used)
Light Yield Measurement
New scintillator bars (5 samples)<ADC counts> = 26.5 3.5
Reference scintillator bars(5 samples)<ADC counts> = 79.1 8.4
Relative Light Yield of new samplesshows 33.5% of reference samples
New sample
Reference sample
ADC counts
ADC counts
Light Yield Measurement
Pico ammeter is used
Relative Light Yield of new samples shows 36.6% of reference samples’ one.
Reference samples Average = 4.35 RMS = 0.39
New samples Average = 1.59 RMS = 0.18
A
Sample ID
Light Yield Measurement
A
cm cm
ARefernce sample
New sample
Summary and Plan
First Polystyrene bar produced with PPO and POPOP The mechanical process is established Light yield measued for new and reference samples new sample shows ~40% light yield of reference sample low light yield because of oxidation in air
To avoid oxidation, we need to change process under Nitrogen or vaccum
If we get good light yield, then we will change die to produce “thin” scintillator for tile calorimeter thickness : 3mm , width : 1cm