R&D status of Scintillator
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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.

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R&D status of Scintillator

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R d status of scintillator

R&D status of Scintillator

8th 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


R d status of scintillator

Current R&D Status

  • 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


  • R d status of scintillator

    Plastic 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


    R d status of scintillator

    Plastic Scintillator – how does it work ?

    Excitation of bas plastic by radiation

    Base plastic

    10-8 m

    Foster energy transfer ( resonant dipole-dipole interaction)

    PPO (~1%)

    Emit UV ~340nm

    10-4 m

    photon

    Absorb UV photon

    POPOP(~0.05%)

    Emit blue ~400nm

    photon

    Detector (PMT, photo diode …. )


    R d status of scintillator

    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


    R d status of scintillator

    1.2 mm

    2mm

    1cm

    4cm

    Die and Materials

    • Die profile

    • Mixture of dopants

      Polystyrene : 3 kg

      PPO : 1.3 %

      POPOP : 0.03%


    R d status of scintillator

    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


    R d status of scintillator

    2nd Production

    • PPO and POPOP were mixed up

    • 110 cm bars were produced

    • We produced this batch in air


    R d status of scintillator

    Comparision of transparency

    Oxidation made the sample opaque

    because of production in air.

    Polysyrene

    bar

    Reference

    samples

    New samples


    R d status of scintillator

    FAN

    IN-OUT

    Disc

    Logic

    unit

    Gate

    Generator

    100 ns

    Delay

    VME

    readout

    Scintillator test setup

    • 5 reference samples and new samples with the same geometrical shape and size were used to compare light yield

    Typical cosmic ray

    From reference sample + WLS


    R d status of scintillator

    Preparation of test samples


    R d status of scintillator

    Light Yield Measurement

    Trigger : threshold = 100mV , Gate=150ns

    New sample

    New scintillator bars (5 samples)

    <ADC counts> = 236.8  25.1

    Reference scintillator bars(5samples)

    <ADC counts> = 590.6 76.9

    ADC counts

    Reference sample

    Relative Light Yield of new samples

    shows 40.1% of reference samples

    ADC counts


    R d status of scintillator

    Light Yield Measurement

    Trigger : random trigger (1000Hz) , Gate=150ns (amplifier used : x100 )

    New sample

    New scintillator bars (5 samples)

    <ADC counts> = 225.9  24.9

    Reference scintillator bars(5 samples)

    <ADC counts> = 534.8 56.9

    ADC counts

    Reference sample

    Relative Light Yield of new samples

    shows 42.3% of reference samples

    ADC counts


    R d status of scintillator

    Light Yield Measurement

    Trigger : random trigger (1000Hz) , Gate = 2 s

    (amplifier not used)

    New sample

    New scintillator bars (5 samples)

    <ADC counts> = 26.5  3.5

    Reference scintillator bars(5 samples)

    <ADC counts> = 79.1  8.4

    ADC counts

    Reference sample

    Relative Light Yield of new samples

    shows 33.5% of reference samples

    ADC counts


    R d status of scintillator

    Reference samples

    Average = 4.35

    RMS = 0.39

    A

    New samples

    Average = 1.59

    RMS = 0.18

    Sample ID

    Light Yield Measurement

    Pico ammeter is used

    Relative Light Yield of new samples shows 36.6% of reference samples’ one.


    R d status of scintillator

    A

    A

    cm

    cm

    Light Yield Measurement

    Refernce sample

    New sample


    R d status of scintillator

    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


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