Beam test of scintillator strips Miho NISHIYAMA Shinshu University ・ scintillator strip calorimeter ・ Kuraray scintillator strips and KNU extruded ・ the result of DESY beam test ・ KEK beam test ・ results ・ conclusion and plan

Scintillator strip 4.5cm 1cm MPPC ・ sampling calorimeter scintillator strips ＋ W ・ MPPC : light sensor ・ PFA requires scintillator fine segmented. → We need 10M scintillator strips. Production cost of scintillator strips must be cheap. Thickness ： 0.3cm Scintillator strip calorimeter

Comparison of scintillator strip MethodExtrudedCasting ProductionExtrusionCasting and machining CharacterFiber hole and reflector (TiO2) are made at the same time. High accuracy of fiber hole ProblemAccuracy of fiber holeexpensive CompanyMisung Chemical Company and Kungpook National University Kuraray

Beam position (mm) Signal (ADC counts) Casting reflector film Extruded TiO 2 Uniformity Layer # Strip # Casting Reflector film Extruded TiO 2 The result of DESY beam test Response of MIP 2007 spring… Extruded scintillator strips ・ Light yield is low. ・ Uniformity is bad. Read out : fiber Signal (ADC counts)

Fiber – MPPC bad matching Fiber Sensitive surface of MPPC extruded ・ Some extruded scintillator strips have too big fiber hole. ・ Sometimes fiber holes aren’t correctly centered. Extruded scintillator strips Too big fiber hole

The objective of KEK beam test We’ll use extruded scintillator strips at FNAL beam test in this summer. So we need them because their cost of production is cheap. Extruded scintillator strips have some problems. position and size of fiber hole Beam test with using carefully chosen extruded scintillator strip was carried out and compared with Kuraray.

KEK Fuji beam line ・ Electron beam ・ This beam is made form bremsstrahlung photons from KEKB ring ・ Beam spot size: ~ 3cm x 4 cm ・ Beam energy : 3 GeV ・ Rate: 3 GeV beam

Setup Semiconductor Tracker (borrowed by ATLAS group) 12cm×6cm Resolution vertical : 23μm horizontal: 580μm Veto counter Beam e - Scintillator Fiber Tracker Trigger counters Movable stage Scintillator strips scintillator Beam e - Semiconductor Tracker Scintillator Fiber Tracker Scintillator strips Movable stage Veto counter Scintillator Setup of side view

A B C D E F beam Scintillator Strips MethodRead- out Cover Thickness (mm) A1 Extruded Fiber TiO 2 3 No fiber ! A2good positioning B1 Reflector big hole B2matched hole C1DirectTiO 2 D Kuraray Direct Reflector 2 E 3 FFiber reference 8 layers with different types of strips 4 same type strips per one layer

MIP selection MIP selected strip spacer Only pedestal signal For the selected strip, MIP event must satisfy following conditions: ・ In the same layer, strips show the pedestal signal but the selected strip. ・ In the front and the rear layer, the strips at same position of the selected strip show the MIP signal. MIP signal e-e-

All collected events MIP events Response for MIP extruded TiO 2 No fiber extruded TiO 2 good matching extruded reflector bad matching extruded reflector good matching extruded TiO 2 Kuraray reflector Kuraray reflector thickness:2mm Kuraray reflector reference Number of events (log scale) Signal (ADC counts)

Response for MIP Variation of strip by strip Number of events (log scale) Signal (ADC counts) All collected events MIP events Extruded scintillator strip ＋ reflector film good matching These plots show the variation of strip by strip is big.

Uniformity extruded TiO 2 No fiber extruded TiO 2 good matching extruded reflector bad matching extruded reflector good matching extruded TiO 2 Kuraray reflector thickness:2mm Kuraray reflector Kuraray reflector reference Beam position (mm) Signal (ADC counts)

Beam position (mm)Signal (ADC counts) Uniformity Variation of strip by strip Extruded scintilattor strip ＋ reflector film good matching These plots show the variations of the uniformity aren’t so big. However light yields aren’t same.

Conclusion The position of fiber and MPPC is important. Reflector film works better than TiO 2. ⇒ We asked KNU to make extruded scintillator with the precise size of fiber hole and position without TiO 2. Plan More detail analysis about KEK beam test is neccesary. In this summer, FNAL beam test will be carried out using improved extruded scintillator strips.

Does direct light cause bad uniformity? 1mm Direct light 100% Direct light 25% 1mmφ Signal (ADC counts) Beam position (mm) Extruded TiO 2 Extruded TiO 2 Good matching

Setup PMT Discriminator Gate Generator 90 Sr MPPC ADC (V bias = 76.5 [ V]) Trigger scintillator Thermostatic chamber (25 ℃ ) Extruded with TiO 2 Collimator with 2 mm  hole Signal input Gate input AMP (x63) 72 [ns] Position of  -ray source × x mm MPPC 57mm

Measurement of 3 types 1mmφ White paint to shield direct light KIMOTO reflector to shield direct light Scintillator with TiO 2 Nothing to shield direct light

Result of measurement Fiber : 43mm Fiber : 57mm ＋ KIMOTO reflector Fiber : 43mm ＋ paint MPPC side

Conclusion Direct light causes bad uniformity. → We have the plan to use the coupler as the left figure shows. Using this, direct light is shielded and the fiber position becomes stable.

Back up

Extruded scintillator strip with a fiber hole （ A,B ） A1 A2 matched hole B2 bigger hole B1 Type : A covered with TiO2 A1 : fiber - MPPC bad matching A2 : fiber – MPPC good matching Type : B covered with KIMOTO reflector film B1 : bigger hole B2 : matched hole MPPC sensitive surface

Scintillator Assembly scintillator strips 3mm black sheet KIMOTO reflector film frame spacer 9 strips for a layer 12cm 9cm FCB With MPPC 4.5cm 0.4cm 1cm Thickness 0.3cm

Response for MIP(strip1) All collected events MIP events extruded TiO 2 No fiber extruded TiO 2 extruded reflector extruded reflector extruded TiO 2 Kuraray reflector Kuraray reflector thickness:2mm Kuraray reflector reference Number of events (log scale) Signal (ADC counts)

All collected events MIP events extruded TiO 2 No fiber extruded TiO 2 extruded reflector extruded reflector extruded TiO 2 Kuraray reflector Kuraray reflector thickness:2mm Kuraray reflector reference Number of events (log scale) Signal (ADC counts) Response for MIP(strip3)

All collected events MIP events extruded TiO 2 No fiber extruded TiO 2 extruded reflector extruded reflector extruded TiO 2 Kuraray reflector Kuraray reflector thickness:2mm Kuraray reflector reference Number of events (log scale) Signal (ADC counts) Response for MIP(strip4)

Response Uniformity (strip1) extruded TiO 2 No fiber extruded TiO 2 extruded reflector extruded reflector extruded TiO 2 Kuraray reflector thickness:2mm Kuraray reflector Kuraray reflector reference Beam position (mm) Signal (ADC counts)

Response Uniformity (strip3) extruded TiO 2 No fiber extruded TiO 2 extruded reflector extruded reflector extruded TiO 2 Kuraray reflector thickness:2mm Kuraray reflector Kuraray reflector reference Beam position (mm) Signal (ADC counts)

Response Uniformity (strip4) extruded TiO 2 No fiber extruded TiO 2 extruded reflector extruded reflector extruded TiO 2 Kuraray reflector thickness:2mm Kuraray reflector Kuraray reflector reference Beam position (mm) Signal (ADC counts)