Comparison of 3 types of scintillator strips and 2 types of reflector films Miho NISHIYAMA Shinshu-U Light yield of 3 scintillator strips have been measured using  -ray source. 1. fiber read out strip ＋ radiant mirror film 2. direct read out strip ＋ radiant mirror film 3. Extruded strip (KNU) ＋ TiO 2 paint Light yield of direct read out strip with 2 types of reflector films have been measured using  -ray source. 1.direct read out strip ＋ radiant mirror film 2.direct read out strip ＋ reflector film (manufactured by Kimoto Co. Ltd) Size is 1 x 4.5 x 0.3 cm for all types of scintillator strips.

Light yield of the scintillator strip is determined as: N p.e = Mean ADC counts for  -ray / d d = Signal corresponds to 1 photoelectron (ADC counts) The parameter “d” is necessary to determine N p.e. It has been measured with dark noise events. Determination of the MPPC gain using dark noise events Clock Generator Gate Generator AMP(x63) MPPC ADC Bias Voltage:78[V] Thermostatic chamber (25 ℃ ) 1 [kHz] Setup Signal input Gate input

d Bias Voltage : 78 [v] Number of Events MPPC signal (ADC counts) Determination of the MPPC gain using dark noise events Log scale d = 25.51±0.03 (ADC counts) Gain= (6.327±0.001)×10 5 d

Measurement of light yield of the scintillator strips using  -ray source

PMT Setup Discriminator Gate Generator 90 Sr MPPC ADC (V bias = 78 [ V]) Trigger scintillator Thermostatic chamber (25 ℃ ) Strip scintillator Collimator with 2 mm  hole Position of  -ray source × cm Signal input Gate input MPPC AMP (x63)

Light yield of 3 types of strip scintillators Fiber read out Direct read outKorean extruded fiber : N p.e = 25.0 [p.e] direct : N p.e = 18.7 [p.e] Extruded : N p.e = 12.7 [p.e]

Light yield of direct readout scintillator with 2types of reflector films 3M Radiant mirror film Kimoto Reflector film 3M : N p.e = 22.1[p.e] Kimoto : N p.e = 18.3[p.e]

Summary Light yields of 3 different types of scintillator strips are : ・ Fiber read out : 25.0 photoelectrons ・ Direct read out : 18.7 photoelectrons ・ Extruded : 12.7 photoelectrons (There may be ~10% systematics from optical coupling issue) Extruded scintillator shows half light yield of the fiber read out strip.  improvement is ongoing by KNU guys. Light yields of direct readout strip with 2 types of reflector films : ・ radiant mirror film : 22.1 photoelectrons ・ reflector film by Kimoto Co.Ltd : 18.3 photoelectrons Results with the Kimoto film shows 82.88% light yield of results with the 3M radiant mirror film.  We may replace the 3M film with Kimoto.

Plans Measure light yield with position scanning Investigate effect of MPPC photon detection efficiency –Change bias voltage –Determine PDE from other studies Measure strip-by-strip variation of light yield Test 2 mm thick scintillator strips

Backups

Strip non-uniformity measured at DESY beam test Kuraray strip with fiberKuraray direct KNU strip with fiber ~75%~66% ~48%

再現性 MPPC の取り外しあり 平均 : (2.49±0.01)×10 2