MPPC for T2K Fine-Grained Detector Kei Ieki for T2K FGD group F Retiere(TRIUMF) S Oser, H Tanaka, T Lindner, J Zalipska(UBC) T Nakaya, M Yokoyama, A Minamino, M Otani(Kyoto Univ.)

Contents Introduction of Fine-Grained Detector MPPC mass test in Kyoto before installation FGD readout electronics Beam test at TRIUMF

Introduction of Fine-Grained Detector -The T2K experiment -Off-axis detectors -The Fine-Grained Detectors(FGDs) -Physics requirements for FGD and MPPC

The T2K Experiment Long baseline neutrino oscillation experiment Tokai Super-Kamiokande Tokai νμ beam 295km Near detectors Kamioka

Off-axis detectors Designed to measure : which is prior to neutrino FGDs Designed to measure : -initial neutrino beam flux -energy spectrum which is prior to neutrino oscillation effects Tracker main signal: 　　νμ+n → p+μ background for main signal: 　　νμ+n→ p+μ+π Tracker consists of 3 Time Projection Chambers, 2 Fine-Grained Detectors FGDs works as a target of neutrino interaction while detecting particle tracks simulated neutrino event

The FGD(Fine-Grained Detector) ････ Consist of X,Y planes of fine segmented scintillator bars. Wavelength shifting fibers collect the light from scintillator. The MPPCs read out the light from fibers. FGD1: 15 X,Y planes FGD2: 7 X,Y planes + 6 water layers to study neutrino interaction in water target. 184cm wavelength shifting fiber(Kuraray Y11) MPPC scintillator(TiO2 coating) 0.96cm 184cm fiber end mirrored with aluminum 192 bars 8448ch MPPCs are installed!

Requirements for FGD Particle detecting efficiency > 99% MPPC’s PDE should be big enough Particle ID capability -By dE/dx, particle range ⇒good energy resolution required 　need enough gain, linearity -By detecting Michel positrons from π+ electronics should be alive long enough Timing resolution -~3ns per neutrino interaction for matching with photons in calorimeter 6pとのつながり table

Requirements for MPPC ＆ electronics Parameter Required Reason Gain > 5×104 For energy resolution PDE ≧1PMT For 100% efficiency for MIP Noise rate <500kHz For timing and energy resolution Dynamic range >400 pixels For more than 50 MIPs dynamic range Crosstalk <20% Electronics time range >5μs+few muon lifetime To identify muons 目的→説明

MPPC mass test in Kyoto before installation -Overview -Results

MPPC mass test for FGD, INGRID We have tested ~18000 MPPCs in Kyoto before installation to check the quality and to understand it’s performance‏ Measured quantities: Gain Breakdown Voltage Noise Rate Crosstalk + Afterpulse Rate ‏ Photon Detection Efficiency compared to reference PMT install前に 数 Each set of measurement were taken in 15℃, 20℃, 25℃ Voltage scan in 0.1V steps from ΔV=0.7 V to 1.8V

Result Gain Excellent device uniformity. for 12064 MPPCs DV = 1.5 V Result for One MPPC for 12064 MPPCs x105 12 800 8 DV = 1.5 V 20 deg. Gain Num. of MPPCs 15 deg. 4 400 20 deg. Mean: 7.3e+5 RMS : 4.2e+4 25 deg. 0.5 1.0 1.5 2.0 2.5 2 4 6 8 10 DV = V – VBD [V] Gain x105 Excellent device uniformity.

Dark noise Device/temperature dependence is seen. Result for one MPPC x 105 For 12064 MPPCs 10 15 deg. 600 8 20 deg. DV = 1.5 V 20 deg. 6 25 deg. Dark noise [Hz] 400 Num. of MPPCs 4 200 Mean :6.9e+5 RMS : 1.3e+5 2 0.5 1.0 1.5 2.0 2.5 4 8 12 16 20 DV = V – VBD [V] x105 Dark noise [Hz] Device/temperature dependence is seen. Satisfy T2K-ND requirements.

“Cross talk + After pulsing ratio” & PDE 0.5 4 15 deg. One MPPC One MPPC 15 deg. 0.4 20 deg. 3 20 deg. 0.3 25 deg. “CT+AP ratio” PDE [/PMT] 25 deg. 2 0.2 PMT x 1 Reference PMT R1818 (Hamamatsu) 1 0.1 0.5 1.0 1.5 2.0 2.5 0.5 1.0 1.5 2.0 2.5 DV = V – VBD [V] DV = V – VBD [V] Satisfy T2K-ND requirements.

Crosstalk+Afterpulse rate Result of mass test Parameter Mean RMS Gain 4.85×105 2.59×104 (5.3%) Breakdown voltage[V] 68.29 0.73 (1.1%) Noise rate[Hz] 4.47×105 1.02×105 (23%) Crosstalk+Afterpulse rate 0.070 0.036 (51%) PDE 1.53 0.33 (22%) rms 分けて flactional fluctuation 分布 Measured mean±RMS at T=20℃, over voltage=1.0V Tested ~400 channels/day 9 broken channels found ← broken rate very low MPPC parameters fulfill FGD and INGRID requirements

FGD readout electronics -Overview -Connector, Bus board -Front End Board -Crate Master Board

(Data Concentrator Card) FGD electronics Mini-crate FGD MPPC scintillator optical cable … Bus-board 1 2 FEB(Front End Board)×4 CMB(Crate Master Board)×1 LPB(Light Pulser Board)×1 3 性能→実際の配置 DCC (Data Concentrator Card) Data flow 4 Heat producing elements are separated from the MPPCs. FEBs will perform waveform digitization for 10μs continuous detection time LAN cable DAQ server 5

MPPC connections Use special connector for MPPC and fiber connection. Bus-board carries 16 MPPCs Optical connector LED temperature sensor Bus-board

Front-End Board Data readout , bias voltage supply AFTER ASIC chip - Waveform digitization at 50MHz by Switched Capacitor Array 20ns × 512(time bin) = 10μs continuous readout - Preamp-shaper Bias voltage supply for individual channels High/Low attenuation channel for wide dynamic range noise waveform

Crate-Master Board Control FEBs, compress data Control Front End Boards Data compression - zero suppression : need waveform only around pulses 赤、黒 black: original waveform red: after compression

Beam test at TRIUMF -Overview -Calibration check -Light attenuation -Physics performance

Beam tests at TRIUMF M11 area Main purpose: - Electronics check - Physics performance test Secondary beams of e, π, μ, p in 100~400MeV/c

Basic Calibrations Tested ADC to p.e. conversion pulse height distribution 1p.e. pulse height (ΔV~0.6V) 1p.e. pulse height[ADC ch] adc 単位 gain over voltage Channel ID pulse height[ADC ch] We can convert pulse height to p.e. by checking pulse height distribution of noise.

Breakdown voltage check Checked bias voltage with FGD electronics and compared to Hamamatsu spec sheet. comparison with Hamamatsu 1p.e. in different ΔV 確認でしかない Result matches with Hamamatsu spec sheet.

Temperature calibration check Checked gain temperature dependency and compared with Kyoto analysis. 1p.e. pulse height temperature dependency pulse height ratio in 21.5℃/19.5℃ pulse height ratio ΔV~0.6V expected value from Kyoto 1p.e. pulse height[ADC ch] 確認したよと broken channels temperature[℃] Channel ID Result well matched with Kyoto mass test

Light attenuation Result well matched with bench test result in Regina. Enough light output for MIP. Light attenuation test @beam test [p.e.] bench test results beam test data points test in Regina

Physics performance test FGD physics performance has been checked. time difference between incident μ and second hit in the bar Number of hits in the layers for 150MeV/c muon ns well matched with muon lifetime muon stops at same depth Events num of hits num of hits 単位 タイトル missing readout of alternating bars in first 4 layers layer number layer number Time diff [*20ns] Muons can be identified by the delayed hit of Michel electron. Particle range well matched with Monte Carlo simulation.

Current status, future FGD1 just arrived at Tokai on June 18. コミッショニング FGD1 just arrived at Tokai on June 18. FGD2 will arrive in July. They will be installed in October after DAQ commissioning. Start data taking in December 2009.

Summary 8448ch of MPPCs are installed in T2K Fine-Grained Detectors. Mass test in Kyoto assured MPPC’s performance to use in T2K detectors. FGD electronics has been developed to handle large number of MPPCs and to fulfill physics requirements. They have been tested in the beam test and working fine. FGDs will be installed this autumn and start data taking from December 2009. mppc sokutei koumoku

Backup

Figures compressed data neutrino event μ noise/beam waveform of high/low attenuation νμ p

Figures 2 MPPC setup Switched Capacitor Array LED light source MPPC Boards