Application of Hamamatsu MPPC to T2K near neutrino detectors

Transcription

1 Application of Hamamatsu MPPC to T2K near neutrino detectors Masashi Yokoyama (Kyoto University) T.Nakaya, S.Gomi, A.Minamino, N. Nagai, K.Nitta, D.Orme (Kyoto) T.Murakami, T.Nakadaira, M.Tanaka (KEK/IPNS) Yu.Kudenko (INR), F.Retiere (TRIUMF), A.Vacheret (Imperial Col. London) (also supported by KEK-DTP)

2 MPPC is for neutrino detection!

3 Introduction T2K experiment Near neutrino detectors MPPC

4 T2K Experiment Near Detector Long baseline neutrino experiment in Japan Search for νe appearance from νμ beam Precision measurements of νμ disappearance Start from April

5 T2K Near Detectors ~280m from target UA1 magnet from CERN Characterize neutrino beam at production. 5

6 Common technique: WLS fiber readout All but TPC will use plastic scintillator + wavelength shifting fiber readout Successful in recent neutrino detectors (K2K-SciBar, MINOS, MINERvA, SciBooNE,...) Kuraray Y11 (1mm diameter) chosen as the fiber Photosensor matched with fiber readout needed! 6

7 Photosensor requirements for T2K-ND Constraints/situation Enough light yield Requirements PDE >PMT for green light 0.2T B-field Immunity to magnetic field Very limited space Low interaction rate Timing from accelerator available Large number of channels (~60,000 in total) Limited access after installation Compact Radiation hardness not an issue Dark noise less harmful, ~1MHz OK Easy operation, price $ Stability/reliability 7

8 Our choice: Multi-Pixel Photon Counter (MPPC) Geiger-mode APD (Pixelized Photon Detector, PPD) Produced by Hamamatsu Photonics, Japan High gain, good PDE, compact, operation in B-field... Ideal device for T2K-ND! Hamamatsu Photonics, K.K. Selected in Aug by collaboration 8

9 MPPC Spec for T2K Item Spec Active area mm 2 Pixel size 50 50μm 2 Number of pixels 667 S C Specially developed for T2K 1.3mm Operation voltage 70V (typ.) Photon detection 550nm >15% Dark count (gain= ) <1.35Mcps(0.5pe) <0.135Mcps(1.5pe) Number of device ~60,000 9

10 Performance Gain, breakdown voltage Noise Photodetection efficiency (PDE) Light yield with scintillator (Cross-talk and afterpulse: talk by F.Retiere)

11 Gain and breakdown voltage Charge distribution with ADC 1p.e Gain 8 4 VBD ADC counts Gain easily measured with p.e. peaks in ADC distribution Applied voltage [V] With linear extrapolation of V-gain, Breakdown voltage (VBD) defined as the point where gain=0 11

12 Gain/VBD for T2K-MPPC For 5820 MPPCs 25 o C 800 RMS=4.5% 5820 MPPCs MPPCs Entries 400 Entries (Δgain)/(Δvoltage) [10 5 V -1 ] VBD [V] Excellent device uniformity. 12

13 Dark noise Noise rate [MHz] 5820 MPPCs overlaid o C ΔV=V-VBD For 5820 MPPCs 0.5pe threshold 25 o C ΔV=1.5V [V] Dark noise rate [MHz] Device/temperature dependence seen Satisfy our requirements 13

14 Photodetection efficiency (PDE) Relative to a reference PMT (QE~15% for green light by catalogue). Number of p.e. derived from fraction of pedestal events and Poisson stat. MPPC with optical connector Reference PMT LED Wavelength shifting fiber Optical connector developed to ensure good contact. 8mm MPPC holder Fiber 18mm 14

15 PDE Temp. dependence is small (except effect from VBD) Excellent PDE. (loss at coupling included) 15

16 Light yield with scintillator MPPC 3GeV e- 1cm Scintillator for on-axis detector ~25 o C ΔV=1.5V 4 scintillators show consistent l.y. ~15p.e. with WLS fiber (Y11, 1mm dia.) and real scintillator (produced at Fermilab). 16

17 Another example: SMRD 870 mm 7mm thickness 167mm Scintillator slab to instrument magnet yoke Need to cover large area: S-shape groove to embed WLS fiber 36±3 p.e. for cosmic ray at the center of counter with both end MPPC readout 17

18 Mass production & testing Mass production started from Feb > MPPCs already shipped. QA/testing ongoing >8,000 at Kyoto (15,000 by July) Also at other testing stations (France, UK, Russia, USA, Poland) within this year See also poster by M. Y. 18

19 Summary and Prospects Established WLS fiber readout with MPPC Successful development of MPPC, measurement method, fiber coupling. T2K near detectors will be the first large scale application of MPPC to a real experiment The experiment will start within a year! 19

20 Supplements

21 Crosstalk/afterpulse Crosstalk/afterpulse ΔV=V-VBD [V] MPPCs Crosstalk/afterpulse Tolerable level for our use. 21

22 Readout electronics Two options of readout ASIC AFTER (Saclay) for FGD Trip-t (Fermilab) for INGRID/P0D/ECAL/SMRD High Voltage trim DACs (8 altogether) PROM GAIN SPLITTING COMPONENTS Trip-t Trip-t TEMPERATURE AND VOLTAGE MONITORING Xilinx Spartan 3 FPGA Trip-t Trip-t Trip-t frontend board developed in UK AFTER electronics by Saclay 22

23 Voltage at gain=7.5x10 5, 25 o C opvol 1000 h1 Entries Mean RMS Operation voltage [V] (Hamamatsu) Data from Hamamatsu

24 Voltage at gain=7.5x10 5, 25 o C opvol2 Operation voltage [V] (Hamamatsu) h2 Entries Mean x 9901 Mean y RMS x 5716 RMS y MPPC serial number Data from Hamamatsu

25 Dark noise rate with 0.5pe threshold, 25 o C dark 400 h1 Entries Mean RMS Dark rate [kcps] (Hamamatsu) Data from Hamamatsu