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MPPC update

MPPC update. S.Gomi, T.Nakaya, M. Yokoyama, M.Taguchi, (Kyoto University) T.Nakadaira (KEK). Nov.8.2006 KEK. Contents. We obtain the latest sample of MPPC this October. Ceramic package, prepared for T2K experiment. 100pixel×10, 400pixel×10

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MPPC update

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  1. MPPC update S.Gomi, T.Nakaya, M.Yokoyama, M.Taguchi, (Kyoto University) T.Nakadaira (KEK) Nov.8.2006 KEK

  2. Contents • We obtain the latest sample of MPPC this October. • Ceramic package, prepared for T2K experiment. • 100pixel×10, 400pixel×10 • We measured the fundamental performance of this sample. • Gain • Noise rate • Cross-talk rate • Photon detection efficiency ( PDE ) 5mm 6mm Ceramic package of MPPC

  3. Gain Estimated by 1p.e signal peak . Gain 100pixel Gain 400pixel • Gain of old sample was… • 1.0×106~3.0×106 (100pixel) • 0.4×106~1.0×106 (400pixel)  Gain of new sample is not so changed compared to old sample. 69.6 70 70.6 69 69.5 69.8 Bias voltage [V] Bias voltage [V] Blue : 15degree Green : 20degree Red : 25degree

  4. The measurement of noise rate • The noise rate is measured by counting the rate of signal with their height over the threshold, imposed on 0.5p.e and 1.5p.e . ( The old sample have ~1.2MHz 1p.e noise rate. ) “ 1p.e noise ” 0.5 p.e = threshold 1 p.e “ 2p.e noise ” Noise signal of 100pixel MPPC at 25 degree. ( integrated ) 1.5 p.e = threshold

  5. Blue : 15degree Green : 20degree Red : 25degree Noise rate Noise rate [ MHz ] 100pixel Noise rate [ kHz ] 400pixel • 1p.e noise rate is about ~0.4 MHz. (old ~1.2 MHz) • 2p.e noise rate is about ~0.2 MHz. (old ~0.2 MHz) 400kHz 500kHz 1p.e 2p.e 1p.e noise 2p.e noise 100kHz 100kHz 69.5 69.1 70 69.2 70 70.4 Improved! Bias voltage [V] Bias voltage [V]

  6. The measurement of cross-talk rate • Sensitive area of 100pixel type is enlarged by 40%.  Geometrical efficiency is increased. • The separation between pixels is smaller than the old sample.  Cross-talk rate may be increased Old sample ( 100pixel ) New sample ( 100pixel )

  7. Measurement of cross-talk rate • The probability of cross-talk is estimated by the number of 1p.e . The number of pedestal are free to cross-talk measurement • the number of each p.e is assumed to be follow the Poisson distribution The number of 1p.e : P(1) ( estimated by pedestal ) || without cross-talk The number of 1p.e : P(1) ( measured ) || with cross-talk This difference corresponds to the decrease by cross-talk. The cross talk rate is determined.

  8. Blue : 15degree Green : 20degree Red : 25degree Cross-talk rate Cross-talk rate 100pixel Cross-talk rate 400pixel ( Cross-talk rate of the old sample is ~30%. )  Cross-talk rate of new sample is ~1.6 times larger than old sample. 50% 50% 10% 10% 69.6 70 70.6 69 69.5 69.8 Bias voltage [V] Bias voltage [V]

  9. relative PDE measurement • Geometrical efficiency is larger than that of the old sample. So, PDE of new sample should be higher. • PDE relative to PMT is measured. set up Moving stage 1mmφslit PMT Blue LED MPPC ( total area 1mm2) PMT made by HPK, type H8643

  10. relative PDE Relative PDE 100pixel Relative PDE 400pixel 3 • PDE is about 2~3 times higher than that of PMT. (Old sample was ~2×PMT)  ~1.4 times larger PDE than old sample. 2 2 1 1 69.6 70 70.6 69 69.5 69.8 Bias voltage [V] Bias voltage [V] Blue : 15degree Green : 20degree Red : 25degree

  11. Summary of measurement About the region the gains of 2sample are same… • The new sample have good performance! But, Cross-talk become worse.  feed back to Hamamatsu Improved! Become worse… Improved!

  12. Future plan… • We will check the device-to-device variation for 500 MPPCs in this ceramic package next March. • So, we have to make system to test many samples. • We want to measure as many sample as possible at once. • Plastic connector • Read out electronics

  13. Supplements

  14. Gain Gain 100pixel Gain 400pixel 0.2 1 1.6 0.8 1 2 2.4 DV DV Blue : 15degree Green : 20degree Red : 25degree

  15. Noise rate Noise rate [ MHz ] 100pixel Noise rate [ kHz ] 400pixel • This new sample have noise rate less than the half of old sample. 400kHz 500kHz 1p.e 2p.e 1p.e 2p.e 100kHz 100kHz 1 0.4 1.6 0.5 1 1.5 2 2.3 DV DV Blue : 15degree Green : 20degree Red : 25degree

  16. Cross-talk rate Cross-talk rate 100pixel Cross-talk rate 400pixel • Cross-talk rate is a function of DV. 50% 50% 10% 10% 1 2 0.2 1 1.6 0.8 1 2 2.4 Delta V DV DV Blue : 15degree Green : 20degree Red : 25degree

  17. relative PDE Relative PDE 100pixel Relative PDE 400pixel • PDE is a function of Delta V. 3 2 2 1 1 0.2 1 1.6 0.8 1 2 2.4 DV DV Blue : 15degree Green : 20degree Red : 25degree

  18. Set up for measuring linearity Paper set up ( to shade off LED light ) MPPC The number of photons emitted to MPPC are monitored by PMT. PMT

  19. Linearity Linearity 100pixel Linearity 400pixel linear linear • The green line shows the expectation value calculated from number of pixels. Fired pixel [ % ] Fired pixel [ % ] 25% 25% Blue : DATA plot Green : expectation Blue : DATA plot Green : expectation Injected photoelectron per pixel Injected photoelectron per pixel MPPC can operate as linear device. ~25p.e about 100pixel type ~100p.e about 400pixel type.

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