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K2K 実験 SciBar 前置ニュートリノ検出器

K2K 実験 SciBar 前置ニュートリノ検出器. 読み出しシステムと時間情報の較正. 久野研　　田窪　洋介. Contents. K2K experiment SciBar detector & readout system Cosmic ray trigger system Timing calibration Conclusion. K2K Experiment. SciBar detector. SciFi detector. Super-Kamiokande. 1kt water cherenkov detector. Pure ν μ. ν μ.

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K2K 実験 SciBar 前置ニュートリノ検出器

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  1. K2K実験 SciBar前置ニュートリノ検出器 読み出しシステムと時間情報の較正 久野研　　田窪　洋介

  2. Contents • K2K experiment • SciBar detector & readout system • Cosmic ray trigger system • Timing calibration • Conclusion

  3. K2KExperiment SciBar detector SciFi detector Super-Kamiokande 1kt water cherenkov detector Pureνμ νμ L = 250km Near Detectors MRD(Muon Range Detector) K2K experiment uses neutrinos made by the accelerator KEK 12GeV PS Pure νμ beam whose Flux and energy are well known, can be obtained .

  4. Neutrino Oscillation Square mass difference(eV2) Flight length (km) Oscillation Probability = Neutrino energy (GeV) Mixing angle Data K2K current status 0.6 GeV Best Fit Best fit Δm2 = 2.8×10－3(eV2) sin22Θ= 1.0 No oscillation En

  5. m pm nm qm n proton Neutrino interaction CC-QE Interaction • Assuming Charged Current Quasi-Elastic interaction • Dominant process around 1GeV neutrinos. • Oscillation maximum ~0.6GeV • Non-QE interactions are backgrounds for En measurement CC-nonQE Interaction m nm N pion nucleon

  6. n SciBar detector • Extruded scintillator with WLS fiber readout • Neutrino target is scintillator itself • 2.5 x 1.3 x 300 cm3 cell • ~15000 channels • Light yield • 7~20p.e./MIP/cm (2 MeV) • Detect 10 cm track • Distinguish proton from pion by using dE/dx • High 2-track CC-QE efficiency • Low non-QE backgrounds Extruded scintillator (15t) EM calorimeter 3m Multi-anode PMT (64 ch.) 3m 1.7m Wave-length shifting fiber Just constructed in this summer!

  7. Detector Components DAQ board 64ch MAPMT Front-end board

  8. Scintillator & WLS Fiber Scintillator 1.8 mmφ • Size : 1.3×2.5×300 cm3 • Peak of emission spectrum : 420 nm • TiO2 reflector (white) : 0.25 mm thick 300 cm • Kuraray • Y11(200)MS 1.5mmφ • Multi-clad • Attenuation length ~3.6m • Absorption peak ~430nm • Emission peak ~476nm 1.3 cm 2.5cm Wave-length Shifting Fiber Charged particle

  9. Multi-anode PMT Top view • Hamamatsu H7546 type 64-channel PMT • 2 x 2 mm2 pixel • Bialkali photo-cathode • Compact • Low power : < 1000V, < 0.5mA • Typical gain : 6 x 105 • Cross talk : ~3% • Gain uniformity : ~20%(RMS) • Linearity : ~200 p.e.@ 6 x 105

  10. sample&hold preamp. VA serial output slow shaper CH1 TA (32ch OR) fast shaper discri. multiplexer CH2 CH32 Readout Electronics 1.2ms hold ∝ charge VATA Chip PMT signal Front-end board VA/TA chip

  11. DAQ board • Control of VA readout sequence • Setting of VA trigger threshold • A/D conversion of VA serial output by FADC • 8 front-end board (8 MAPMT) are connected to one DAQ board. 8 front-end boards(8×64ch） 16ch×2 TA signal

  12. Scintillator Installation 64 X and 64 Y layers X and Y planes were glued

  13. WLS Fiber and PMT installation

  14. Logic Diagram for Cosmic Ray Trigger Identification of hit track Make coincident with two trigger signals Top 112 TA Trigger Board 7 DAQ Board 56 Front-end Board 56 MAPMT Master trigger board Timing Distributor Side TRG 112 TA Trigger Board 7 DAQ Board 56 Front-end Board 56 MAPMT Distribute signals made from the trigger signal to other modules Top view Side view We use half of the TA channels (224ch/448ch) for cosmic ray trigger.

  15. Trigger Board Output : 1ch input : 128 ch (16×8) Output : 16 ch FPGA decide to make trigger signal. • VME 9U module • Front panel : input 128 (16×8) ch LVDS/ECL • Back plane : output 16ch LVDS/ECL • Using FPGA, trigger logic can be easily implemented for any combinations of 128 inputs.

  16. Timing Distributor Daughter board 16ch NIM I/O 8ch LVDS I/O 16×2ch LVDS/ECL Input FPGA • VME 6U module to distribute timing signals made by trigger system to DAQ backend boards • 4ch NIM I/O on main board + 2 daughter boards Daughter board 16×2 ch LVDS/ECL Input 16ch NIM I/O • Flexible data processing is realized using FPGA.

  17. Requirement for Cosmic Ray Trigger • Horizontally through-going muons are taken for calibration effectively. • Distribution of cosmic ray hits is uniform. • Decision time is less than 100 ns (due to the cable length of electron catcher) • 32ch OR’ed signals from TA*1 (fast-triggering ASIC) are trigger board input signals.

  18. Trigger Design • Trigger is generated, based on the hit pattern identification. Preparing hit patterns, track pattern matching them is selected. • Track which is less than 45 degree of zenith angle is taken. Zenith angle > 45 degree Zenith angle < 45 degree • Pre-scale factor can be set on the hit pattern to make hit distribution uniformly.

  19. Achieved Performance & Current Status Achieved performance • Decision time is 100 nsec. • Single rate of one TA is about 100 Hz. • Trigger rate is about 100 Hz. • Data acquisition rate is about 20 Hz. Current Status We now use a trigger logic for the commissioning. We make “or” signals of every other layer, and make coincident with those of the top and side separately. We make “and” signal of the top and side.

  20. Angle distribution of cosmic ray event taken by commissioning trigger Zenith angle(degree) 60 0 Horizontal line -60 -80 0 80 Azimuth angle (degree)

  21. Hit distribution of cosmic ray event taken by commissioning trigger 250 250 Vertical position(cm) Horizontal position(cm) 150 150 0 0 80 160 80 160 Z(cm) Z(cm) ν ν

  22. Event display of cosmic ray event Side View Top View μ μ

  23. TQ Distribution Correction function : ΔT = A/(ADC ＋B) + C A,B,C : const ΔT = T(X12Z1) – T(X12Z2) ΔT(nsec) ΔT(nsec) 25 25 ΔT = 1719.8/(ADC ＋65.5）－5.6 10 10 -5 -5 600 0 300 0 300 600 ADC ADC

  24. Time Resolution ΔT = T(X12Z1) – T(X12Z2) Before TQ correction After TQ correction count count Time resolution σ/√2 = 2.83 nsec Time resolution σ/√2 = 1.70 nsec ΔT(nsec) ΔT(nsec)

  25. Light velocity in the fiber y15z8 ΔT(nsec) ΔT(nsec) 0.05847E－01 ±0.8594E－03 Light velocity in a fiber = 17.2 nsec/cm Δx(cm) Δx(cm)

  26. Conclusion & Next step • Cosmic ray data is taken by commissioning trigger and useful for timing and energy calibration, and so on. • Timing correction was done by cosmic ray data. • Timing resolution is 1.70 nsec. • Light velocity in a fiber is 17.2 nsec. Next step Ability of direction ID by using TOF will be estimated.

  27. n n CC-QE candidate Top view Side view • Area of circle is proportional to ADC • Hits along the proton track are larger p μ μ p

  28. n n 3-Track Event Top view Side view 1 3 3 2 2 1

  29. n n Neutral Current p0 Candidate Top view Side view e Vertex! e γ γ π0 π0 γ e e

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