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Calibration of Under Water Neutrino Telescope ANTARES

Calibration of Under Water Neutrino Telescope ANTARES. Garabed HALLADJIAN October 15 th , 2008 GDR Neutrino, CPPM, Marseille. Presentation plan. Introduction Time calibration Dark room calibration In situ calibration Efficiency control Acoustic positioning system Conclusion.

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Calibration of Under Water Neutrino Telescope ANTARES

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  1. Calibration of Under Water Neutrino Telescope ANTARES Garabed HALLADJIAN October 15th, 2008 GDR Neutrino, CPPM, Marseille

  2. Presentation plan • Introduction • Time calibration • Dark room calibration • In situ calibration • Efficiency control • Acoustic positioning system • Conclusion GDR Neutrino - G. Halladjian

  3. Introduction Good neutrino astronomy = Good angular resolution neutrino telescope GDR Neutrino - G. Halladjian

  4. Introduction Good neutrino astronomy = Good angular resolution neutrino telescope = Good calibration GDR Neutrino - G. Halladjian

  5. Detection principle 3D OM network Cherenkov light water earth muon interaction neutrino neutrino GDR Neutrino - G. Halladjian

  6. Detection principle 3D OM network Cherenkov light • Time • Positions • Charge water earth muon interaction neutrino GDR Neutrino - G. Halladjian

  7. ANTARES ν-telescope 12 lines 25 stories 3 OM 2475m 450m 70m GDR Neutrino - G. Halladjian

  8. Optical Beaconwith blue LEDs: timing calibration Optical Module:10” Hamamatsu PMT in 17” glass sphere (sTTS 1.3 ns) photon detection Local Control Module(in Ti cylinder): Front-end ASIC, DAQ/SC, DWDM, Clock, tilt/compass, power distribution… Hydrophone: acoustic positioning Storey components GDR Neutrino - G. Halladjian

  9. mrec−mtrue mrec−n dominated by kinematics m n dominated by reconstruction Angular resolution • Angular resolution better than 0.3° above a few TeV, limited by: • Light scattering + chromatic dispersion in sea water: σ ~ 1.0 ns • TTS in photomultipliers: σ ~ 1.3 ns • Electronics + time calibration: σ < 0.5 ns • OM position reconstruction: σ < 10 cm (↔ σ < 0.5 ns) GDR Neutrino - G. Halladjian

  10. Time calibration • Internal clock calibration system • Optical Beacons • K40 decay • Internal Optical Module LEDs • … GDR Neutrino - G. Halladjian

  11. E/O/E GPS START STOP TX RX START STOP TDC Clock distribution Junction Box 116 passive splitter On-shore Station Link Cables 200-500 m fibre Main Electro-Optical Cable 40 km from shore to Junction Box Single bidirectional fibre (1534 nm / 1549 nm) Local Control Modules LCM clock boards String Control Module BIDI modules O/E and E/O converters by sectors (5 storeys) GDR Neutrino - G. Halladjian

  12. In situ measurementsof clock delay Transit time measuring of principal EO cable GDR Neutrino - G. Halladjian

  13. Clock phase in situmeasurements Individual relative delay measuring of clock for each storey σ ~ 9 ps σ ~ 11 ps Line 4, storey 16 Line 12, storey 8 GDR Neutrino - G. Halladjian

  14. OM time calibration Dark room calibration In situ calibration GDR Neutrino - G. Halladjian

  15. Dark room calibration Apparatus check ! t0 Filter t2 t1 Laser 532 nm t3 Attenuator Optical fibers Optical Splitter GDR Neutrino - G. Halladjian

  16. OMs calibration in dark room t (ns) GDR Neutrino - G. Halladjian

  17. OMs calibration in dark room t (ns) GDR Neutrino - G. Halladjian

  18. Optical Beaconwith blue LEDs: timing calibration Optical beacon • 36 LEDs • λ= 470 nm • Rise time ~ 1.9 ns • FWHN ~ 5 ns GDR Neutrino - G. Halladjian

  19. Time in OMs relative to reference PMT in OB 15 m Time difference between signals from 2 OMs in a storey Optical beacon MILOM Intense light flash:PMT TTS contributionis negligible Timing resolution of electronics <0.5ns Led OpticalBeacon: 32 blue LEDs synchronisedflash < 0.5 ns GDR Neutrino - G. Halladjian

  20. s = 2.6 ns • "diagonal" • larger distance • less intensity • light scattering s = 0.7 ns "horizontal" Dt [ns] Line 1 time calibrationwith MILOM LED beacon All timing measurements in good agreement with expectations Line 1 MILOM ~150 m ~70 m GDR Neutrino - G. Halladjian

  21. Light attenuation measuredby optical LED beacons GDR Neutrino - G. Halladjian

  22. Light attenuation measuredby optical LED beacons GDR Neutrino - G. Halladjian

  23. LED beacon Time calibration RMS 0.74ns On shore laser system RMS 0.60ns In sea LED beacon system Optical fibres Laser GDR Neutrino - G. Halladjian

  24. In situ calibration with K40 Integral under peak = rate of correlated coincidences MC prediction =13 ± 4 Hz Gaussian peak on coincidence plot Peak time offset : Cross check of time calibration High precision (~5%) monitoring of OM efficiencies Cherenkov photons e- 40Ca 40K GDR Neutrino - G. Halladjian

  25. Coincidence on 2 storeys 2 pairs of coincidences in adjacent storeys ±20 ns in same storey GDR Neutrino - G. Halladjian

  26. ±100 ns between storey Preliminary Calibration with down-goingmuons 2 pairs of coincidences in adjacent storeys GDR Neutrino - G. Halladjian

  27. Relative positioning of detector Z(m) Example for Sea current V = 25 cm/s rmax = 22 m r(m) GDR Neutrino - G. Halladjian

  28. Acoustic positioning system 5 + 1 Receiver / line AutonomousTransponder Transmitter Receiver GDR Neutrino - G. Halladjian

  29. Acoustic positioning system • Frequency = 40 – 60 kHz • Accuracy < 10 cm • Acoustic cycle: Successive emission of each BSS in each second • Simultaneous measure of acoustic propagation times between each transmitter and all hydrophones • 3D position determination of each hydrophone using all RxTxRx distances of acoustic cycle (global positioning each 2 minutes) GDR Neutrino - G. Halladjian

  30. Acoustic components Current velocity Pressure E. Conductivity Temperature CCTD Receiver Celerimeter After current correction Pressure sensor Transmitter / Receiver GDR Neutrino - G. Halladjian

  31. Sound Velocity GDR Neutrino - G. Halladjian

  32. Acoustic measurementsof fixed distances L2→L3 L3→L2 average 5 mm After current correction GDR Neutrino - G. Halladjian

  33. Acoustic measurementsof fixed distances L2→L3 L3→L2 average 5 mm After current correction + = + = GDR Neutrino - G. Halladjian

  34. Acoustic measurementsof fixed distances L2→L3 L3→L2 average 5 mm After current correction GDR Neutrino - G. Halladjian

  35. Acoustic measurementsof hydrophone distances Hydrophone : Ligne 4 étage 25 Emission transpondeur Emission RxTx ligne 5 GDR Neutrino - G. Halladjian

  36. Acoustic triangulationof hydrophones GDR Neutrino - G. Halladjian

  37. Acoustic triangulationof hydrophones GDR Neutrino - G. Halladjian

  38. Acoustic triangulationof hydrophones Radial displacement GDR Neutrino - G. Halladjian

  39. Storey 1 Storey 8 Storey 14 Storey 20 Storey 25 Acoustic triangulationof hydrophones Radial displacement GDR Neutrino - G. Halladjian

  40. Radial displacement Radial displacement GDR Neutrino - G. Halladjian

  41. BSS absolute positions • BSS position are measured by the boat • Boat position are measured by satellites DGPS LF LBL (σx σy ~ 1m) GDR Neutrino - G. Halladjian

  42. Before triangulation GDR Neutrino - G. Halladjian

  43. Before triangulation 7 m GDR Neutrino - G. Halladjian

  44. BSS position uncertainty Before triangulation GDR Neutrino - G. Halladjian

  45. BSS position uncertainty Before triangulation GDR Neutrino - G. Halladjian

  46. BSS position uncertainty Before triangulation GDR Neutrino - G. Halladjian

  47. BSS position uncertainty Before triangulation GDR Neutrino - G. Halladjian

  48. BSS absolute positions Distances between BSSs (acoustic distances) decrease the uncertainty on BSS positions. DGPS HF GDR Neutrino - G. Halladjian

  49. BSS position uncertainty Before triangulation After triangulation GDR Neutrino - G. Halladjian

  50. BSS position uncertainty Before triangulation After triangulation GDR Neutrino - G. Halladjian

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