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

15/10/2008GDR Neutrino - G. Halladjian2 Presentation plan Introduction Time calibration –Dark room calibration –In situ calibration Efficiency control Acoustic positioning system Conclusion

15/10/2008GDR Neutrino - G. Halladjian3 Introduction Good neutrino astronomy = Good angular resolution neutrino telescope

15/10/2008GDR Neutrino - G. Halladjian4 Introduction Good neutrino astronomy = Good angular resolution neutrino telescope = Good calibration

15/10/2008GDR Neutrino - G. Halladjian5 Detection principle neutrino muon interaction Cherenkov light earth water 3D OM network neutrino

15/10/2008GDR Neutrino - G. Halladjian6 Detection principle neutrino muon interaction Cherenkov light earth water 3D OM network 1.Time 2.Positions 3.Charge

15/10/2008GDR Neutrino - G. Halladjian7 ANTARES ν -telescope 2475m 450m 70m 12 lines 25 stories 3 OM

15/10/2008GDR Neutrino - G. Halladjian8 Storey components Hydrophone: acoustic positioning Optical Module: 10” Hamamatsu PMT in 17” glass sphere (  TTS  1.3 ns) photon detection Local Control Module (in Ti cylinder): Front-end ASIC, DAQ/SC, DWDM, Clock, tilt/compass, power distribution… Optical Beacon with blue LEDs: timing calibration

15/10/2008GDR Neutrino - G. Halladjian9 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) dominated by reconstruction   rec −  true  rec − dominated by kinematics

15/10/2008GDR Neutrino - G. Halladjian10 Time calibration Internal clock calibration system Optical Beacons K40 decay Internal Optical Module LEDs …

15/10/2008GDR Neutrino - G. Halladjian11 Local Control Modules LCM clock boards Link Cables m fibre STARTSTOP TDC STARTSTOP GPS E/O/E TX RX Main Electro-Optical Cable 40 km from shore to Junction Box Single bidirectional fibre (1534 nm / 1549 nm) Junction Box 1  16 passive splitter String Control Module BIDI modules O/E and E/O converters by sectors (5 storeys) On-shore Station Clock distribution

15/10/2008GDR Neutrino - G. Halladjian12 Transit time measuring of principal EO cable In situ measurements of clock delay

15/10/2008GDR Neutrino - G. Halladjian13 σ ~ 9 ps Line 4, storey 16Line 12, storey 8 σ ~ 11 ps Clock phase in situ measurements Individual relative delay measuring of clock for each storey

15/10/2008GDR Neutrino - G. Halladjian14 OM time calibration Dark room calibrationIn situ calibration

15/10/2008GDR Neutrino - G. Halladjian15 Optical fibers t0t0 t1t1 t2t2 t3t3 Optical Splitter Laser 532 nm Attenuator Filter Dark room calibration Apparatus check !

15/10/2008GDR Neutrino - G. Halladjian16 OMs calibration in dark room t (ns)

15/10/2008GDR Neutrino - G. Halladjian17 OMs calibration in dark room t (ns)

15/10/2008GDR Neutrino - G. Halladjian18 Optical beacon Optical Beacon with blue LEDs: timing calibration 36 LEDs λ = 470 nm Rise time ~ 1.9 ns FWHN ~ 5 ns

15/10/2008GDR Neutrino - G. Halladjian19 Led Optical Beacon: 32 blue LEDs synchronised flash < 0.5 ns Timing resolution of electronics <0.5ns Time difference between signals from 2 OMs in a storey Time in OMs relative to reference PMT in OB MILOM 15 m Intense light flash: PMT TTS contribution is negligible Optical beacon

15/10/2008GDR Neutrino - G. Halladjian20 Line 1 time calibration with MILOM LED beacon MILOM ~70 m ~150 m  = 0.7 ns  = 2.6 ns  t [ns] "horizontal" "diagonal" larger distance less intensity light scattering All timing measurements in good agreement with expectations Line 1

15/10/2008GDR Neutrino - G. Halladjian21 Light attenuation measured by optical LED beacons

15/10/2008GDR Neutrino - G. Halladjian22 Light attenuation measured by optical LED beacons

15/10/2008GDR Neutrino - G. Halladjian23 Optical fibres Laser On shore laser system In sea LED beacon system LED beacon RMS 0.74ns RMS 0.60ns Time calibration

15/10/2008GDR Neutrino - G. Halladjian24 In situ calibration with K40 40 K 40 Ca e-e- Cherenkov photons Gaussian peak on coincidence plot Peak time offset : Cross check of time calibration Integral under peak = rate of correlated coincidences High precision (~5%) monitoring of OM efficiencies MC prediction =13 ± 4 Hz

15/10/2008GDR Neutrino - G. Halladjian25 Coincidence on 2 storeys 2 pairs of coincidences in adjacent storeys ±20 ns in same storey

15/10/2008GDR Neutrino - G. Halladjian26 Calibration with down-going muons 2 pairs of coincidences in adjacent storeys ±100 ns between storey Preliminary

15/10/2008GDR Neutrino - G. Halladjian27 Relative positioning of detector Z(m) r(m) Example for Sea current V = 25 cm/s r max = 22 m

15/10/2008GDR Neutrino - G. Halladjian28 Autonomous Transponder Transmitter Receiver Receiver / line Acoustic positioning system

15/10/2008GDR Neutrino - G. Halladjian29 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)

15/10/2008GDR Neutrino - G. Halladjian30 Acoustic components After current correction Transmitter / Receiver Pressure sensor Celerimeter CCTD Receiver Current velocity Pressure E. Conductivity Temperature

15/10/2008GDR Neutrino - G. Halladjian31 Sound Velocity

15/10/2008GDR Neutrino - G. Halladjian32 Acoustic measurements of fixed distances After current correction L2→L3L3→L2average 5 mm

15/10/2008GDR Neutrino - G. Halladjian33 Acoustic measurements of fixed distances After current correction L2→L3L3→L2average 5 mm + + = =

15/10/2008GDR Neutrino - G. Halladjian34 Acoustic measurements of fixed distances After current correction L2→L3L3→L2average 5 mm

15/10/2008GDR Neutrino - G. Halladjian35 Hydrophone : Ligne 4 étage 25 Emission RxTx ligne 5Emission transpondeur Acoustic measurements of hydrophone distances

15/10/2008GDR Neutrino - G. Halladjian36 Acoustic triangulation of hydrophones

15/10/2008GDR Neutrino - G. Halladjian37 Acoustic triangulation of hydrophones

15/10/2008GDR Neutrino - G. Halladjian38 Radial displacement Acoustic triangulation of hydrophones

15/10/2008GDR Neutrino - G. Halladjian39 Storey 1 Storey 8 Storey 14 Storey 20 Storey 25 Radial displacement Acoustic triangulation of hydrophones

15/10/2008GDR Neutrino - G. Halladjian40 Radial displacement

15/10/2008GDR Neutrino - G. Halladjian41 BSS absolute positions BSS position are measured by the boat Boat position are measured by satellites DGPS LF LBL (σx σy ~ 1m)

15/10/2008GDR Neutrino - G. Halladjian42 Before triangulation

15/10/2008GDR Neutrino - G. Halladjian43 Before triangulation 7 m

15/10/2008GDR Neutrino - G. Halladjian44 BSS position uncertainty Before triangulation

15/10/2008GDR Neutrino - G. Halladjian45 BSS position uncertainty Before triangulation

15/10/2008GDR Neutrino - G. Halladjian46 BSS position uncertainty Before triangulation

15/10/2008GDR Neutrino - G. Halladjian47 BSS position uncertainty Before triangulation

15/10/2008GDR Neutrino - G. Halladjian48 BSS absolute positions Distances between BSSs (acoustic distances) decrease the uncertainty on BSS positions. DGPS HF

15/10/2008GDR Neutrino - G. Halladjian49 BSS position uncertainty Before triangulationAfter triangulation

15/10/2008GDR Neutrino - G. Halladjian50 BSS position uncertainty Before triangulationAfter triangulation

15/10/2008GDR Neutrino - G. Halladjian51 Before triangulation 7 m

15/10/2008GDR Neutrino - G. Halladjian52 After triangulation 7 m

15/10/2008GDR Neutrino - G. Halladjian53 Angular Error due to BSS σ (horizontal) = 0.13 degree σ (vertical) = 0.02 degree

15/10/2008GDR Neutrino - G. Halladjian54 Conclusion ANTARES is complete and working very well Detector calibration is permanently controlled in situ Calibration performance agree with expectation: –Time uncertainty < 0.5 ns –Position uncertainty < 10 cm ANTARES should reach its excellent angular resolution ~ 0.3 o