Simona Toscano In the frame of KM3NeT consortium VLV T workshop - Toulon, April 2008

2 Dark Room calibration Light sources: LED and Laser Optical Beacon 40 K Optical fibre Absolute timing Timing Calibration Systems What we have learnt from the pilot projects Ideas and studies for Km3NeT Relative Position Calibration Systems Acoustic Method Sea Surface Detector Moon Shadow Absolute Orientation Systems S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/2008 Conclusions

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/ Timing Relative Positioning Absolute OrientationConclusions  Cost?  Needs little labour to implement?  From photocathode up to readout?  Calibration at very low intensity?  Provides self-redundancy? (auto-check)  Provides coincidences (relative timing)?  Works very well with most of the OM designs?  Measures water optical parameters?  Can be used right from the start?  Always reaches desired resolution? F. Salesa’s talk in Parallel Session on Physics on ANTARES time calibration S Koutsoukos’s talk on Calibration from ten to hundreds of meters in an underwater neutrino telescope M. Circella’s talk in this Session on Time Calibration of the NEMO apparatus B. Lubsandorzhiev’s talk in this Session on LED based powerful nanosecond light sources for calibration systems of deep underwater neutrino telescopes For details on timing calibration see:

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/ Timing Relative Positioning Absolute OrientationConclusions ANTARES Dark Room at CPPM: Laser-fibre system, Clock calibration system LEDs in Optical Modules. Cost?  Needs little labour to implement?  From photocathode up to readout? Calibration at very low intensity?  Provides self-redundancy? (auto- check) Provides coincidences (relative timing)? Works very well with most of the OM designs? Measures water optical parameters?  Can be used right from the start? Always reaches desired resolution?

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/ Timing Relative Positioning Absolute OrientationConclusions Cost?  Needs little labour to implement?  From photocathode up to readout? Calibration at very low intensity?  Provides self-redundancy? (auto- check) Provides coincidences (relative timing)? Works very well with most of the OM designs? Measures water optical parameters? Can be used right from the start? Always reaches desired resolution? storey 2 storey 9 storey 15 storey 21 Cost? Needs little labour to implement? From photocathode up to readout? Calibration at very low intensity? Provides self-redundancy? (auto- check) Provides coincidences (relative timing)? Works very well with most of the OM designs? Measures water optical parameters? Can be used right from the start? Always reaches desired resolution? Cost? Needs little labour to implement? From photocathode up to readout? Calibration at very low intensity? Provides self-redundancy? (auto- check) Provides coincidences (relative timing)? Works very well with most of the OM designs? Measures water optical parameters? Can be used right from the start? Always reaches desired resolution? Cost? Needs little labour to implement? From photocathode up to readout? Calibration at very low intensity? Provides self-redundancy? (auto- check) Provides coincidences (relative timing)? Works very well with most of the OM designs? Measures water optical parameters? Can be used right from the start? Always reaches desired resolution? Intra-line calibration Intra-line calibration (may be with just 1 LED per floor?): New uncleaved LED with higher intensity New measurements from ANTARES: 1LED (cleaved) reaches ~150m. Intra-line calibration Intra-line calibration (may be with just 1 LED per floor?): New uncleaved LED with higher intensity New measurements from ANTARES: 1LED (cleaved) reaches ~150m. Collected amplitude times R 2 as a function of the distance R for three LED Beacons located along Line 2. The normalization depends on the LED Beacon intensity which is not the same for the different beacons.

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/ Timing Relative Positioning Absolute OrientationConclusions Cost? Needs little labour to implement? From photocathode up to readout? Calibration at very low intensity? Provides self-redundancy? (auto- check)  Provides coincidences (relative timing)? Works very well with most of the OM designs?  Measures water optical parameters?  Can be used right from the start? Always reaches desired resolution?  Cost? Needs little labour to implement? From photocathode up to readout? Calibration at very low intensity? Provides self-redundancy? (auto- check) Provides coincidences (relative timing)? Works very well with most of the OM designs? Measures water optical parameters? Can be used right from the start? Always reaches desired resolution? e - (  decay) Cherenkov light γ 40 K 40 Ca Always present in sea water Cost? Needs little labour to implement? From photocathode up to readout? Calibration at very low intensity? Provides self-redundancy? (auto- check) Provides coincidences (relative timing)? Works very well with most of the OM designs? Measures water optical parameters? Can be used right from the start? Always reaches desired resolution? coincidences are extremely useful for relative OM calibration. As seen in ANTARES coincidences are extremely useful for relative OM calibration. Coincidences between lines from the same source might be difficult to achieve in some schemes. OM 0 OM 1 OM 2 Taking differences by pairs

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/2008 Multi PMTs in one glass sphere 7 Timing Relative Positioning Absolute OrientationConclusions Cost?  Needs little labour to implement?  From photocathode up to readout? Calibration at very low intensity? Provides self-redundancy? (auto- check)  Provides coincidences (relative timing)? Works very well with most of the OM designs?  Measures water optical parameters?  Can be used right from the start? Always reaches desired resolution? The fibre solution may be too cumbersome if several small PMTs per OM are used For details see M. Circella’s talk on Time Calibration of the NEMO apparatus

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/ Relative timing in Km3NeT Absolute timing in KM3NeT It is required to correlate the events with observations from other instruments (i.e. satellite for GRBs...).Studies indicate that time-stamping at millisecond accuracy is sufficient for this purpose and this is easily achievable with commercially available GPS units. Dark Room 40 KLight Sources Optical fibres Muons Cost?  Needs little labour to implement?  From photocathode up to readout? Calibration at very low intensity?  Provides self-redundancy? (auto- check)   Provides coincidences (relative timing)? Works very well with most of the OM designs?   Measures water optical parameters?  Can be used right from the start?  Always reaches desired resolution?  

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/ Relative Positioning Absolute OrientationConclusions Hydrophones: spatial position accuracy ~ 5 cm Line-shape (based on tilt-meter and compass): accuracy ~ 40 cm. It seems to work well but it should be scaled to KM3NeT Timing Positioning systems used in the pilot projects already reviewed in this session: M. Ardid’s talk on Positioning System of the ANTARES Neutrino Telescope F. Simeone’s talk on The acoustic positioning system for NEMO Phase 2 What we have learnt from pilot projects???  Reduce substantially the number of acoustic emitters (not for all the lines) (  1/5)  Larger distances  lower frequency  Hydrophones: reduce the unit price  Piezos glued to OM:  direct position of the optical module, compasses and tilt-meters probably not needed  more R&D needed (be sure that the optical system does not interfere with the acoustic one and vice-versa), more electronics  Try to reduce the number of tilt-meters and compasses (  50%) + reduction of the unit price

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/ Timing Relative Positioning Absolute OrientationConclusions Two steps: 1.LED Beacons to determine the position of OMs. 2.Acoustic system to determine the position of LOB (with hydrophones mounted on LOB and transponders at the sea bed) Two steps: 1.LED Beacons to determine the position of OMs. 2.Acoustic system to determine the position of LOB (with hydrophones mounted on LOB and transponders at the sea bed) Acoustic-Optical Positioning System: Acoustic-Optical Positioning System: use the LED Beacons in the positioning system. LED Beacon + Acoustic Receiver Autonomous transponder OMs 1 2 ADVANTAGES Reduction of the number of calibration units.DRAWBACKS Interference with the neutrino detector operation Calibration more problematic with light sources. ADVANTAGES Reduction of the number of calibration units.DRAWBACKS Interference with the neutrino detector operation Calibration more problematic with light sources.

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/ To observe celestial objects a precise absolute pointing calibration is needed. Timing Relative Positioning Absolute OrientationConclusions 1.Acoustic Method Measurements of the geographical coordinates (x,y, UMT grid system) give the absolute azimuth of the detector: a surface boat, equipped with an acoustic transducer, determines its own position with a GPS/Galileo receiver and the distance to a given deep-sea transducer by sound transit time. Absolute azimuth accuracy ~ 0.02º Measurements of the depth z give the tilt of the detector: the depth of the acoustic transducer is measured by a pressure sensor located in the anchor of the detection unit and measurements are verified using a ROV equipped with an accurate pressure sensor. A temperature+salinity profile is performed to get the pressure-depth relationship. Absolute tilt angles accuracy ~ 0.01 Absolute pointing accuracy of the telescope better than 0.03º 1.Acoustic Method Measurements of the geographical coordinates (x,y, UMT grid system) give the absolute azimuth of the detector: a surface boat, equipped with an acoustic transducer, determines its own position with a GPS/Galileo receiver and the distance to a given deep-sea transducer by sound transit time. Absolute azimuth accuracy ~ 0.02º Measurements of the depth z give the tilt of the detector: the depth of the acoustic transducer is measured by a pressure sensor located in the anchor of the detection unit and measurements are verified using a ROV equipped with an accurate pressure sensor. A temperature+salinity profile is performed to get the pressure-depth relationship. Absolute tilt angles accuracy ~ 0.01 Absolute pointing accuracy of the telescope better than 0.03º

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/ Timing Relative Positioning Absolute OrientationConclusions 2.Sea Surface Detector 2.Sea Surface Detector [see J-P. Ernenwein’s talk on Study of the calibration potential of HELYCON detectors with ANTARES] The method employs cosmic ray induced showers that contain muons of sufficient energy (E > 2 TeV) to reach the undersea detector. Based on the HELYCON design [ ]. Based on the HELYCON design [ Tsirigotis, A.G. Proceedings of 20th European Cosmic Ray Symposium, Lisbon, Portugal, 5-8 Sep 2006 ]. A Monte Carlo study has been performed to quantify the calibration capabilities of three autonomous detector arrays on floating (4000 m above the telescope) platforms at distances of 150 m from each other. The direction of the shower axis (reconstructed for the surface detector) is compared with the direction of the  (reconstructed for the telescope) Absolute pointing accuracy of the telescope ~ 0.05º in ten days The absolute position can be estimated by measuring the distance between the impact points of the reconstructed  track and the shower axis. The accuracy is better than a meter within a ten day data taking period.

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/ Timing Relative Positioning Absolute OrientationConclusions 3.Looking at the Moon Shadow Since the Moon absorbs cosmic rays, a deficit of atmospheric muons from the direction of the Moon disk (angular radius 0.26º) is expected. Simulations indicate that a 3  effect can be detected in less than 1 year of data-taking with a km 3 detector. 3.Looking at the Moon Shadow Since the Moon absorbs cosmic rays, a deficit of atmospheric muons from the direction of the Moon disk (angular radius 0.26º) is expected. Simulations indicate that a 3  effect can be detected in less than 1 year of data-taking with a km 3 detector. Results from C.Distefano et al., Nucl.Instrum.Meth.A567: , 2006 Moon disk Moon rest frame angular resolution = 0.19º±0.2º

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/ Timing Relative Positioning Absolute OrientationConclusions The angular resolution and the absolute pointing of the detector depends on the timing and position resolutions.  A time accuracy of ~ 2ns and a positioning precision of ~ 40 cm is suitable to achieve the desired angular resolution and pointing accuracy.  The experiences in the pilot projects have been evaluated to implement new ideas and to study the feasibility for KM3NeT.  These ideas have been reviewed: the advantages and drawbacks of each system have been shown.  All these systems are within the guidelines of the KM3NeT Conceptual Design Reports [ ]. The culmination of the current studies on these systems will be a good basis for the design of the calibration systems in the TDR with the final telescope configuration.

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S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/2008 LED Beacons & K40 OM offsets Projection on Y-axis LED beacons K40 Line 1

S.Toscano (IFIC-Valencia) - VLV T08 workshop Toulon, 23/04/2008 LED Beacons & K40 OM offsets LED Beacon 40 K 40 Ca e - (  decay) Cherenkov light  K40 LED beacons K40 LED beacons – K40 Lines 1-5