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Calibration group

Calibration group . (convenors: Juan.J.Hernandez@ific.uv.es and L.Thompson@sheffield.ac.uk). “ Mission statement ”. Define the detector parameters (“calibration constants”) that must be determined to operate an undersea km 3 telescope at the desired accuracy.

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Calibration group

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  1. Calibration group (convenors: Juan.J.Hernandez@ific.uv.es and L.Thompson@sheffield.ac.uk) “Mission statement” • Define the detector parameters (“calibration constants”) that must be determined to operate an undersea km3 telescope at the desired accuracy. • Establish the precisionat which this parameters must be/ can be estimated. • Propose the systems that may be used to reach this goal. • Studyconcrete solutions, adapted to the selected final design, to implement these systems. Version 8/10 11:30

  2. Calibration goals Determine the necessary constants to allow the reconstruction of events in spacetimeenergy Position Timing Amplitude All other constants (temperature, voltages) are used to determine these parameters

  3. Detector Physics Layout Requirements Mechanics Data transmission Readout Photo Detector Interdependence Calibration

  4. Positioning Position calibration Absolute Relative • w.r.t. external objects • depends on site • GPS + acoustic transponders • Moon? •  Local geological peculiarities? •  Other detectors? • New ideas are most welcome among inner components depends on detector design  Semi-rigid/fixed parts: tiltmeters, compasses  Moving parts: Non-luminous devices (sonic, other?)

  5. Time Timing calibration Absolute Relative w.r.t. to UTC Should not be a major problem (in the msec range) But several junction points would mean new problems in relative calibration • among inner components • extremely important •  Affects reconstruction efficiency and angular resolution • Limited by intrinsic processes: photosensor time fluctuations, medium time dispersion, electronics.

  6. Timing calibration 1st level electronics Light Photosensor Digitization Time stamping Additional electronics Data decoding and storage Data transfer Each level can introduce delays, jitters and shiftswith time At which levels is convenient to have time calibration? How?

  7. Timing calibration

  8. Amplitude • Photodetectors can be calibrated at the laboratory (the site is a “quiet” place). • For conventional PMTs, gain can be monitored via 40K (site dependent). • Transparency losses are more difficult to monitor. • New devices may need different calibration.

  9. R&D road map • Study the scalability to km3 of existing techniques and technologies. • Position: • Positioning within one detector “unit” (string, tower, etc) and “sub-unit” (storey, floor, star). • Relative positioning between “units” Acoustic devices? Systematics @ 1km? Horizontal tracks. How frequently? • Absolute positioning (GPS plus several reference points?) • Timing: • Clock based: echo system, synchronous data. • Optical calibration within detector units: through fibers? through the water (shadowing)? • Optical calibration among detector units: needed? (redundancy is not a luxury) Feasible? (distance between beacon-OM  λabs and λscat) • Amplitude : • Gain calibration via 40K • Overall monitoring (transparency loss) more difficult (site dependent)

  10. R&D road map (continued) • Explore new ideas in all domains: • Independent calibration array? Farfetched idea: needs to be studied in detail • Synchronous Digital Hierarchy •  beam from CERN?? • … • Start studies with some likely designs

  11. Summary • The review of existing/near future detectors showed common basic approaches to calibration. • Are these concepts scalable to a km3 detector? • New ideas are needed and already some appeared and were discussed. • Calibration is closely related to other topics. Next step requires an interaction with convenors of other task groups.

  12. END OF TALK

  13. Synchronous Digital Hierarchy (SDH)

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