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Selected Calibration Highlights

Selected Calibration Highlights. Kurt Woschnagg, UCB. IceCube Collaboration Meeting, Lake Geneva, April 2007. Selected Calibration Topics. Geometry Deployment data Interstring flasher data [Chihwa Song] Waveform Calibration Droop correction [Cecile Roucelle]

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Selected Calibration Highlights

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  1. Selected Calibration Highlights Kurt Woschnagg, UCB IceCube Collaboration Meeting, Lake Geneva, April 2007

  2. Selected Calibration Topics • Geometry • Deployment data • Interstring flasher data [Chihwa Song] • Waveform Calibration • Droop correction [Cecile Roucelle] • ATWD channel non-linearity [Chris Wendt] • Ice Properties • Ice properties systematics → tomorrow AM • Flasher measurements • 2007 dust logger data → dust layer tilt [Ryan Bay] • Hole ice measurement [Brendan Fox] • Standard Candle

  3. IceCube Geometry Status Stage 1: • 22-string + IceTop-26 geometry release on Feb 8 • Deployment data • Surface surveys • Verified with flashers and muons Stage 2: • Interstring geometry calibration (Chihwa Song) • Geometry with depth corrections to be released soon Get your coordinates from offline database (I3Db)

  4. survey data • drill tower • IceTop tanks/DOMs deployment data • pressure data • compressibility correction • well depth • DOM spacing drill data Hole profile Geometry Calibration(Stage 1) tower base plate Absolute (x,y,z) on surface well depth water surface String depth DOM spacing pressure sensors string depth in water Corrections (x,y) along string Absolute (x,y,z) for all DOMs DB bottom DOM (defines string depth)

  5. Stage 2 geometry: interstring flasher data Chihwa Song Gaussian fit 38 39 t0 = a - b·d t (ns) dD L z=0 Hyperbola fit Distance between DOMs [m] Flash all horizontal LEDs and look at photon arrival times at receiving DOMs z [m]

  6. Stage 2 geometry: a global fit Performed a global fit of all parameters/hyperbolas at once Fixed (x, y) positions of DOMs - this method would give large uncertainties in (x,y) because of the large spacings between strings Random sampling: Take a randomly chosen subset of all available string pairs and use only the selected hyperbolas in the global fit Repeat many times → distributions whose widths = σstat

  7. IC-9 depth shifts from the global fit Distributions from set of randomly sampled subsets

  8. IC-9 results after depth corrections

  9. large uncertainties in Stage 1 Depth shifts for 22 strings Random sampling over 3 sub-arrays Depth Offset (rel. to Stage-1 geometry) [m] reference [Chihwa Song] Make depth correction if shift > 1 sigma Corrected geometry to be released soon

  10. [Cecile Roucelle]

  11. [Chris Wendt] Combined ATWD waveform

  12. DOMcal fits here

  13. Extending the ice map for IceCube Need to complement AMANDA data

  14. 2007 flasher data for ice properties Bright runs: readout 48 SPE runs: readout 29/30/38/40/49/48 SPE runs Bright runs

  15. DOMcalibrator droop correction not applied

  16. Suggests that deepest ice is even cleaner than expected PRELIMINARY Scattering tracks model based on AMANDA measurements Absorption artificially “strong” from these fits because of drooping waveforms

  17. Time difference for DOM pair above flasher [Dawn Williams] N-2 Δt prompt time N-1 occupancy flashing N

  18. Laser ~1 m Baffles Receiver Dust Logger 2007 Update Ryan Bay Andres Morey, Robert Rohde

  19. A retrievable IceCube Dust Logger Before After colder dustier

  20. IceCube hi-res dust logging of South Pole Prevailing wind Ice flow

  21. SP horizon mapping Distortion gradient Prevailing wind ~235o SW Ice flow To lake 2nd-orderwind “ripples” 1st-order distortion points to SP lake

  22. Analysis of three dust logs

  23. Still not severe enough for a modification of ice model Analysis of three dust logs preliminary

  24. Analysis of three dust logs preliminary sloping toward lake sloping along flow

  25. Dust Logger this coming Season • Repair Robertson winch • Configure probe without bottom weight • Log down fast (40-50 m/min) • and up slow (20-30 m/min) • Implement minor soft/hardware • improvements • Refurbish and ship in August • Log two holes: 75 & 44 (prel.)

  26. Dust Logger this coming Season

  27. Hole ice update • Air bubbles trapped in the refrozen ice column • increase scattering close to the modules • → Make angular acceptance more isotropic • →Uncertainty is major systematic in many • analyses • Measurement approaches: • flasher data (single LED) • string 4 → 48 YAG laser measurement • bubble camera hole ice (trapped bubbles) bulk ice (some dust)

  28. 1 2 3 4 5 6 1 2 3 4 5 6 [Michelangelo D’Agostino, 2006] An illustration of the complexity of the hole ice situation… Average waveforms at DOM above flashing DOM Vertical LED’s Horizontal LED’s black = water; green/blue = ice Bubble formation appears to be non-azimuthally symmetric…

  29. The string 4→48 hole ice measurement Brendan Fox [et al.] All OMs on AMANDA string 4 have a diffusing fiber ball connected to surface laser

  30. The string 4→48 hole ice measurement “In-water” data taken for almost all fibers: • Taken within 48 hours of deployment • Thanks to all who helped make it happen! • Each ball flashed twice: • LC run w/128 sample ATWD0 readout • no-LC run w/32 sample ATWD0 readout “Just-frozen” data taken for some fibers: • 2-3 weeks after deployment “Frozen” data to be taken later (May?)

  31. Red - InWater Red - InWater Blue - JustFrozen Blue - JustFrozen First look at 4→48 hole ice data: LC 1 DOM above fiber 1 DOM below fiber Receiver LE of First Hit - AMANDA trigger Time (ns) 2 DOMs below 2 DOMs above

  32. Red - InWater Red - InWater Blue - JustFrozen Blue - JustFrozen First look at 4→48 hole ice data: noLC 1 DOM above fiber 1 DOM below fiber Not corrected for increased noise during freeze-in Receiver LE of First Hit - AMANDA trigger Time (ns) 2 DOMs below 2 DOMs above

  33. The string 4→48 hole ice measurement • “In-water” data set pretty good quality • Promising hint of a noticeable change • Need more “Frozen” data to do a real comparison • Use photonics simulations for quantitative analysis • fit scattering length in hole ice

  34. Calibrations using the Standard Candle SC1 output calibration done • Uncertainty in number of photons per pulse: ~10% • For a typical run at 100%: Nphotons = (4.0±0.4)·1012 • Run-by-run calibration constants on wiki page • Internal report icecube/200704001 SC1 data used for • Cascade reconstruction calibration [Joanna Kiryluk] • Simulation tuning/verification [Michelangelo D’A.] • EHE studies (w/ golden DOMs) [Aya Ishihara] http://wiki.icecube.wisc.edu/index.php/Standard_Candle

  35. 57 IceCube Standard Candles • Standard Candle II • deploy next season • pointing downward 63 55 64

  36. Up-looking “bubble camera” in air

  37. Down-looking “bubble camera” in air

  38. Up-looking “bubble camera” in water

  39. Down-looking “bubble camera” in water

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