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Characterization of biofouling process on glass spheres in Toulon and Capo Passero sites.

Characterization of biofouling process on glass spheres in Toulon and Capo Passero sites. Manuela Vecchi KM3NeT CM Pylos April 16th 2007 Antonio Capone, Jean Pierre Schuller, M.V. Outline. The “biofouling” process …what does it mean? Experimental set - up.

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Characterization of biofouling process on glass spheres in Toulon and Capo Passero sites.

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  1. Characterization of biofouling process on glass spheres in Toulon and Capo Passero sites. Manuela Vecchi KM3NeT CM Pylos April 16th 2007 Antonio Capone, Jean Pierre Schuller, M.V.

  2. Outline • The “biofouling” process …what does it mean? • Experimental set - up. • Biofouling : what kind of effects? • Parametrisation of transparency variation as a function of “latitude” on the OMs. • Time evolution of the fouling “speed” .

  3. Toulon site ~ 2400 m deep Capo Passero site ~3300 m deep

  4. Time • The “biofouling effect” • Cause:the growing - up of bacteria colonies and sedimentation processes. • Effect: it can led to OMs transparency losses. How can we evaluate it? Transparency

  5. Buoy Metal frame 2m × 2m equipped with 4 Benthos spheres Sphere A Sphere B Modem Current meter Antares sea campaign: June 2000 – October 2001 NEMO sea campaign: March 2003 – October 2004 Buoy Sphere C Sphere D Releases Sphere A contains: CPU, 14 detectors, 1 source (blue LED); Sphere B contains: 2 sources (blue LEDs); Sphere C contains: 1 source (blue LED), 14 detectors; Sphere D was empty and used to balance the structure. Ballast Experimental Set -up The same apparatus in Toulon and Capo Passero site.

  6. PINs on sphere A as seen from sphereB PINs on sphere C as seen from sphere B Photodiodes 14 photodiodes (PINs) have been placed on the internal surface of Benthos Sphere A and C. B A TOULON DATA: For technical reasons we cannot use the sources on sphere B C C  Experimental set – up (2)

  7. About the sources... Reference PINs A B D C Blue LEDs Experimental set – up (3)

  8. North PINs onphere A as seen from B PINs on sphere C as seen from B Latitude on the OM The “biofouling” process Transparency has been estimated using: Transparency Time

  9. North Time Transparency variation Transparency variation time Transparency ..and its variations… Latitude on the OMs

  10. Time The most regular contributions are likely to come from the biofilm growing - up. Tails contain events with bigger fluctuations. Transparency variation per sample interval Transparency time evolution and variations Transparency

  11. Double gaussian fit Biofilm Sediments Experimentally observed: ΔTransp/Δt distributions fit the sum of 2 gaussian functions. Transparency variation per sample interval

  12. Latitude on Oms North Sphere A Sphere B For each PIN we can calculate the transparency variation PINs onphere A as seen from B Sphere C Sphere D PINs on sphere C as seen from B Is there a relation between ∆Transp/∆t and the latitude on the OMs? Considering that … ... we can calculate the transparency loss for several latitudes… Photodiodes disposition on OMs

  13. Latitude on Oms North Transparency variation vs latitude Transparency variation [% per year] Transparency variation [% per year] Astropart. Phys. 19 (2003) 253-267 ANTARES Collaboration Transparency variation as a function of latitude on OMs. Toulon site Capo Passero site Latitude 2% transparency loss per year @ the Equator has been taken from Latitude 

  14. The evaluation comes from the value (-2% per year at the Equator) previously obtained by the ANTARES Collaboration and slightly changing it. Systematic error evaluationfor ANTARES data

  15. Short summary… • Biofouling does matter! • Transparency variation is slight for downward-looking surfaces ~ -2% per year (or less in CP site); • Transparency variation is important for upward-looking surfaces, both in CP and Toulon especially for latitudes bigger than 50°…

  16. Underwater currents [cm/s] Toulon site Capo Passero site Current Compass Angle Roll Angle Pitch Angle Time Time

  17. Transparency variation [% per year] Latitude on Oms North Dividing the time slice in 7 equal parts and doing the same analysis... Focusing our attention... Transparency variation [% per year] Time Downward - looking surfaces

  18. Latitude on Oms North Focusing our attention... (2) Upward - looking surfaces Transparency variation [%per year] Transparency variation [%per year] Time Time

  19. …close to the end … • Biofouling process can reduce OMs transparency; • Transparency losses depend on latitude!! especially for upward-looking surfaces; • The speed of this process depends on underwater current behaviour (“saturation-like” trend for transparency losses at CapoPassero / fouling speed rise at Toulon site)

  20. …the end …

  21. ANTARES site NEMO site Luminescent bacteria quantity

  22. ANTARES transparency evolution Transparency evolution for downward-looking PINs Transparency evolution for upward-looking PINs

  23. Effective area reduction because of the biofouling process (only for NEMO) 20% reduction after 10 years @ E < 1TeV Less than 5% reduction after 10yrs @ > 10 TeV

  24. Angular resolution + biofouling (only for NEMO) No effect for energies > 10TeV

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