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PROGRESS ON WATER PROPERTIES ON TRACKS RECONSTRUCTION

PROGRESS ON WATER PROPERTIES ON TRACKS RECONSTRUCTION. ANTARES Collaboration Meeting Strasbourg, November 21 st -25 th , 2011. H Yepes -Ramirez IFIC (CSIC – Universitat de València). OUTLINE.

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PROGRESS ON WATER PROPERTIES ON TRACKS RECONSTRUCTION

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  1. PROGRESS ON WATER PROPERTIES ON TRACKS RECONSTRUCTION ANTARES Collaboration Meeting Strasbourg, November 21st-25th, 2011 H Yepes -Ramirez IFIC (CSIC – Universitat de València)

  2. OUTLINE Brief reminder of light propagation in sea water: ANTARES Monte Carlo model Simulation: data selection, absorption and scattering length inputs and codes Selected results Conclusions and outlook ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  3. Brief reminder of light propagation in sea water

  4. Brief reminder of light propagation in sea water Absorption length Scattering Length Scattering phase function (b) • Morel and Loisel approach • Molecular scattering (Rayleigh)  Isotropic (<cosq>=0) • h = contribution of Rayleigh scattering • Particle scattering (Mie)  Strong forward peaked (<cosq>Mie=0.924) Attenuation Length (COLIMATED BEAM) Effective Attenuation Length (ISOTROPIC SOURCE) Scattering length wavelength dependence (Kopelevich parameterization) Petzold values for particle scattering b = scattering coefficient. vs, vl = scattering centers. <Cosq> = Average cosine of the global distribution ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  5. Simulation

  6. Simulation • DATA/MonteCarlo SELECTION: • Data 2008 – 2010 data from the official SeaTray production May 2011 (5997 runs). • First run: 31051, Last run: 54244. Subsample from Point Sources data from Juan Pablo analysis (2007-2010). • Lifetime: 618.96 days. • MonteCarlo (no run-by-run) SoS prepared (C. Bogazzi) with the previous subsample (5997 data runs). • Mupage for muons + Geasim for neutrinos. • Statistics hugely increased from CM Moscow (two runs per water model: 2 n, 2 n-, 2 m), right now: sc = scattering centers; aa = om angular acceptance; abs = absorption; sca = scattering; eta = fraction of Rayleigh scattering. ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  7. Simulation • Water models are selected based on: • Three models with the same h value and different scattering spectrum for a given absorption length. • Three models with different h values, but h is computed in such a way that the three models will have the same effective scattering length at 470 nm, for a given absorption length. • OM Angular acceptance of June 2009 (Genova Meeting 2009). ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  8. Simulation Simulation chain: • WATER MODEL: • Photon tables production (water tables) Water tables (hbook files) + Description files (ASCII files). GEN • OM PARAMETERS: • Hit probability computation from the water tables for a given OM parameters Hit tables (hbook files) + Description files (ASCII files). HIT • Simulated events: Geometry + Kinematics • Physics events reading and OM hits production based on event geometry and hit probability tables Detector events: Signal hits (muons, not tracks from hadronic showers), physical background. KM3 • Simulations OF ATMOSPHERIC NEUTRINO INTERACTIONS. • Process (and evaluation) tracks from particles coming from the hadronic showers (also muons from KM3). GEASIM MCEW TRANSLATION OF INFO ASCII FILES INTO ROOT FORMAT. FORMAT CONVERSION TO “LOOK LIKE DATA”: electronics smearing effects (calibration, ARS response) and optical background. TE RECONSTRUCTION: Reconstruction of track direction (AAfit) and ntuples information arrangement as number of hits, zenith distribution…(AntDST). RECO ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  9. Simulation Main options and software versions in muons and neutrinos simulation: ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  10. Simulation Sanity check with the official production (sc0.0075 aa09 abs55 sca53 eta0.17): My production Official production • It is not a run-by-run simulation. • 5997 data runs (2008-2010). • 312 mupage muon runs. • 90 neutrino + 40 anti-neutrino Geasim files. • TE May 2011. • Down-going neutrinos not used in this MC. • Run-by-run simulation. • 5997 data runs (2008-2010). • 5941 mupage muon runs. • 5898 neutrino + 5900 anti-neutrino Geasim files. • TE September 2010. • Down-going neutrinos are used in the run-by-run MC. L >-5.2 removes some events close to the horizon (my sample), L > -5.4 relax this zone (SEE NEXT SLIDE) ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  11. Simulation ±[31-43]%  [-1, -0.1] ±25% [>0.2] ±45%  [-0.1, +0.1] • A restrictive cut at L > -5.2 removes neutrinos and muons near the horizon (and some muons below the horizon). This may have a large impact on this analysis due to the smaller statistics (concerning the run-by-run MC statistics). • If we relax the cut to L > -5.4 the agreement to data is better within the different available samples (typical cut on point sources analysis before run-by-run MC). ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  12. Selected Results

  13. Selected results • Lessons learnt since the CM in Moscow: • Lower effective scattering lengths could not be an good approach. • Higher absorption lengths should not be discarded. • Determination of the effective scattering length seems to be more critical than the estimation of absorption length. ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  14. Selected results • DATA/MC rates for zenith angle distribution: • Lowest effective scattering lengths could be discarded (< 100 m)     • Contribution of Rayleigh scattering seems to be lower  Comparison improves. • lsca = 41 m && h = 0.11 && labs = 55 m fit better to data, overall at neutrino region   • The “hole” close to the horizon could be filled by means of the use of down-going neutrinos, improving the comparison. ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  15. Selected results • DATA/MC rates for zenith angle distribution: • Higher absorption lengths should not be discarded. • Lowest effective scattering lengths can be discarded (< 100 m)     • Contribution of Rayleigh scattering seems to be lower. • Two models with higher absorption length, equal effective scattering length and different contribution of eta and scattering length show nice agreement to data     ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  16. Selected results Influence of labs on reconstructed tracks: Strategy  For a couple of water models with different labs but same scattering parameters, estimate the difference on the reconstructed track rate. Previous systematic studies in ANTARES (J.A et al / Astroparticle Physics 34, 2010, 179-184, Pag. 182)  “The uncertainty of the light absorption length in water is assumed to be ±10% over the whole wavelength spectrum and yields a variation of ±20% on the number of expected events”. CASE 1 ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  17. Selected results CASE 2 CASE 3 ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  18. Selected results CASE 4 CASE 5 ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  19. Selected results •  THE UNKNOWLEDGE ABOUT ABSORPTION LENGTH FOR DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT ≈ 18% ON AVERAGE ON THE RECONSTRUCTED MUON RATE  ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  20. Selected results Case 2: sn_rate ≈ 15 % Case 1: sn_rate ≈ 0 % Case 3: sn_rate ≈ 15 % Case 4: sn_rate ≈ 15 % Case 5: sn_rate ≈ 15 % •  THE UNKNOWLEDGE ABOUT ABSORPTION LENGTH FOR DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT ≈ 15% ON THE RECONSTRUCTED NEUTRINO RATE  ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  21. Selected results INFLUENCE OF lsca,eff ON RECONSTRUCTED TRACKS: Strategy Two optical parameters fixed (absorption, eta) and one free parameter (scattering length), for both absorption lengths. ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  22. Selected results ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  23. Selected results •  THE UNKNOWLEDGE ABOUT EFFECTIVE SCATTERING LENGTH FOR DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT BETWEEN 15-25% ON THE RECONSTRUCTED MUON-NEUTRINO RATE DEPENDING OF THE ZENITH ANGLE  ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  24. Selected results •  THE UNKNOWLEDGE ABOUT EFFECTIVE SCATTERING LENGTH FOR DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT BETWEEN 15-25% ON THE RECONSTRUCTED MUON-NEUTRINO RATE DEPENDING OF THE ZENITH ANGLE  ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  25. Selected results INFLUENCE OF h ON RECONSTRUCTED TRACKS: Strategy One optical parameters fixed (absorption) and two free parameters (scattering length and eta), for both absorption lengths. ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  26. Selected results ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  27. Selected results •  THE UNKNOWLEDGE ABOUT RAYLEIGH SCATTERING FOR DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT LESS THAN 18 % ON THE RECONSTRUCTED MUON-NEUTRINO RATE  ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  28. Selected results •  THE UNKNOWLEDGE ABOUT RAYLEIGH SCATTERING FOR DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT LESS THAN 18% ON THE RECONSTRUCTED MUON-NEUTRINO RATE  ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  29. Conclusions and outlook

  30. CONCLUSIONS AND OUTLOOK Current study shows that, for the current physics conditions simulated in the ANTARES KM3 code the uncertainty on water parameters could be summarized as follow: The effective scattering length seems to be the most relevant parameter for muons. Neutrino tracks reconstruction is very sensitive to the absorption length and Rayleigh scattering. An extensive study to effective areas and angular resolution will be performed. An internal note will be prepared soon with a dedicated description of the analysis. ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

  31. Backup

  32. BACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21st-25th

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