PROGRESS ON WATER PROPERTIES ON TRACKS RECONSTRUCTION Harold Yepes-Ramirez 17/11/2011

Water Model   data sc aa09 abs55 sca53 eta sc0.01 aa09 abs55 sca41 eta sc0.02 aa09 abs55 sca22 eta sc0.01 aa09 abs55 sca41 eta sc0.02 aa09 abs55 sca22 eta sc aa09 abs63 sca53 eta sc0.01 aa09 abs63 sca41 eta sc0.02 aa09 abs63 sca22 eta sc0.01 aa09 abs63 sca41 eta sc0.02 aa09 abs63 sca22 eta DATA/MonteCarlo SELECTION: Data  2008 – 2010 data from the official SeaTray production May 2011 (5997 runs). First run: Last run: Subsample from PS data from Juan Pablo. Lifetime: days. MonteCarlo (no r-b-r)  SoS prepared (C. Bogazzi) with the previous runs (5997 data runs). Mupage for muons + Geasim for neutrinos. Statistics hugely increased: CM Moscow two runs per water model (2, 2 , 2  ), right now: sc = scattering centers; aa = om angular acceptance; abs = absorption; sca = scattering; eta = fraction of Rayleigh scattering.

SANITY CHECKS WITH PREVIOUS PRODUCTIONS: Harold: It is not a run-by-run simulation data runs ( ). 312 mupage muon runs. 90 neutrino + 40 anti-neutrino Geasim files. TE May Down-going neutrinos not used in this MC. Juan Pablo: Run-by-run simulation data runs ( ) mupage muon runs neutrino anti-neutrino Geasim files. TE September Down-going neutrinos are used in the r-b-r MC.  >-5.2 removes some events close to the horizon (my sample),  > -5.4 relax this zone (SEE NEXT SLIDE).

±25% [>0.2] ±45% [-0.1, +0.1] ±31-43% [-1, -0.1] A restrictive cut at  > -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  > -5.4 the agreement to data is better within the different available samples (typical cut on point sources analysis before run-by-run MC).

UPDATED PLOTS FOR THE ZENITH ANGLE CONTRIBUTION: UNCERTAINITY ESTIMATION OF RECONSTRUCTED TRACKS DUE WATER OPTICAL PARAMETERS

Lesson learnt since the CM in Moscow: the extreme scattering models ( sca <22) shows the worst agreement to data: Lower values (~0.02) of contribution of Rayleigh scattering (  ) over-estimates the data, and higher (~0.17) values under-estimates it. Values of abs > 55 m could not be an good approach. The best agreement to data is then expected for large scattering lengths and not enough higher absorption lengths. The ANTARES site seems to have a large scattering length.

DATA/MC rates for zenith angle distribution: sca < 22 m discarded. sca > 41 m:  ~ 0.11 MC overestimates the data. sca > 41 m &&  ~ 0.17 && abs ~ 55 m fit better to data, overall at neutrino region.

DATA/MC rates for zenith angle distribution: abs > 63 m could be discarded. sca < 22 m for lower , seems to compensate the effect of large absorption lengths  An intermediate value of abs = 60 m could confirm it to us.

INFLUENCE OF abs ON RECONSTRUCTED TRACKS: 1.Strategy  For a couple of water models with different labs but same scattering parameters, estimate the difference on the reconstructed track rate  Uncertainty on labs Vs uncertainty on the muon rate. 2.Previous systematic studies in ANTARES (J.A et al / Astroparticle Physics 34, 2010, , 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”. Muons uncertainty (   _rate )  abs ± 7% (8 m)   _rate ≈ 25% (0.14 Hz) Neutrinos uncertainty (  _rate )  abs ± 7% (8 m)   _rate ≈ 8% (0.002 Hz)

Muons uncertainty (   _rate )  abs ± 7% (8 m)   _rate ≈ 13% (0.07Hz) Neutrinos uncertainty (  _rate )  abs ± 7% (8 m)   _rate ≈ 8% (0.002 Hz) Muons uncertainty (   _rate )  abs ± 7% (8 m)   _rate ≈ 10% (0.07Hz) Neutrinos uncertainty (  _rate )  abs ± 7% (8 m)   _rate ≈ 4 % (0.001 Hz)

Muons uncertainty (   _rate )  abs ± 7% (8 m)   _rate ≈ 13% (0.07Hz) Neutrinos uncertainty (  _rate )  abs ± 7% (8 m)   _rate ≈ 29 % ( Hz) Muons uncertainty (   _rate )  abs ± 7% (8 m)   _rate ≈ 15% (0.08Hz) Neutrinos uncertainty (  _rate )  abs ± 7% (8 m)   _rate ≈ 64 % ( Hz)

Case 1:   _rate ≈ 25 % Case 2:   _rate ≈ 13 % Case 3:   _rate ≈ 14 % Case 4:   _rate ≈ 14 % Case 5:   _rate ≈ 14 % UNCERTAINTY ON abs ±7% MEAN UNCERTAINTY  rate ≈ 15%  THE UNKNOWLEDGE ABOUT ABSORPTION LENGTH FOR DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT LESS THAN THE 15% ON THE RECONSTRUCTED MUON RATE  UNCERTAINTY ON abs (± 7%) and UNCERTAINTY ON MUON RATES: FUNCTION OF ZENITH ANGLE

Case 1:  _rate ≈ 8 % Case 2:  _rate ≈ 8 % Case 3:  _rate ≈ 4 % Case 4:  _rate ≈ 29 % Case 5:  _rate ≈ 64 % UNCERTAINTY ON abs ±7% UNCERTAINTY rate ≈ [4-64]% RECONSTRUCTED NEUTRINO RATE IS VERY SENSITIVE TO THE RAYLEIGH SCATTERING CONTRIBUTION GIVING A UNCERTAINTY BETWEEN [29-64]%. TAKING INTO ACCOUNT THAT EXTREME SCATTERING MODELS ARE DISCARDED, THE UNCERTAINTY ON NEUTRINO RATES DUE TO THE UNKNOWLEDGE OF ABSORPTION LENGTH IS LESS THAN THE 29 %. UNCERTAINTY ON abs (± 7%) and UNCERTAINTY ON NEUTRINO RATES: FUNCTION OF ZENITH ANGLE

INFLUENCE OF sca,eff ON RECONSTRUCTED TRACKS: 1.Strategy  Two optical parameters fixed (absorption, eta) and one free parameter (scattering length), for both absorption lengths. UNCERTAINTY ON sca_eff [23-58]% UNCERTAINTY  rate [16-17]% Uncertainty on sca_eff : ~23 % (51.5 m). Uncertainty on muon rate: ~16 % (0.08 Hz). Uncertainty on sca_eff : ~46 % (81.5 m). Uncertainty on muon rate: ~17 % (0.1 Hz). Uncertainty on sca_eff : ~58 % (133 m). Uncertainty on muon rate: ~31 % (0.18 Hz). Uncertainty on sca_eff : ~23 % (51.5 m). Uncertainty on neutrino rate: ~0 % (0 Hz). Uncertainty on sca_eff : ~46 % (81.5 m). Uncertainty on neutrino rate: ~2% ( Hz). Uncertainty on sca_eff : ~58 % (133 m). Uncertainty on neutrino rate: ~2 % ( Hz). UNCERTAINTY ON sca_eff [23-58]% UNCERTAINTY rate < 2%

Uncertainty on sca_eff : ~23 % (51.5 m). Uncertainty on muon rate: ~4 % (0.02 Hz). Uncertainty on sca_eff : ~46 % (81.5 m). Uncertainty on muon rate: ~14 % (0.09 Hz). Uncertainty on sca_eff : ~58 % (133 m). Uncertainty on muon rate: ~17 % (0.11 Hz). Uncertainty on sca_eff : ~23 % (51.5 m). Uncertainty on neutrino rate: ~0 % (0 Hz). Uncertainty on sca_eff : ~46 % (81.5 m). Uncertainty on neutrino rate: ~6 % ( Hz). Uncertainty on sca_eff : ~58 % (133 m). Uncertainty on neutrino rate: ~6 % ( Hz). UNCERTAINTY ON sca_eff [23-58]% UNCERTAINTY  rate [4-17]% UNCERTAINTY ON sca_eff [23-58]% UNCERTAINTY rate < 6%

INFLUENCE OF  ON RECONSTRUCTED TRACKS: 1.Strategy  One optical parameters fixed (absorption) and two free parameters (scattering length and eta), for both absorption lengths. Uncertainty on  : ~35 % (0.06). Uncertainty on muon rate: ~13 % (0.06 Hz). Uncertainty on  : ~81 % (0.09). Uncertainty on muon rate: ~2 % (0.01 Hz). Uncertainty on  : ~88 % (0.15). Uncertainty on muon rate: ~15 % (0.07 Hz). Uncertainty on  : ~35 % (0.06). Uncertainty on neutrino rate: ~38 % ( Hz). Uncertainty on  : ~81 % (0.09). Uncertainty on neutrino rate: ~67 % ( Hz). Uncertainty on  : ~88 % (0.15). Uncertainty on neutrino rate: ~79 % ( Hz). UNCERTAINTY ON  [35-88]% UNCERTAINTY  rate [2-15]% UNCERTAINTY ON  [35-88]% UNCERTAINTY  rate [38-79]%

Uncertainty on  : ~35 % (0.06). Uncertainty on muon rate: ~2 % (0.01 Hz). Uncertainty on  : ~81 % (0.09). Uncertainty on muon rate: ~2 % (0.01 Hz). Uncertainty on  : ~88 % (0.15). Uncertainty on muon rate: ~4 % (0.02 Hz). Uncertainty on  : ~35 % (0.06). Uncertainty on neutrino rate: ~21 % ( Hz). Uncertainty on  : ~81 % (0.09). Uncertainty on neutrino rate: ~34 % ( Hz). Uncertainty on  : ~88 % (0.15). Uncertainty on neutrino rate: ~48 % ( Hz). UNCERTAINTY ON  [35-88]% UNCERTAINTY  rate < 4% UNCERTAINTY ON  [35-88]% UNCERTAINTY  rate [21-48]%

CONCLUSIONS/COMMENTS: 1.Current study shows that, for the current physics conditions simulated in the ANTARES KM3 code (whichever they are), the impact of water parameters could be summarized as follow (  = uncertainty): 2.The effective scattering length seems to be the most relevant parameter for muons. 3.Neutrino tracks reconstruction is very sensitive to the Rayleigh scattering, if the contribution of  could be less than These uncertainties could be more lower if we consider that scattering lengths less than 22 m are not possible in ANTARES site, however the strongest impact on tracks reconstruction mainly comes from the effective scattering length and not from the absorption length. 5.An extensive study to effective areas and angular resolution will be performed. 6.An internal note will be prepared soon with a dedicated description of the analysis. Parameter (for muon tracks)  abs [%]  sca_eff [%]   [%]   rate [%] Absorption length±7<15 Effective scattering length±60<17 Rayleigh scattering±90<15 Parameter (for neutrino tracks)  abs [%]  sca_eff [%]   [%]   rate [%] Absorption length±7±[4-64] Effective scattering length±60<6 Rayleigh scattering±90±[21-79]

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