PROGRESS ON WATER PROPERTIES ON

TRACKS RECONSTRUCTION

Harold Yepes-Ramirez17/11/2011

Water Model n n- m data

sc0.0075 aa09 abs55 sca53 eta0.17 90 40 312 5997

sc0.01 aa09 abs55 sca41 eta0.17 87 39 90 5997

sc0.02 aa09 abs55 sca22 eta0.17 88 40 84 5997

sc0.01 aa09 abs55 sca41 eta0.11 60 20 98 5997

sc0.02 aa09 abs55 sca22 eta0.02 22 6 63 5997

sc0.0075 aa09 abs63 sca53 eta0.17 86 36 65 5997

sc0.01 aa09 abs63 sca41 eta0.17 88 38 41 5997

sc0.02 aa09 abs63 sca22 eta0.17 85 40 32 5997

sc0.01 aa09 abs63 sca41 eta0.11 71 30 54 5997

sc0.02 aa09 abs63 sca22 eta0.02 46 18 44 5997

DATA/MonteCarlo SELECTION:Data 2008 – 2010 data from the official SeaTray production May 2011 (5997 runs).•First run: 31051. Last run: 54244. Subsample from PS data from Juan Pablo.•Lifetime: 618.96 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 n, 2 n-, 2 m), 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.•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.

Juan Pablo:•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 r-b-r MC.

L >-5.2 removes some events close to the horizon (my sample), L > -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 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).

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 (lsca<22) shows the worst agreement to data:

• Lower values (~0.02) of contribution of Rayleigh scattering (h) over-estimates the data, and higher (~0.17) values under-estimates it.

• Values of labs > 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: • lsca < 22 m discarded.• lsca > 41 m: h ~ 0.11 MC overestimates the data.• lsca > 41 m && h ~ 0.17 && labs ~ 55 m fit better to data, overall at neutrino region.

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

INFLUENCE OF labs 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, 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”.

Muons uncertainty (sm_rate)

slabs ± 7% (8 m)sm_rate ≈ 25% (0.14 Hz)

CASE 1

Neutrinos uncertainty (sn_rate)

slabs ± 7% (8 m)sm_rate ≈ 8% (0.002 Hz)

CASE 2Muons uncertainty (sm_rate)

slabs ± 7% (8 m)sm_rate ≈ 13% (0.07Hz)

Neutrinos uncertainty (sn_rate)

slabs ± 7% (8 m)sm_rate ≈ 8% (0.002 Hz)

CASE 3Muons uncertainty (sm_rate)

slabs ± 7% (8 m)sm_rate ≈ 10% (0.07Hz)

Neutrinos uncertainty (sn_rate)

slabs ± 7% (8 m)sm_rate ≈ 4% (0.001 Hz)

CASE 4Muons uncertainty (sm_rate)

slabs ± 7% (8 m)sm_rate ≈ 13% (0.07Hz)

Neutrinos uncertainty (sn_rate)

slabs ± 7% (8 m)sm_rate ≈ 29% (0.0006 Hz)

Muons uncertainty (sm_rate)

slabs ± 7% (8 m)sm_rate ≈ 15% (0.08Hz)

Neutrinos uncertainty (sn_rate)

slabs ± 7% (8 m)sm_rate ≈ 64% (0.0006 Hz)

Case 1:sm_rate ≈ 25 %

Case 2:sm_rate ≈ 13 %

Case 3:sm_rate ≈ 14 %

Case 4:sm_rate ≈ 14 %

Case 5:sm_rate ≈ 14 %

UNCERTAINTY ON labs ±7%

MEAN UNCERTAINTY mrate ≈ 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 labs (± 7%) and UNCERTAINTY ON MUON RATES: FUNCTION OF ZENITH ANGLE

Case 1:sn_rate ≈ 8 %

Case 2:sn_rate ≈ 8 %

Case 3:sn_rate ≈ 4 %

Case 4:sn_rate ≈ 29 %

Case 5:sn_rate ≈ 64 %

UNCERTAINTY ON labs ±7%UNCERTAINTY nrate ≈ [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 labs (± 7%) and UNCERTAINTY ON NEUTRINO RATES: FUNCTION OF ZENITH ANGLE

INFLUENCE OF lsca,eff ON RECONSTRUCTED TRACKS:1. Strategy Two optical parameters fixed (absorption, eta) and one free parameter

(scattering length), for both absorption lengths.

UNCERTAINTY ON lsca_eff [23-58]% UNCERTAINTY mrate [16-17]%

Uncertainty on lsca_eff: ~23 % (51.5 m).Uncertainty on muon rate: ~16 % (0.08 Hz).

Uncertainty on lsca_eff: ~46 % (81.5 m).Uncertainty on muon rate: ~17 % (0.1 Hz).

Uncertainty on lsca_eff: ~58 % (133 m).Uncertainty on muon rate: ~31 % (0.18 Hz).

Uncertainty on lsca_eff: ~23 % (51.5 m).Uncertainty on neutrino rate: ~0 % (0 Hz).

Uncertainty on lsca_eff: ~46 % (81.5 m).Uncertainty on neutrino rate: ~2% (0.00005 Hz).

Uncertainty on lsca_eff: ~58 % (133 m).Uncertainty on neutrino rate: ~2 % (0.00005 Hz).

UNCERTAINTY ON lsca_eff [23-58]% UNCERTAINTY nrate < 2%

Uncertainty on lsca_eff: ~23 % (51.5 m).Uncertainty on muon rate: ~4 % (0.02 Hz).

Uncertainty on lsca_eff: ~46 % (81.5 m).Uncertainty on muon rate: ~14 % (0.09 Hz).

Uncertainty on lsca_eff: ~58 % (133 m).Uncertainty on muon rate: ~17 % (0.11 Hz).

Uncertainty on lsca_eff: ~23 % (51.5 m).Uncertainty on neutrino rate: ~0 % (0 Hz).

Uncertainty on lsca_eff: ~46 % (81.5 m).Uncertainty on neutrino rate: ~6 % (0.00015 Hz).

Uncertainty on lsca_eff: ~58 % (133 m).Uncertainty on neutrino rate: ~6 % (0.00015 Hz).

UNCERTAINTY ON lsca_eff [23-58]% UNCERTAINTY mrate [4-17]% UNCERTAINTY ON lsca_eff [23-58]% UNCERTAINTY nrate < 6%

INFLUENCE OF h ON RECONSTRUCTED TRACKS:1. Strategy One optical parameters fixed (absorption) and two free parameters (scattering

length and eta), for both absorption lengths.

Uncertainty on h: ~35 % (0.06).Uncertainty on muon rate: ~13 % (0.06 Hz).

Uncertainty on h: ~81 % (0.09).Uncertainty on muon rate: ~2 % (0.01 Hz).

Uncertainty on h: ~88 % (0.15).Uncertainty on muon rate: ~15 % (0.07 Hz).

Uncertainty on h: ~35 % (0.06).Uncertainty on neutrino rate: ~38 % (0.00095 Hz).

Uncertainty on h: ~81 % (0.09).Uncertainty on neutrino rate: ~67 % (0.00105 Hz).

Uncertainty on h: ~88 % (0.15).Uncertainty on neutrino rate: ~79 % (0.0019 Hz).

UNCERTAINTY ON h [35-88]% UNCERTAINTY mrate [2-15]% UNCERTAINTY ON h [35-88]% UNCERTAINTY mrate [38-79]%

Uncertainty on h: ~35 % (0.06).Uncertainty on muon rate: ~2 % (0.01 Hz).

Uncertainty on h: ~81 % (0.09).Uncertainty on muon rate: ~2 % (0.01 Hz).

Uncertainty on h: ~88 % (0.15).Uncertainty on muon rate: ~4 % (0.02 Hz).

Uncertainty on h: ~35 % (0.06).Uncertainty on neutrino rate: ~21 % (0.00055 Hz).

Uncertainty on h: ~81 % (0.09).Uncertainty on neutrino rate: ~34 % (0.0007 Hz).

Uncertainty on h: ~88 % (0.15).Uncertainty on neutrino rate: ~48 % (0.00125 Hz).

UNCERTAINTY ON h [35-88]% UNCERTAINTY mrate < 4% UNCERTAINTY ON h [35-88]% UNCERTAINTY mrate [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 (s = 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 h

could be less than 0.17.4. 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) slabs [%] slsca_eff [%] s h [%] s _m rate [%]

Absorption length ±7 <15

Effective scattering length ±60 <17

Rayleigh scattering ±90 <15

Parameter (for neutrino tracks) slabs [%] slsca_eff [%] s h [%] s _n rate [%]

Absorption length ±7 ±[4-64]

Effective scattering length ±60 <6

Rayleigh scattering ±90 ±[21-79]

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