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

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

Brief reminder of light propagation in sea water 3

ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 4 Scattering phase function (  ) Morel and Loisel approach  Molecular scattering ( Rayleigh )  Isotropic ( =0)  = contribution of Rayleigh scattering  Particle scattering ( Mie )  Strong forward peaked ( Mie =0.924) Attenuation Length (COLIMATED BEAM) Effective Attenuation Length (ISOTROPIC SOURCE) Absorption length Scattering Length Scattering length wavelength dependence (Kopelevich parameterization) b = scattering coefficient. v s, v l = scattering centers. = Average cosine of the global distribution Petzold values for particle scattering

SimulationSimulation 5

SimulationSimulation ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 6 DATA/MonteCarlo SELECTION: Data  2008 – 2010 data from the official SeaTray production May 2011 (5997 runs). First run: 31051, Last run: Subsample from Point Sources data from Juan Pablo analysis ( ). Lifetime: 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, 2 -, 2  ), right now: 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 sc = scattering centers; aa = om angular acceptance; abs = absorption; sca = scattering; eta = fraction of Rayleigh scattering.

SimulationSimulation ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 7 Water models are selected based on: Three models with the same  value and different scattering spectrum for a given absorption length. Three models with different  values, but  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).

SimulationSimulation ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 8 GEN WATER MODEL: Photon tables production (water tables)  Water tables (hbook files) + Description files (ASCII files). HIT OM PARAMETERS: Hit probability computation from the water tables for a given OM parameters  Hit tables (hbook files) + Description files (ASCII files). KM3 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. GEASIM MCEW TE RECO SIMULATIONS OF ATMOSPHERIC NEUTRINO INTERACTIONS. Process (and evaluation) tracks from particles coming from the hadronic showers (also muons from KM3). TRANSLATION OF INFO ASCII FILES INTO ROOT FORMAT. FORMAT CONVERSION TO “LOOK LIKE DATA”: electronics smearing effects (calibration, ARS response) and optical background. RECONSTRUCTION: Reconstruction of track direction (AAfit) and ntuples information arrangement as number of hits, zenith distribution…(AntDST). Simulation chain:

SimulationSimulation ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 9 Main options and software versions in muons and neutrinos simulation: CODE/INPUTOPTIONS/VERSIONS GENv3r7 HITv3r7 KM3v3r7 DETECTORr12_c00_s01 GEASIMv4r10 MCEW TriggerEfficiencyGaussian ARS threshold file: threshold_gaus_0.33_0.08_0.1.txt SoS file: noise_basic_harold_new.root (based on data subsample) -n –t –C3 – p t  Frame time in ms. To determine the number of background hits to be generated in case the summary data are used. -C3  Hit generator type: 3, Gaussian, according observed charge distribution, with time- dependent contribution of after pulses. May 2011 version Aafitv0r9 AntDSTv1r2p3

SimulationSimulation ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 10 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. Run-by-run simulation data runs ( ) mupage muon runs neutrino anti-neutrino Geasim files. TE September Down-going neutrinos are used in the run-by-run MC.  >-5.2 removes some events close to the horizon (my sample),  > -5.4 relax this zone (SEE NEXT SLIDE) Sanity check with the official production (sc aa09 abs55 sca53 eta0.17): My productionOfficial production

SimulationSimulation ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 11 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). ±[31-43]%  [-1, -0.1] ±25% [>0.2] ±45%  [-0.1, +0.1]

Selected Results

Selected results ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 13 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.

Selected results ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 14 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. sca = 41 m &&  = 0.11 && abs = 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.

Selected results ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 15 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    

Selected results ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 16 Influence of abs on reconstructed tracks: 1.Strategy  For a couple of water models with different abs but same scattering parameters, estimate the difference on the reconstructed track 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”. CASE 1

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

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

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

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

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

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

Selected results ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 23  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 

Selected results ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 24  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 

Selected results ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 25 INFLUENCE OF  ON RECONSTRUCTED TRACKS: 1.Strategy  One optical parameters fixed (absorption) and two free parameters (scattering length and eta), for both absorption lengths.

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

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

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

Conclusions and outlook

CONCLUSIONS AND OUTLOOK ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 30 1.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: 2.The effective scattering length seems to be the most relevant parameter for muons. 3.Neutrino tracks reconstruction is very sensitive to the absorption length and Rayleigh scattering. 4.An extensive study to effective areas and angular resolution will be performed. 5.An internal note will be prepared soon with a dedicated description of the analysis. Parameter (for muon tracks)  abs [%]  sca_eff [%]   [%] Absorption length < 18 Effective scattering length < 25 Rayleigh scattering < 18 Parameter (for neutrino tracks)  abs [%]  sca_eff [%]   [%] Absorption length < 15 Effective scattering length < 25 Rayleigh scattering < 18

BackupBackup 31

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

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 33

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 34

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 35

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 36

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 37

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 38

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 39

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 40

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 41

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 42

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 43

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 44

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 45

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 46

BACKUPBACKUP ANTARES Collaboration Meeting Strasbourg, Nov 21 st -25 th 47