1. WATER PROPERTIES ON TRACKS RECONSTRUCTION AND DETECTOR PERFORMANCE H Yepes -Ramirez IFIC (CSIC – Universitat de València) ANTARES Collaboration Meeting CERN, February 06 th -09 th, 2012

2. OUTLINEOUTLINE ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 2 Brief reminder of light propagation in sea water: Brief reminder of light propagation in sea water: ANTARES Monte Carlo model Status of the analysis and simulation: Status of the analysis and simulation: review of the analysis, data selection and MC inputs Selected results: Selected results: muon time residuals and detector performance for neutrinos/anti- neutrinos Conclusions and outlook Brief reminder of light propagation in sea water: Brief reminder of light propagation in sea water: ANTARES Monte Carlo model Status of the analysis and simulation: Status of the analysis and simulation: review of the analysis, data selection and MC inputs Selected results: Selected results: muon time residuals and detector performance for neutrinos/anti- neutrinos Conclusions and outlook

3. Brief reminder of light propagation in sea water 3

4. ANTARES Collaboration Meeting CERN, Feb 06 th -09 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

5. Status of the analysis and simulation 5

6. ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 6 STATUS OF THE ANALYSIS: Summary of the presented work: 1.Ten different water models with 2 MC runs for each type of event: muon, neutrino and anti-neutrino  Mupage for muons and Geasim for neutrinos/anti-neutrinos + June2009 OM angular acceptance from Genova measurements. 2.Reduced data sample for a 12L detector  1044 data files between 08/05/2008-30/12/2008 with 76.77 days of lifetime. 3.Data/MC comparissons for: reconstruction quality parameter, number of hits used in the fit, Zenith angle, azimuth angle and muon time residuals.

7. Status of the analysis and simulation ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 7 Conclusions of the presented work: 1.MC statistics (number of runs) were a critical point for data/MC comparissons, however it was concluded that water models with lower effective scattering lengths could be discarded. 2.Water models with  ≥ 0.11 shows the best agreement. 3.Effective scattering length seems to be a more relevant parameter than the absorption length. 4.It wasn’t enough clear the independent contribution of each optical parameter to each reconstruction parameter. 5.Muon time residuals data/MC comparison had to be reviewed due to a 2 ns delay in data distributions. Higher absorption lengths seemed to fit better to the tail than the peak, opposite case for lower absorption lengths.

8. Status of the analysis and simulation ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 8 Summary of the presented work: Extended MC sample concerning Moscow CM analysis  Ten different water models with No quality cuts for tracks.

9. Status of the analysis and simulation ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 9 Conclusions of the presented work: 1.The mass production allowed to be clear about the lack of statistics and then to improve the data/Mc agreement for the analysis showed at Moscow CM.

10. Status of the analysis and simulation ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 10 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 and Dec2011 MC phone-conference: Water Model   data sc0.0075 aa09 abs55 sca53 eta0.1790403125997 sc0.01 aa09 abs55 sca41 eta0.1782343125997 sc0.02 aa09 abs55 sca22 eta0.1781353125997 sc0.01 aa09 abs55 sca41 eta0.1174393125997 sc0.02 aa09 abs55 sca22 eta0.0278393125997 sc0.0075 aa09 abs63 sca53 eta0.1782373125997 sc0.01 aa09 abs63 sca41 eta0.1780383125997 sc0.02 aa09 abs63 sca22 eta0.1779383125997 sc0.01 aa09 abs63 sca41 eta0.1180363125997 sc0.02 aa09 abs63 sca22 eta0.0281393125997 sc = scattering centers; aa = om angular acceptance; abs = absorption; sca = scattering; eta = fraction of Rayleigh scattering.

11. Status of the analysis and simulation ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 11 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:

12. Status of the analysis and simulation ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 12 Main options and software versions in muons and neutrinos simulation: CODE/INPUTOPTIONS/VERSIONS GENv3r7 HITv3r7 KM3v3r7 DETECTORr12_c00_s01 GEASIMv4r10 MCEW2011-01-27 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 10000000 –t 104.858 –C3 – p 0.035 -t 104.858  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

13. SELECTED RESULTS: muon time residuals 13

14. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 14 MUON TIME RESIDUALS Arrival time of photons is expressed relative to the expected (theoretical) arrival time (t exp ) which can be computed from the muon tracks parameters: resulting time residuals (r). The true arrival time (t hit ) could be change due to photons emitted from secondary electrons being their path influenced by the scattering. r = t hit - t exp CONSIDERATIONS: Quality cuts:  > -5.4 (quality parameter). IMPACT STUDIES STRATEGY: Absorption length:  For a couple of water models with different absorption lengths but same scattering parameters estimate the difference on the angular resolution for a neutrino energy range. Effective scattering length:  Two optical parameters fixed (absorption, eta) and one free parameter (scattering length), for both absorption lengths. Rayleigh scattering contribution:  Two optical parameters fixed (absorption, effective scattering length) and two free parameters (scattering length and eta), for both absorption lengths.

15. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 15 ABSORPTION LENGTH INFLUENCE:

16. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 16 EFFECTIVE SCATTERING LENGTH INFLUENCE:

17. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 17 RAYLEIGH SCATTERING CONTRIBUTION INFLUENCE:

18. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 18 DATA/MC RATES:

19. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 19 DATA/MC RATES:

20. 20 SELECTED RESULTS: detector performance for neutrinos/anti-neutrinos

21. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 21 ANGULAR RESOLUTION Median value of the difference in absolute value between the reconstructed direction (  rec ) and the true MC direction (  true ) : resol=|  rec -  true | CONSIDERATIONS: Weighted by the generation weight (w2) and by the energy spectrum of the primary MC particle as E -2 (GeV): w2*E -2. Energy bins (GeV): 25; E min = 1, E max = 7 (Log 10 ). Quality cuts:  > -5.4 (quality parameter), cos(  ) > 0 (zenith angle),  < 1 (angular error). IMPACT STUDIES STRATEGY: Absorption length:  For a couple of water models with different absorption lengths but same scattering parameters estimate the difference on the angular resolution for a neutrino energy range. Effective scattering length:  Two optical parameters fixed (absorption, eta) and one free parameter (scattering length), for both absorption lengths. Rayleigh scattering contribution:  Two optical parameters fixed (absorption, effective scattering length) and two free parameters (scattering length and eta), for both absorption lengths.

22. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 22 H Yepes It is not a run-by-run simulation. 5997 data runs (2008-2010). JP Gomez (Moscow talk, the “closest reference”) Run-by-run simulation. 2007-2010 data runs. Sanity check with the official production (sc0.0075 aa09 abs55 sca53 eta0.17):

23. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 23 Observations: The absorption length influence on detector’s angular resolution has impact less than 0.1º for the whole range of neutrino energy. The best angular resolution is obtained for scattering lengths ≈ 41 m  0.25º for neutrino high energies. ABSORPTION LENGTH INFLUENCE:

24. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 24 EFFECTIVE SCATTERING LENGTH INFLUENCE: Observations: The absorption length hasn’t a strong impact on angular resolution. For the lowest neutrino energies an overall estimation of less than 0.1º can be deduced. At higher energies the effect is reduced up to half (0.05º). This due to the unknowledge on the effective scattering length contribution. Nonetheless, the lowest effective scattering lengths give the “worst” angular resolution for the whole neutrino energy range.

25. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 25 Observations: The absorption length hasn’t a strong impact on angular resolution. For the lowest neutrino energies an overall estimation of less than 0.05º can be deduced. At higher energies the effect gets to worst up to twice (0.1º). This due to the unknowledge on the Rayleigh scattering contribution. Opposite case in effective scattering length plots. Nonetheless, the lowest effective scattering lengths give the “worst” angular resolution for the whole neutrino energy range. RAYLEIGH SCATTERING CONTRIBUTION INFLUENCE:

26. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 26 EFFECTIVE AREA Equivalent surface perpendicular to the incident particle beam, which is 100% efficient and detects the same number of particles (neutrinos or muons) than the detector. It depends on the energy and the direction of the incident neutrino. Could be considered as the ANTARES detection efficiency (ratio between the selected neutrino event rate and the cosmic neutrino flux): w2 i  w3 i /(d  /dE) (GeV*m 2 *sr*s*yr -1 ). w3i (yr- 1 ) is the weight of the event i per one year and d  /dE is the signal neutrino differential flux (GeV -1 *m -2 *sr -1 *s -1 *yr -1 ). n  number of reconstructed events which pass the quality cuts. N  total number of simulated events.   generated energy spectrum index (1.4 in GENHEN). t  time window of the simulation (1 year in GENHEN). I   2  [cos  max -cos  min ] angular phase space factor (2  srad in GENHEN). I E  energy phase space factor (E min =10 GeV and E max =10 7 GeV in GENHEN). n  E  number of reconstructed events in  E (true neutrino energy bin) which pass the quality cuts. F  E  fraction of simulated events in  E.

27. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 27 CONSIDERATIONS: Energy bins (GeV): 20; E min = 1, E max = 7 (Log 10 ). Quality cuts:  > -5.4 (quality parameter), cos(  ) > 0 (zenith angle),  < 1 (angular error). IMPACT STUDIES STRATEGY: Absorption length:  For a couple of water models with different absorption lengths but same scattering parameters estimate the difference on the angular resolution for a neutrino energy range. Effective scattering length:  Two optical parameters fixed (absorption, eta) and one free parameter (scattering length), for both absorption lengths. Rayleigh scattering contribution:  Two optical parameters fixed (absorption, effective scattering length) and two free parameters (scattering length and eta), for both absorption lengths.

28. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 28 Sanity check with the official production (sc0.0075 aa09 abs55 sca53 eta0.17): H Yepes It is not a run-by-run simulation. 5997 data runs (2008-2010). JP Gomez (Moscow talk, the “closest reference”) Run-by-run simulation. 2007-2010 data runs.

29. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 29 ABSORPTION LENGTH INFLUENCE: Observations: Higher the absorption length higher the detector effective are and more neutrinos are detected, nonetheless the difference is small.

30. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 30 EFFECTIVE SCATTERING LENGTH INFLUENCE: Observations: The lowest effective scattering lengths give the “worst” detector effective area for the whole neutrino energy range. Absorption length hasn’t a strong impact on the “ANTARES detection efficiency”.

31. SELECTED RESULTS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 31 RAYLEIGH SCATTERING CONTRIBUTION INFLUENCE: Observations: The contribution of Rayleigh scattering doesn’t have a strong impact on the detection effective area.

32. CONCLUSIONSCONCLUSIONS ANTARES Collaboration Meeting CERN, Feb 06 th -09 th 32 MUONS TIME RESIDUALS: ANGULAR RESOLUTION FOR NEUTRINOS/ANTI-NEUTRINOS: 1.The best angular resolution (≈ 0.25º) is obtained for water models with a scattering length ≈ 41 m; The worst one (≈0.3º) for water models with extreme effective scattering lengths. 2.An overall impact of less than 1º no matter the water model we are testing is deduced. EFFECTIVE AREA FOR NEUTRINOS/ANTI-NEUTRINOS: The absorption length and the contribution of Rayleigh scattering have a minimum impact on the detection effective area. In addition, the lowest effective scattering lengths give the worst effective area estimation.