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Introduction to Irene’s talk (reminder) Coincidence window 500s GWHEN group, Astropart. Phys. 35 (2011) 1-7 Ph. D Thesis of I. Di Palma (AEI) Ph. D Thesis of B. Bouhou (APC) Updates on this work: - 17 May - 20 May Clermont-Ferrand meeting (2010) - 20 Sep - 24 Sep Paris meeting (2010) - 22 Nov - 25 Nov Amsterdam meeting (2010) - 07 Feb - 10 Feb CERN meeting (2011) - 06 Jun - 10 Jun Moscow meeting (2011) Internal note: ANTARES-PHYS-2011-003 wiki page: http://antares.in2p3.fr/internal/dokuwiki/doku.php?id=link The selection criteria follow G. Halladjian’s strategy Optimization for (steady) PS E -2 Unblinding granted before summer 2010 (Referee: Aart Heijboer) The 2007 analysis’ scheme (triggered search)
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Data and MC samples lifetime of the selected data sample: 103.281 days (37.8 days for 10pe and 65.5 days for 3pe high threshold) Data sample The coincident period of 5L/S5/VSR1 is between January 27th and September 30th, 2007 Simulation package: Genhen, weight : Bartol flux energy range between 10 GeV and 10 7 GeV Simulation package : Corsika, weight : Battistoni’s parameterization Atmospheric neutrinos : Atmospheric muons: Simulation package: Genhen w eighted with a E -2 energy spectrum Data and MC sample are reconstructed with the BBfit reconstruction package (v3r6) Cosmic neutrinos : MC sample
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Better angular accuracy than if taking random track solution Smaller search box for GW detectors Two possible tracks (Mirror solution) Two possible azimuth values (Same zenith) ● ● ● ● ● ● Track 1 Track 2 Detector line Reconstruction used Events reconstructed with 2 lines == Due to simplified detector geometry == The version of the reconstruction offers the possibility to get the azimuth of the mirror solution in the case of events reconstructed with two lines
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Cut optimization Cut are applied to maximize the discovery potential in search for E -2 point sources Only up-going events are considered. Method : test statistics LR to get optimum n sig Different values of track and bright point 2 for different zenith angles are tested 70 possible combinations G. Halladjian, Ph. D, University Marseilles, Dec 2010
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Chosen cuts (up-going events) b 2 >2.2 (reduced contamination of atmospheric muons) t 2 <=1.8 for zenith<80° t 2 <=1.4 for 80°<zenith<90° 20% contamination from atmospheric muons for zenith<80° for 80°<zenith<90°
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Angular search window β μ ν The space angle β between the true neutrino direction and the reconstructed muon direction (E -2 spectrum) defines the angular accuracy The angular search window is defined as 50% quantile ( or 90% quantile ) of the β distribution in bins of reconstructed declination (10°) and number of hits 90% quantile nhit=7 Log-normal (instead of Fisher) distributions are fitted and provided for processing with X-pipeline (weight the scan directions inside the angular window) θ is the location parameter m is the scale parameter σ is the shape parameter
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The HEN candidate list time Dec(°) RA (°) lines hits ASW(50%) ASW(90%) weight …. 18 events reconstructed with 3 lines and more. 198 events reconstructed with exactly two lines : 2 solutions Total number of events ( 18 + 2*198 )
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Spare
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Coincidence window Fig. 1. (a) active central engine before the relativistic jet has broken out of the stellar envelope; (b) active central engine with the relativistic jet broken out of the envelope; (c) delay between the onset of the precursor and the main burst; (d) duration corresponding to 90% of GeV photon emission; (e) time span of central engine activity. Based on BATSE T90’s And FERMI-LAT data Collapsar model Time to break out envelope Opaque to ’s Precursors were observed for ~15% of GRBs (long and short (8%)) Emission mechanisms might be that of prompt GRBs same model Precursor Upper bound for BATSE GWHEN group, Astropart. Phys. 35 (2011) 1-7
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Angular search window β μ ν The error β on the neutrino direction is defined as the angular difference between the true neutrino direction and the reconstructed muon direction (E -2 spectrum) The angular search window is defined as 50% quantile ( or 90% quantile ) of the β distribution in bins of reconstructed declination (10°) and number of hits ASW 50% ASW 90% used for GW+HEN search
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φ1φ1 |φ1 – φ2| + + zenith φ2 θ1=θ 2 φ1φ1 azimuth 3° 6° 3° β best β random Reduction on ASW 50% ~ 3.8 For -50<dec<-40 Median ~ 2.5° Median~ 6.5° Median ~13° Median~14° Angular search window
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12 Updates on HEN candidates list Additional parameters for the X-Pipeline: lognormal fit parameters for each bin (dec, nhit) Fisher distribution log-normal distribution Where ν1 and ν2 are the shape parameters and Г is the gamma function Fisher distribution Lognormal distribution θ is the location parameter m is the scale parameter σ is the shape parameter
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