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Anisotropy in Cosmic Ray Arrival Directions Using IceCube and IceTop Frank McNally ISCRA

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IceCube and IceTop IceCube Rate: ~ 2 kHz Energy Range: ~100 GeV – 1 PeV Data in Data Storage and Transfer (DST) format contains limited information IceTop Rate: ~ 20 Hz Energy Range: ~100 TeV – 1EeV More information per event 2

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Anisotropy in IceCube (Published) IC59 Relative Intensity Map Median Energy: ~20 TeV IC59 Dipole & Quadropole Fit Residuals (20 o smoothing) 3 Abbasi et al., ApJ, 740, 16, 2011 arxiv/1105.2326

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Anisotropy in IceCube (Preliminary) Median Energy: ~20 TeV Dipole & Quadropole Fit Residuals (5 o smoothing) 4 4 years of data (IC59 – IC86-II) 1.24 x 10 11 events IceCube Preliminary Relative Intensity

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IT59 + IT73 + IT81 Anisotropy in IceTop Median energy: ~400 TeV Median energy: ~2 PeV 5 IT59 + IT73 + IT81+ IT81-II High energy IceTop Preliminary IceTop Published Aartsen et al., ApJ 765, 55, 2013 arxiv/1210.5278

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Taking the Next Step Goal Study anisotropy as a function of energy and composition New energy estimator Use additional information provided by IceTop for more accurate energy and composition reconstruction 14

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Likelihood-based Energy Reconstruction – Building the tables Using simulation, create histograms that store: Primary information Composition, energy, zenith, and distances from tanks to shower core Observables Charge registered at each tank Environment Snow depth at each tank Bin all information 110 Energy Bins, 4 Zenith Bins, 4 Snow Bins, 70 Distance Bins, 46 Charge Bins Normalize histograms, so a bin [C, E, Z, Q, S, D] gives the probability that… …a particle with: composition C, energy E, and zenith angle Z deposited a charge Q at a tank with snow depth S at a distance D from the shower core 15

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Reconstruction Iterative grid search tests core positions across array Returns best core position, energy, and corresponding likelihood for each composition Example of likelihood space for a fine grid search 16

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Performance 17 Log 10 (E_reco / E_true (GeV)) Core_reco - Core_true (m)

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Composition Separation 18

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Energy Split Example (IT73+IT81): Split by NStations 3 stations 4 stations 5 stations 6 stations 7 stations 8 - 9 stations 10 - 14 stations 15 + stations 9.69x10 7 6.54x10 7 4.74x10 7 3.22x10 7 2.17x10 7 2.47x10 7 1.72x10 7 6.05x10 6 19 Relative Intensity Plots

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Summary & Moving Forward Large Scale Anisotropy appears to change as a function of energy Small scale Significant structure visible at 5 o scale with IceCube data Future Goals More data now available: IT81-III / IC86-III New energy estimation Use likelihood-based energy reconstruction to look at anisotropy as a function of energy and potentially composition 20

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