TeVPA, July , SLAC 1 Cosmic rays at the knee and above with IceTop and IceCube Serap Tilav for The IceCube Collaboration South Pole 4 Feb 2009

TeVPA, July , SLAC 2 IceCube Neutrino Observatory Neutrino Telescope & 3D Cosmic Ray Detector IceTop IceCube IceTop EM component near shower max shower size & arrival times over 1km 2 IceCube Muonic 1450m-2450m depth in ice muon bundle energy over 1km Air shower 2835m altitude (680 g/cm 2)

TeVPA, July , SLAC 3 Motivation for Air Shower Measurements in Energy Range eV – eV from Andreas Haungs, Kascade spectrum & composition around the knee iron bump ? 2 nd knee ? transition from galactic to extra-galactic

TeVPA, July , SLAC 4 IceTop Tank Solid block of clear ice “ Ice Cherenkov Tank” Single tank detects secondary particles in air showers : -- MeV e ± -- converting γ -- ~1 GeV μ Light yield (Cherenkov and stochastic) for each particle type is derived from a detailed GEANT4 simulation and parameterized

TeVPA, July , SLAC 5 Tank response to VEM and calibration with Muon telescope All events Vertical muons (tagged with muon telescope ) Full Spectrum Muon Peak Vertical Muon Peak signals in coincidence with muon telescope all particle spectrum of the DOM L. Demirors et al., ICRC07 arXiv:

TeVPA, July , SLAC 6 IceTop Station 2 tanks per station 1 tank hit  muon, e or γ both tanks hit  air shower 2 DOMs per tank 1 HG, 1 LG for dynamic range Photo: James Roth, Dec 8, 2007

TeVPA, July , SLAC 7 IceTop Deployment stations stations stations stations stations IceTop-26 IceTop-40 IceTop-59 IceTop-26 First attempt on Energy Spectrum IceTop-40 First attempt on Composition 14 stations in stations in 2011

TeVPA, July , SLAC 8 IceTop-26 Reconstruction Lateral shower profile at 125m S 125 : signal at r = 125m β : slope at r = 125m κ = fixed  Fluctuations extracted from data  Likelihood function from data & simulation -- untriggered stations are also accounted for  Direction reconstruction : curved shower front S. Klepser et al., ICRC07 arXiv:

TeVPA, July , SLAC 9 IceTop-26 Resolution & Efficiency Simulations: CORSIKA with Sibyll and Fluka for 3 zenith bins [0-30]°,[30-40] °,[40,46] ° S 125 E primary derived from proton simulations for zenith range [0-30] ° Direction ~1.5° Core ~9 m Energy ~ 16% Effective area ~ km 2 requires ≥ 5 station triggers containment criteria quality cuts full efficiency reached > 1 PeV

TeVPA, July , SLAC 10 IceTop-26 Detector Response Proton Iron Detector response is characterized as Response Matrix (RM) Primary particle Primary Energy Zenith Angle Resolution Efficiency …. + RM

TeVPA, July , SLAC 11 Unfolded Spectrum IceTop-26 Energy Spectrum Response Matrix Raw Energy Spectrum 5 months of data 1 Jun – 31 Oct events processed events passed Proton only Iron only Composition sensitive zenith behavior F. Kislat et al., ICRC09

TeVPA, July , SLAC 12 Method Reconstruct shower direction and core location with IceTop fix core, improve direction using IceCube reconstruction, improve core using the improved direction iterations Reconstruct muon bundle energy loss using charge flow information at each layer in IceCube Muon bundle energy loss is composition sensitive IceTop-40/IceCube Coincident Events Data collected at 2 Hz rate

TeVPA, July , SLAC 13 IceTop-40/IceCube Direction Resolution Core resolution ~ m Angular resolution < 1°

TeVPA, July , SLAC 14 IceTop-40/IceCube Muon Bundle Energy Loss & Composition Data: 28 days Sep 2008 Slant depth behavior of muon bundle energy loss Data and H, Fe simulations Resolution, efficiency, systematics work in progress T. Feusels et al., ICRC09 preliminary

TeVPA, July , SLAC 15 IceTop-40 Near Threshold ~300 TeV Restrict event selection -- 3 station triggers only nearby stations forming triangle -- 4 station triggers only nearby stations forming quadrangle -- use flat shower front -- use the same LDF -- stronger containment

TeVPA, July , SLAC 16 IceTop-40 Near Threshold ~300 TeV Proton MC Iron MC 3 stations only 4 stations only Reconstructed energy distribution for H & Fe simulations 3 station events Data compared with H & Fe simulations for zenith [0-26]°

TeVPA, July , SLAC 17 Summary Work in Progress: IceTop-26 2 PeV < E < 100 PeV -- Unfolded Energy Spectrum using 5 months of data -- Further exploit zenith angle dependence on composition IceTop-40/IceCube coincidence 1 PeV < E < 50 PeV -- Muon bundle energy loss measured in IceCube is sensitive to composition -- simulations are limited beyond 50 PeV IceTop-40 at threshold ~ 300 TeV -- use 3 station events only upgrade shower simulations  start using thinned CORSIKA showers beyond 50 PeV upgrade detector simulation  calibrations better known than 2 yrs ago re-work systematics