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Cosmic rays at the knee and above with IceTop and IceCube

South Pole 4 Feb 2009. Cosmic rays at the knee and above with IceTop and IceCube. Serap Tilav for The IceCube Collaboration. IceCube Neutrino Observatory Neutrino Telescope & 3D Cosmic Ray Detector. Air shower detection @ 2835m altitude (680 g/cm 2). IceTop. IceTop

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Cosmic rays at the knee and above with IceTop and IceCube

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

  2. IceCube Neutrino Observatory Neutrino Telescope & 3D Cosmic Ray Detector Air shower detection @ 2835m altitude (680 g/cm2) IceTop • IceTop • EM component near shower max • shower size & arrival times over 1km2 • IceCube • Muonic component @ 1450m-2450m depth in ice • muon bundle energy over 1km IceCube

  3. IceTop/IceCube Motivation for Air Shower Measurements in Energy Range 3.1014 eV – 1.1018 eV spectrum & composition around the knee iron bump ? 2nd knee ? transition from galactic to extra-galactic from Andreas Haungs, Kascade

  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

  5. All events Vertical muons (tagged with muon telescope) Tank response to VEM and calibration with Muon telescope Full Spectrum Muon Peak all particle spectrum of the DOM Vertical Muon Peak signals in coincidence with muon telescope L. Demirors et al., ICRC07 arXiv:0711.0353

  6. IceTop Station Photo: James Roth, Dec 8, 2007 • 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

  7. 2005 4 stations 2006 12 stations IceTop-26 2007 10 stations IceTop-40 2008 14 stations IceTop-59 2009 19 stations IceTop Deployment 2005-2009 IceTop-26 First attempt on Energy Spectrum IceTop-40 First attempt on Composition 14 stations in 2010 7 stations in 2011

  8. IceTop-26 Reconstruction Lateral shower profile at 125m S125 : signal at r = 125m β: slope at r = 125m κ = 0.303 fixed S. Klepser et al., ICRC07 arXiv:0711.0353 • Fluctuations extracted from data • Likelihood function from data & simulation -- untriggered stations are also accounted for • Direction reconstruction: curved shower front

  9. IceTop-26 Resolution & Efficiency Simulations: CORSIKA with Sibyll and Fluka for3 zenith bins [0-30]°,[30-40]°,[40,46]° S125 Eprimary derived from proton simulations for zenith range [0-30]° Direction ~1.5° Core ~9 m Energy ~ 16% Effective area ~ 0.094 km2 full efficiency reached > 1 PeV • requires ≥ 5 station triggers • containment criteria • quality cuts

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

  11. Unfolded Spectrum Composition sensitive zenith behavior IceTop-26 Energy Spectrum Raw Energy Spectrum Proton only Response Matrix Iron only 5 months of data 1 Jun – 31 Oct 2007 1.1 107 events processed 4.106 events passed F. Kislat et al., ICRC09

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

  13. IceTop-40/IceCube Direction Resolution Core resolution ~ 12-14 m Angular resolution < 1°

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

  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

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

  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

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