South Pole Astro April 4, 2011 Tom Gaisser1 125 m Cosmic-ray physics with IceCube IceTop is the surface component of IceCube as a three-dimensional cosmic-ray air shower detector

South Pole Astro April 4, 2011 Tom Gaisser2 IceTop 1450 m 2450 m Cosmic ray showers from above Neutrinos from all directions Primarily  -induced  from below Two different kinds of events Closely related scientifically: Neutrinos from cosmic ray sources Cosmic rays after propagation IceCube South Pole 2835 m.a.s.l.

South Pole Astro April 4, 2011 Tom Gaisser3 EeV event in IceCube-40 Ratio: Deep muons / Surface size Sensitive to primary composition

South Pole Astro April 4, 2011 Tom Gaisser4 Cosmic-ray physics with IceCube IceCube sees cosmic ray events from all directions –30,000 atmospheric /year –100 billion atmospheric  /year –1 billion air showers/yr in IceTop –~10% in coincidence with deep IceCube Spectrum/composition: –TeV to EeV

South Pole Astro April 4, 2011 Tom Gaisser5 Huge  statistics allows study of < 1 per mil

South Pole Astro April 4, 2011 Tom Gaisser6 From presentation of R. Abbasi, SNOPAC 2011

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South Pole Astro April 4, 2011 Tom Gaisser8 Weather with IceCube Muon production samples stratospheric temperature –Higher T, lower , more  ± decay before interaction  more 

South Pole Astro April 4, 2011 Tom Gaisser9 Solar & heliospheric physics ~2 kHz rate per IceTop tank, now with 162 tanks –study of solar cosmic ray events & solar modulation with fine time resolution & spectral resolution ApJ 689 (2008) L65-L68 32 tanks in 2006

South Pole Astro April 4, 2011 Tom Gaisser10 Energy range of atmospheric  Most events –0.3 to 10 TeV –E CR ~ 3 to 100 TeV/nucleon Rate (>100 TeV) –Prompt (charm) –~100’s per yr –Absorption in Earth distorts angular dist.

South Pole Astro April 4, 2011 Tom Gaisser11 Neutrino effective area Rate: = ∫  ( E )A eff ( E ) dE Earth absorption –Starts TeV –Biggest effect near vertical –Higher energy ’s absorbed at larger angles ( P ~  X R  

South Pole Astro April 4, 2011 Tom Gaisser12 Atmospheric muons in IceCube Similar energy range to atmospheric

South Pole Astro April 4, 2011 Tom Gaisser13 Primary composition with  & Calibration criterion: consistency of –Primary spectrum / composition –Spectrum & angular distribution of  and Interesting region for primary spectrum/composition –ATIC, CREAM, PAMELA Spectra harder E > 200 GeV/A PAMELA, Adriani et al., arXiv:

South Pole Astro April 4, 2011 Tom Gaisser14 All-particle spectrum modeled with 3 populations & 5 groups of nuclei Primary spectrum & composition affect atmospheric neutrinos Spectrum of nucleons (GeV/A) E -2.7 Realistic

South Pole Astro April 4, 2011 Tom Gaisser15 Spectrum/composition with IceCube/IceTop Threshold energy – < 300 TeV Maximum energy –Limited by km 2 size –Coincident events A  = 0.3 km 2 sr E max = EeV –IceTop only (  < 60 o ) A  = 3 km 2 sr E max = 3 EeV –In-ice trigger & reco E max = 3 EeV EeV Anchor to direct measurement of composition ~300 TeV Look for transition to extra-galactic < EeV

South Pole Astro April 4, 2011 Tom Gaisser16 Composition from IceTop, In-ice coincident events Reconstruct muon bundle to get energy deposition by muons in deep IceCube Reconstruct surface shower to get E primary Require consistency with angular distribution and  /e measured on the surface Muon multiplicity hard to measure Muon energy deposition in IceCube is directly measured has good sensitivity IceCube sims; Patrick Berghaus

South Pole Astro April 4, 2011 Tom Gaisser17 Composition from IceTop, In-ice coincident events Patrick Berghaus, Sept IceCube collaboration mtg Good experimental correlation Simulations & study of systematics is in progress

South Pole Astro April 4, 2011 Tom Gaisser18 Recent data (June 2010, large, vertical event)

South Pole Astro April 4, 2011 Tom Gaisser19 Large, inclined event in IceTop-73

South Pole Astro April 4, 2011 Tom Gaisser20 Current IceTop size spectrum Six months IceTop /11

South Pole Astro April 4, 2011 Tom Gaisser21 Extending the reach of IceTop With present array we can use events reconstructed in deep ice that pass outside of IceTop Two benefits: 1.Veto for horizontal GZK neutrino candidates 2.Spectrum / composition physics

South Pole Astro April 4, 2011 Tom Gaisser22 IceTop as a veto ~3 km Present IceTop improves point source sensitivity by a factor of 2 for overhead sources

South Pole Astro April 4, 2011 Tom Gaisser23 Proposal for RASTA Radio Air Shower Test Array –Goal is to establish feasibility of radio air shower detection at South Pole Proposal to be submitted to NSF June, 2011 –3 yr study to confirm the concept

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South Pole Astro April 4, 2011 Tom Gaisser30 Summary comments High rate of atmospheric   fine resolution for –Anisotropy –Temperature effects –Solar, heliospheric studies with IceTop Primary spectrum & composition –To > 100 TeV with atmospheric , –IceTop, IceCube coincidenct events extend to EeV Uniform acceptance from below knee to EeV Look for transition to extra-galactic component E < EeV (Auger &TA are lowering thresholds to do this) Extend IceTop acceptance for veto and science –Use events with cores outside IceTop –Build RASTA

South Pole Astro April 4, 2011 Tom Gaisser31 Photo: James Roth, Dec 8, 2007 IceTop Nov 23, 2007 Two tanks per station for calibration, muon ID High-gain, low-gain DOMs for dynamic range Waveforms give some  /e discrimination at the surface (not yet implemented) Calibration with few GeV muons

South Pole Astro April 4, 2011 Tom Gaisser32 RASTA Proposed radio air shower array on surface Symbiotic with ARA

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South Pole Astro April 4, 2011 Tom Gaisser34 Extra slides

South Pole Astro April 4, 2011 Tom Gaisser35 Coincident event: June 2010

South Pole Astro April 4, 2011 Tom Gaisser36 ISVHECRI

South Pole Astro April 4, 2011 Tom Gaisser37 In-fill for overlap with direct measurements > 100 TeV Response for Iron primaries Response for proton primaries Good response for p through Fe for 100 – 300 TeV -- overlaps ATIC, TRACER, CREAM 100 TeV Single in-fill triangle 100 TeV

South Pole Astro April 4, 2011 Tom Gaisser38 Composition from angular dependence of spectrum Reconstruct primary spectrum assuming primary Protons only … or … Iron only Fabian Kislat et al., ICRC 2009 paper #0970 Protons showers more penetrating  relatively greater contribution at large angle

South Pole Astro April 4, 2011 Tom Gaisser39 Composition-dependence: factor between p and Fe T. Feusels, J. Eisch, C. Xu (IceCube, ICRC 2009, paper 0518)

South Pole Astro April 4, 2011 Tom Gaisser40 Thanks to Mark Krasberg … Dec 13 during transition from TICL to ICL

South Pole Astro April 4, 2011 Tom Gaisser41 Spectral Information Excess count rate (averaged over approximately one hour near the peak of the event) as a function of pre-event counting rate. Each point represents one discriminator in one DOM. The higher count rate cluster comes from the SPE discriminators, the lower cluster from the MPE. Due to various technical issues, not all of the 64 DOMS have produced useful data at this time. Deconvolution of this relationship will result in an energy spectrum estimate. Excess flux increasing with count rate (i.e. decreasing with response energy) indicates that the flare spectrum is softer than the galactic cosmic ray spectrum that produces the background. It turns out that a linear fit to the average increase as a function of count rate is a good approximation.