1 Cosmic Ray Physics with IceTop and IceCube Serap Tilav University of Delaware for The IceCube Collaboration ISVHECRI2010 June 28 - July 2, 2010 Fermilab

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 )

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

4 IceTop Signals 2 DOMs per tank: 1 High Gain + 1 Low Gain for better dynamic range IceCube Digital Optical Module (DOM) signals digitized with 3.5ns resolution full waveforms are transmitted

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:

6 Tank response to Vertical Equivalent Muon (VEM) HighGain DOMs continuously record single particle signals via a special calibration trigger Tank response to vertical muons is extracted weekly by a fit to the single particle spectrum 1 VEM is defined as 0.95 x Full spectrum muon peak From MC 1 VEM ~ 3-5 GeV

7 IceTop Station 2 tanks per station 1 tank hit  muon, e or γ both tanks hit  air shower

stations stations stations stations stations IceTop-26 IceTop-40 IceTop-59 IceTop Deployment The array will be completed with 8 more stations in stations IceTop-73

9 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:

10 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

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

12 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

13 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

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

15 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 arXiv: preliminary

16 IceTop-40 Near Threshold ~300 TeV Restrict event selection: -- use 3 or 4 neighboring stations only -- use flat shower front -- use the same LDF -- stronger containment reconstructed core locations Lower the threshold below 300 TeV for better overlap with direct measurements

17 IceTop-40 Near Threshold ~300 TeV 3 stations only Reconstructed energy distributions for 3 Station events.  Data is consistent with Proton Showers in TeV range Proton MC Iron MC Increased sensitivity down to 100 TeV for Proton showers No sensitivity to to Iron showers below 100 TeV RuzybayevRuzybayev, et all arXiv:

18 IceTop-59 DAQ upgrade: Single tank hits are registered (only charge and arrival times)  possibility to identify single muons in tanks Station hits Single tank hits Single tank hits complement the Station hits mostly at the shower outskirts will greatly improve inclined shower reconstruction

19 IceTop-73 IceTop array is 92% complete with 73 stations out of 81 deployed Data taking started on Jun Differential rate of Energy proxy E* 8 or more station triggers total rate = 1 Hz First look at the high multiplicity data above 1 PeV reconstructed shower rate 1 Hz  expect to see ~10 events per month above 300 PeV

20 IceTop-73 Snow build up on tanks deployed in early years affect their trigger rates and signals Low energy electrons, gammas attenuate Muons not affected We will account for the snow effect in our analysis Finally an almost circular array Core Locations

21 IceTop PeV 50 deg HighGain DOM near the core saturates, LowGain takes it over. Signals last over 3μsec

22 IceTop-73 IceTop/IceCube coincident shower 293 deg

23 Summary IceCube project is almost complete: 79 IceCube strings + 73 IceTop stations We have achieved good understanding of the detector -- re-working our systematics Still lack of simulation statistics due to ever changing detector size -- will get easier now as the detector is almost reached full size Enhancing our reconstruction techniques (specially for inclined showers) using detailed waveforms shapes and single tank signals