tevpa, july 13-17 2009, slac 1 cosmic rays at the knee and above with icetop and icecube serap tilav...
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TeVPA, July 13-17 2009, SLAC1
Cosmic rays at
the knee and above with
IceTop and IceCube
Serap Tilav
for The IceCube Collaboration
South Pole4 Feb 2009
TeVPA, July 13-17 2009, SLAC2
IceCube Neutrino Observatory Neutrino Telescope & 3D Cosmic Ray Detector
IceTop
IceCube
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
Air shower detection @ 2835m altitude (680 g/cm2)
TeVPA, July 13-17 2009, SLAC3
Motivation for Air Shower Measurementsin Energy Range 3.1014 eV – 1.1018 eV
from Andreas Haungs, Kascade
spectrum & composition around the knee
iron bump ?
2nd knee ?
transition from galactic to extra-galactic
TeVPA, July 13-17 2009, SLAC4
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 13-17 2009, SLAC5
Tank response to VEM and
calibration with Muon telescope
All eventsVertical muons(tagged with muon telescope)
Full SpectrumMuon Peak
VerticalMuon Peak
signals in coincidencewith muon telescope
all particlespectrumof the DOM
L. Demirors et al.,ICRC07arXiv:0711.0353
TeVPA, July 13-17 2009, SLAC6
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 13-17 2009, SLAC7
IceTop Deployment 2005-2009
2005 4 stations
2006 12 stations
2007 10 stations
2008 14 stations
2009 19 stations
IceTop-26
IceTop-40
IceTop-59
IceTop-26First attempt on Energy Spectrum
IceTop-40First attempt on Composition
14 stations in 2010 7 stations in 2011
TeVPA, July 13-17 2009, SLAC8
IceTop-26 Reconstruction
Lateral shower profile at 125m
S125 : signal at r = 125m
β : slope at r = 125m
κ = 0.303 fixed
Fluctuations extracted from data
Likelihood function from data & simulation-- untriggered stations are also accounted for
Direction reconstruction : curved shower front
m
r
m
rSrS
125log
125
10
125)(
S. Klepser et al.,ICRC07arXiv:0711.0353
TeVPA, July 13-17 2009, SLAC9
IceTop-26 Resolution & EfficiencySimulations: CORSIKA with Sibyll and Fluka for 3 zenith bins [0-30]°,[30-40]°,[40,46]°
S125 Eprimary derived from proton simulations
for zenith range [0-30]°
Direction ~1.5°Core ~9 mEnergy ~ 16%Effective area ~ 0.094 km2
• requires ≥ 5 station triggers• containment criteria• quality cuts
full efficiency reached > 1 PeV
TeVPA, July 13-17 2009, SLAC10
IceTop-26 Detector Response
ProtonIron
Detector response is characterized as
Response Matrix (RM)
measjij
truei FRMF 1
Primary particlePrimary EnergyZenith Angle
ResolutionEfficiency….
+
RM
TeVPA, July 13-17 2009, SLAC11
Unfolded Spectrum
IceTop-26 Energy Spectrum
ResponseMatrix
Raw Energy Spectrum
5 months of data 1 Jun – 31 Oct 20071.1 107 events processed4.106 events passed
Proton only
Iron only
Composition sensitive zenith behaviorF. Kislat et al.,ICRC09
TeVPA, July 13-17 2009, SLAC12
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
IceTop-40/IceCube Coincident EventsData collected at 2 Hz rate
TeVPA, July 13-17 2009, SLAC13
IceTop-40/IceCube
Direction Resolution
Core resolution ~ 12-14 m Angular resolution < 1°
TeVPA, July 13-17 2009, SLAC14
IceTop-40/IceCube Muon Bundle Energy Loss & Composition
Data: 28 days Sep 2008Slant 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 13-17 2009, SLAC15
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 13-17 2009, SLAC16
IceTop-40 Near Threshold ~300 TeV
Proton MC
Iron MC
3 stations only
4 stations only
Reconstructedenergy distribution
for H & Fe simulations
3 station events
Data compared with H & Fe simulations
for zenith [0-26]°
TeVPA, July 13-17 2009, SLAC17
SummaryWork 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