Title: Cosmic rays
1 South Pole 4 Feb 2009
Cosmic rays at the knee and above with IceTop
and IceCube
Serap Tilav for The IceCube Collaboration
2IceCube Neutrino Observatory Neutrino
Telescope 3D Cosmic Ray Detector
Air shower detection _at_ 2835m altitude (680 g/cm2)
IceTop
- IceTop
- EM component near shower max
- shower size arrival times over 1km2
- IceCube
- Muonic component _at_ 1450m-2450m depth in ice
- muon bundle energy over 1km
IceCube
3Motivation 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
4IceTop Tank
Solid block of clear ice Ice Cherenkov Tank
Single tank detects secondary particles in air
showers -- MeV e -- converting ? -- 1
GeV µ
Light yield (Cherenkov and stochastic) for each
particle type is derived from a detailed GEANT4
simulation and parameterized
5Tank 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 arXiv0711.0353
6IceTop Station
Photo James Roth, Dec 8, 2007
- 2 tanks per station
- 1 tank hit ? muon, e or ?
- both tanks hit ? air shower
- 2 DOMs per tank
- 1 HG, 1 LG for dynamic range
7IceTop Deployment 2005-2009
IceTop-26 First attempt on Energy
Spectrum IceTop-40 First attempt on Composition
14 stations in 2010 7 stations in 2011
8IceTop-26 Reconstruction
Lateral shower profile at 125m
S125 signal at r 125m ß slope at r
125m ? 0.303 fixed
S. Klepser et al., ICRC07 arXiv0711.0353
- Fluctuations extracted from data
- Likelihood function from data simulation
- -- untriggered stations are also accounted for
-
- Direction reconstruction curved shower front
9IceTop-26 Resolution Efficiency
Simulations 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 m Energy 16 Effective area
0.094 km2
full efficiency reached gt 1 PeV
- requires 5 station triggers
- containment criteria
- quality cuts
10IceTop-26 Detector Response
Detector response is characterized as Response
Matrix (RM)
Proton Iron
Resolution Efficiency .
Primary particle Primary Energy Zenith Angle
RM
11IceTop-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
12IceTop-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 lt 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
15IceTop-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
16IceTop-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
17Summary
Work in Progress IceTop-26 2 PeV lt
E lt 100 PeV -- Unfolded Energy Spectrum using 5
months of data -- Further exploit zenith angle
dependence on composition IceTop-40/IceCube
coincidence 1 PeV lt E lt 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