Cosmic Ray Physics with the IceCube Observatory

ECRS, July 3-8, 2012 H.Kolanoski - Cosmic Ray Physics with IceCube 1

Hermann KolanoskiHermann Kolanoski

Humboldt-UniversitHumboldt-Universitäät zu Berlin and t zu Berlin and DESYDESY

for the IceCube Collaborationfor the IceCube Collaboration

Cosmic Ray Physics Cosmic Ray Physics with the with the

IceCube ObservatoryIceCube Observatory


IceCube DetectorDetector Completion Dec 2010

IceCube with IceTop is a 3-dim Air Shower Detector

unprecedented volume

CR Analyses

•air showers in IceTop

•muon (bundle)s in IceCube

•atm. neutrinos in IceCube

•IceCube - IceTop coinc.


Energy range of IceCube/IceTop< PeV > EeV

Anchor to direct measurement of

composition ~300 TeV

Look for transition to extra-galactic <

EeV

(IceTop EAS)

(in-ice µ,ν)

Outline



Final IceTop Detector Array 2011

final detector:81 stations (162 tanks)

mostly ~ 125 m; In-fill array: 3 inserts +5 closest stations

In-fill

~125 m

Calibration: Vertical Equivalent Muons

1 VEM ≈ 125 PE

signal distribution in untriggered

calibration runs


IceTop Signal Recording

charge [PE]

volta

ge

time [ns]

leading edge

baseline

3.3 ns; 128 bins 420 ns

DOMs

snow height on tanksmuon signal

e.m. background


Trigger and Data SelectionSingle DOM above threshold (~0.2 VEM):

digitization of waveform (3.3 ns bins)

Local Coincidence (‘HLC hits’): both tanks above threshold

readout of full waveform to IceCube Lab

Soft Local Coincidence (‘SLC hits’):all DOMs above threshold send a timestamp and integrated charge

catch single muons

Single tank trigger for calibration with single muons

Reconstruction: standard ( 3 stations) 0.3 PeVinfill extension: 100 TeV

Select extended air showers:

Shower Size Spectrum with IT73


IT73 (90% of final) cos𝛉 > 0.8 A = 52×104 m2 >3 stations

10

100

1000events per bin

per year

(log10S125 = 0.05)

IT73 data(preliminary)

IT73 simulation

Work in progress

Effective Area

IceTop only

IC-IT coinc.

ECRS, July 3-8, 2012 H.Kolanoski - Cosmic Ray Physics with IceCube

IT73/IC79 configuration, >3 stations , cos𝛉>=0.8, A=0.52 km2

9

Cosmic Ray Spectrum


IceTop IT73 only:>5 stations cos𝛉>=0.8, A=52.1×104 m2

‘flattening’, also observed in IT26,

Kascade-G.

work on systematics in progress

CR Spectrum with IT26


preliminary

arXiv 1202.3039, submitted to ApP

CR Spectrum: Comparison with other Experiments


Cosmic Rays: spectrum and composition


IceCubes

ho

we

r a

xis

HE MuonsTeV’s

electro-mag. particles: MeV’s

LE MuonsGeV’sIceTop

IceCube/IceTop's Strength

EM

IN-ICE COMPOSITION SENSITIVE VARIABLES I

S125: shower size at the surface

K70: size of muon bundle in-ice

IceTopIn

-ice

Pure Iron

Pure proton

Neural Networkoutput

IC/IT40 Composition Analysis


FIRST ATTEMPT FOR COMPOSITION (IC40)

Preliminary

Preliminary

Preliminary

IC/IT40 Composition Analysis: Results

~ 1month of IC40 subarray (with little snow)

energy from 1 to 30 PeV (only)

systematics dominated


major progressexpected for the next

analyseswith larger detector

Submitted to Astrop. Phys.

separation power(expected to improve)

IN-ICE COMPOSITION SENSITIVE VARIABLES II

IT73/IC79 Composition Analysis

16

In-ic

e

IceTop

Muon stochastic loss

Avg. muon energy loss

for same deposited energy:

more stochastic loss

more HE muons lighter elements

ECRS, July 3-8, 2012 H.Kolanoski - Cosmic Ray Physics with IceCube

Exploit additional mass sensitive observables


Supporting Composition Measurements

1 VEM charge enhanced if

signalem signalmuon

Muon counting in air shower dataZenith angle dependence of shower size

Proton assumption

Iron assumption

IT26 spectrum analysis 1-100 PeV- arXiv:1202.3039

preliminary

preliminary

Surface muon content

simulation

PeV Gamma with InIce Veto against muons


HI column densities

IceTop shower with no activity in IceCube

upper limit E = 1.2 – 6.0 PeV (90% c.l.)

--- sensitivity E = 1 – 10 PeV (90% c.l.)

• sensitivity for E = 1 PeV (90% c.l.)

preliminary

PeV Gamma: Point source sensitivity


TeV-sources extrapolatedto 1PeV without cut-off

IceCube 5 year sensitivity to point sources

lowest declination reached by the Galactic plane

preliminary


Low energy transient rate variations from Sun, SN, GRB, ...

Since than: IceTop increased spectral sensitivity taking differential rates at multiple thresholds

[ApJ Lett 689 (2008) L65]Sun flare observation Dec 13, 2006:

rate increase at 2 different thresholds

Galactic CR Spectrum

• GOES spacecraft

GRB sensitivity: Large events but unmonitored part of the sky

GeV 10 ,200 ,cm erg10 oo25 EF

May 17, 2012 – GLE 71

H.Kolanoski - Cosmic Ray Physics with IceCube 21

MPE

SPE1

SPE2SPE3

IceTop Rates plotted here are averages of the four groups

shown above.

• ~1% enhancement in SPE1 & SPE2• Tiny enhancements in SPE3/MPE• Unusual slow decay or second phase

ECRS, July 3-8, 2012

Observations

preliminary

Cosmic rays in IceCube (deep ice)


High Energy Muons in the Deep Ice


muon bundlesingle HE muon

Nµ~A0.23 E0.77

Muon Multiplicity

Q3.

5 d

N/d

Q

Q ~ Nµ

Test composition models

10 TeV 10 EeV

enlarged energy range witout coincidence

Spectra from Muon Bundles


preliminary

preliminary

preliminary

room for prompt muons from charm?

Comparison to Poly-Gonato Model


Poly-Gonato (+G-H3a extra-galactic)

E1

.7-w

eig

hte

d

total (polygonato + extragal.)no efficiency correction included

heavier than iron(extrapolated from

low energies)

extragalactic

room for prompt muons?

Atmospheric


at high energies remaining background

for comic neutrinos


Cosmic Rays: High-pT muonsHigh-pT muons modeled by QCD simulation (π, K, c, …)

O(10 m)

> 135 m

bundle

LS muon

power law

exponential

pQCD

preliminary

preliminary


High-pT Muons: Zenith Angle Distribution

DPMJET

QGSJET

MC=data

strong disagreementfor QGSJET & Sybill

π

K

c

Zenith angle dependences:

• π, K interaction vs. decay competition

• prompt: no dependence larger K/π ratio and/or more prompt?

d > 135 m


Cosmic Ray Anisotropy Large Scale ─ Compared to Northern Sky

the orientation of the dipole momentdoes not correspond to the relative motion

in the Galaxy (Compton-Getting effect)

diffusive transport from nearby sources?observed small scale (10°) structures few pc distance

in-ice only

Cosmic Ray Anisotropy


IceCube

IceTop

• CR Rate ~ 10 Hz in IT81 (E > 100 TeV)

• ~3 x 108 events / year

• Sensitive to > 10-4 anisotropy

• CR Rate ~ 2 kHz in IC86 (E > 10 TeV)

• ~6 x 1010 CR events / year

• Sensitive to > 10-5 anisotropy

Measurements with IceCube and IceTop

Air showers in IceTop :

in principle much betterenergy resolution, binning limited by statistics

potential of including composition sensitivity

Muons in IceCube:

lower energy; larger zenith range;higher sensitivitiessmall scale structures

IC59 - 400 TeV

IC59 - 20 TeV

IT73 - High energy (~2 PeV), preliminary

Energy Dependence of CR Anisotropy

31

• Anisotropy changes in position, size

• Above 400 TeV there’s indication of an increase in strength.ECRS, July 3-8, 2012 H.Kolanoski - Cosmic Ray Physics with IceCube

preliminary (IT73)

Summary


• Cosmic Ray energy spectrum (‚flattening‘ at ~ 23 PeV)

• CR composition (first coinc. results, different methods model test), PeV γ rays

• connecting direct measurements with dominantly extra-galactic CR

• physics of airshowers: high-pT muons, composition, K/π, charm, …

• transient events: heliospheric physics, GRB, …

• CR anisotropy in PeV range, likely increase with energy

IceCube/IceTop is a unique 3-dim Air Shower Detector

Results:


Backup Slides


35

ENERGY RESOLUTION

SNOW CORRECTIONS


Feb. 2012

cos

0 z

meas eSS

Snow corrected(in shower reco)

Events selected bycore location

CR Spectrum: Comparison with IT26 and IT40



Strategies of Composition Analyses

proton

N

X / g cm-2

earlier

e/m

μ

first interaction

observationN

X / g cm-2

e/m

μearlier

more

heaviernucleus

• IceTop & InIce

IceTop EM vs InIce MUON

• IceTop

- zenith angle of e.m. - curv. of shower front

- GeV-muons in IceTop:

• IceTop & Radio

(future?)- shower max. Xmax

Complementary methods

reduce model dependency~ 680 g cm-2

Big Coincident Event


http://inwfsun1.ugent.be/~tom/IceCube/BigEvents/BigIT73_IC79_Run00116545.gif

CR Spectrum: Comparison with other Experiments


Documents

Cosmic Ray Physics with the IceCube Observatory