1 IceCube: A Neutrino Telescope at The South Pole Chihwa Song UW-Madison photographed by Mark Krasberg 4 th Korean Astrophysics Workshop May 17-19, 2006.
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IceCube: A Neutrino Telescope at The South Pole
Chihwa Song
UW-Madison
photographed by Mark Krasberg
4th Korean Astrophysics Workshop May 17-19, 2006
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Multi-messenger Astronomy Radio
Infrared
Optical
Gamma Ray
deflected
absorbed
pee p + + n
+radio
+IRe+e-
+MW
Local Group
3C279
Mrk421
Gal Center <100 Mpc 1-10<100 Mpc 1-1099 TeV TeV
3
Neutrino Fluxes Confirmed extraterrestrial sources: Sun, SN1987A
4
Cosmic Accelerators
Discovery of neutrinos would confirm hadronic acceleration
5
Origin of Astrophysical Neutrinos
Source candidates: AGN, SNR, GRB, microquasar
Protons accelerated at source produce pions which decay into neutrinos:
e = 1 : 2 : 0
p + p (or e
e = 1 : 1 : 1
p DX
p X
10 3
@ source
@ Earth
oscillation(maximal mixing)
6
Neutrino Telescopes
Detection Requirements: - small neutrino cross section huge detector volume
- optically transparent medium use water or ice
Neutrino telescopes: - Water: Baikal, ANTARES, NESTOR, NEMO, KM3 - Ice: AMANDA, IceCube (successor of AMANDA)
Water Ice
Location Northern Southern
Deployment weather allowed austral summer
Background high low
Scattering length ~100 m ~20 m @ 400nm
Attenuation length 20-40 m ~110 m @ 400 nm
Detector geometry variable stable
Neutrino Detection Detect Cherenkov light from charged particles produced by neutrinos
: CC e : NC, CC
: NC, CC: NC
CascadeMuon track
CC NC
= 41o
8
E = 10 TeV
e
E = 375 TeV
Neutrino Flavor
E = 10 PeV
travel ~2km
Two showers separated by roughly 50(E/PeV) m
80 string IceCube
~300m0.65o (E/TeV)-0.48
(3TeV < E< 100TeV)
Background
Zenith angle
• Miss-reconstructed down-going events• Up-going atmospheric neutrino events
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Signal: harder spectrum (E-2) than background (Fermi acceleration)
E-3.7 atmospheric
E-2 flux
True neutrino energy Number of fired OMs
Diffuse Neutrinosfrom unidentified faint sources
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12
USA (14)
Europe (15)Japan
New Zealand
• Alabama University, USA• Bartol Research Institute, Delaware, USA• Pennsylvania State University, USA• UC Berkeley, USA• UC Irvine, USA• Clark-Atlanta University, USA• University of Alaska, Anchorage, USA• Univ. of Maryland, USA
• IAS, Princeton, USA• University of Wisconsin-Madison, USA• University of Wisconsin-River Falls, USA• LBNL, Berkeley, USA• University of Kansas, USA• Southern University and A&M College, Baton Rouge, USA
• Universite Libre de Bruxelles, Belgium• Vrije Universiteit Brussel, Belgium• Université de Mons-Hainaut, Belgium• Universiteit Gent, Belgium• Humboldt Universität, Germany• Universität Mainz, Germany• DESY Zeuthen, Germany• Universität Dortmund, Germany
• Universität Wuppertal, Germany• MPI Heidelberg, Germany • Uppsala university, Sweden• Stockholm university, Sweden• Imperial College, London, UK• Oxford university, UK• Utrecht university, Netherlands
• Chiba university, Japan• University of Canterbury, Christchurch, NZ
ANTARCTICA
The IceCube Collaboration
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IceCube
InIce80 strings60 OMs / string17 m vertical spacing125 m between strings
IceTop80 stations2 frozen-water tanks / station2 OMs / tank
Super Kamiokande
40m
14
main board
LED flasher board
PMT base
PMT
33 cm Benthosphere
Digital Optical Module (DOM)
Hamamatsu R7081-02 (10”, 10-stage, 108 gain)
- Time-stamp at the PMT- Capture complex waveforms at PMT anode with analog Transient Waveform Digitizer (ATWD)
16
Hot Water Drill
speed: 1.5m/min
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Drilling
String 49 – drill stopped for ~one hour at ~2300 meters
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Freezing IceNoise rates increase during freeze-in String freezes from top (colder ice) to bottom (warmer ice)
Top
Botto
m
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Dust Logger
ash layer
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Ice Properties
Scattering
bubbles
Absorption
Average optical parameters:abs ~ 110 m @ 400 nmsca ~ 20 m @ 400 nm
dust layer
DOM occupancy at string 21
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Two ice tanks 3.6 m2 x 1 m deep
IceTop Station
To DAQ
IceCubeDrill Hole
10-15 m
Local coincidence cable
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04/05 1 IceCube string8 IceTop tanks
05/06 8 IceCube strings24 IceTop tanks
Deployment Status
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An Up-going Event
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Data/MC Comparison
Event reconstructionwith only one string
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Down-going Muon Events
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A Flasher Event
Color: arrival timeSize: amplitude
6 vertical (top) LEDs
6 horizontal (bottom) LEDs
(Single LED run)
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Diffuse Neutrinos
No significant excesswas seen with AMANDA!
by Jessica Hodges
Astrophysical and prompt neutrino models
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Bursts of low-energy (MeV) neutrinos from core collapse supernovae
The produced positron is emitted almost isotropically
- AMANDA sees 90% of the galaxy- IceCube will see out to the LMC (Large Magellanic Cloud, ~50 kpc)
SN Neutrino Search
detection
radius
AMANDA
IceCube30 kpc
0 5 10 sec
Count ratesSimulation(IceCube)
O(10cm) long tracks
SNEWS (SuperNova Early Warning System) is a collaborative effort among Super-K, SNO, LVD, KamLAND, AMANDA, BooNE and gravitational wave experiments
Rate increaseon top of dark
noise
e+ p n + e+
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The Sun sinks maximally 23o below the horizon at the south pole
Horizontal events are very important!!
qql+l-
W+W-
ZoZo
Higgs…
Indirect search
Velocity distribution
Cosmic Rays:
WIMP Annihilation in the Sun
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New Method - Radio
– One cluster (4 antennas) in the next season– Increase to 2 clusters in the following seasons
~50m
Motivation: difficulties to cover very large detector volume with optical sensors
ROCSTAR (Retrofitted OptiCal SysTem Adapted for Radio)
35
New Method - AcousticCalibration method in water has been developedIn-situ calibration in ice is needed
SPATS (South Pole Acoustic Test Setup)
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Summary
• IceCube will be a powerful all-flavor neutrino detector
• Significant improvement in angular and energy resolutions
• IceTop will measure cosmic rays up to ~ EeV with high resolution
• AMANDA will overlap the lower energy tail of IceCube sensitivity
• AMANDA has taken data for the 7th year
• String deployment speed reached expectation
• DOM survival rate is very good (~99%)
• Verifications of the new IceCube strings in progress
• The current IceCube is larger than AMANDA and provides science quality data
• On-going activities (radio, acoustic) toward ~100km3 detector
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Time DelayTime delay in arrival times of photons due to scattering in icedepends on the distance with respect to the muon track.
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Glacial Ice Flow
Rigid downto 2000 m
Stuck atbedrock
Lagging behind
Modeling from temperature profile
Flow direction
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A Neutrino Candidate Event
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Point Source Search
Final sample (4 yrs): 3369
0.214.502SS433
1.255.3610Crab Nebula
0.405.214Cygnus X-1
0.775.046Cygnus X-3
0.383.7151ES1959+650
0.685.586Markarian 421
Flux Upper Limit 90%(E>10 GeV)
[10-8cm-2s-1]
Expectedbackgr.
(4 years)
Nr. of events
(4 years)
Source
Search for excesses of events compared to the background from: 1. the full Northen sky 2. a set of selected candidate sources
•64% chance occurrence
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Search for Clusters in Northern Sky
• 2000-2003 data: 807 days livetime• 3329 neutrino events observed• Cluster search radius between 2.25o – 3.75o w.r.t. • Largest significance = 3.4 (92% chance occurrence)• No significant excess observed
Significance map
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Search For WIMPs
Limits on muon flux from Earth center Limits on muon flux from Sun
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Surprises?
Telescope User date Intended Use Actual use
Optical Galileo 1608 Navigation Moons of Jupiter
Optical Hubble 1929 Nebulae Expanding Universe
Radio Jansky 1932 Noise Radio galaxies
Micro-wave Penzias, Wilson
1965 Radio-galaxies, noise 3K cosmic
background
X-ray Giacconi … 1965 Sun, moon neutron stars
accreting binaries
Radio Hewish,
Bell 1967 Ionosphere Pulsars
-rays military 1960? Thermonuclear
explosions Gamma ray
bursts
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Sensitivities & Limits
ave
rag
e fl
ux
up
per
lim
it [
cm-2s-1
]sin
AMANDA-B10
AMANDA-II
IceCube 1/2 year
*
all-flavor limits
νμ (A-II 4yr)
νe+νμ+ντ (cascades A-II 1yr)
νe+νμ+ντ (UHE B10 1yr)
νe (cascades B10 1yr)
νμ (B10 1yr)
νμ (A-II 1yr)
νe+νμ+ντ (UHE A-II 1yr)
Icecube (1yr)
WB bound
LimitSensitivity
Diffuse search (E-2 flux hypothesis) Steady point source sensitivity
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