Status and results from the IceCube neutrino observatory

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Status and results from the IceCube neutrino
observatory

• Georges Kohnen
• Université de Mons-Hainaut, Belgium
• for the IceCube collaboration
• XLIV. Rencontres de Moriond La Thuile, Italy,
  Feb. 1-8, 2009

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The IceCube Collaboration
Germany DESY-Zeuthen Universität Mainz
Universität Dortmund Universität Wuppertal
Humboldt Universität MPI Heidelberg RWTH Aachen
Sweden Uppsala Universitet Stockholm
Universitet
USA Bartol Research Institute, Delaware
University of California, Berkeley University of
California, Irvine Pennsylvania State
University Clark-Atlanta University Ohio State
University Georgia Tech University of Maryland
University of Alabama, Tuscaloosa University of
Wisconsin-Madison University of Wisconsin-River
Falls Lawrence Berkeley National Lab.
University of Kansas Southern University and
AM College, Baton Rouge University of
Alaska, Anchorage
UK Oxford University
Netherlands Utrecht University
Belgium Université Libre de Bruxelles Vrije
Universiteit Brussel Universiteit Gent
Université de Mons-Hainaut
Japan Chiba University
Switzerland EPFL
New Zealand University of Canterbury
33 institutions, 250 members
http//icecube.wisc.edu
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The IceCube Detector
1 km3 of antarctic ice instrumented to detect
extraterrestrial neutrinos

• IceTop
• Surface air shower array
• Shower threshold 300 TeV
• 320 DOMs in 160 ice-filled
• tanks
• 2 tanks per IceCube string
• Cosmic ray detection
• Veto for IceCube

• InIce
• Up to 4800 Digital Optical Modules (DOM) on 80
  strings arranged in a hexagonal grid
• 1450 2450m deep
• 17m vertical distance between DOMs
• 125m horizontal distance between strings

• AMANDA
• proof-of-concept detector
• active 1996-2009
• 677 optical modules on 19 strings
• denser array, string spacing 40m

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The IceCube Detector Aerial view
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The IceCube Detector current state

• 19 strings/stations installed during the
  2008-2009 austral summer, commissioning ongoing
• Total of 59 strings and 118 IceTop tanks ? over
  two thirds complete!
• Integrated exposure reaching 1 km3.year

2004-2005 1 string
2005-2006 8 strings
2006-2007 13 strings
2007-2008 18 strings
2008-2009 19 strings
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Construction Drilling
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Construction Drill site
Drill camp (5 MW hot water heater)
Hose Reel
Hot water hoses
IceTop Tanks (with sun shields)
Drill speeds 2 m/minute 40 hours to drill a
hole 12 hours to deploy a string
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Construction Drilling and Deployment
2 days per hole
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DOMs
10 Hamamatsu Photomultiplier tubes (PMT) 3.5 W
Power Internal digitization and timestamping
ATWD 300 MHz (400 ns) fADC 40 MHz (6400
ns) Dynamic range from one to thousands of
photo-electrons Transmit digital data to surface
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Data Acquisition
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IceCube Datasets
Strings Year CR µ rate ? rate
1 2005 5 Hz 0.01 / day
9 2006 80 Hz 1.5 / day
22 2007 550 Hz 20 / day
40 2008 1000 Hz
59 2009
? 2010
80 2011 1650 Hz 200 / day
After triggering, noise cleaning, first guess
reconstruction and online filter 32 GB/day of
satellite data transfer (2008)
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Neutrino detection

• Detection of neutrinos of all flavors from 1011
  to 1020 eV
• Neutrinos interact
• with a nucleon and
• produce a charged lepton
• Lepton emits Cherenkov light cone (41) as it
  travels through the ice (plus Bremsstrahlung,
  ee- pairs,)
• Cherenkov radiation is detected by DOMs

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Neutrino flavour identification
Muon neutrino Straight track, points to
neutrino source, angular resolution lt1 -
Cosmic ray muon background
Electron neutrino - Cascade, must be in
detector - Poor angular resolution Good energy
measurement
Tau neutrino Double bang signature, low
background Pointing capability
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Ice Properties

• Analyses sensitive to the optical properties of
  ice
• South Pole Ice extremely pure but presence of
  non-planar dust layers
• Determine optical properties using LED and LASER
  sources
• Average optical parameters at 400 nm
• ?abs 110 m, ?sca 20 m above the dust layer
• ?abs 220 m, ?sca 40 m below the dust layer
• No bioluminescence

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Multi-messenger astronomy

• At the earth, most of the cosmic rays are
  protons deflected by intergalactic magnetic
  fields (lt10EeV, do not point back to source) or
  GZK suppression (gt50EeV)
• Gamma rays (photons) propagate in a straight
  line but may be absorbed
• Neutrinos propagate in a straight line, not
  absorbed but difficult to detect ? large detector
  volume needed to compensate for small cross
  section

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Cosmic Ray spectrum
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Neutrino sources
?
Active Galactic Nuclei, proton accelerators
?
Gamma Ray Bursts
Diffuse and Point Sources Dark Matter Exotics
Atmospheric ?
??
Solar WIMPs
??
GZK ?
Supernovae
Cosmic Rays
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IceCube Physics prospects

• Astronomy/Astrophysics
• Point source search GRB, AGN,
• Diffuse searches
• Supernova detection
• ?t detection
• Cosmic Rays Physics (IceTop)
• Composition
• Energy spectrum
• Particle Physics
• Neutrino oscillations
• Cross sections
• New Physics
• WIMPs
• Magnetic monopoles
• SUSY (staus,)

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Cosmic Ray
Signal and Background
Atmospheric ?
MC simulations
Atmospheric muons (background)
Muons induced by ?? (atmos or astroph)
Up-going
Down-going
Reconstructed Zenith angle
Atmospheric ?
Most analyses remove CR muon background using a
cut on the angle. Other background coincident CR
muons
Astrophysical ?
Cosmic Ray
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Neutrino energy
Astrophysical neutrino energy spectra are
expected to be harder than the atmospheric
neutrino spectrum IceCube effective area
increases with energy
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Angular Energy resolution
Angular resolution also obtained by a moon
shadow analysis
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Point Source Search
AMANDA/IC9/IC22 E-2 sensitivity
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Point Source Search (IC22)

• One of the main goals of IceCube
• Search for excess of astrophysical neutrinos from
  known directions over the background of
  atmospheric neutrinos (looking through the
  earth at northern hemisphere)
• Two methods binned and unbinned (likelihood)
• 22 strings, 276 days (2007) 20 ?µ/day, 1.5
  angular resolution
• 5 times as sensitive as IC9, better than AMANDA 5
  year

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Diffuse Neutrino Flux

• Sources for diffuse neutrinos flux
• Atmospheric neutrinos (conventional and prompt)
• Astrophysical neutrinos
• Cosmogenic neutrinos
• Use energy based variables to separate
  astrophysical and atmospheric neutrinos

Harder energy spectrum

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Neutrinos from GRBs

• Search for events correlated in time an direction
  with observed GRBs
• Small time and space window reduces background
  rate
• 93 SWIFT bursts during IC22 runs
• IceCube will be able to set limits below the
  Waxman-Bahcall bound or similar GRB fluxes within
  the next few years

GRB Neutrino flux predictions
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Indirect search for WIMPs

• Search for neutrino flux from objects with large
  dark matter density
• Rate depends on MSSM and astrophysical parameters
• Neutralino
• popular dark matter candidate
• stable, weakly interacting and massive
• Majorana particle ? self-annihilation to SM
  particles that produce neutrinos (E? O(GeV-TeV))

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Indirect search for WIMPs
No significant excess found (Solar or Earth WIMPs)
Green area MSSM models not yet excluded by
direct searches
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Indirect search for WIMPs
Expected sensitivity after 10 (5) years of
data-taking
Blue area MSSM models not yet excluded by direct
searches
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Magnetic Monopoles

• Extremely bright events (more than 8000 times
  more Cherenkov radiation than muons
• Speed 0.75c 0.99c

B. Christy et al., ICRC 2007
Supernovae

• Signature simultaneous increase in noise rate in
  all DOMs
• IceCube (80 strings) can see out to the Large
  Magellanic Cloud
• IceCube participates in SNEWS

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DeepCore

• 6 new planned DeepCore strings
• 60 DOMs per string
• lower energy threshold to 100 GeV
  (WIMPs and atmospheric neutrinos)
• Smaller spacing
• In the clearest ice layers
• High quantum efficiency
  photomultipliers
• veto with the rest of IceCube
• First DeepCore string installed during 2008-2009
  season

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Future detection methods

• A high-energy ?N has three signatures in ice
• Optical (Cherenkov) lepton
• Radio hadronic and electromagnetic cascades
• Acoustic hadronic cascade
• Towards a 100 km2 hybrid detector
• Goal detect 100 GZK neutrinos in a few years
  (increase sensitivity at higher energies)
• Better background rejection through coincident
  detection
• Control systematic uncertainties (no calibration
  beam!)

arXivastro-ph/0406105
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Acoustic detection

• South Pole Acoustic Test Setup (SPATS) ?
  determine acoustic properties of Ice in the 0
  100 kHz range
• 28 Acoustic modules (sensors and pingers)
  deployed in 4 IceCube holes
• Fast thermal energy causes local expansion giving
  rise to a pressure wave
• Ring-shaped shock front that expands
  perpendicularly to the cascade direction
• Stable noise in ice
• Attenuation length 8 km in ice ? sensors can be
  placed far apart

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Radio detection

• Askaryan Underice Radio Array (AURA)
• 5 digital radio modules on IceCube strings (plus
  1 transmitter only module)
• 4 broadband dipole antennas (highest sensitivity
  400 MHz)
• 1 antenna calibration unit
• In-ice digitization

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Conclusions

• IceCube deployment is more than two thirds
  complete, largest running neutrino telescope!
• IceCube is actively taking data and shows a good
  long-term hardware reliability (over 98 of DOMs
  fully functional, over 96 uptime)
• Many analyses with the 22-string detector
  published, but no evidence for a source of
  extraterrestrial neutrinos yet
• Analyses with the 40-string detector underway
• DeepCore (low-energy extension) funded
• Exciting prospects!
• Future plans
• High- and Low-Energy extensions
• Acoustic and Radio detection
• Correlations with ROTSE, AGILE, MAGIC, LIGO

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Thank you! Questions?
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