IceCube a neutrino observatory at the South Pole

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IceCube a neutrino observatory at the South
Pole

• Howard Matis
• Lawrence Berkeley National Laboratory

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Outline

• New instruments and advances in astronomy
• What is a neutrino?
• Why do neutrino astronomy?
• How do you detect neutrinos in ice (or water)?
• The IceCube Observatory
• Physics to be done with it
• How does it work?
• What is its status?
• Short trip to the South Pole

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First Astronomers

• Simple observations using the eye
• Just look up in the sky
• Sun
• Moon
• Stars
• Comets
• Planets
• Meteors
• Supernovae

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The Optical Telescope

• Galileo uses the optical telescope
• Sensitive to light from red to blue
• Limited by human eye
• Discovers mountains and craters of the moon
• Moons of Jupiter
• Dominant astrophysical device for centuries

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Radio Telescope

• Arno Penzias and Robert Wilson discover (1964)
  the cosmic microwave background radiation using a
  radio telescope
• Different part of electromagnetic spectrum
• Signal was 3 K noise that came from all
  directions
• Cosmic ray background provides detailed data and
  constraints for Big Bang model

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X-ray Astronomy

• Riccardo Giacconi
• Put an X-ray detector on rockets
• Escape Earths atmosphere
• Discovered
• Properties of the Sun
• Identify large number of objects
• Binary X-ray sources (Cygnus X-3)
• neutron star
• period decreasing

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Cosmic Rays

• Particles from outer space
• Victor Hess - discover 1912
• Led to
• Discovery of antimatter - positron
• Mystery of origin
• Mass of neutrino

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Prediction of the Neutrino (n?

• Experimental results for nuclear beta decay
  (nucleus decaying into another plus an electron)
  require
• either an "invisible" particle or
• violation of the laws of conservation of momentum
  and energy.
• Wolfgang Pauli, 1930
• "I have done a terrible thing - I have invented
  a particle that cannot be detected"

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Discovery of the n

• 1956 - Fred Reines and Clyde Cowan detect
  neutrinos from the Savannah River nuclear
  reactor.
• 200 liters of H2O
• 12 meters underground
• 3 events/hr

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The Sun, seen in neutrino light
From the CERN Courier June, 2000
Low energy neutrinos from the sun afford low
angular resolution
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Quick Course in Fundamental Particles

• Quarks
• Makes up all matter
• Proton uud
• Neutron ddu
• Leptons
• Electron - part of normal matter
• Muon (?) - heavy electron
• Nobel Prize winner Rabi said, Who ordered that?
• Tau (?)- even heavier
• Each of these particles has its own neutrino - ?

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Neutrinos

• Three types
• Electron neutrino - ?e
• Muon neutrino - ??
• Tau neutrino - ??
• Electron neutrinos produced in normal beta decay
• Neutrinos when proton converts to a neutron
• Antineutrinos when a neutron turns into a proton
• Anti-electron neutrinos produced in reactors

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Simple Properties

• Mass really small lt 3 eV
• Three and only three neutrinos
• Zero charge
• They only interact with gravitation and the weak
  force
• Pass through the Earth
• An electron neutrino only decays into an electron
  X
• A muon neutrino only decays into an muon X
• A tau neutrino only decays into an tau X
• However, they can change into each other

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Each is a mixture of a ?1, ?2, or ?3
or
(Mass)2
?m2atm
Inverted
Normal


?m2sol 8 x 105 eV2 ?m2atm 2.5
x 103 eV2
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Neutrino Fluxes

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Physics Motivation

• Neutrinos point to cosmic-ray accelerators
• Protons are bent in galactic magnetic fields
• ns are produced by hadron (i.e. proton)
  accelerators
• High Energy (gt5 ? 1013 eV) photons are absorbed
  by interaction with 30K cosmic microwave
  background (cmb) photons
• g???gcmb ? e e-
• Neutrinos study the High-Energy Universe
• 100 GeV 1019 eV
• Cross section effective area rise with energy,
  so a single detector can cover a very wide energy
  range

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Supernova Remnants (SNR)

• Leading candidate accelerator of most galactic
  cosmic rays
• Powerful blast waves driven to the interstellar
  medium by core collapse supernovae
• Super Nova Remnants power matches cosmic rays
• Super Nova Remnants chemical abundances match
  cosmic rays (after spallation)
• Fermi acceleration in the blast waves up to
  1015eV for thousands of years after SN explosion,
  producing a spectrum

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Proving the Cosmic Ray Hypothesis

• p0 channel
• The smoking guns of cosmic ray-ions
  acceleration
• A 67.5 MeV peak in the g-ray spectrum from p0
  decay
• Searches for the peak are inconclusive so far

• Neutrino channel
• Discovery of High Energy neutrinos from Super
  Nova Remnants would unequivocally establish the
  origin of galactic rays!

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The Fireball PhenomenologyGamma Ray Bursters
(GRBs)n Connection
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GRBs (continued)

• Maximum proton energies of 1020 eV attainable
• possible source of very high energy cosmic rays.
• Energy injection similar to very high energy
  cosmic rays
• Detection in coincidence (time and direction) of
  neutrinos and satellite g rays
• reduces background dramatically
• By comparing arrival time
• extra bonus Tests of Relativity

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Active Galactic Nuclei (AGN)

• Most distant objects in the Universe
• Redshift of 5
• 1012 brighter than the sun
• 106 more massive than the sun

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Diffuse Fluxes Predictions and Limits
Mannheim Learned, 2000
1 pp core AGN (Nellen) 2 p? core AGN Stecker
Salomon) 3 p? maximum model (Mannheim
et al.) 4 p? blazar jets (Mannh) 5 p? AGN
(Rachen Biermann) 6 pp AGN (Mannheim) 7 GRB
(Waxman Bahcall) 8 Annihilation of
topological defects (Sigl)
Macro
Baikal
Amanda
IceCube
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WIMP Capture and Annihilation
n
nm
DETECTOR
c c ? W W ? n n
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Relativistic Magnetic Monopoles
Soudan
KGF
Baikal
MACRO
Orito
upper limit (cm-2 s-1 sr-1)
Cherenkov light output ? n2(g/e)2
Amanda
? electrons
n 1.33 (g/e) 137/ 2
IceCube
? 8300
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How do you Detect a ??

• Only interact through the weak force
• Enormous range
• Solar neutrinos easily penetrate a light-year of
  lead
• Difficult to detect
• Leaves no visible track
• Fortunately, there are a huge number of them
• Detected when
• They collide with matter
• Produce fast-moving charged particles

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The earth as a cosmic ray muon filter
l

• 70 TeV neutrino
• interaction length equal to the diameter of the
  earth
• Look at neutrinos coming from the earth
• reject against cosmic ray background from above

n
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Atmospheric Neutrinos
Cosmic Ray
p
??
e
??
?e
??
15 Km
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Measurement by our Previous Experiment AMANDA
Neutrino Energy in GeV
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How does IceCube or Amanda Detect these charged
particles?

• Charged particles moving faster than the speed of
  light in a material produce light
• Called Cherenkov radiation
• The electromagnetic sonic boom

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• optical sensors capture and map the light

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IceCube is a Discovery Instrument

• 1 gigaton instrumented volume
• gt 1 km3 after all cuts
• Energy measurement
• secondary muons ( lt 0.3 in ln E)
• electromagnetic showers ( lt 20 in E)
• Identification of neutrino flavor
• which type of neutrino was detected
• Sub-degree angular resolution
• unavoidable neutrino-muon misalignment

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IceCube Observatory

• IceTop air shower array
• 80 Stations / 2 Tanks each
• 2 DOMs per tank
• Ethres 300 TeV for ? 4 stations
• Useful rate up to EeV

50 m
Firn
Digital Optical Module
Ice
AMANDA
1450 m
324 m
2450 m

• IceCube deep ice array
• 80 Strings / 60 DOMs each
• 17 m DOM spacing
• 125 m between strings

Start the Application
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Digital Optical Module - DOM
LED flasher board
PMT base
25 cm PMT
main board
33 cm Benthosphere
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10 PMT Hamatsu-70
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nm, ne and nt

• IceCube will distinguish nm, ne and nt based on
  the event characteristics
• nm ? m produce long muon tracks
• Good angular resolution, limited energy
  resolution
• Atmospheric nm are a significant background to
  searches for extra-terrestrial n
• ne ? e produce electromagnetic showers
• Good energy resolution, poor angular resolution
• nt produce double-bang events
• Above 1016 eV
• One shower when the t is created, another when it
  decays

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Muon Events
Eµ 10 TeV (1012 eV)
Eµ 6 PeV (1015 eV)
Measure energy by counting the number of fired PMT
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Cascade event
E 375 TeV
ne N ? e- X

• Length cascade
• 10 m
• small compared to the spacing of sensors
• 1 PeV 500 m diameter
• Fully active calorimeter
• Linear energy resolution

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Tau Neutrino Detection
t with energy of PeV travels 300 m
nt? t
t decays
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Schedule Logistics

• Can work November ? mid-February
• Logistics are a huge concern
• Freight, power, are expensive!
• Weather is always a factor

The new South-Pole station
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Drill with Hot Water
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Drill BitHot Water Jet
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Last Optical Sensor
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IceTop Tank
Each 2 m diameter IceTop tank contains two DOMs.
m signals from IceTop DOMs
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View as DOMs Freeze in the Water
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First Results fromString 21

• Last January installed
• One string of 60 detectors
• 4 IceTop tanks
• Do they work?
• How well do they work?

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A Flasher Event
Flasher
Color ? Arrival time Circle size ? Amplitude

• Equivalent to 60 TeV ne

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Energy Measurement for Flashers

• Reconstruct energy of flash for each flashing
  DOM, using known position
• Variation due to
• Ice models
• LED intensity
• Detector Response..
• Good agreement across entire string

All LEDs Side LEDs 450 LEDs 1/3 Intensity
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Timing verification with light-flashers
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Timing studies with Muons

• Random and systematic time offsets
• Small
• 3 ns

Residual Timing (ns)
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Recon-structed Events
Depth (m)
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Muon Zenith Angle Distribution
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How to Get to IceCube
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Start from North America
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Arrive in Christ Church, New Zealand
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Get Some Clothes
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Take a Plane to Antarctica
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Use a Propeller Plane
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Ample LegroomFlight 8 to 12 hours
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Friendly Pilots
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Arrive McMurdo Station, Antarctica
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On the Coast
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See Some Wildlife
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Tourist Site Scott Base Camp
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Mt. Erebus
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Go to the Pole
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Go to Nearest Airport
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Take another Airplane
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Little More Room
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Good Views
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Arrive
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Visit the Pole
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Wrong Place
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Finally There
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Ice Sheet Moves 10 m/yr
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Start to Work on IceCube
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Summary

• IceCube to explore the high-energy neutrino sky
• 1 km3 effective volume
• power to observe extra-terrestrial neutrinos
• First string deployed in January 2005
• 76 out of 76 DOMs are working well
• Timing resolution is lt 2 nsec
• Detector working well
• This season (2005-2006) plan to deploy 10 more
  strings
• Largest neutrino observatory in the world
• By 2010 fully instrumented
• IceCube will be discovering new things for
  years???

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The IceCube Collaboration
Germany Humboldt Universität Universität
Mainz DESY-Zeuthen Universität Dortmund
Universität Wuppertal Universität Berlin
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The End
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Neutrino sources
The Big Bang Radioactive decay Nuclear
fission reactors Nuclear fusion reactor (the
Sun) Supernovae Particle collisions Accelera
tors Cosmic rays in the atmosphere WIMP
annihilation Active Galactic Nuclei Gamma Ray
Bursts
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??- flavors and energy ranges
Filled area particle id, angle, energy Shaded
area energy and angle.
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IceCube deployment schedule