First Results from IceCube

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First Results from IceCube
Spencer Klein, LBNL for the IceCube Collaboration

• Physics Motivation
• Hardware Overview
• Deployment
• First Results
• Conclusions Future Plans

See Paolo Desiatis AMANDA talk
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• Alabama University, USA
• Bartol Research Institute, Delaware, USA
• Pennsylvania State University, USA
• UC Berkeley, USA
• UC Irvine, USA
• Clark-Atlanta University, 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 AM College, Baton
  Rouge, USA

The IceCube Collaboration
USA (12)
Japan
Europe (12)

• Chiba university, Japan
• University of Canterbury, Christchurch, NZ

New Zealand

• 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
• Kalmar university, Sweden,
• Uppsala university, Sweden
• Stockholm university, Sweden
• Imperial College, London, UK
• Oxford university, UK
• Utrecht university, Netherlands

ANTARCTICA
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Physics Motivation

• Search for cosmic-ray accelerators
• Protons are bent in galactic magnetic fields
• n are produced by hadron accelerators
• HE (gt51013 eV) photons are absorbed by
  interaction with 30K microwave background photons
• gg --gt ee-
• 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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Physics Topics

• Source searches
• Active Galactic Nuclei
• Supernova remnants
• Gamma-Ray Bursts
• Calculations predict 1-10 n/km3/year from many
  source models
• Neutrino physics
• Expect 100,000 atmospheric n/year
• Cross-section measurements
• Absorption in earth
• Decoherence
• Oscillations
• Searches for supersymmetry, WIMPs, MeV n from
  supernovae, monopoles, Q-balls.

Active Galactic Nucleus
Crab Nebula
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Detector Requirements

• Need 1 km3 area for a good chance to see signals
• Requires a natural material
• Ice or water
• South Pole Ice has
• Long absorption length
• Shorter scattering length
• Depth dependent
• Low dark noise rates

Ice model Scattering vs. wavelength and depth
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Lessons from AMANDA

• AMANDA pioneered n astronomy at the South pole
• Deployed first OMs 1993/4
• Observed atmospheric nm
• Deep ice (gt 1 km) has good optical qualities
• Data transmission to surface nontrivial
• Paolo Desiatis talk will present AMANDA results

A muon in AMANDA
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IceCube

• 1 gigaton instrumented volume
• 80 strings of 60 digital optical modules
• 1450-2450 m deep
• 17 m spacing
• 125 m hexagonal grid
• Each DOM is an autonomous data collection unit
• IceTop air shower array
• 160 surface water tanks
• Each contains 2 DOMs

• 1 string 8 tanks deployed Jan. 2005

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nm, ne and nt

• IceCube will distinguish nm, ne and nt based on
  the event characteristics
• nm --gt m produce long muon tracks
• Good angular resolution, limited energy
  resolution
• Atmospheric nm are a significant background to
  searches for extra-terrestrial n
• Soft energy spectra --gt may improve signal to
  noise ratio by optimizing for higher energy n
• ne --gt e produce EM showers
• Good energy resolution, poor angular resolution
• Above 1016 eV nt produce double-bang events
• One shower when the t is created, another when it
  decays

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Simulated m Events
Eµ10 TeV, 90 hits
Eµ6 PeV, 1000 hits
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A simulated multi-Pev nt event
A ne would appear as a single shower n.b. gbct
300 m for Et 6 TeV
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Digital Optical Module
Hardware
LED flasher board
PMT base
25 cm PMT
main board
33 cm Benthosphere
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Analog Front-End

• Want to measure arrival time of every photon
• 2 waveform digitizer systems
• 200-700 Megasamples/s, 10-bit
• switched capacitor array
• 3 parallel digitizers give 14 bits of dynamic
  range
• 128 samples --gt 400 nsec range
• Dual chips to minimize dead-time
• 40 Megasamples/s, 10-bit ADC
• 256 samples --gt 6.4 ms range
• Self-triggered
• Also, local-coincidence circuitry looks for
  hits in nearby modules

Time bin (3.3 ns)
An ATWD waveform
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DOM Readout

• Each DOM is a mini-satellite
• FGPA ARM7 CPU for
  control, data compression
• Packetized data is sent to surface
• Baseline data transmission
• waveforms for local coincidence data
• Rate 15-30 Hz
• timing and charge info for isolated hits
• Rate 700 Hz
• Rapcal timing calibration maintains
  clock calibration to lt 2 nsec

A Main Board
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Surface DAQ

• Trigger based on multiplicity topology (in a
  sliding time window)
• Selected data saved to tape
• High-priority data sent north over a satellite
  link
• GPS clock for overall timing

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IceCube
AMANDA
South Pole
Skiway
Dome (old station)
road to work
Summer camp
Amundsen-Scott South Pole station
http//icecube.wisc.edu
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Hose reel
IceTop tanks
The drilling site in January, 2005 Hot-water
drilling
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The 5 MW water heater for the hot water
drill (car-wash technology)
Hose Reel
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An IceTop tank
Each 2 m dia. IceTop tank contains two DOMs.
m signals from IceTop DOMs
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Schedule Logistics

• Can work December --gt 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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IceCubes First String January 28, 2005
27.1, 1008 Reached maximum depth of 2517
m 28.1, 700 preparations for string
installation start 915 Started installation of
the first DOM 2236 last DOM installed 12
min/DOM 2248 Start drop 29.1, 131 String
secured at depth of 2450.80 2040 First
communication to DOM
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2 high-multiplicity muon events
Time Residual (ns)
Depth (m)
Time Residual (ns)
Time Residual (ns)
Depth (m)
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First Results from String 21

• Time calibration
• Muon reconstruction
• Timing verification with muons
• Timing and Energy measurement with LED flashers
• Coincidence events
• IceCube - IceTop

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Time Calibration
In-ice DOMs
Time
IceTop
IceTop
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Muon and Flasher Reconstruction
10m-long cascades, ne nt neutral current

• Observe Cherenkov radiation from charged particle
  tracks
• Muons produce km long tracks
• hadronic shower at interaction point
• EM cascades produce point sources
• LED flashers are a surrogate for ne
• Reconstruct both with maximum likelihood
  techniques
• Use arrival times of all photons, as determined
  from waveform information

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Muon zenith angle distribution
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Timing studies with muons
The random and systematic time offsets from one
DOM to the next are small, /- 3ns
Residual Timing (ns)
Scattering L (1/m)
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A flasher event
Flasher
Color --gt arrival time Circle size --gt
Amplitude

• Equivalent to 60 TeV ne

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Timing resolution from flashers
Photon arrival time difference between DOM45 46

1.74 ns rms
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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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IceTop and in-ice coincidences
Some of the difference is due to shower curvature
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Conclusions Outlook

• IceCube will explore the high-energy n sky.
• With a 1 km3 effective area, IceCube has the
  power to observe extra-terrestrial neutrinos.
• We deployed our first string in January, 2005.
• 76 out of 76 DOMs are working well.
• Timing resolution is lt 2 nsec
• Next austral summer, we will deploy 8-12 more
  strings.
• Largest neutrino observatory in the world.
• By 2010, we will have instrumented 1 km3.

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Extras/Backup

• IceCube reviewers read no farther

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10 PMT Hamatsu-70
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Muon Angular Resolution
Waveform information not used. Will
improve resolution for high energies !
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Timing verification with light-flashers