IceCube Status and first results

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IceCube Status and first results

• November 9, 2005
• Albrecht Karle
• University of Wisconsin - Madison
• for the IceCube Collaboration

See also - Elisa Bernardinis AMANDA talk for
more on the physics - Thorsten Stezelbergers
talk for details on DAQ
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Outline

• Introduction
• Detector overview
• Construction in 2004/05 Drilling and Deployment
  experience.
• First results
• Monitoring Data, noise rates
• Time calibration
• Muon reconstruction
• Measurements with LED flashers
• Coincidence events
• IceCube - IceTop
• Brief excursion on cosmic rays and mass
  composition
• Summary on performance for full array

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• Bartol Research Institute, Delaware, USA
• Univ. of Alabama, USA
• Pennsylvania State University, USA
• UC Berkeley, 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
ANTARCTICA

• Universität Wuppertal, Germany
• Uppsala university, Sweden
• Stockholm university, Sweden
• Imperial College, London, UK
• Oxford university, UK
• Utrecht,university, Netherlands

• Universite Libre de Bruxelles, Belgium
• Vrije Universiteit Brussel, Belgium
• Université de Mons-Hainaut, Belgium
• Universität Mainz, Germany
• DESY-Zeuthen, Germany
• Universität Dortmund, Germany

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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 bursters
• Neutrino physics
• Cross-section measurements
• Via absorption in earth
• Decoherence
• Oscillations
• Searches for supersymmetry, WIMPs, MeV n from
  supernovae, monopoles, .

Active Galactic Nucleus
Crab Nebula
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Detector Requirements

• Many theoretical calculations find that a 1 km3
  detector is needed and large enough 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

• First detector strings at the South pole in
  1993/94
• Observed atmospheric nm
• Deep ice (gt 1.4 km) has very good and well
  measured optical qualities.
• Low absorption
• Minimal optical light background
• Wiring individual sensors to surface avoids
  single point failures.
• Optimize strategies for drilling and deployment.

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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
• ne --gt e produce EM showers
• Good energy resolution, poor angular resolution
• nt --gt produce double-bang events at high
  energy
• One shower when the t is produced, 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) nt event
Et o(PeV) A ne would appear as a single
shower. A low energy nt, ne and NC events
produce a single Shower. They cannot be
distinguished.
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Eexected pulseshapes from cascades

• SCOPE recording in AMANDA.
• Event generated by Nitrogen laser located at a
  depth of 1850 m in AMANDA Array.
• Pulse Shapes recorded at 3 distances from laser
  45m, 115m, and 167m
• --gt Waveform readout in IceCube

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Fundamental detector elements
Digital Receiver (PCI card)
IT (TCP-IP)
20C
up to 3.3 km copper, 0.9mm (twisted pair, power,
data, time synchronization)
-40C
Intelligent Digitizer (DOM)
PMT
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DOM (Digital Optical Module) Power consumption
3 W Digitize at 300 Mhz (and 40 MHz) Dynamic
range 200pe/15 nsec Send all data to surface
over copper Two sensors/twisted
pair. Flasherboard with 12 LEDs Local HV
Clock stability 10-10 0.1 nsec /
sec Synchronized to GPS time every 10 sec at a
precision of rms 2 nsec (design goal 5 nsec)
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DOM

• Pairs of DOMS connected by one twisted pair for
  power and communication (one terminated and one
  unterminated DOM).
• Each DOM independent acquisition and
  communication.
• Power to PMT
• Operate flasher board
• Digitizes PMT signals
• Synchronize time periodically(every 10 sec) to
  rms 2ns
• Digital data are 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

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Data Recording

• Want to measure arrival time of every photon
• 2 waveform digitizer systems
• Adjustable 200-700 Megasamples/s, 10-bit (run at
  300)
• 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

An ATWD waveform
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Surface electronics, Data processing and operation

• Trigger based on multiplicity and topology.
• Store all data on tape.
• Online reconstruction and filtering of data.
• Send filtered data, monitoring data etc. to the
  North by satellite on a daily basis.
• Local monitoring, maintenance and operation by
  winter-over personnel on ice.
• Monitoring in the North and daily feedback to the
  winter-overs from the North.

Temporary IceCube Lab
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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
Hose Reel
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Drilling

• Drill time for first hole 50h
• Expect drill time less than 40 h
• Challenging operation.
• Safety important.
• Eventual goal to drill up to 18 holes in less
  than 2 months.

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Schedule Logistics

• Can work November --gt mid-February
• New South Pole Station
• Logistics
• Icebreakers, planes on skies,
• Planes only from McMurdo to Pole. Possible land
  traverse in the future

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First string installation
DOM being deployed in the ice String
installation very successful. Installation
time 16 hours Time allocated 35h
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String installation
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Drilling/deployment plan 2005/06

• January 05
• Strings 1
• Tanks/stations 8/4
• 05/06 Plan
• Strings 8 - 12
• Tanks/stations 24/12

runway
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IceCube with IceTop surface array
Area--solid-angle 1/3 km2sr (including angular
dependence of EAS trigger)

• Calibration
• Veto of HE shower background
• Cosmic Ray/air shower physics up to 1018 eV

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IceTop tank
Each 2 m diameter IceTop tank contains two DOMs.
Yes, this is ice, not water!
m signals from IceTop DOMs
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IceTop
4 IceTop Stations (8 Tanks) deployed in Dec 2004
Pair of tanks spaced at distance of 10 m
10 Hamamatsu R-7081
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Noise rates after freeze-in 0.65 kHz
NOISE Rates Less than 700 pulses/sec at T -20
to -40C (AMANDAII, smaller PMT 900) gt Very
low noise background lt10 Hits/event (3µsec) Good
for - low energy event reconstruction, -
supernova detection mode (measure noise
fluctuations)
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Dark count rates of sensors measured on first
string.All sensors work!

• Noise rates 700 Hz (measured without dead
  time.)
• Slightly exceeded expectations
• Low Noise important for
• Supernova detection sensitivity
• Ease of data transmission, DAQ, bandwidth

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n from Supernovæ
Bursts of low-energy (MeV) neutrinos from core
collapse supernovae Noise data from first string
well within expectations.
AMANDA-II sees 90 of the galaxy IceCube will
see out to the LMC
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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

Flashers more than 1010 photons
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Some typical high-multiplicity muon events
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Downward Muon reconstruction
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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 61 TeV ne

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Timing verification with fast and bright Light
flashers Redundant calibration systems allow to
verify detector response in ice. Data taken on
string 21show the arrival time distribution of
light pulses over a distance of 320 m (20
sensors)up and down the string.
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Timing resolution from flashers
Photon arrival time difference between DOM45 46

1.74 ns rms
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IceCube - IceTop coincident event
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IceTop and in-ice coincidences
The difference is due to shower curvature
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Coincidences between Surface detector and AMANDA
SPASE air shower array
? calibration of AMANDA angular resolution and
pointing !

• Amanda-II (med) 2
• absolute pointing lt 1.

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SPASE - AMANDA Energy resolution of air shower
primary
Energy resolution of air shower primary for
1ltE/PeVlt10 ????????????????sE 7 log(E) (Mass
independent based on MC)
Proton
Iron
5 6 7 8
Log(E_true/GeV)
5 6 7 8
Log(E_reconstructed/GeV)
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Primary composition with IceCube

• Nm from deep IceCube Ne from IceTop
• High altitude allows good energy resolution
• Good mass separation from Nm/Ne
• 1/3 km2 sr (2000 x SPASE-AMANDA)
• Covers sub-PeV to EeV energies

Figure by Ralph Engel
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Mass Composition of cosmic rays at the knee

• Data
• electrons at surface
• and muons at depth.
• Mass independent energy measurement.
• Measure mass of primary.
• Method is relatively robust against systematic
  uncertainties.

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Muon Angular Resolution
Waveform information not used. Will
improve resolution for high energies !
Final verification of absolute pointing with Moon
shadow
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IceCube m effective areas
100000 atmospheric Neutrinos/year
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IceCube sensitivities
Diffuse nm sensitivity
Point source nm sensitivity
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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
• First data consistent with requirements and with
  expectations.
• This austral summer we hope to deploy 10 more
  strings.
• By 2010, we plan to have instrumented 1 km3.

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Diffuse Limits and sensitivities
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Point sources event rates
Flux dN/dE 10-6E-2/(cm2 sec GeV)