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IceCube

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IceCube predecessor:

AMANDA (Antarctic Muon And Neutrino Detector Array)

Completed in year 2000

From 2005 on: Amanda will merge with its successor experiment IceCube (currently in construction)

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cosmic rays + neutrinos

cosmic rays + gamma-rays

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• Search of colliding galaxies, exploding stars, gamma-ray bursts and dark matter

• New types of telescopes using high-energy neutrinos• Neutrinos= ideal astronomical messangers: Are able to

leave compact sources and travel unhindered from distant reaches and violent astrophysical phenomena

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UHE neutrinos are a new observation channel for studying astrophysical objects and the highest energy phenomena producing UHE cosmic rays

Travel in straight line (≠protons)

Transparent Universe (≠γ)

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• Cross section for neutrino interaction is very small. So, giant detectors are needed

• Using large quantities of ice as neutrino detector

AMANDA / IceCube Main Goal: IceCube will search for extra-terrestrial neutrinos in the

high-energy range (1011eV-1019eV) , from sources such as active galaxies, or gamma-ray bursts

(supernova explosions, gamma-ray bursts, black holes or other extra-galactic events)

One hopes to find some information about the physical processes associated with those high energies. As well as to reveal (parts of) the nature of Dark Matter.

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Advantage of ice (over water):

• Clean, transparent material

• Lack of radioactivity

• Absence of biological activity

• Low temperatures reduce dark noise rates

• Stable ground

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• Neutrino collides with atom of ice

=> produces muon• In ultra-transparent ice,

muon radiates Cherenkov light and Cherenkov photons are detected by array of photomultiplier tubes

• Tracks are reconstructed of photon arrival times

• Geometry: relative OM position known within 0.5 m, absolute depth to within 1m

Detection Method:

Optical module

15m

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Neutrinos are measured from below (neutrino separation: upward going tracks)

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USA (14)USA (14)

Europe (15)Europe (15)JapanJapan

New ZealandNew 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

• 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

• 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

• 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

• 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

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

ANTARCTICA

The IceCube Collaboration(formerly known as AMANDA)

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The IceCube array in the deep ice. The dark cylinder is the AMANDA detector, incorporated into

IceCube.

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IceTop

(= Surface component of IceCube):

80 IceTop stations at the surface with 2 tanks per station.

Air shower array to study cosmic ray composition. Further, coincident events between IceTop and the in-Ice detector provide useful cross-checks of the detector performance

Inside an IceTop tank

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AMANDA IceCube

• ~677 photomultiplier tubes (PMTs) arranged on 19 strings

• Placed between 1500m and 2000m

• Detector area

500m x 200m

• 4800 photomultiplier tubes (PMTs) on 80 strings (60 on each string)

• Placed at depths between 1450m-2450m

• 1km3 of ice as detector

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How it works:

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• Drilling: Using a hot water drill (drill holes are more than 2.5 km deep)

• Photomultiplier tubes record (PMT) Cherenkov radiation• Each photomultiplier is enclosed in a transparent

pressure sphere, a digital optical module (DOM) which also contains a digitally controlled high voltage supply to power the photomultiplier, an analog transient waveform digitizer and LED flashers

• Signals digitized in the DOM are communicated to the IceCubeLab at the surface for data acquisition and data analysis

• Data is transmitted via satellite from the South Pole to data storage facilities for more data analysis effort

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Drilling and deployment:•1st step: Drill though the firn layer (compacted snow, 50m) down to the actual ice. Circulate and re-circulate hot water through the firn drill

•2nd step: Drilling by using hot water. Pumping hot water down the ice hole made by firn drill, results in melting the ice. Cooler water flowes back up, is reheated and reused

Drill water comprises a total of 15 buildings that host hot water heaters, generators, pumps and storage tanks in temporary camps

•Strings of modules are deployed into holes

•Takes ~18 h to deploy a string

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Digital optical Module= fundamental detector element

•Consists of Photomultiplier Tube (PMT) and a suite of electronics board assemblies contained within 35cm diameter glass pressure housing

•Are downward facing

•Is able to digitize and time-stamp the photonic signal internally and transmit packetized digital data to the surface

•First demonstrated in AMANDA: each DOM allowes to operate as a complete and autonomous data acquisition system

•Derives its internal power (incl. PMT hight voltage) by the cable

•Within a DOM, data acquisition is initiated when the PMT signal exceeds a programmable threshold

•Will operate for at least 15 years

Schematic view of IceCube DOM

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IceCube array shown in relation to the drill camp and the bedrock beneath

IceCube DOM array and a Cerenkov cone of

blue light passing throug

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The path of the light is reconstructed using the times of detection. The earliest hits are displayed in red and subsequent ones in orange, yellow, green . . . .

Event illustration in the array

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• Animated IceCube Event:http://gallery.icecube.wisc.edu/external/animations/icecube_snabb.swf.html

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AMANDA effectiv area (30,000-50,000m2)

AMANDA-II has nearly uniform response over all zenith angles.

Detected muons from the Northern Hemisphere that penetrated the Earth and exit through Antarctica:

=> Sensitivity independent of direction

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Sky plot: Neutrino flux integrated above 10GeV in equitorial coordinates

•2000-03 data sample collected by the AMANDA-II detector (live-time 807 days)

•Search for point sources of high energy neutrinos

No obvious clustering.

No evidence of a significant flux excess above the background

3329 neutrinos from northern hemisphere

3438 neutrinos expected from atmosphere

Search for point sources of neutrinos

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Steady Point Source Search

Search for excess events from the direction of known gamma-ray emitters

=> No statistically significant excess found from 33 objects

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Future:

January 2008 Construction Status :40 Strings and 80 Tanks deployed. Set of measurements performed to confirm the design of the detector and check its performance

• March 2010: Full Operational Capability.

• September 2010:Complete IceCube Construction Project.

• January 2011: 70 Strings and 160 Tanks deployed.

• Detector will be operated 20 years.

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Summary:

• AMANDA has searched the sky for high energy neutrinos

• So far no source or no diffuse flux of high energy extraterrestrial neutrinos has been identified

• More analysis under way• IceCubes first string with 60 OMs was deployed in

January 2005• All OMs communicate and deliver data as expected• Hope that km- scale experiment (IceCube) will be able to

increase the detection sensitivity

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Wisconsin Research Journal: Video