2 IceCube predecessor:AMANDA (Antarctic Muon And Neutrino Detector Array)Completed in year 2000From 2005 on: Amanda will merge with its successor experiment IceCube (currently in construction)
3 New types of telescopes using high-energy neutrinos Search of colliding galaxies, exploding stars, gamma-ray bursts and dark matterNew types of telescopes using high-energy neutrinosNeutrinos= ideal astronomical messangers: Are able to leave compact sources and travel unhindered from distant reaches and violent astrophysical phenomenapecosmic rays +neutrinosgamma-rays0+n
4 Travel in straight line (≠protons) Transparent Universe (≠γ)UHE neutrinos are a new observation channel for studying astrophysical objects and the highest energy phenomena producing UHE cosmic rays
5 Using large quantities of ice as neutrino detector Cross section for neutrino interaction is very small. So, giant detectors are neededUsing large quantities of ice as neutrino detectorAMANDA / IceCubeMain 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.
6 Advantage of ice (over water): Clean, transparent materialLack of radioactivityAbsence of biological activityLow temperatures reduce dark noise ratesStable ground
7 Detection Method: Neutrino collides with atom of ice => produces muonIn ultra-transparent ice, muon radiates Cherenkov light and Cherenkov photons are detected by array of photomultiplier tubesTracks are reconstructed of photon arrival timesGeometry: relative OM position known within 0.5 m, absolute depth to within 1m+ N XnmmOptical module15m
8 Neutrinos are measured from below (neutrino separation: upward going tracks)
9 The IceCube Collaboration (formerly known as AMANDA) Alabama University, USABartol Research Institute, Delaware, USAPennsylvania State University, USAUC Berkeley, USAUC Irvine, USAClark-Atlanta University, USAUniversity of Alaska, Anchorage, USAUniv. of Maryland, USAIAS, Princeton, USAUniversity of Wisconsin-Madison, USAUniversity of Wisconsin-River Falls, USALBNL, Berkeley, USAUniversity of Kansas, USASouthern University and A&M College, Baton Rouge, USAThe IceCube Collaboration(formerly known as AMANDA)USA (14)JapanEurope (15)Chiba University, JapanUniversity of Canterbury, Christchurch, NZNew ZealandUniversite Libre de Bruxelles, BelgiumVrije Universiteit Brussel, BelgiumUniversité de Mons-Hainaut, BelgiumUniversiteit Gent, BelgiumHumboldt Universität, GermanyUniversität Mainz, GermanyDESY Zeuthen, GermanyUniversität Dortmund, GermanyUniversität Wuppertal, GermanyMPI Heidelberg, GermanyUppsala University, SwedenStockholm University, SwedenImperial College, London, UKOxford University, UKUtrecht University, NetherlandsANTARCTICA
11 The IceCube array in the deep ice The IceCube array in the deep ice. The dark cylinder is the AMANDA detector, incorporated into IceCube.
12 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 performanceInside an IceTop tank
13 AMANDA IceCube~677 photomultiplier tubes (PMTs) arranged on 19 stringsPlaced between 1500m and 2000mDetector area500m x 200m4800 photomultiplier tubes (PMTs) on 80 strings (60 on each string)Placed at depths between 1450m-2450m1km3 of ice as detector
15 Drilling: Using a hot water drill (drill holes are more than 2 Drilling: Using a hot water drill (drill holes are more than 2.5 km deep)Photomultiplier tubes record (PMT) Cherenkov radiationEach 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 flashersSignals digitized in the DOM are communicated to the IceCubeLab at the surface for data acquisition and data analysisData is transmitted via satellite from the South Pole to data storage facilities for more data analysis effort
16 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 drill2nd 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 reusedDrill water comprises a total of 15 buildings that host hot water heaters, generators, pumps and storage tanks in temporary campsStrings of modules are deployed into holesTakes ~18 h to deploy a string
17 Schematic view of IceCube DOM Digital optical Module= fundamental detector elementConsists of Photomultiplier Tube (PMT) and a suite of electronics board assemblies contained within 35cm diameter glass pressure housingAre downward facingIs able to digitize and time-stamp the photonic signal internally and transmit packetized digital data to the surfaceFirst demonstrated in AMANDA: each DOM allowes to operate as a complete and autonomous data acquisition systemDerives its internal power (incl. PMT hight voltage) by the cableWithin a DOM, data acquisition is initiated when the PMT signal exceeds a programmable thresholdWill operate for at least 15 yearsSchematic view of IceCube DOM
18 IceCube array shown in relation to the drill camp and the bedrock beneath IceCube DOM array anda Cerenkov cone ofblue light passing throug
19 Event illustration in the array 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
21 AMANDA effectiv area (30,000-50,000m2) Detected muons from the Northern Hemisphere that penetrated the Earth and exit through Antarctica:AMANDA-II has nearly uniform response over all zenith angles.=> Sensitivity independent of direction
22 Search for point sources of neutrinos data sample collected by the AMANDA-II detector (live-time 807 days)Search for point sources of high energy neutrinosNo obvious clustering.No evidence of a significant flux excess above the backgroundSky plot: Neutrino flux integrated above 10GeV in equitorial coordinates3329 neutrinos from northern hemisphere3438 neutrinos expected from atmosphere
23 Steady Point Source Search Search for excess events from the direction of known gamma-ray emitters=> No statistically significant excess found from 33 objects
24 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 performanceMarch 2010:Full Operational Capability.September 2010:Complete IceCube Construction Project.January 2011:70 Strings and 160 Tanks deployed.Detector will be operated 20 years.
25 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 identifiedMore analysis under wayIceCubes first string with 60 OMs was deployed in January 2005All OMs communicate and deliver data as expectedHope that km- scale experiment (IceCube) will be able to increase the detection sensitivity