Ice Cube Exploring the Universe from the South
Ice. Cube: Exploring the Universe from the South Pole with high energy neutrinos Kirill Filimonov for Kurt Woschnagg University of California – Berkeley and the Ice. Cube Collaboration SCAR Open Science Conference - 2010
Cosmic rays: a 100 year-old mystery Balloon flights 1911 -1913 Victor Hess Nobel 1936 1 event km -2 yr -1 Equiv. LHC energy Power law over many decades
Cosmic ray – g-ray – Neutrino connection Cosmic accelerator (SNR, AGN, GRB, etc) p+p p+g p 0 g+g p± m± + m ( m) Cosmic ray • Progenitor outflow • Interstellar material • Ambient photon field g Cosmic ray g Photons e Neutrinos p, He, . . . e± + e ( e)+ m ( m)
Neutrinos as Astronomical Messengers R. C. Cosmic ray 1012 109 En er Ph ot on s gy 1015 (e V) B Neutrino 1021 1018 ut p, He, . . . CMB star-light neutral - good not absorbed good and bad! Ne g neutrinos rin os Cosmic accelerator
Neutrino interaction with matter m tracks ( m) W N Cascades ( e, t CC, e, m, t NC) e, W N e, , Z N E ~ 1 Me. V, ~10 -43 cm 2: mean free path is 50 light years in water! E ~ 10 Te. V, ~10 -34 cm 2 : small, but manageable with BIG detector… Hadronic Cascade 1 km > 3 km muon track Cascade q 0. 7 o q ~ ( E / 10 Te. V )0. 7 Neutrino Telescope
Why the South Pole? Antarctic Ice is the most transparent natural solid known Average optical ice parameters: labs ~ 110 m @ 400 nm lsca ~ 20 m @ 400 nm
Problem: Background rejection Cosmic rays interacting in the atmosphere: high energy muons Use Earth as a filter to look for neutrinos: throw out down-going tracks
All-sky muon flux (IC 22, 2008) 106 Muons ar. Xiv: 0902. 0021 Neutrinos
Where are we ? Amundsen-Scott South Pole Station runway South Pole AMANDA-II
The Ice. Cube Collaboration University of Alabama University of Alaska, Anchorage University of California, Berkeley University of California, Irvine Clark-Atlanta University Bartol Research Institute, University of Delaware Georgia Institute of Technology University of Kansas Lawrence Berkeley Natl. Laboratory University of Maryland Ohio State University Pennsylvania State University Southern University and A&M College University of Wisconsin, Madison University of Wisconsin, River Falls RWTH Aachen Ruhr-Universität Bochum Universität Bonn DESY, Zeuthen Universität Dortmund MPIf. K Heidelberg Humboldt Universität, Berlin Universität Mainz BUGH Wuppertal Stockholms Universitet Uppsala Universitet Vrije Universiteit Brussel Université Libre de Bruxelles Universiteit Gent Université de Mons University of Alberta Chiba University of Canterbury EPF Lausanne Oxford University of the West Indies
Ice. Cube Detector Ice. Top: Surface Air Shower Array AMANDA 145 0 m 245 0 m Ice. Cube: (“Main Instrument”) 80 Strings / 60 DOMs each 1 km 3 instrumented 324 m Deep Core: (Low energy extension) Digital Optical Module
Digital Optical Module (DOM) … each DOM, independently collects light signals Digitized Waveform …time stamps them with 2 nanoseconds precision and sends them to an event builder
Ice. Cube Current Status: 79 -Strings Taking Data
Ice. Cube Selected Results: IC 22, IC 40
Ice. Cube measures the atmospheric neutrino flux predicted: zenith angle number of PMT
Atmospheric muon neutrino spectrum • Ice. Cube 22 string analysis • 4492 neutrino events at high purity (>95%)
Moon Shadow • Cosmic rays blocked by the moon lead to a point-like deficit in the distribution of down-going muons in the detector.
Moon Shadow • Cosmic rays blocked by the moon lead to a point-like deficit in the distribution of down-going muons in the detector. Need high statistics and good angular resolution!
Moon Shadow Pointing accuracy is confirmed!
Full-sky point source search (IC 40) Northern sky: atmospheric neutrino background J. Dumm ICRC 2009 J. Aguilar Vulcano 2010 Southern sky: atmospheric muon background demand high energy events Preliminary results from 375. 5 days exposure 36, 900 events: 14, 121 upgoing and 22, 779 downgoing Maximum p-value 5. 2 x 10 -6, seen in 18% of randomized sky maps
Point Source List
Sensitivity to Neutrino Point Sources compilation J. Dumm/T. Montaruli Includes preliminary limits on 39 pre-selected point sources, largest p-value 62%
Ultra-high energy neutrino search (IC 22) Phys. Rev. Lett. 103, 221102 (2009) Look for neutrinos from entire sky by demanding high energies (~Pe. V) • Reduces data to 1, 877 events; max p-value 37. 4% – not significant Also search for correlations with Auger, Hi. Res UHE events within 3º radius • Observe 60 events, 43. 7 expected • p-value 0. 98%, 2. 33σ (preliminary)
Diffuse All-Flavor Neutrino Flux Limits
Indirect Dark Matter Search: the Sun Sensitivity to muon flux from neutralino annihilations in the Sun or the center of the Earth
Indirect Dark Matter Search: the Sun
Indirect Dark Matter Search: Galactic Halo ● No observed excess in IC 22 (275 days of data) ar. Xiv 0912. 5183
Summary • Ice. Cube construction is nearly complete • 79 of a planned 86 strings now operating • Ice. Cube is detecting neutrinos: ~ 20 000 neutrinos already observed in two seasons of partially built detector (consistent with expected rate of atmospheric neutrinos) • Results from 22 -string and 40 -string configurations consistent with atmospheric flux, but several interestingly low p-values • Rich physics is ahead cosmic ray (CR) spectrum, CR composition CR anisotropies atmospheric neutrinos (oscillations, effects of quantum gravity, … ) neutrino point sources gamma ray bursts multimessenger approaches diffuse fluxes dark matter magnetic monopoles supernova bursts shadow of the moon atmosphere physics glaciology new technologies for highest energies (radio, acoustics)
- Slides: 29