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First Results from IceCube

First Results from IceCube. Spencer Klein, LBNL for the IceCube Collaboration. Physics Motivation Hardware Overview Deployment First Results Conclusions & Future Plans. See Paolo Desiati’s AMANDA talk. Alabama University, USA Bartol Research Institute, Delaware, USA

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First Results from IceCube

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  1. First Results from IceCube Spencer Klein, LBNL for the IceCube Collaboration Physics Motivation Hardware Overview Deployment First Results Conclusions & Future Plans See Paolo Desiati’s AMANDA talk

  2. 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 A&M 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 S. Klein,LBNL

  3. Physics Motivation • Search for cosmic-ray accelerators • Protons are bent in galactic magnetic fields • n are produced by hadron accelerators • HE (>5*1013 eV) photons are absorbed by interaction with 30K microwave background photons • gg --> e+e- • 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 S. Klein,LBNL

  4. 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 S. Klein,LBNL

  5. 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 S. Klein,LBNL

  6. Lessons from AMANDA • AMANDA pioneered n astronomy at the South pole • Deployed first OMs 1993/4 • Observed atmospheric nm • Deep ice (> 1 km) has good optical qualities • Data transmission to surface nontrivial • Paolo Desiati’s talk will present AMANDA results A muon in AMANDA S. Klein,LBNL

  7. AMANDA String 21 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 S. Klein,LBNL

  8. nm, ne and nt • IceCube will distinguish nm, ne and nt based on the event characteristics • nm --> 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 --> may improve signal to noise ratio by optimizing for higher energy n • ne --> 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 S. Klein,LBNL

  9. Simulated m Events Eµ=10 TeV, 90 hits Eµ=6 PeV, 1000 hits S. Klein,LBNL

  10. A simulated multi-Pev nt event A ne would appear as a single shower n.b. gbct =300 m for Et = 6 TeV S. Klein,LBNL

  11. Digital Optical Module Hardware LED flasher board PMT base 25 cm PMT main board 33 cm Benthosphere S. Klein,LBNL

  12. 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 --> 400 nsec range • Dual chips to minimize dead-time • 40 Megasamples/s, 10-bit ADC • 256 samples --> 6.4 ms range • Self-triggered • Also, ‘local-coincidence’ circuitry looks for hits in nearby modules Time bin (3.3 ns) An ATWD waveform S. Klein,LBNL

  13. 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 < 2 nsec A ‘Main Board’ S. Klein,LBNL

  14. 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 S. Klein,LBNL

  15. IceCube AMANDA South Pole Skiway Dome (old station) road to work “Summer camp” Amundsen-Scott South Pole station http://icecube.wisc.edu S. Klein,LBNL

  16. Drill tower Hot water generator Hose reel IceTop tanks The drilling site in January, 2005 Hot-water drilling S. Klein,LBNL

  17. Hose Reel The 5 MW water heater for the hot water drill (car-wash technology) S. Klein,LBNL

  18. An IceTop tank Each 2 m dia. IceTop tank contains two DOMs. m signals from IceTop DOMs S. Klein,LBNL

  19. Schedule & Logistics • Can work December --> mid-February • Logistics are a huge concern • Freight, power, … are expensive! • Weather is always a factor The new South-Pole station S. Klein,LBNL

  20. IceCube’s First String: January 28, 2005 27.1, 10:08: Reached maximum depth of 2517 m 28.1, 7:00: preparations for string installation start 9:15: Started installation of the first DOM 22:36: last DOM installed 12 min/DOM 22:48: Start drop 29.1, 1:31: String secured at depth of 2450.80 20:40: First communication to DOM S. Klein,LBNL

  21. 2 high-multiplicity muon events Time Residual (ns) Depth (m) Time Residual (ns) Time Residual (ns) Depth (m) S. Klein,LBNL

  22. First Results from String 21 • Time calibration • Muon reconstruction • Timing verification with muons • Timing and Energy measurement with LED flashers • Coincidence events • IceCube - IceTop S. Klein,LBNL

  23. for 76 DOMs Time Calibration In-ice DOMs Time IceTop IceTop S. Klein,LBNL

  24. Muon and Flasher Reconstruction ~10m-long cascades, nentneutral 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 S. Klein,LBNL

  25. Muon zenith angle distribution S. Klein,LBNL

  26. 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) S. Klein,LBNL

  27. A flasher event Flasher • Equivalent to ~ 60 TeV ne Color --> arrival time Circle size --> Amplitude S. Klein,LBNL

  28. All 60 DOMs Timing resolution from flashers Photon arrival time difference between DOM45 & 46 { 1.74 ns rms S. Klein,LBNL

  29. 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 S. Klein,LBNL

  30. IceTop and in-ice coincidences Some of the difference is due to shower curvature S. Klein,LBNL

  31. 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 < 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. S. Klein,LBNL

  32. Extras/Backup • IceCube reviewers – read no farther S. Klein,LBNL

  33. 10” PMT Hamatsu-70 S. Klein,LBNL

  34. Muon Angular Resolution Waveform information not used. Will improve resolutionfor high energies ! S. Klein,LBNL

  35. 47 Photons going down Photons going up Timing verification with light-flashers S. Klein,LBNL

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