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EHE Neutrino Search with the IceCube

EHE Neutrino Search with the IceCube. Aya Ishihara The University of Wisconsin - Madison for the EHE Verification working group. Outline. Expected the highest energy region signal neutrinos How they might look like from the point of IceCube detector

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EHE Neutrino Search with the IceCube

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  1. EHE Neutrino Search with the IceCube Aya Ishihara The University of Wisconsin - Madison for the EHE Verification working group

  2. Outline • Expected the highest energy region signal neutrinos • How they might look like from the point of IceCube detector • Results from MC simulation analysis with full and this year’s configuration • Outlook toward real data analysis with 9 strings

  3. Recent Activities by EHE Working Group Convener: Shigeru Y. Muon Reconstruction: Sean G., Keiichi M., David B. Tau Reconstruction: Rodin P. MC study: Shigeru, Kotoyo H., Aya I. MC (semi-) mass production: Paolo D., Keiichi Data check: Hiroko M., Kotoyo, Aya • See Shigeru’s talk @ analysis session on Thursday

  4. Extremely High Energy Neutrino Possible Signals… • Standard scenarios Ex. GZK mechanism – EHE cosmic-ray induced neutrinos ( En ~ 109-10 GeV ) • Exotic scenarios Ex. Top-Down – decays/interaction of massive particles ( En ~ 1011-15 GeV )

  5. EHE Neutrino with km3 Detector (I)Where to look for events? Filtering from large background - Atmospheric m distinguishable by their energy • Need good energy resolution down-going EHE neutrino mean free path ln ~ 100 km << REarth EHE neutrino events are down-going Not up-going up-going

  6. m p e+e- photo-nuclear g pair-creation bremsstrahlung EHE Neutrino with km3 Detector (II)How do they look like? • Series of cascade • Energy deposit indicates the primary particle energy

  7. IceCube EHE Event Channels • Possible EHE particles in depth Fluxes at the IceCube depth Atm m n EGZK >> EAtmm n t m Secondary m and t

  8. MC Simulation Setup • Event Samples • Muon events with E-1 spectra 95,000 events • Muon events with E-2 spectra 110,000 events • Tau events with E-1 spectra 99,000 events • 105 GeV ~ 1011 GeV

  9. Simple Primary Energy Indicator Estimated total number of photo-electrons per event m t Contained Uncontained Contained Uncontained

  10. How NPE is Estimated from Waveforms (I) ATWD or FADC? Estimated number of photo-electrons per DOM Integrated charge over a waveform divided by single pe charge Log10 (FADC based estimated NPE) Red: DOM of which ATWD charge is larger Blue: DOM FADC is larger Log10 (ATWD based estimated NPE) Log10 (FADC estimated NPE) Log10 (ATWD estimated NPE) Log10 (MC Truth NPE) Log10 (MC Truth NPE)

  11. How NPE is Estimated from Waveforms (II) MC Truth NPE vs. Larger Charge waveform based estimated NPE per DOM This, “use the larger charge waveform”, in principle applies also for the finer waveform based reco Log10 ( Best estimated NPE) Log10 (MC Truth NPE)

  12. Signal vs. Background: Energy/event-sum NPE GZK m Atmospheric m GZK t Contained events only

  13. Event Rate without Background Cut Zenith angle NPE GZK m GZK t Atmospheric m GZK m GZK t Atmospheric m down up

  14. Signal Domain: Zenith/NPE GZK m Atmospheric m

  15. Event Rate in Signal Domain GZK m GZK t Atmospheric m GZK m GZK t Atmospheric m GZK m3.5 events/year GZK t0.56events/year Atmospheric m0.33 events/year

  16. Event Rate based on simple reconstruction GZK m GZK t Atmospheric m GZK m GZK t Atmospheric m

  17. IceCube AMANDA Event Rate with 9-strings GZK m0.67 events/year Atmospheric m0.0085 events/year GZK m Atmospheric m GZK m Atmospheric m

  18. GZK t Atmospheric m For taus… Assuming we have extremely good geometrical reconstruction,

  19. Event Rate with the optimistic cut GZK m GZK t Atmospheric m GZK m GZK t Atmospheric m

  20. Muon Effective Area – Full String Black (up-going): -1.0 < cos(qMC) < -0.8 Red: -0.6 cos(qMC) < -0.4 Blue (horizontal, slightly up-going) -0.2 < cos(qMC) < 0.0 Pink: 0.4 < cos(qMC) < 0.6 Green (down-going): 0.8 < cos(qMC) < 1.0

  21. Effective Area – 9 strings ~10 % strings are much more than 10 % as an effective area ! Black (up-going): -1.0 < cos(qMC) < -0.8 Red: -0.6 cos(qMC) < -0.4 Blue (horizontal, slightly up-going) -0.2 < cos(qMC) < 0.0 Pink: 0.4 < cos(qMC) < 0.6 Green (down-going): 0.8 < cos(qMC) < 1.0

  22. Summary and Outlook • IceCube is indeed capable of detecting EHE neutrinos with both full and this year’s 9-string configuration • First-level background filtering can be done with very simple parameters such as NPE-sum, zenith • Further understandings of detector performance • Comparison between real data and MC simulation • Energy and geometrical reconstructions!!

  23. Extra

  24. N_DOM vs. NPE with 9 strings

  25. Event Rate vs. Primary Energy IceCube Collaboration Meeting

  26. Predicted Fluxes

  27. 9-string Geo

  28. The IceCube Detector

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