EHE Neutrino Search with the Ice Cube Aya
EHE Neutrino Search with the Ice. Cube Aya Ishihara The University of Wisconsin - Madison for the EHE Verification working group April 11, 2006 Ice. Cube Collaboration Meeting 1
Outline Expected the highest energy region signal neutrinos How they might look like from the point of Ice. Cube detector Results from MC simulation analysis with full and this year’s configuration Outlook toward real data analysis with 9 strings April 11, 2006 Ice. Cube Collaboration Meeting 2
Recent Activities by EHE Working Group 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 Convener: See Shigeru’s talk @ analysis session on Thursday April 11, 2006 Ice. Cube Collaboration Meeting 3
Extremely High Energy Neutrino Possible Signals… n Standard scenarios Ex. GZK mechanism – EHE cosmic-ray induced neutrinos ( En ~ 109 -10 Ge. V ) n Exotic scenarios Ex. Top-Down – decays/interaction of massive particles ( En ~ 1011 -15 Ge. V ) April 11, 2006 Ice. Cube Collaboration Meeting 4
EHE Neutrino with km 3 Detector (I) Where to look for events? down-going EHE neutrino mean free path ln ~ 100 km << REarth EHE neutrino events are down-going Not up-going Filtering from large background Atmospheric m distinguishable by their energy Need good energy resolution April 11, 2006 Ice. Cube Collaboration Meeting up-going 5
EHE Neutrino with km 3 Detector (II) How do they look like? Series of cascade Energy deposit indicates the primary particle energy m p g e+e- photo-nuclear pair-creation bremsstrahlung April 11, 2006 Ice. Cube Collaboration Meeting 6
Ice. Cube EHE Event Channels Possible EHE particles in depth Fluxes at the Ice. Cube depth Atm m n t n EGZK >> EAtmm m Secondary m and t April 11, 2006 Ice. Cube Collaboration Meeting 7
MC Simulation Setup Event Samples n n 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 Ge. V ~ 1011 Ge. V April 11, 2006 Ice. Cube Collaboration Meeting 8
Simple Primary Energy Indicator Estimated total number of photo-electrons per event m Contained Uncontained April 11, 2006 t Contained Uncontained Ice. Cube Collaboration Meeting 9
ATWD or FADC? Estimated number of photo-electrons per DOM Integrated charge over a waveform divided by single pe charge Red: DOM of which ATWD charge is larger Blue: DOM FADC is larger Log 10 (FADC estimated NPE) Log 10 (ATWD based estimated NPE) Log 10 (ATWD estimated NPE) Log 10 (FADC based estimated NPE) How NPE is Estimated from Waveforms (I) April 11, 2006 Ice. Cube. Log Collaboration Meeting (MC Truth NPE ) 10 10 Log 10 (MC Truth NPE)
How NPE is Estimated from Waveforms (II) Log 10 ( Best estimated NPE) MC Truth NPE vs. Larger Charge waveform based estimated NPE per DOM April 11, 2006 This, “use the larger charge waveform”, in principle applies also for the finer waveform based reco Log 10 (MC Truth NPE) Ice. Cube Collaboration Meeting 11
Signal vs. Background: Energy/event-sum NPE GZK m Atmospheric m GZK t Contained events only April 11, 2006 Ice. Cube Collaboration Meeting 12
Event Rate without Background Cut Zenith angle NPE GZK m GZK t Atmospheric m up April 11, 2006 Ice. Cube Collaboration Meeting down 13
Signal Domain: Zenith/NPE GZK m April 11, 2006 Atmospheric m Ice. Cube Collaboration Meeting 14
Event Rate in Signal Domain GZK m GZK t Atmospheric m April 11, 2006 GZK m GZK t Atmospheric m GZK m 3. 5 events/year GZK t 0. 56 events/year Atmospheric m 0. 33 events/year Ice. Cube Collaboration Meeting 15
Event Rate based on simple reconstruction GZK m GZK t Atmospheric m April 11, 2006 Ice. Cube Collaboration Meeting 16
Ice. Cube Event Rate with 9 -strings GZK m Atmospheric m April 11, 2006 0. 67 events/year 0. 0085 events/year AMANDA GZK m Atmospheric m Ice. Cube Collaboration Meeting 17
For taus… Assuming we have extremely good geometrical reconstruction, GZK t April 11, 2006 Atmospheric m Ice. Cube Collaboration Meeting 18
Event Rate with the optimistic cut GZK m GZK t Atmospheric m April 11, 2006 Ice. Cube Collaboration Meeting 19
Muon Effective Area – Full String Black (up-going): -1. 0 < cos(q. MC) < -0. 8 Red: -0. 6 cos(q. MC) < -0. 4 Blue (horizontal, slightly up-going) -0. 2 < cos(q. MC) < 0. 0 Pink: 0. 4 < cos(q. MC) < 0. 6 Green (down-going): 0. 8 < cos(q. MC) < 1. 0 April 11, 2006 Ice. Cube Collaboration Meeting 20
Effective Area – 9 strings ~10 % strings are much more than 10 % as an effective area ! Black (up-going): -1. 0 < cos(q. MC) < -0. 8 Red: -0. 6 cos(q. MC) < -0. 4 Blue (horizontal, slightly up-going) -0. 2 < cos(q. MC) < 0. 0 Pink: 0. 4 < cos(q. MC) < 0. 6 Green (down-going): 0. 8 < cos(q. MC) < 1. 0 April 11, 2006 Ice. Cube Collaboration Meeting 21
Summary and Outlook Ice. Cube 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!! April 11, 2006 Ice. Cube Collaboration Meeting 22
Extra April 11, 2006 Ice. Cube Collaboration Meeting 23
N_DOM vs. NPE with 9 strings April 11, 2006 Ice. Cube Collaboration Meeting 24
Event Rate vs. Primary Energy April 11, 2006 Ice. Cube Collaboration Meeting 25
Predicted Fluxes April 11, 2006 Ice. Cube Collaboration Meeting 26
9 -string Geo April 11, 2006 Ice. Cube Collaboration Meeting 27
The Ice. Cube Detector April 11, 2006 Ice. Cube Collaboration Meeting 28
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