EHE Neutrino Search with the IceCube Aya Ishihara The University of Wisconsin - Madison for the EHE...
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Transcript of EHE Neutrino Search with the IceCube Aya Ishihara The University of Wisconsin - Madison for the EHE...
EHE Neutrino Search with the IceCube
Aya IshiharaAya IshiharaThe University of Wisconsin - MadisonThe University of Wisconsin - Madisonfor the EHE Verification working groupfor the EHE Verification working group
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
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
Extremely High Energy Neutrino
Possible Signals… Standard scenariosEx. GZK mechanism – EHE cosmic-ray induced neutrinos
( E ~ 109-10 GeV )
Exotic scenariosEx. Top-Down – decays/interaction of massive particles
( E ~ 1011-15 GeV )
seXp K '7.2
xM
EHE Neutrino with km3 Detector (I)
Where to look for events?
Filtering from large background - Atmospheric distinguishable by their energy
Need good energy resolution
EHE neutrino mean free path ~ 100 km << REarth
down-going
up-going
EHE neutrino events are down-goingNot up-going
EHE Neutrino with km3 Detector (II)
How do they look like?
Series of cascade
Energy deposit indicates the primary particle energy
e+e-
pair-creation
bremsstrahlung
photo-nuclear
IceCube EHE Event Channels
Possible EHE particles in depth
Atm
Secondary and
EGZK >> EAtm
Fluxes at the IceCube depth
MC Simulation SetupEvent 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
Simple Primary Energy Indicator
Estimated total number of photo-electrons per event
ContainedUncontained
ContainedUncontained
How NPE is Estimated from Waveforms (I)
Log
10 (A
TW
D e
stim
ated
NP
E)
Estimated number of photo-electrons per DOM
ATWD or FADC?
Log
10 (F
AD
C b
ased
est
imat
ed N
PE
)
Log10 (ATWD based estimated NPE)
L
og10
(FA
DC
est
imat
ed N
PE
)
Log10 (MC Truth NPE) Log10 (MC Truth NPE)
Red: DOM of which ATWD charge is largerBlue: DOM FADC is larger
Integrated charge over a waveformdivided by single pe charge
How NPE is Estimated from Waveforms (II)
MC Truth NPE vs. Larger Charge waveform based estimated NPEper DOM
Log10 (MC Truth NPE)
Log
10 (
Bes
t es
tim
ated
NP
E)
This,“use the larger charge waveform”,
in principle applies also for the finer waveform based reco
Signal vs. Background: Energy/event-sum NPE
GZK Atmospheric GZK
Contained events only
Event Rate without Background Cut
GZKGZK
Atmospheric
GZKGZK
Atmospheric
Zenith angleNPE
up down
Signal Domain: Zenith/NPE
GZK Atmospheric
Event Rate in Signal Domain
GZK 3.5 events/year
GZK 0.56events/year
Atmospheric 0.33 events/year
GZKGZK
Atmospheric
GZKGZK
Atmospheric
Event Rate based on simple reconstruction
GZKGZK
Atmospheric
GZKGZK
Atmospheric
Event Rate with 9-strings
GZK 0.67 events/year
Atmospheric 0.0085 events/year
GZKAtmospheric
GZKAtmospheric
AMANDA
IceCube
For taus…
GZK Atmospheric
Assuming we have extremely good geometrical reconstruction,
Event Rate with the optimistic cut
GZKGZK
Atmospheric
GZKGZK
Atmospheric
Muon Effective Area – Full String
Black (up-going):
-1.0 < cos(MC) < -0.8
Red:
-0.6 cos(MC) < -0.4
Blue (horizontal, slightly up-going)
-0.2 < cos(MC) < 0.0
Pink:
0.4 < cos(MC) < 0.6
Green (down-going):
0.8 < cos(MC) < 1.0
Effective Area – 9 strings~10 % strings are much more than 10 % as an effective area !
Black (up-going):
-1.0 < cos(MC) < -0.8
Red:
-0.6 cos(MC) < -0.4
Blue (horizontal, slightly up-going)
-0.2 < cos(MC) < 0.0
Pink:
0.4 < cos(MC) < 0.6
Green (down-going):
0.8 < cos(MC) < 1.0
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!!
Extra
N_DOM vs. NPE with 9 strings
April 11, 2006 IceCube Collaboration Meeting
25
Event Rate vs. Primary Energy
Predicted Fluxes
9-string Geo
The IceCube Detector