1. Diffuse neutrino flux
J. Brunner
CPPM
ESA/NASA/AVO/Paolo Padovani

2. Neutrino Spectrum on Earth Close to a nuclear power plant
GRB,SNR
Snap-hook

3. Diffuse Neutrino Spectrum
GRBs

4. Diffuse Neutrino Spectrum
Remnant from ~1min
after Big Bang
Non-relativistic speed
(at least 2 & 3)
No direct detection
method known
SNR, etc.

5. Diffuse Neutrino Spectrum
Integrated flux from
nuclear fusion of
all stars
Spectrum similar to
solar neutrino
Did not find any
flux estimates
SNR, etc.

6. Diffuse Neutrino Spectrum
Integrated flux from
core-collapse SuperNovae
Limits from Underground
Experiments (SK)
Tuesday session
GRBs

7. Diffuse Neutrino Spectrum
Diffuse flux at
TeV energies
This talk
GRBs

8. Neutrino Flux components @ TeV-PeV energies
Conventional flux from  & K decay () ~ 20 (e) soft  ~ E-3.7
Harder spectrum from prompt  from c,b-meson decay  ~ E-2.7
Astrophysical neutrinos:  ~ E-2
 ~ E-2
figure: courtesy IceCube

9. Diffuse astrophysical neutrinos
Flux of Cosmis Rays
Extragalactic origin
otherwise not diffuse
AGNs & GRBs
Upper bound (W&B)
derive  flux from CR-flux
CR (mainly protons)
from neutrons which escape acceleration site (n-transparent)
Other models
“opaque” sources
try to avoid this bound

10. Experimental results Recent publication
Atmospheric neutrinos ()
IC40 atmospheric neutrinos
Phys. Rev. D 83 (2011)
Diffuse flux search with Cascades (x)
5 years Amanda
Astropart. Phys. 34 (2011)
IC22 (submitted PhysRev)
arXiv: (astro-ph.HE)
Diffuse flux search with tracks ()
IC40
arXiv: (astro-ph.HE)
Antares
Phys. Lett. B 696 (2011) 16-22

11. Analyzed data sets
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Amanda
1001days
IC22
257 days
IC40
359 days
ANTARES
334 days
Better understanding of apparatus  delay between data taking and publication gets shorter

12. Studies in the Muonic channel
Easy to reject down-going atm. Muons from tracking
Precision of E at detector at highest energies only factor ~2 (0.3 in lg(E))
Conversion of to E depends on flux
Neutrino
Telescope 
Muon track at TeV/PeV
energies significantly longer than detector size
Hadronic shower
Stochastic energy loss
(e.g. bremsstrahlung) 
Vertex mostly
outside detector volume

13. IceCube-40 atmospheric 
~18000 upward-going events in final sample
Regularized unfolding from dE/dx variable
Uncertainties increase with energy
Zenith angle distribution
Uncertainties
OM & Ice
Zenith angle effects
Unfolding method

14. Atmospheric  flux PRELIMINARY
3 measurements from Amanda and IC40 are compatible
2 Methods used
Forward folding
Unfolding
Compatible with Honda flux
Within errors no choice between conventional models possible
PRELIMINARY
L. Gerhardt, Trento, Dec2010

15. Test of prompt flux component
No sign of prompt neutrinos seen so far
there should be an “ankle” in the  spectrum
Several high predictions can be constrained
Notably RQPM
PRELIMINARY 3 2
90%
S. Grullon
L. Gerhardt, Trento, Dec2010

16. ANTARES search for diffuse flux
Data sample Dec to Dec 2009
first result from 2 years of data with (almost) complete detector
335 days active
R: energy estimator based on hit multiplicity on PMTs
Good correlation with true muon energy observed
R>1.31 : 90% of expected signal between 20 TeV and 2 PeV

17. Antares - Results 9 events in final sample conventional atm. : 8.7 ,
Conventional  + prompt (RQPM) 10.7
Prompt 
(RQPM)
E-2 flux
at limit
No high energy
Not sensitive to prompt component
Limit for astrophysical flux

18. Brightest Neutrino in the sample
height
E~80 TeV
time

19. ANTARES - Result E2F(E)90%= 5.3 10-8 GeV cm-2 s-1 sr-1
20 TeV<E<2.5 PeV
90% C.L. upper limit assuming E-2 flux spectrum
At time of publication (Sep 2010) world best limit on diffuse flux !
Physics Letters B696 (2011)

20. Study in the Cascade channel
Same topology for NC and e-- CC interactions
ignore here “double bang” signature for E > 10 PeV
When using containment condition:
E measured calorimetric
Precision 10-20% possible
Problem: background from showers from down-going muons
Neutrino
Telescope 
atm 
Shower
Vertex mostly
inside detector volume
bremsstrahlung

21. IC22 Cascades 257 days of data taking
Good agreement data with (normalized) atmospheric muon MC
So far no clean sample of atmospheric -cascade events could be isolated

22. IC22 cascades Final sample (after energy cut)
14 (shower) events above 16 TeV
MC: 8.3 +/- 3.6
Limit per flavour (all-flavour/3)
E2(E)90%= GeV cm-2 s-1 sr-1

23. Summary of results Baikal NT-200 (e++)/3
Amanda II UHE (e++)/3
IC22 (e++)/3
Amanda (e++)/3

24. Summary of results Cascade limits cluster around 10-7
Baikal NT-200 (e++)/3
Amanda II UHE (e++)/3
IC22 (e++)/3
Amanda (e++)/3
Cascade limits cluster around 10-7
No cascade  seen so far

25. Summary of results Antares 07-09 Best published limit
Baikal NT-200 (e++)/3
Amanda II UHE (e++)/3
IC22 (e++)/3
Amanda (e++)/3
Antares 07-09
Best published limit

26. Summary of results IC40 : best Preliminary limit
Baikal NT-200 (e++)/3
Amanda II UHE (e++)/3
IC22 (e++)/3
Amanda (e++)/3
IC40 : best
Preliminary limit

27. Summary of results
IC40 5 excluded

28. Conclusion
Wealth of new results for diffuse neutrino fluxes from IceCube & ANTARES
Fast publication of results now standard
Start to test realistic models
Detection of prompt atmospheric neutrinos &/or astrophysical fluxes in reach
Stay Tuned !

29. END