1. Atmospheric neutrinos with Deep Core
In the context of atmospheric neutrinos in IceCube

2. Outline Atmospheric n in IceCube
Zenith-angle dependence measured √
Spectrum of atmospheric nm TBD
km3 extends reach to E(nm) ~ TeV
Look for new physics
What about electron neutrinos?
Deep core opens lower-energy window
Neutrino oscillation studies
Hierarchy?
Some comments on signal and background for both low and high energy

3. Atmospheric n spectrum
Comment on charm models
RQPM model shown here:
(Bugaev et al., 1998)
ne crossover at 3 TeV
nm crossover at 100 TeV
Calculation of Enberg, Reno,
Sarcevic (arXiv: ):
nm, ne intensities factor 10 lower
crossovers factor of two higher e nm ne m p
Neutrino spectrum summed over all directions
from below the horizon
( TKG & M Honda, Ann Revs 52, 153, 2002)

4. Muons in IceCube-22 (2007)
Downward
atmospheric muons
Upward
neutrino-induced muons
Patrick Berghaus et al., Cosmo-08 and ISVHECRI-08

5. Muon neutrinos in IC22
6000 /yr expected with point-source cuts

6. Oscillations + Deep Core = new opportunities < 100 GeV
q13 = 0
If sin22q13 = 0.1
nm survival probability
nm  nt oscillation probability
From Carsten at Utrecht
Mena, Mocioiu & Razzaque
arXiv: v2

7. Expected in IC80 With deep core Standard IceCube
3.2E5 / yr – 2.7E5 / yr = 50K/yr
At trigger level

8. What about electron neutrinos?
They might look like this:
Kotoyo Hoshina IC22
But it can also be a muon with a large
radiative energy loss

9. On the other hand muon energy loss is stochastic
Strange things can happen
For example, here’s the energy loss history of the first TeV random muon simulated with the Lipari-Stanev code:
2 photo-nuclear interactions
One low-energy brem

10. Naïve expectations for rates of atmospheric n
Assumptions:
Muon neutrinos: full efficiency for m range > 0.5 km (En > 150 GeV)
Electron neutrinos: Efficiency for ne from PDD is 0 for En < TeV
Note advantage of lowering Eth for ne
~800 ne interactions per km3 yr
Spectrum of ne events
per km3 yr (perfect eff)

11. Differential and integral spectrum of atmospheric muons
Energy loss: Em (surface) = exp{ b X } · ( Em +e ) - e
Set Em = e { exp[ b X ] - 1 } in Integral flux
to get depth – intensity curve

12. High-energy atmospheric neutrinos
Primary cosmic-ray spectrum
(nucleons)
Nucleons produce
pions
kaons
charmed hadrons
that decay to neutrinos
Kaons produce most nm
for 100 GeV < En < 100 TeV
Eventually “prompt n”
from charm decay dominate,
….but what energy?

13. Importance of kaons at high E
vertical
60 degrees
Importance of kaons
main source of n > 100 GeV
p  K+ + L important
Charmed analog important for prompt leptons at higher energy

14. Neutrinos from kaons Critical energies determine
where spectrum changes,
but AKn / Apn and ACn / AKn
determine magnitudes
New information from MINOS
relevant to nm with E > TeV

15. Electron neutrinos K+  p0 ne e± ( B.R. 5% )
KL0  p± ne e ( B.R. 41% )
Kaons important for ne
down to ~10 GeV

16. TeV m+/m- with MINOS far detector
1.27
1.37 x
100 to 400 GeV at depth  > TeV at production
Increase in charge ratio shows
p  K+ L is important
Forward process
s-quark recombines with leading di-quark
Similar process for Lc?
Increased contribution from kaons
at high energy

17. MINOS fit ratios of Z-factors
Z-factors assumed constant for E > 10 GeV
Energy dependence of charge ratio comes from
increasing contribution of kaons in TeV range
coupled with fact that charge asymmetry is larger for
kaon production than for pion production
Same effect larger for nm / nm because kaons dominate

18. Muon veto of atmospheric n

19. Vertical neutrino flux: comparison
M. Honda et al.,
PR D70 (2004)
G.D. Barr et al. (Bartol flux)
PR D70 (2004)
M. Honda et al.
PR D75 (2007)

20. Unfolding SK measurements Gonzalez-Garcia, Maltoni, Rojo JHEP 2007

21. Atmospheric neutrino spectrum
1.27
1.37 x
increased m+/m- charge ratio
in MINOS far detector
suggests corresponding increase
in TeV neutrino flux from
contribution of p  K+ L
AMANDA atmospheric neutrino
arXiv: v1

22. Neutrinos from charm Main source of atmospheric n for En > ??
Gelmini, Gondolo, Varieschi
PRD 67, (2003)
Main source of atmospheric n for En > ??
?? > 20 TeV
Large uncertainty!

23. Angular dependence
For eK < E cos(q) < ec , conventional neutrinos ~ sec(q) , but
“prompt” neutrinos independent of angle
Uncertain charm component
most important near the vertical

24. Muon multiplicity at depth
protons
Iron
Total energy per nucleus

25. Some comments on m background
Atmospheric muons
(shape only)

26. Muon energy spectrum at depth
Nm= 7
5.5
4.4
2.0
0.2
0.1
Nm=40 32 25 11
1.2
0.7
Muon energy spectrum at depth
Invariant shape for slant depth > ~ 2 km. w. e.

27. Muon energy spectrum at depth
Nm=230
180
145 64
7.1
0.4
Nm=1300
1000
830
370 41 2
Muon energy spectrum at depth

28. A B
Energy deposit per 17 m
Todor’s plot:
--a single event
~ 300 muons

29. New Geometries
Slightly better performance for highest energy muons coming sideways
Best for both highest and intermediate ( PeV) energy muons
(probably preferred)
Drilling of 9 holes in the last season inside a circle with radius of 423 m is possible. The most ambitious geometries possible in the last season are presented above.