1. Atmospheric Neutrinos
Stefan Söldner-Rembold
University of Manchester
19 December 2013
19 December 2013

2. Atmospheric Neutrinos
Provide complementary results with other neutrino sources.
Increase precision of global fits of neutrino parameters.
Tools to search for new physics.
19 December 2013
NuPhys Söldner-Rembold  

3. NuPhys 2013 - Söldner-Rembold
Three Questions
arXiv: , see talk by E. Lisi
Is θ23 mixing maximal and which
is the right octant ?
Is the mass hierarchy normal or
inverted ?
3) Is δCP > 0 ?
19 December 2013
NuPhys Söldner-Rembold  

4. Neutrino Propagation in the Earthν ν ν
Preliminary Reference Earth Model
Atmospheric neutrinos interact
with Earth’s mantle and core.
- MSW effect alters oscillation properties
(energy, electron density, MH and flavour dependent).
- “parametric enhancement” at Core/Mantle interface.
19 December 2013
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5. NuPhys 2013 - Söldner-Rembold
MSW Effect
+: neutrinos
-: anti-neutrinos
CC interactions
Effective mixing angle in matter:
Resonance condition for
- neutrinos in normal hierarchy.
- anti-neutrinos in inverted hierarchy.
depends on energy and density profile.
19 December 2013
NuPhys Söldner-Rembold  

6. NuPhys 2013 - Söldner-Rembold
MSW Effect in the Earth SK
cos θ
cos θ
Energy
Energy
Distortions for cos θ < -0.5 and at 10 GeV caused by MSW effect
arXiv:
19 December 2013
NuPhys Söldner-Rembold  

7. NuPhys 2013 - Söldner-Rembold
Neutrino Energies
Super-K
Deep
Core
IceCube
10 MeV
100 MeV
1 GeV
10 GeV
100 GeV
1 TeV
10 TeV
100 TeV
1 PeV
10 PeV
ANITA
Borexino
KamLAND
Double Chooz
Daya Bay
SNO
PINGU
Fill gap in intermediate energy region in
region of MSW resonance effects.
Several future experiments: INO, PINGU,
Hyper-K, LBNE..
19 December 2013
NuPhys Söldner-Rembold  

8. NuPhys 2013 - Söldner-Rembold
Super-Kamiokande
Water Cherenkov Detector located
in Mozumi Mine, Kamioka, Japan
50,000t of water
11,146 PMTs
First observation of
muon-neutrino deficit due to
oscillations in 1993
19 December 2013
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9. Super-Kamiokande (SKI-IV)
red: un-oscillated
blue: best oscillation fit
19 December 2013
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10. NuPhys 2013 - Söldner-Rembold
ντ Appearance (SK)
Phys. Rev. Lett. 110, (2013)
fitted signal in grey
Unambiguous evidence for oscillations
(νμ  ντ) since not present in source.
2806 day running period.
Energy threshold E > 3.5 GeV.
Reconstruct hadronic tau decays
using neural network.
3.8 standard deviation significance
(complements OPERA result)
19 December 2013
NuPhys Söldner-Rembold  

11. NuPhys 2013 - Söldner-Rembold
MINOS
see presentation by C. Backhouse
5,400 ton Far Detector
Alternating layers of steel calorimeter and
plastic scintillator.
Magnetized for charge identification
19 December 2013
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12. MINOS Beam/Atmospheric Data
19 December 2013
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13. MINOS Combined Analysis
19 December 2013
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14. NuPhys 2013 - Söldner-Rembold
Future Experiments
19 December 2013
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15. Indian Neutrino Observatory
Located in Madurai City, Tamil Nadu
19 December 2013
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16. NuPhys 2013 - Söldner-Rembold
Iron sampling calorimeter (ICAL) with
Resistive Plate Chamber (RPCs)
as active component.
50,000 t of iron.
T magnetic field for charge identification
and momentum reconstruction
Pre-project activities approved.
19 December 2013
NuPhys Söldner-Rembold  

17. NuPhys 2013 - Söldner-Rembold
INO Sensitivity
arXiv:
sin2 2θ13 = 0.12, 0.1, and sin2θ23 = 0.5.
19 December 2013
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18. NuPhys 2013 - Söldner-Rembold
PINGU
Extension of IceCube located at the South Pole.
40 strings with 60 PINGU Digital Optical Modules (PDOMs) per string.
Design still being optimised.
In-fills DeepCore in clearest ice at bottom centre of IceCube.
Effective mass about 3Mt for energies > 5 GeV
19 December 2013
NuPhys Söldner-Rembold  

19. NuPhys 2013 - Söldner-Rembold
PINGU
μ direction
4.4 GeV νµ
Nγ: circle size
tγ: colour
PINGU Digital Optical Module:
HQE PMT, electronics, pressure vessel.
Very similar to IceCube DOM.
19 December 2013
NuPhys Söldner-Rembold  

20. NuPhys 2013 - Söldner-Rembold
MH Signature
Need good energy and
angular resolution.
Energy +
= Pattern A NH IH +
= Pattern B
cos(θ)
Diagonals are lines of constant L/E
19 December 2013
NuPhys Söldner-Rembold  

21. “Distinguishability”
Parametrized
reconstruction,
PID: tracks
Parametrized
reconstruction,
PID: cascades
With realistic particle identification
No systematics
19 December 2013
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22. NuPhys 2013 - Söldner-Rembold
PINGU
Consistent results from different
statistical techniques, includes systematics
(mainly energy scale, cross sections).
First vs second octant
First octant only
Expect 1.75 standard deviations
after first year of data.
Reach 3 standard deviations in
roughly 3 years.
PINGU currently being considered
by P5 in the US – will possibly be
part of a larger NSF facility at South Pole.
19 December 2013
NuPhys Söldner-Rembold  

23. NuPhys 2013 - Söldner-Rembold
KM3NeT/ORCA
1000 optical modules with 6 m spacing, over 50 strings.
Semi random pattern in a circular footprint.
Mean distance between strings is 20 m.
- Instrumented volume: 1.8 Mton
not being pursued ?
19 December 2013
NuPhys Söldner-Rembold  

24. NuPhys 2013 - Söldner-Rembold
LBNE
LBNE Far Detector
needs to be underground
for atmospheric neutrino
detection.
see talk by R. Wilson
Data taking to start around 2025
Liquid Argon TPC
ArgoNeuT
19 December 2013
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25. NuPhys 2013 - Söldner-Rembold
LBNE
35 kt x 10 yrs = 350 kt-yrs
arXiv:
19 December 2013
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26. NuPhys 2013 - Söldner-Rembold
LBNE
arXiv:
19 December 2013
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27. NuPhys 2013 - Söldner-Rembold
Hyper-Kamiokande
arXiv:
8 km south of SK
Total mass: 1 Mt
Fiducial mass: 560 kt
(25 times SK)
99,000 inner detector PMTs (20’’)
Data taking expected to start 2023
19 December 2013
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28. Sensitivity to Mass Hierarchy
10 years of data
Lowest sensitivity for first octant.
arXiv:
19 December 2013
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29. Sensitivity to θ23 Octant
10 years of data
19 December 2013
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30. Mass Hierarchy Bottom Line
plus Hyper-K with > 3 sigma around 2033.
arXiv:
19 December 2013
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31. NuPhys 2013 - Söldner-Rembold
Summary
Atmospheric neutrinos are a unique source of information,
complementary to neutrino long-baseline beam results.
Several next-generation experiments based on (frozen) water
(PINGU, Hyper-K), liquid argon (LBNE) or iron sampling
calorimeters (INO) are currently being designed.
These experiments have potential to determine neutrino mass
hierarchy and to constrain θ23 , providing, among others,
important input for δCP determinations.
19 December 2013
NuPhys Söldner-Rembold