Atmospheric Neutrinos Stefan Söldner-Rembold University of Manchester 19 December 2013 19 December 2013 1
Jan 11, 2016
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Atmospheric Neutrinos
Stefan Söldner-RemboldUniversity of Manchester
19 December 2013
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Atmospheric Neutrinos
• Provide complementary results with other neutrino sources.
• Increase precision of global fits of neutrino parameters.
• Tools to search for new physics.
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Three QuestionsarXiv:1312.2878, see talk by E. Lisi 1) Is θ23 mixing maximal and which
is the right octant ?2) Is the mass hierarchy normal or inverted ?3) Is δCP > 0 ?
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Neutrino Propagation in the Earth
Preliminary Reference Earth Modelν νν
Atmospheric neutrinos interactwith Earth’s mantle and core.
- MSW effect alters oscillation properties (energy, electron density, MH and flavour dependent).
- “parametric enhancement” at Core/Mantle interface.
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+: 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.
MSW Effect
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Energy
cos θ
Energy
cos θ
SK
Distortions for cos θ < -0.5 and at 10 GeV caused by MSW effectarXiv:1310.6677
MSW Effect in the Earth
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Neutrino Energies
Super-K DeepCore IceCube
10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV 10 TeV 100 TeV 1 PeV 10 PeV
ANITA
BorexinoKamLAND
Double ChoozDaya Bay
SNO
PINGU
Fill gap in intermediate energy region inregion of MSW resonance effects.
Several future experiments: INO, PINGU,Hyper-K, LBNE..
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Super-Kamiokande
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Water Cherenkov Detector locatedin Mozumi Mine, Kamioka, Japan
50,000t of water11,146 PMTs
First observation of muon-neutrino deficit due tooscillations in 1993
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Super-Kamiokande (SKI-IV)
red: un-oscillatedblue: best oscillation fit
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ντ Appearance (SK)
Phys. Rev. Lett. 110, 181802 (2013)
fitted signal in grey
3.8 standard deviation significance
(complements OPERA result)
Unambiguous evidence for oscillations(νμ ντ) since not present in source.
2806 day running period.
Energy threshold E > 3.5 GeV.
Reconstruct hadronic tau decaysusing neural network.
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MINOS
5,400 ton Far Detector
Alternating layers of steel calorimeter and plastic scintillator.
Magnetized for charge identification
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see presentation by C. Backhouse
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MINOS Beam/Atmospheric Data
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MINOS Combined Analysis
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Future Experiments
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Indian Neutrino Observatory
Located in Madurai City, Tamil Nadu
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ICAL@INO
Iron sampling calorimeter (ICAL) withResistive Plate Chamber (RPCs)as active component.
50,000 t of iron.
1.3-1.5 T magnetic field for charge identificationand momentum reconstruction
Pre-project activities approved.
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INO Sensitivity
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sin2 2θ13 = 0.12, 0.1, 0.08 and sin2θ23 = 0.5. arXiv: 1303.2534
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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
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PINGU Digital Optical Module:HQE PMT, electronics, pressure vessel.Very similar to IceCube DOM.
4.4 GeV νµ
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PINGU
Nγ: circle sizetγ: colour
μ direction
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Ener
gy
cos(θ)
NH
IH
+
+
= Pattern A
= Pattern B
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MH Signature
Diagonals are lines of constant L/E
Need good energy andangular resolution.
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Parametrizedreconstruction, PID: tracks
Parametrizedreconstruction, PID: cascades
“Distinguishability”
With realistic particle identification
No systematics
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PINGU
First octant onlyFirst vs second octant
Expect 1.75 standard deviationsafter first year of data.
Reach 3 standard deviations inroughly 3 years.
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PINGU currently being consideredby P5 in the US – will possibly bepart of a larger NSF facility at South Pole.
Consistent results from different statistical techniques, includes systematics (mainly energy scale, cross sections).
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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
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not being pursued ?
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LBNE
ArgoNeuT
LBNE Far Detectorneeds to be undergroundfor atmospheric neutrinodetection.
see talk by R. Wilson
Liquid Argon TPC
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Data taking to start around 2025
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LBNE
35 kt x 10 yrs = 350 kt-yrs arXiv:1307.7335
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LBNE
arXiv:1307.7335
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Hyper-Kamiokande
Total mass: 1 MtFiducial mass: 560 kt(25 times SK)
99,000 inner detector PMTs (20’’)
Data taking expected to start 2023
arXiv:1109.3262
8 km south of SK
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Sensitivity to Mass Hierarchy
arXiv:1309.0184
10 years of dataLowest sensitivity for first octant.
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Sensitivity to θ23 Octant
10 years of data
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arXiv:1311.1822
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plus Hyper-K with > 3 sigma around 2033.
Mass Hierarchy Bottom Line
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Summary
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• 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.