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

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Atmospheric Neutrinos

Stefan Söldner-RemboldUniversity of Manchester

19 December 2013

19 December 2013

NuPhys 2013 - Söldner-Rembold

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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.

19 December 2013


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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 ?

19 December 2013


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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

19 December 2013

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

19 December 2013

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.

19 December 2013


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INO Sensitivity

19 December 2013

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.

19 December 2013

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

19 December 2013

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

19 December 2013

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

19 December 2013

• 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.

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