Ken Clark, SNOLAB

Neutrinos at the South Pole with IceCube,

DeepCore and PINGU

Ken Clark, SNOLAB

SNOLAB Users Meeting - Sept 1, 2016

Neutrinos• Neutrinos obviously

need no introduction at SNOLAB

• VERY light, neutral particles

• Only interact very weakly • Very prevalent in the

universe • Three flavours

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Sources of Neutrinos• Experiments study neutrinos from different

sources

• Solar neutrinos (Homestake, Borexino, SNO)

• Reactor neutrinos (KamLAND, Daya Bay, RENO)

• Neutrino Beams (MINOS, T2K, OPERA)

• Atmospheric Neutrinos (SuperK, Antares, IceCube)

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Atmospheric Neutrinos

• Source of neutrinos is the interaction of particles in the atmosphere

• These interactions produce neutrinos with an understood flux and flavour content

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Neutrino Energy Spectrum

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• Studying neutrinos at high energies was the motivation

• Success with intermediate IceCube configurations

GeV TeV PeV EeV

SNOLAB Users Meeting - Sept 1, 2016 6

100

10Events

/km2 year

GeV TeV PeV EeV

• Studying neutrinos at high energies was the motivation

• Success with intermediate IceCube configurations

Neutrino Energy Spectrum


Detector Wish List

• In order to detect these neutrinos, a detector was needed which would:

1. Have a large target mass 2. Provide a very clear medium so that

light can be detected 3. Be at least somewhat shielded from

outside radiation

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IceCube/DeepCore

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Skiway

South Pole Station


The IceCube Neutrino Telescope

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Detection Method

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muon

neutrino

interaction


IceCube Events

• Usual map overlay of event?

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Events in the Detector

• Events are separable using their signature in the detector

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Time

Early Late

CC Muon Neutrino νμ + N μ + X

“Track”

NC Neutrino νX + X νX + X

“Cascade”


Event Selection

• Use an extensive veto to remove specific classes of events

• Want to retain only events which have their first interaction inside the detector

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IceTop Water Tanks

1.45 km

90 m

2450m

2085m2165m

Veto Region

Dust Layer

Veto Region


Event Selection

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YES NO


Why So Strict?

• This is 10 ms of data

• In one year IceCube will detect:

~1011 atmospheric muons (3000 per second)

~105 atmospheric ν->μ (1 every 6 minutes)

~10 cosmic ν->μ

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Analysis Preparation

• Several aspects required to prepare for the full analysis of the high energy events

• Need to determine the number of neutrinos expected and their energy spectrum

• Need to verify the veto procedure with existing data/Monte Carlo

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Anticipated Events

Atmospheric μ: Determined from experimental data using

the new veto 6±3.4

Atmospheric ν: Determined using Monte Carlo simulation

and previous data 4.6+3.7-1.2


IceCube Results

1.04±0.16 PeV

• Try out these new methods on a subsample of the IceCube data

• Completely unexpectedly, two very high energy events were found (and named)

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1.14±0.17 PeV


IceCube Results

1.04±0.16 PeV

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1.14±0.17 PeV




IceCube Results

1.04±0.16 PeV

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1.14±0.17 PeV




Predicted Results

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Expected to see 10.6+5.0-3.6


Actual Results

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Actually saw 28 (in the first 2 years of data)


IceCube Results

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(This has been updated to ~3 years)


Source?

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There is no convincing source so far…


Highest Energy

• Ernie & Bert stood as the highest energy events for some time

• During the full analysis, a new record-setting event was found

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2.2 PeV


On to the Next Analysis

• Want to expand beyond just high energy neutrino detection

• Neutrino oscillations are very exciting field right now…

• Why not see if we can do something with those?

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Neutrino Oscillations

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• SNOLAB users probably don’t need an introduction to oscillations

• The oscillation pattern is shown here

Blue: muon neutrino Red: tau neutrino

Black: electron neutrino

Image credit: Wikipedia


Atmospheric Neutrinos

• Source of neutrinos is the interaction of particles in the atmosphere

• These interactions produce neutrinos with an understood flux and flavour content

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• IceCube has a maximum path length of ~13000 km • If the lower energy threshold is ~200 GeV, L/E <~65



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• IceCube has a maximum path length of ~13000 km • If we can lower the energy threshold to ~10 GeV, L/

E <~1300





IceCube

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• 78 Strings

• 125m string spacing

• 17m DOM spacing

• Add 8 strings


• 7m DOM spacing

• Add 20 strings


• 5m DOM spacing10 TeV 1 EeV1 TeV100 GeV10 GeV1 GeV100 MeV10 MeV

IceCube


IceCube

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• 78 Strings


• 17m DOM spacing

• Add 8 strings


• 7m DOM spacing

• Add 20 strings


• 5m DOM spacing10 TeV 1 EeV1 TeV100 GeV10 GeV1 GeV100 MeV10 MeV

IceCube

125m


IceCube + DeepCore

• 78 Strings


• 17m DOM spacing

• Add 8 strings


• 7m DOM spacing

• Add 20 strings


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75m

10 TeV 1 EeV1 TeV100 GeV10 GeV1 GeV100 MeV10 MeV

DeepCore IceCube

125m



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IceCube

DeepCore

Skiway

South Pole Station


DeepCore Results

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Phys. Rev. D 91 072004 (2015)

• Approximately 3 years of data analyzed

• High rate in detector provides large event sample

• Oscillation parameter constraints approaching those of dedicated experiments


DeepCore Results

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• Approximately 3 years of data analyzed

• High rate in detector provides large event sample

• Oscillation parameter constraints approaching those of dedicated experiments

Phys. Rev. D 91 072004 (2015)


Even Lower Energies

• Deep Core is a success, but we get access to more physics with a lower threshold

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• muon neutrino disappearance

• maximal θ23 measurement

• lower energy dark matter

• neutrino mass hierarchy


IceCube + DeepCore• 78 Strings


• 17m DOM spacing

• Add 8 strings


• 7m DOM spacing

• Add 20 strings


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75m


DeepCore IceCube

125m


• 78 Strings


• 17m DOM spacing

• Add 8 strings


• 7m DOM spacing

• Add 40 strings


• 3m DOM spacing

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IceCube + DeepCore + PINGU

125m22m

75m


DeepCorePINGU IceCube


Improvement with PINGU

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DeepCore PINGU

Neutrino energy: 12 GeV Lepton energy: 10 GeV



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IceCube

DeepCore

PINGU

High EnergyExtension

Skiway

South Pole Station


Mass Hierarchy Determination

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1

1


1

1

2

2

Mass Hierarchy Determination


Neutrino Oscillograms

• The cross-section and flux are different for νμ and νμ

• The patterns are therefore different!

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• Sum of νμ and νμ

• Reconstruction and PID not included here

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• Sum of νμ and νμ

• Reconstruction and PID not included here


So Why am I Talking Here?

• PINGU is investigating using new DOMs with multiple PMTs

• Need to study how these would work in a low background environment

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So Why am I Talking Here?

• PINGU is investigating using new DOMs with multiple PMTs

• Need to study how these would work in a low background environment

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Conclusion

• IceCube and DeepCore have been very successful and have shown that particle physics is possible in ice

• PINGU will provide insight into the nature of the NMH as well as the oscillation parameters

• SNOLAB is an ideal site to test the new PMT structures

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Exciting Times To Come!

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SNOLAB

Ken Clark, SNOLAB

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