Neutrino Mass Hierarchy Sensitivity Analysis in INO-ICAL ...Kolahal Bhattacharya Prof. Naba K. Mondal In Collaboration with Tarak Thakore XXI DAE BRNS High Energy Physics Symposium

Neutrino Mass Hierarchy Sensitivity Analysis in INO-ICAL experiment with Reconstructed Data

Neutrino Mass Hierarchy Sensitivity Analysis inINO-ICAL experiment with Reconstructed Data

Kolahal BhattacharyaProf. Naba K. Mondal

In Collaboration with Tarak Thakore

XXI DAE BRNS High Energy Physics SymposiumIIT, Guwahati

December 11, 2014

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Outline of the Talk

1 Motivation of the analysis

Most realiastic ν Mass Hierarchy sensitivity analysis done so far.caveats

2 Analysis Procedure

Full neutrino event simulation.Track reconstructionEvent selectionMH sensitivity results

3 Few observations for better sensitivity

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Outline of the Talk

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Outline of the Talk

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Outline of the Talk

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Outline of the Talk

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Outline of the Talk

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Outline of the Talk

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Outline of the Talk

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Motivation for Neutrino Mass Hierarchy Sensitivity Analysis with Reconstructed Data

Motivation of the analysis

INO-ICAL (capable to distinguishthe charge of the leptons coming ofcharged current ν interactions) isable to resolve ν Mass OrderingarXiv 0707.1723v2.

Previous authors estimated thesensitivity based on simplifieddetector response arXiv0610196v3, 1212.1305, 1406.3689 .

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INO-ICAL (capable to distinguishthe charge of the leptons coming ofcharged current ν interactions) isable to resolve ν Mass OrderingarXiv 0707.1723v2.

Previous authors estimated thesensitivity based on simplifieddetector response arXiv0610196v3, 1212.1305, 1406.3689 .

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Mono-energetic andmono-directional muons weresimulated by GEANT4 anddetector response look uptables were prepared with muonreconstruction in thecentral region of the centralmodule.

Hadron response tableproduced by disabling muon inNUANCE CC data (hadron hit- energy calibration).

No statistical fluctuations weretaken into account.

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Current Analysis

Analysis Schematics

We generate neutrino interactions (by NUANCE) throughout theICAL volume (50kt) for 1000 years.

We simulate all the particles coming from the neutrino chargecurrent events through ICAL code.

The reweighting algorithm [arXiv 1212.1305] is used to decide whichevents will be detected as νµ events after the neutrino oscillationeffects.

We then apply various event selection criteria (completely based onthe quantities measureable in ICAL) to the set of accepted neutrinoevents for which we obtained some reconstruction.

The muon events are then binned according to their reconstructed(Eµ, cos θµ) and scaled down to 10 years.

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Current Analysis

Analysis Schematics

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Current Analysis

Analysis Schematics

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Current Analysis

Analysis Schematics

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Current Analysis

Analysis Schematics

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Current Analysis

Event Reconstruction

Full Event Reconstruction

1 Pν(ν̄) ∈ [0.5− 100.0]GeV /c .2 Nµ : 4007677, Ne : 1740150.

3 Track finding: improvement andtroubleshooting done recently.

All possible track showercombination NuInstance

Muon-hadron separationCorrect track direction

4 Track fitting based on extendedKalman filter [Bhattacharya et al,Comp. Phys. Comm.].

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Current Analysis

1 Pν(ν̄) ∈ [0.5− 100.0]GeV /c .2 Nµ : 4007677, Ne : 1740150.

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Current Analysis

1 Pν(ν̄) ∈ [0.5− 100.0]GeV /c .2 Nµ : 4007677, Ne : 1740150.

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Current Analysis

1 Pν(ν̄) ∈ [0.5− 100.0]GeV /c .2 Nµ : 4007677, Ne : 1740150.

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Current Analysis

1 Pν(ν̄) ∈ [0.5− 100.0]GeV /c .2 Nµ : 4007677, Ne : 1740150.

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Current Analysis

1 Pν(ν̄) ∈ [0.5− 100.0]GeV /c .2 Nµ : 4007677, Ne : 1740150.

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Current Analysis

1 Pν(ν̄) ∈ [0.5− 100.0]GeV /c .2 Nµ : 4007677, Ne : 1740150.

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Current Analysis

Event Selection

Event Selection Procedure

1 Do not know which reconstructed events are good enough.

Correct charge identification ChargeID

Very good momentum resolution

2 Use measureable properties to pick up ‘good’ events.

Remove events with unstable q/p along the track.Remove Events with vanishing sagitta.

3 *

νµ → νµ 4007677 1000000 98.4% 45%νe → νµ 1740150 400000 98.3% 44%

Table: Event Selection Results (Without Oscillations)

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Current Analysis

Event Selection

3 *

νµ → νµ 4007677 1000000 98.4% 45%νe → νµ 1740150 400000 98.3% 44%

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Current Analysis

Event Selection

3 *

νµ → νµ 4007677 1000000 98.4% 45%νe → νµ 1740150 400000 98.3% 44%

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Current Analysis

Event Selection

3 *

νµ → νµ 4007677 1000000 98.4% 45%νe → νµ 1740150 400000 98.3% 44%

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Current Analysis

Event Selection

3 *

νµ → νµ 4007677 1000000 98.4% 45%νe → νµ 1740150 400000 98.3% 44%

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Current Analysis

Event Selection

3 *

νµ → νµ 4007677 1000000 98.4% 45%νe → νµ 1740150 400000 98.3% 44%

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Current Analysis

Event Selection

3 *

νµ → νµ 4007677 1000000 98.4% 45%νe → νµ 1740150 400000 98.3% 44%

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Current Analysis

Event Selection

Selected events

hEnEntries 1002219Mean 0.03229RMS 0.2399

true)/Ptrue-Prec(P

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 10

5000

10000

15000

20000

25000

hEnEntries 1002219Mean 0.03229RMS 0.2399

Momentum Resolution

(a) Momentum distribution

hCTEntries 1002219Mean 0.001458RMS 0.0515

trueθ-cosrecθcos-0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.20

5000

10000

15000

20000

25000

30000

35000

hCTEntries 1002219Mean 0.001458RMS 0.0515

Resolutionθcos

(b) cos θ distribution

Figure: Distributions of (Pµ(Reconstructed) − Pµ(True))/Pµ(True) andcos θµ(Reconstructed) − cos θµ(True)

These distributions are made for all events which are selected for the χ2

analysis [0.5 GeV-20.0 GeV].

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Current Analysis

Event Selection

Selected events-Contour Plot

|µ|P0 1 2 3 4 5 6 7 8 9 10

µθco

s

0

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1EventSpectrum2

Entries 1002219Mean x 2.566Mean y 0.6504RMS x 1.9RMS y 0.2372

0

2000

4000

6000

8000

10000

12000

14000

16000

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EventSpectrum2Entries 1002219Mean x 2.566Mean y 0.6504RMS x 1.9RMS y 0.2372

)µθ-cos(µP

Figure: Contour plot of selected events

These distributions are made for all events which are selected for the χ2

analysis [0.5 GeV-20.0 GeV]..

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Current Analysis

MH Sensitivity Results

χ2 Analysis

here

Parameter Best-fit Value

sin2 2θ12 0.86

sin2 2θ13 0.1

sin2 θ23 0.5∆m221 (eV

2) 7.5 × 10−5|∆m2eff | (eV 2) 2.4 × 10−3

δCP 0.0Hierarchy Normal

Table: True values of oscillationparameters

Data simulated with best fitparameters and NH.

Npredij obtained for NH and IH.

Wrong model gives χ2false whichis greater than χ2true comingfrom correct model

Sensitivity of ruling out wronghierarchy scales as∼

√∆χ2 ≡

√χ2false − χ2true

The MH result shown here arefor the fixed oscillationparameters in 10 years ofexposure.

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Current Analysis

Effect of statistical fluctuations

There are three sources of fluctuations :

Fluctuation of the number of neutrino interactions at the NUANCEoutput level. Effect reduced by dealing with 1000 years of NUANCEdata and then, scaling it down to 10 years.Randomness in Event Reweighting. Perform the analysis multipletimes, with different seeds to get the mean sensitivity.Fluctuations in event reconstruction (simulation, digitization andreconstruction). This can again be dealt with by changing randromnumber seeds in the reweighting algorithm, which picks up differentneutrino events each time.

The effect is that, χ2true 6= 0 and we must take that into account,while calculating ∆χ2 = χ2false − χ2true .

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Current Analysis

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Current Analysis

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Current Analysis

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Current Analysis

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Current Analysis

Mass Hierarchy sensitivity Results (50 kt × 10 years)

∆χ2 = χ2false - χ2true

Number of µ− Number of µ+ Total χ2false χ2true ∆χ

2

4426.00 1784.57 6210.57 12.1977 6.34305 5.854654427.31 1782.64 6209.95 12.3941 6.23456 6.159544425.35 1781.83 6207.18 12.8054 6.35180 6.453604428.71 1783.96 6212.67 12.1175 6.68314 5.434364419.06 1782.21 6201.27 11.6164 6.30656 5.30984

Average sensitivity is found to be ∼5.85

Table: Outcome of different simulation runs

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Current Analysis

Conclusions

We have performed a realiastic physics analysis with the fullsequence : Event Generator → Detector MC → χ2 analysis.In this analysis, our average reconstruction efficiency is lower thanthe one in the look up table based analysis.

We obtain a mean ∆χ2 for the MH discovery of ∼5.9. (Look uptable ∆χ2 is 6.5-7.2) for 2D analysis (Pµ, cos θµ).

If we disregard statistical fluctuation, we get ∆χ2 ∼ 7.5− 8.0The event selection criterion and the binning scheme are still beingimproved.

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Current Analysis

Conclusions

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Current Analysis

Conclusions

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Current Analysis

Conclusions

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Current Analysis

Conclusions

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Few Comments

Comments

More rigorous event selection is absolutely crucial for getting bettersensitivity. Use of TMVA might be of help. ROC

There are certain detector specific aspects that we must consider:

Dead space of active planes: staggered geometry???Directionality of tracks.

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Few Comments

Comments

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Few Comments

Comments

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Few Comments

Comments

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Few Comments

Thank You

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Caveats

We have used the atmospheric neutrino flux at the SK location.

We have only considered CC νµ (ν̄µ) events and that they can beseparated from all the other kinds of interactions.

The correlated noise were not considered.

Addition of priors and marginalizations were not performed - this isfixed parameter result.

Back to caveats .

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Caveats

Back to caveats .

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Caveats

Back to caveats .

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Caveats

Back to caveats .

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NuInstance

X (m)-10 -5 0 5 1015 20 25

Y (m)

-4-3

-2-1

01

23

4

Z (

m)

-4

-2

0

2

4

6

8

Neutrino Event

Back to NuInstance .

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More

CID

(in GeV/c)µP1 2 3 4 5 6 7 8 9 10

CID

effic

iency (

%)

90

91

92

93

94

95

96

97

98

99

100

-µcontinuous line:

=0.95θcos

=0.75θcos

=0.55θcos

+µbroken line:

=0.95θcos

=0.75θcos

=0.55θcos

Back to CID .

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χ2 Definition and Systematics

Poisson definition of Chi square: [NIM 221(1984)]

χ2(µ±) =

NE∑i=1

Ncos θ∑j=1

[2(Npredij − Nobsij )− 2Nobsij ln

NpredijNobsij

]

We consider 5 systematic errors as used for the muon analysis in,arXiv:1212.1305.

Flux Normalization error: 20%Cross section error: 10%Flux tilt error: 5%Zenith angle error: 5%Overall systematic error: 5%

Back to chisq .

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χ2(µ±) =

NE∑i=1

Ncos θ∑j=1

NpredijNobsij

]

Back to chisq .

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More

χ2(µ±) =

NE∑i=1

Ncos θ∑j=1

NpredijNobsij

]

Back to chisq .

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More

χ2(µ±) =

NE∑i=1

Ncos θ∑j=1

NpredijNobsij

]

Back to chisq .

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More

χ2(µ±) =

NE∑i=1

Ncos θ∑j=1

NpredijNobsij

]

Back to chisq .

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More

χ2(µ±) =

NE∑i=1

Ncos θ∑j=1

NpredijNobsij

]

Back to chisq .

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More

χ2(µ±) =

NE∑i=1

Ncos θ∑j=1

NpredijNobsij

]

Back to chisq .

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TMVA

Signal efficiency0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Bac

kgro

und

reje

ctio

n

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1

Background rejection versus Signal efficiency

Back to ROC .

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Motivation for Neutrino Mass Hierarchy Sensitivity Analysis with Reconstructed DataCurrent AnalysisEvent ReconstructionEvent SelectionMH Sensitivity Results

Few CommentsAppendixMore