Decomposition Methods in the NOvA Near Detector for e ...€¦ · Decomposition Methods in the NOvA...

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Decomposition Methods in the NOvA Near Detector for ν e appearance Nitish Nayak (UC-Irvine) for the NOvA collaboration New Perspectives 2017

Transcript of Decomposition Methods in the NOvA Near Detector for e ...€¦ · Decomposition Methods in the NOvA...

Page 1: Decomposition Methods in the NOvA Near Detector for e ...€¦ · Decomposition Methods in the NOvA Near Detector for e appearance Nitish Nayak (UC-Irvine) for the NOvA collaboration

Decomposition Methods in the NOvA Near Detector forνe appearance

Nitish Nayak (UC-Irvine)

for the NOvA collaboration

New Perspectives 2017

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Neutrino Oscillations

I (νe , νµ, ντ ) superpositions of propagating mass eigenstates (ν1, ν2, ν3) →many parameters still unknown!

I NOvA looks at νµ → νµ and νµ → νe channels to constrain theseparameters

I mass hierarchy (NH, IH)

I mixing angle, θ23

I CP-violating phase, δCP

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NOvA

I ND useful for handle on neutrinospectrum

I Ensures we don’t get overwhelmedby systematics at FD

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The νe appearance analysis

Muon

Proton

Michel e-

Electron

Proton

π0 (→γγ)

νμ + n → μ + p

νe + n → e + p

ν + X → ν + X'Proton

1m

1m

νμ Charged Current

νe Charged Current

Neutral Current

I Look for νeCC signal at FD

I Use ND to predict both signal and bkg (beam νeCC, NC, νµCC) at FD

I Fit in oscillation parameter space

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Event classification

FEATURE MAPS

::

I CVN : Raw pixel maps →convolutional filters → NN layers

I CVN improvement in sensitivity ≡30% more exposure

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ND selection

I ND data/MC needed for beambackground decomposition

I Different backgrounds → differentoscillation rates

I Apply FD optimized PID selectionto ND

I Cut out events in surrounding rock

I Ensure good match withkinematics at FD

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Prediction Strategy

I Further bin FD energy into 3 PID bins → same for ND

Decomposition :

I Crude option : split data/MCproportionally based on fractionsin MC

I Better option : find data-drivenconstraints

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BEN Decomposition for beam νe

I beam νe shares ancestry with high-statistics νµCC

I By constraining flux from π, K through νµCC → constrain beam νe

True Neutrino Energy (GeV)0 5 10 15 20

Eve

nts

/ Bin

/ 6E

20 P

OT

0

5

10

15

20

310×

All AncestorsOther Ancestor

Ancestor0LK Ancestor+K Ancestor+π

beam νe CC

True Neutrino Energy (GeV)0 5 10 15 20

Eve

nts

/ Bin

/ 6E

20 P

OT

0

1

2

3

4

610×

All AncestorsOther Ancestor

Ancestor0LK Ancestor+K Ancestor+π

νµCC

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BEN Decomposition

I beam νe shares π phasespace with contained νµ

I Shape correction →important for systematics

Reconstructed neutrino energy (GeV)0 2 4 6 8 10

PO

T20

10×E

vent

s / 3

.72

0

20

40

60

80310×

in NDµνContained

CC from Pionsµν

CC from Kaonsµν

Bkgd. + other

NOvA Preliminary

(GeV/c)πz

tp0 10 20 30 40 50 60

(G

eV/c

)π T

tp

0

0.2

0.4

0.6

0.8

1

0.7

0.8

0.9

1

1.1

1.2

1.3Pion weights

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BEN Decomposition

I Normalization correction fromoverall scales incontained/uncontained events

I π scale goes down by 3%, K goesup by 17%

I Smaller fraction of beam νes fromK → only normalizationconsidered for K

Reconstructed neutrino energy (GeV)0 2 4 6 8 10 12

PO

T20

10×E

vent

s / 3

.72

0

50

100

150

310×

in NDµνUncontained

CC from Pionsµν

CC from Kaonsµν

Bkgd. + other

NOvA Preliminary

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Michel Decomposition for νµ, NC

I On average, 1 more Michel e− in νµCC

I µ decay lifetime ∼ 2.2µs � our resolution → find at µ track-end

I Michels from beam νe and NC come from hadronic portion (π → µ → e)

Number of Michels0 1 2+

PO

T20

10×E

vent

s / 3

.72

0

5000

10000

15000

NOvA Preliminary

Data

CCµνMC

MC NC

eνMC Beam I Input BEN result → NC, νe

degeneracy broken

I Fit with Poisson Likelihood

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Combo

I BEN + Michel prefers higherνµCC and NC (17.7% and 10.4%)

I Small increase in beam νes (1%)

I Takes into account uncertainties influx, cross-section and νe selectionefficiency

Reconstructed neutrino energy (GeV)

Rat

io

0

0.5

1

1.5

2

2.5

CVN

0.75 < CVN < 0.87 0.87 < CVN < 0.95 0.95 < CVN < 1

0 1 2 3 4 0 1 2 3 4 0 1 2 3 4 5

NOvA Preliminary

/ MCeνBeam

CC / MCµν

NC / MC

Reconstructed neutrino energy (GeV)

PO

T20

10×E

vent

s / 3

.72

0

1000

2000

3000

NOvA Preliminary

0.75 < CVN < 0.87 0.87 < CVN < 0.95 0.95 < CVN < 1

0 1 2 3 4 0 1 2 3 4 0 1 2 3 4 5

Data

eνMC Beam

CCµνMC

MC NC

Reconstructed neutrino energy (GeV)

PO

T20

10×E

vent

s / 3

.72

0

1000

2000

3000

NOvA Preliminary

0.75 < CVN < 0.87 0.87 < CVN < 0.95 0.95 < CVN < 1

0 1 2 3 4 0 1 2 3 4 0 1 2 3 4 5

Data

eνBeam

CCµν

NC

Uncorrected MC

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Extrapolation for νµ → νe

I Signal : Correct νµ MC by Reco/True Mapping, map back to Reco in νeafter extrapolation

I F/N helps flux/cross-section uncertainties, but care still needed!

I MC embedded in procedure, Reco/True map doesn’t help reco-levelsystematics

I Background : PID misidentifies at both ND, FD → no need for Reco/Truemap, extrapolate directly

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νe selection efficiency

I Expect good EM showersimulation but hadronic?

I νµCC events → remove µ-tracks,simulate EM shower (MRE)

I ∼ 1% data/MC disagreement

I Similar strategy for EM showers →FD cosmic muons with brems(MRBrem)

I Very good agreement

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Summary

I Setting expectations of what we should be seeing at FD is tricky but wehave..

I Number of data-driven techniques using the ND to make precisepredictions

I Cross-checks at ND to make sure we are on the right track

I Good systematics treatment taking advantage of near-identical detectors

I Look out for Shiqi’s talk on the νe appearance results and many othersfrom NOvA

I Stay tuned for further exciting results!

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Backup

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νe ND Data/MC

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νµ ND Data/MC

Reconstructed muon energy (GeV)0 1 2 3 4 5

Eve

nts

310

0

20

40

60

80

100 Simulated selected eventsSimulated backgroundData

syst. rangeσFull 1- POT20 10×ND POT norm., 3.72

NOvA Preliminary

Hadronic energy (GeV)0 0.5 1 1.5 2 2.5 3

Eve

nts

310

0

100

200

300Simulated selected eventsSimulated backgroundData

syst. rangeσFull 1- POT20 10×ND POT norm., 3.72

NOvA Preliminary

Muon ID0 0.2 0.4 0.6 0.8 1

Eve

nts

310

410

510

610

710 Simulated selected eventsSimulated backgroundData

syst. rangeσFull 1- POT20 10×ND POT norm., 3.72

NOvA Preliminary

Length of primary track (m)0 5 10 15

Eve

nts

310

0

20

40

60

80Simulated selected eventsSimulated backgroundData

syst. rangeσShape-only 1- POT20 10×ND area norm., 3.72

NOvA Preliminary

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Systematics Budgeting

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Simulated Flux at NOvA

E (GeV)0 5 10 15

CC

/ 6E

20 P

OT

/ kT

ON

/ 50

MeV

ν 610

0.5

1

1.5

2

2.5

Total

µν

µν

eν + eν

A SimulationνNO

FLUKA11

E (GeV)0 5 10 15

CC

/ 6E

20 P

OT

/ kT

ON

/ 50

MeV

ν 3−10

2−10

1−10

1

10

Total

µν

µν

eν + eν

A SimulationνNO

FLUKA11

ND FD

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νe Selected Event

NOvA - FNAL E929

Run: 19741 / 3Event: 67330 / --

UTC Sun Jun 7, 201517:09:42.290953856 sec)µt (

218 220 222 224 226 228

hits

110

210

q (ADC)10 210 310

hits

110

210

400 600 800 1000 1200 1400x

(cm

)

200

300

400

z (cm)400 600 800 1000 1200 1400

y (c

m)

200−

100−

0

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Muon Removed Electron Events (MRE)

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Muon Removed Bremstrahlung Events (MRBrem)

New Perspectives 2017 22 / 14 Nitish Nayak (UC-Irvine)