VaLOR Off-Axis angle optimisation studies Costas Andreopoulos 1 , 2 - - PowerPoint PPT Presentation

VaLOR Off-Axis angle optimisation studies

Costas Andreopoulos1,2 ∗, Giles Barr4, Fatih Bay3, Thomas Dealtry2,4, Steve Dennis2,5, Lorena Escudero6, Nick Grant7, Silvestro Di Luise3, Davide Sgalaberna3, Raj Shah2,4, Dave Wark2,4 and Alfons Weber2,4.

1University of Liverpool, 2STFC Rutherford Appleton Laboratory, 3ETH Zurich, 4University of Oxford, 5University of Warwick, 6IFIC Valencia, 7University of Lancaster

presented at the 6th Open Meeting of the HyperK project

January 29, 2015

∗Contact: costas.andreopoulos@stfc.ac.uk

Outline

Quick introduction to the VALOR T2K 3-flavour oscillation fit Motivation δcp Discovery sensitivity 2D Confidence contours Summary

Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 2 / 26

VALOR 3-flavour analysis

Joint measurement of: sin2θ13, sin2θ23, δCP and ∆m2

32

Implementing the agreed 2013 analysis strategy. Analysis uses the official T2K 2013 inputs with appropriate scaling (MC and flux, cross-section and detector-response error assignments and correlations). Performs an indirect extrapolation by tuning the far detector Monte-Carlo to near detector constraints Neutrino oscillation probabilities calculated in a 3-active-neutrino framework, including matter effects in constant-density matter. Minimization: Binned likelihood ratio method, using MINUIT.

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Introduction - Updates

Analysis Setup 10 years nominal annual exposure of 7.5 MW · 107 sec = 1.56 · 1022 POT Assuming ±320kA horn current 1:3 FHC-RHC running ratio Consider 93 sources of systematic error :

1

66 (33 + 33) Near detector correlated for FHC and RHC mode.

2

12 uncorrelated cross-section errors 100% correlated between FHC and RHC.

3

19 FSI + HK detector errors 100% correlated between FHC and RHC.

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List of systematics considered

Type Systematics Comment Nsyst Ntot ND correlated (FHC) f banff

• f banff

24

νµ flux 11 ¯ νµ flux 5 νe flux 7 ¯ νe flux 2 f banff

25

CCQE axial mass 1 f banff

26

Resonant axial mass 1 f banff

27

• f banff

28

CCQE Norm 3 f banff

30

• f banff

31

CC1π Norm 2 f banff

32

NC1π0 1 33 ND correlated (RHC) FHC * 1.06 33 Uncorrelated fWShape π p-distribution (50%) 1 fπ−less∆ πless ∆ decay (20%) 1 fCCcoh σ CC coherent (50%) 1 fNCoth σ NC other (30%) 1 fNCcoh σ NC coherent (30%) 1 fNCπ σ NCπ (30%) 1 fCCνe/νµ σνe/σνµ (3%) 1 fCC ¯

ν/ν

σ¯

ν/σν (6%)

1 fpF FermiMomentum (14%) 1 fbindE Bindingenergy (30%) 1 fWshape PionMomentum (52%) 1 fSF SpectralFunction 1 12 (SK+ FSI)/ √ 20 fE Energy scale 1 f SK − f SK

5

1Rµ efficiencies 6 f SK

6

− f SK

17

1Re efficiencies 12 19 93

Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 5 / 26

Motivation

1 Choice of off axis angle can have considerable impact on the beam

energy distribution, composition and total flux seen at HK.

2 2.5 ◦ off-axis beam was optimised for T2K experiment.

Discovery of θ13 Precise measurements of 23 sector parameters ∆m2

32 and θ23

3 What about HK goals? CP Sensitivity Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 6 / 26

Motivation

Current (2.5◦) Off-Axis angle spectrum peaks at 0.6 GeV CCQE Cross section is rising in this region σe x appearance probability for ¯ νe (and νe also rising) On axis beam can lead to improved statistics Studied the effect of moving to 2.25 and 2.0 degrees off axis

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1Rµ Spectra

FHC RHC

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1Rµ FHC Spectra

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1Rµ RHC Spectra

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1Re Spectra

FHC RHC

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1Re FHC Spectra

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1Re RHC Spectra

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δcp Sensitivity Studies

Create MC spectra for given value of δCP Do multiple fits to determine χ2

min(sin(δCP) = 0)

Do fits with δCP = π, 0 Do each fit with true hierarchy

∆χ2 = χ2

BestFit − χ2 True

Plotted ∆χ2 for each value of δcp Studies assumed 10yr HK data (1.56 x 1022pot) True oscillation parameters: sin2(θ13) = 0.0241, sin2(θ23) = 0.5, sin2(θ12) = 0.306, ∆m2

21 = 7.5 · 10−5eV 2, ∆m2 32 = 2.4 · 10−3eV 2

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δcp Sensitivity Studies - True Normal Hierarchy

cp

• Input
• 3
• 2
• 1

1 2 3

2

• =
• 1

2 3 4 5 6 7 8 9

Fraction of CP space

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

• 1

2 3 4 5 6 7 8 9

20 225 25

sin2(θ13) = 0.0241, sin2(θ23) = 0.5, sin2(θ12) = 0.306, ∆m2

21 = 7.5 · 10−5eV 2, ∆m2 32 = 2.4 · 10−3eV 2

Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 15 / 26

δcp Sensitivity Studies - True Inverted Hierarchy

cp

• Input
• 3
• 2
• 1

1 2 3

2

• =
• 1

2 3 4 5 6 7 8 9

Fraction of CP space

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

• 1

2 3 4 5 6 7 8 9

20 225 25

sin2(θ13) = 0.0241, sin2(θ23) = 0.5, sin2(θ12) = 0.306, ∆m2

21 = 7.5 · 10−5eV 2, ∆m2 32 = 2.4 · 10−3eV 2

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δcp Sensitivity Studies - sin2(θ23) Dependance

Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 17 / 26

δcp Sensitivity Studies - 20%,50% Exposure

20%

cp

δ Input

• 3
• 2
• 1

1 2 3

2

χ ∆ = σ

1 2 3 4 5

Fraction of CP space

0.2 0.4 0.6 0.8 1

σ

1 2 3 4 5 20_5 225_5 25_5

50%

cp

δ Input

• 3
• 2
• 1

1 2 3

2

χ ∆ = σ

1 2 3 4 5 6 7

Fraction of CP space

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

σ

1 2 3 4 5 6 7 20_2 225_2 25_2

sin2(θ13) = 0.0241, sin2(θ23) = 0.5, sin2(θ12) = 0.306, ∆m2

21 = 7.5 · 10−5eV 2, ∆m2 32 = 2.4 · 10−3eV 2, NH

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Sensitivity- 2D Contours sin2(θ13)-δcp (90% Confidence)

sin2(θ13) = 0.0241, sin2(θ23) = 0.5, sin2(θ12) = 0.306, ∆m2

21 = 7.5 · 10−5eV 2, ∆m2 32 = 2.4 · 10−3eV 2, δcp = − π 2

Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 19 / 26

Sensitivity- 2D Contours δcp-∆m2

32 (90% Confidence)

sin2(θ13) = 0.0241, sin2(θ23) = 0.5, sin2(θ12) = 0.306, ∆m2

21 = 7.5 · 10−5eV 2, ∆m2 32 = 2.4 · 10−3eV 2, δcp = − π 2

Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 20 / 26

Sensitivity-2D Contours sin2(θ23)-∆m2

32 (90% Confidence)

sin2(θ13) = 0.0241, sin2(θ23) = 0.5, sin2(θ12) = 0.306, ∆m2

21 = 7.5 · 10−5eV 2, ∆m2 32 = 2.4 · 10−3eV 2, δcp = − π 2

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Summary

Moving on axis has a much larger effect on 23 sector due to background around oscillation dip δcp discovery potential unchanged when moving on axis No difference when systematics or statistics limited

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Backup Slides

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Sensitivity- 2D Contours sin2(θ13)-δcp (90% Confidence)

cp

δ

• 2.4
• 2.2
• 2
• 1.8
• 1.6
• 1.4
• 1.2
• 1
• 0.8

)

13

θ (

2

sin

0.019 0.02 0.021 0.022 0.023 0.024 0.025

2.0 2.25 2.50

sin2(θ13) = 0.0241, sin2(θ23) = 0.55, sin2(θ12) = 0.306, ∆m2

21 = 7.5 · 10−5eV 2, ∆m2 32 = 2.4 · 10−3eV 2, δcp = − π 2

Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 24 / 26

Sensitivity- 2D Contours δcp-∆m2

32 (90% Confidence)

cp

δ

• 2.4
• 2.2
• 2
• 1.8
• 1.6
• 1.4
• 1.2
• 1
• 0.8

32 2

m ∆

0.00235 0.00236 0.00237 0.00238 0.00239 0.0024 0.00241 0.00242 0.00243 0.00244 0.00245

2.0 2.25 2.50

sin2(θ13) = 0.0241, sin2(θ23) = 0.55, sin2(θ12) = 0.306, ∆m2

21 = 7.5 · 10−5eV 2, ∆m2 32 = 2.4 · 10−3eV 2, δcp = − π 2

Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 25 / 26

Sensitivity-2D Contours sin2(θ23)-∆m2

32 (90% Confidence)

)

23

θ (

2

sin

0.46 0.48 0.5 0.52 0.54 0.56 0.58

32 2

m ∆

0.00236 0.00238 0.0024 0.00242 0.00244

2.0 2.25 2.50

sin2(θ13) = 0.0241, sin2(θ23) = 0.55, sin2(θ12) = 0.306, ∆m2

21 = 7.5 · 10−5eV 2, ∆m2 32 = 2.4 · 10−3eV 2, δcp = − π 2

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