Impact of large 13 on long-baseline measurements at PINGU

PINGU WorkshopErlangen universityMay 5, 2012

Walter Winter

Universität Würzburg

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Contents

Introduction Oscillation physics using a core-crossing

baseline Neutrino beam to PINGU:

Beams and detector parameterization Detector requirements for large 13

Matter density measurement? Summary

3

Three flavor mixing

Use same parameterization as for CKM matrix

Pontecorvo-Maki-Nakagawa-Sakata matrix

( ) ( ) ( )= xx

(sij = sin ij cij = cos ij)

Potential CP violation ~ 13

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13 discovery 2012

First evidence from T2K, Double Chooz Discovery (~ 5) independently (?)

by Daya Bay, RENO

(from arXiv:1204.1249)

1 error bars

Daya Bay 3

5

Three flavors: 6 params(3 angles, one phase; 2 x m2)

Describes solar and atmospheric neutrino anomalies, as well as reactor antineutrino disapp.!

Three flavors: Summary

Coupling: 13

Atmosphericoscillations:Amplitude: 23

Frequency: m312

Solaroscillations:Amplitude: 12

Frequency: m212

Suppressed

effect: CP

(Super-K, 1998;Chooz, 1999; SNO 2001+2002; KamLAND 2002;Daya Bay, RENO 2012)

MH?

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Consequences

Parameter space for CP starts to become constrained; MH/CPV difficult (need to exclude CP=0 and )

Need new facility!

Huber, Lindner, Schwetz, Winter, 2009

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Mass hierarchy measurement?

Mass hierarchy [sgn(m2)] discovery possible with atmospheric neutrinos? (liquid argon, HyperK, MEMPHYS, INO, PINGU?, LENA?, …)

Barger et al, arXiv:1203.6012;Smirnov‘s talk!

However: also long-baseline proposals! (LBNO: superbeam ~ 2200 km – LAGUNA design study; CERN-SuperK ~ 8870 km – Agarwalla, Hernandez, arXiv:1204.4217)

Perhaps differentfacilities for MH and CPV

proposed/discussed?

Oscillation physics using a core-crossing baseline

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Matter profile of the Earth… as seen by a neutrino

(PR

EM

: Prelim

inary R

eference E

arth M

odel)

Core

Innercore

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Beams to PINGU? Labs and potential detector locations (stars) in

“deep underground“ laboratories: (Agarw

alla, Hu

ber, Tang, W

inter, 2010)

FNAL-PINGU: 11620 kmCERN-PINGU: 11810 kmRAL-PINGU: 12020 kmJHF-PINGU: 11370 km

All these baselines cross the Earth‘s outer core!

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Matter effect (MSW) Ordinary matter:

electrons, but no , Coherent forward

scattering in matter: Net effect on electron flavor

Hamiltonian in matter (matrix form, flavor space):

Y: electron fraction ~ 0.5

(electrons per nucleon)

(Wolfenstein, 1978; Mikheyev, Smirnov, 1985)

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Parameter mapping (two flavors)

Oscillation probabilities invacuum:matter:

Matter resonance: In this case: - Effective mixing maximal- Effective osc. frequency minimal

For appearance, m312:

- ~ 4.7 g/cm3 (Earth’s mantle): Eres ~ 7 GeV- ~ 10.8 g/cm3 (Earth’s outer core): Eres ~ 3 GeV

Resonance energy:

MH

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Mantle-core-mantle profile

Probability for CERN-PINGU (numerical)

(Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998)

Coreresonance

energy

Mantleresonance

energyInter-ference

Thresholdeffects

expected at:2 GeV 5 GeV 10 GeV

Beam energyand detector thresh. have

to pass these!

Is thatpart

useful?

Challenge: Relative size of

CP-termssmaller forlonger L

Neutrino beam to PINGU?

Beams and detector parameterization

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There are three possibilities to artificially produce neutrinos

Beta decay:Example: Nuclear reactors, Beta beams

Pion decay:From accelerators:

Muon decay:Muons produced by pion decays! Neutrino Factory

Muons,neutrinos

Possible neutrino sources

Protons

Target Selection,focusing

Pions

Decaytunnel

Absorber

Neutrinos

Superbeam

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Considered setups

(for details: Tang, Winter, JHEP 1202 (2012) 028, arXiv:1110.5908; Sec. 3)

Single baseline reference setups:

Idea: similar beam, but detector replaced by PINGU/MICA [need to cover ~ 2 – 5 GeV]:

L [km]

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Want to study e- oscillations Beta beams:

In principle best choice for PINGU (need muon flavor ID only) Superbeams:

Need (clean) electron flavor sample. Difficult? Neutrino factory:

Need charge identification of + and - (normally)

Oscillation channels

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PINGU fiducial volume? In principle: Mton-size detector in relevant ranges:

Unclear how that evolves with cuts for flavor-ID etc. (background reduction); MICA even larger? Use effective detector parameterization to study requirements: Eth, Veff, Eres

(Tang, Winter, JHEP 1202 (2012) 028; Veff somewhat smaller than Jason‘s current results)

Eth

Veff

Eres (E) = E

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Detector paramet.: mis-ID

misIDtracks << misID <~ 1 ?

(Tang, Winter, JHEP 1202 (2012) 028)

misID: fraction of events of a

specific channel

mis-identified as signal

Detector requirements for large 13

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Superbeam

Mass hierarchy measurement very robust(even with largemisID and totalrates only possible)

Even with much smaller-scale beam?

Existing equipment, such as CNGS? NuMI?

CPV not promising (requires flavor mis-ID at the level of 1%, Veff > 5 Mt, Eres = 0.2 E or better)

(Tang, Winter, JHEP 1202 (2012) 028)

(misIDtracks = 0.01)

Fra

ctio

n of

C

P

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NuMI-like beam to PINGU?

Difference to atmospherics: can even live without energy resolution and cascade ID (NC and added)(if some track ID and systematics controlled)

NuMI

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Beta beam

Similar results for mass hierarchy measurement (easy)

CPV not so promising:

long L, asymmetric beam energies (at least in CERN-SPS limited case

~656 for 8B and =390 for 8Li) although moderate detector requirements

(Tang, Winter, JHEP 1202 (2012) 028)

(misID ~ 0.001, Eth=2 GeV, Eres=50% E, Veff=5 Mt)

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Neutrino factory

No magnetic field, no charge identification Need to disentangle Pe and P by energy

resolution:

(from: Tang, Winter, JHEP 1202 (2012) 028; for non-magnetized detectors, see Huber, Schwetz, Phys. Lett. B669 (2008) 294)

)

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contamination

Challenge:

Reconstructed at lower energies!(Indumathi, Sinha, PRD 80 (2009) 113012; Donini, Gomez Cadenas, Meloni, JHEP 1102 (2011) 095)

Choose low enough E to avoid

Need event migration matrices (from detector simulation) for reliable predictions! (neutral currents etc)

(sin2213=0.1)

(Tang, Winter, JHEP 1202 (2012) 028)

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Precision measurements?

… only if good enough energy resolution ~ 10% E and misID (cascades versus tracks) <~ 1% can be achieved!

(Tang, Winter, JHEP 1202 (2012) 028)

The BONUS program: Matter density measurement of the Earth‘s core?

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Example: Superbeam

Precision ~ 0.5% (1)

Highly competitive to seismic waves (seismic shear waves cannot propagate in the liquid core!)

(Tang, Winter, JHEP 1202 (2012) 028)

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Conclusions [my personal view]

Superbeams Electron sample (cascades) probably contaminated by other flavors;

therefore precision measurements unlikely Interesting option: Use more or less existing equipment for a

mass hierarchy measurement? (e.g. CNGS/MINOS with new beam line?)

Bonus: matter density measurement of Earth‘s core Unique experiment as low-budget alternative to LBNE?

Neutrino factory Energy resolution critical, since non-magnetized detector Detector simulation needed to produce event migration matrices

for reliable conclusions if Eres ~ 10% E achievable? Beta beams

Intrinsically best-suited for PINGU/MICA: flavor-clean beam, requires muon neutrino flavor-ID

However: need high intensity, high energy 8B-8Li setups for reasonable sensitivities; there are better ways to build a beta beam for large 13 to do both MH+CPV

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Statement of PINGU collaboration needed

now (or never)!?

BACKUP

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Beams: Appearance channels

(Cervera et al. 2000; Freund, Huber, Lindner, 2000; Akhmedov et al, 2004)

Antineutrinos: Magic baseline:

L~ 7500 km: Clean measurement of 13 (and mass hierarchy) for any energy, value of oscillation parameters! (Huber, Winter, 2003; Smirnov 2006)

In combination with shorter baseline, a wide range of very long baseline will do! (Gandhi, Winter, 2006; Kopp, Ota, Winter, 2008)

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Quantification of performanceExample: CP violation discovery

Sensitive region as a

function of true 13 and CP

CP values now stacked for each 13

Read: If sin2213=10-3, we

expect a discovery for 80% of all values of CP

No CPV discovery ifCP too close to 0 or

No CPV discovery forall values of CP3

~ Precision inquark sector!

Best performanceclose to max.

CPV (CP = /2 or 3/2)

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Effective volume

Difference Eth = 2 GeV, Veff=5 Mt to actual (energy-dependent) fiducial volume:

(Tang, Winter, JHEP 1202 (2012) 028)

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Note:

Pure baseline effect!

A 1: Matter resonance

VL baselines (1)

(Factor 1)2

(Factor 2)2

(Factor 1)(Factor 2)Prop. To L2; compensated

by flux prop. to 1/L2

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Factor 1: Depends on energy; can be matter enhanced for long L; however: the longer L, the stronger change off the resonance

Factor 2:Always suppressed for longer L; zero at “magic baseline” (indep. of E, osc. Params)

VL baselines (2)

(m312 = 0.0025, =4.3 g/cm3, normal hierarchy)

Factor 2 always suppresses CP and solar terms for very long baselines; note that these terms include 1/L2-dep.!