MEASUREMENT OF THE NEUTRINO MASS HIERARCHY IN THE DEEP SEA J. Brunner

MEASUREMENT OF THE NEUTRINO MASS HIERARCHY

IN THE DEEP SEA

J. Brunner

Matter effects & Mass Hierarchy• Solar Neutrinos : Matter effects inside sun

• m2 > m1

• Matter effects in Earth (not yet measured !)• m3 >< m1,m2

• Normal Hierarchy Inverted Hierarchy

Matter effects & Mass Hierarchy

• e see additional potential due to W-exchange in +e +e scattering

• Illustration for constant electron density ne

• At resonant energy 13 maximal

• A changes sign with ne via / • A changes sign with m2 mass hierarchy !

Example Earth Matter Effect : P(µe)

cos = 0.6Baseline = 7645 kmInclination = 36.9˚

Resonance energy Earth mantle : 6-7 GeV

NH IH

GLOBES

Example Earth Matter Effect : P(µµ)

cos = 0.6Baseline = 7645 kmInclination = 36.9˚

Resonance energy Earth mantle : 6-7 GeV

NH IH

GLOBES

Sensitivity Calculation• Fit of event count in Energy-Zenith space• Color code : bin-by-bin significance of hierarchy difference

W. Winter : arXiv:1305.5539

Oscillation parameter fixed Oscillation parameter fitted

ORCA Dense Mton detector with KM3Net design

Oscillation Research with Cosmics in the Abyss

Less than 20 MEuro with current KM3Net technology

PINGU : Sensitivity combined

ORCA Sensitivity Comparable or Better !

Muons only

6 yearsCascadesMuonsNo particle ID

Cascades better than MuonsCombination improves sensitivity by about a factor 2

Huber : Sensitivity over time

• ArXiv:1311.1822

A NEUTRINO BEAM TOWARDS ORCA

Why consider Beams ?• PINGU / ORCA Motivations

• Fast : Construction within few years• Significant measurement after few years• Stay within low budget

• Neutrino Beams• Expensive & long(er) Timescale• counter intuitive

• Matter effects with Atmospheric Nu’s• More challenging than originally hoped for• Beam allows for complementary measurement

• Neutrino Beams• Easier to motivate if pointing towards an existing detector• Maybe possible in “parasitic mode”

Why consider Beams ?

• Recently : change of paradigm for European LBL program

• Opens new, so far neglected options

Optimal Baseline ?• For L>2000km the oscillation probabilities are always well

separated for both MH hypotheses• To find optimal baseline calculate event rates

• N ~ 1/L2

• N ~ E (cross section)• Fixed beam profile• ORCA detector response

NH IH

Optimal Baseline• L=2600km maximizes the difference in event rates

between two MH hypotheses

Event rate differenceNH - IH

Proton Accelerator Complex Protvino

Presentation S. Ivanov (IHEP) on 22/11/2012 @ CERN Talk Wednesday

Proton Accelerator Complex Protvino

Presentation S. Ivanov (IHEP) on 22/11/2012 @ CERN

Protvino – ORCA• Baseline 2588km ; beam inclination : 11.7˚ (cos = 0.2)• Deepest point 134km : 3.3 g/cm3

SKAT bubble chamber

Courtesy: R. Nahnhauer

p target

focus

Decay pipe55m

Shielding SKAT

140m270m

245m

Beam parametrisation (1988)• Neutrino Focus • Anti-Neutrino Focus

Scaling to ANTARES site(0.245/2600)2

Z. Phys. C 40 (1988) 487

Off-Axis Beam : suppress HE tail• Beam optimisation still to be done• Off-axis or combination on-axis/off-axis might be favorable

Event rates - Signal

• Event numbers for 1.5 1021 p.o.t.s (3 years NOVA beam) • 20 statistical separation of both Mass Hierarchy

hypotheses from signal• 10000 muon events for beam normalisation

• 3.5% separation between MH hypotheses

• Other contributions: : 1316 +/- 13 ; 1416 +/- 8 ; NC : 4732

µ CCe CC

NH 1621 +/- 255

IH 497 +/- 100

NH 10927 +/- 24 IH 10548 +/- 43

Event rates – All Flavours & Mis-ID

• Event numbers for 1.5 1021 pots • 9-18% difference for NH/IH• 7 statistical separation of MH hypotheses• Can allow for 3-4 % syst. uncertainty• No requirement of energy reconstruction

tracks cascadesNH 7300 +/- 200 IH 6420 +/- 80

NH 10690 +/- 45 IH 10244 +/- 15

Flavour identification & Neutrino Energy

• Need to separate “tracks” from “cascades”• 2004 @ Villars : C2GT project (F. Dydak)

• CERN to Gulf of Taranto

Flavour identification• 2004 @ Villars : C2GT project (F. Dydak)• Clean separation of µ CC and e CC at 0.8 GeV

• OM spacing 3m

Dense detector 3x3 with cone display• Electron-Neutrino Event, C-Cone clearly visible• E = 5 GeV ; Ee= 4 GeV

50nsec100 nsec

Synergies between potential Sites

Modane2393km

Antares2588km

Gran Sasso2189km

Nemo2574km

Protvino

4.1˚ 11.0˚

13.6˚

Conclusion• Preliminary Performance Figures of ORCA encouraging• Mass hierarchy measurement in the deep sea possible• Upgraded proton accelerator at Protvino well suited for LBL

towards Mediterranean Sea• Needed : 1021 p.o.t. within few years• Perfect subject for Russian Mega-Science program• Synergy with Underground Labs in the same beam• Complementary to measurement with atmospheric • Complementary between ORCA / PINGU

• High Significance determination of Mass Hierarchy

Possible Timescale

• 2014-2015 : Finalize optimization work for both options• Currently active groups : CPPM, APC, ECAP (Erlangen)• Publish comprehensive document

• ~2016 : Planning “Phase II” of KM3Net• Parallel : Contact with Russian partners, LoI ?

• First encouraging contact 08/2013 (Y. Kudenko, INR)

• Start contact with Modane project(s) (ex LBNO)• First discussion 08/2013

Backup

Neutrinos from Beams• Eliminate ambiguities• Improve mass hierarchy sensitivity

arXiv:1301.4577

Narrow band beam 6-9 GeV1020 p.o.t.

P(µ µ)

cos = 0.1Baseline = 1274 kmInclination = 5.7˚

GLOBES

NH IH

P(µ µ)

cos = 0.2Baseline = 2548 kmInclination = 11.5˚

GLOBES

NH IH

P(µ µ)

cos = 0.3Baseline = 3823 kmInclination = 17.4˚

GLOBES

NH IH

P(µ µ)

cos = 0.4Baseline = 5097 kmInclination = 23.6˚

GLOBES

NH IH

P(µ µ)

cos = 0.5Baseline = 6371 kmInclination = 30.0˚

GLOBES

NH IH

P(µ µ)

cos = 0.6Baseline = 7645 kmInclination = 36.9˚

GLOBES

NH IH

P(µ µ)

cos = 0.7Baseline = 8919 kmInclination = 44.4˚

GLOBES

NH IH

P(µ µ)

cos = 0.8Baseline = 10194 kmInclination = 53.1˚

GLOBES

NH IH

P(µ µ)

cos = 0.9Baseline = 11468 kmInclination = 64.2˚

GLOBES

NH IH

Beam to IceCube

P(µ µ)

cos = 1.0Baseline = 12742 kmInclination = 90.0˚

GLOBES

NH IH

Counting Muons from Beam Neutrinos

• Optimal Beamline : 7000-8000 km

• Favoured Option:• FermiLab – KM3Net site in Mediterranean Sea• 1300 versus 950 events for both mass hierarchy hypotheses in

Mton underwater detector (ORCA)

• Inverse approach : Counting “Electrons”

arXiv:1301.4577

P(µe)

cos = 0.1Baseline = 1274 kmInclination = 5.7˚

GLOBES(CP-phase varied in steps of 30˚)

NH IH

P(µe)

cos = 0.2Baseline = 2548 kmInclination = 11.5˚

GLOBES

NH IH

P(µe)

cos = 0.3Baseline = 3823 kmInclination = 17.4˚

GLOBES

NH IH

P(µe)

cos = 0.4Baseline = 5097 kmInclination = 23.6˚

GLOBES

NH IH

P(µe)

cos = 0.5Baseline = 6371 kmInclination = 30.0˚

GLOBES

NH IH

P(µe)

cos = 0.6Baseline = 7645 kmInclination = 36.9˚

GLOBES

NH IH

P(µe)

cos = 0.7Baseline = 8919 kmInclination = 44.4˚

GLOBES

NH IH

P(µe)

cos = 0.8Baseline = 10194 kmInclination = 53.1˚

GLOBES

NH IH

P(µe)

cos = 0.9Baseline = 11468 kmInclination = 64.2˚

GLOBES

NH IH

Beam to IceCube

P(µe)

cos = 1.0Baseline = 12742 kmInclination = 90.0˚

GLOBES

NH IH

Oscillation parameters

• Taken from Global Fit (Fogli et al.) for both hierarchy options

• CP phase left free

Neutrino Cross sectionsSimple parton scaling assumed (QE, Res. ignored)

Flavour universality

m threshold

NC approximation

Neutrino Cross sectionsSimple parton scaling assumed (QE, Res. ignored)

Flavour universality

m threshold

NC approximationNC, CC: e µ

Solid : neutrino , dashed : antineutrino

Event rates• Here : no flavour misidentification• CC Rates

• NC Rates

Event rates• Include Background and Flavour tagging• Total Background :

• Total Event Rate :

Flavour identification

• Misidentification probability : • assume same for both directions• 50% at 2 GeV random ; 20% at 5 GeV ; 10% at GeV

V. Ludwig (ECAP)

Systematic Uncertainties

• Detector Response• Water parameters

–Extensively studied in ANTARES

• Neutrino flux–Can be monitored with muon events

• Neutrino Cross Section–Ongoing and planned short baseline Experiments

• Oscillation parameters–ORCA with atmospheric neutrinos