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)


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)


GLOBES

NH IH

P(µ µ)


GLOBES

NH IH

Beam to IceCube

P(µ µ)


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)


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

NH IH

P(µe)


GLOBES

NH IH

P(µe)


GLOBES

NH IH

Beam to IceCube

P(µe)


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

measurement of the neutrino mass hierarchy in the deep sea j. brunner

Documents

optimal energy range

resonant energy

resonance energy earth

m2 mass hierarchy

pingu orca motivations

neutrino mass hierarchy

e e scatteringillustration

m2 m1matter effects