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
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