NEUTRINO OSCILLATION STUDIES IN THE DEEP SEA - KM3NET/ORCA: S. HALLMANN - CERN INDICO
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KM3NeT/ORCA: Neutrino oscillation studies in the deep sea S. Hallmann ECAP, Universität Erlangen-Nürnberg on behalf of the KM3NeT Collaboration 30th Rencontres de Blois, 05/06/2018
KM3NeT Collaboration
Research infrastructure in the
Mediterranean Sea with
2 main physics objectives:
ARCA:
High energy v astronomy
ORCA:
Measurement of
neutrino properties >40 Institutes
+ Deep Sea Observatory >220 Scientists
(Oceanography, bioacoustics,
bioluminescence, seismology)
Collaboration
→ single Technology Low energy
Management ORCA
High energy
ARCA
+ Western Sydney University, Australia
ARCA: “Astroparticle Research with Cosmics in the Abyss”
ORCA: “Oscillation Research with Cosmics in the Abyss”
Updated results w.r.t. LoI: KM3NeT LoI , arXiv:1601.07459
shown today Journal of Physics G: Nuclear and Particle Physics, 43 (8), 084001, 2016
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 2
KM3NeT Technology
18 Digital Optical Modules
per detection line
9m ORCA
(36m ARCA) Launcher vehicle:
43 cm
rapid deployment
autonomous unfurling
recoverable
Digital Optical Modules:
31 3” PMTs
LED beacon & piezo
PMT HV
FPGA readout
→ Photon counting
→ Direction information
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 3
K3NeT/ORCA Detector
ORCA ARCA
ORCA will consist of one dense String spacing 23 m 90 m
KM3NeT Building Block: Vertical spacing 9m 36 m
115 detection lines Depth 2470 m 3500 m
Total: 64k * 3” PMTs Instrumented 1x 8 Mton 2x 0.6 Gton
mass
Height:
~160m ORCA
(600m ARCA)
Radius:
~120m ORCA
(500m ARCA)
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 4
Effective mass
Effective mass of after atmospheric muon rejection and containment cuts:
Events/yr (atm):
νeCC: 20 k
νμCC: 30 k
ντCC: 4k
ν NC 7k
- Effective volume reaches instrumented volume at ~ 10 GeV
- 50% effective at 5 GeV
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 5
Event type identification: Track↔Shower
Random Decision Forest technique:
- Allows to suppress atmospheric muon + pure noise contamination
to 3%-level while preserving 95% of neutrino signal @10 GeV:
- Discriminates track-like and shower-like events
- 90% correct
identification of νe CC
- 70% correct
identification of νμ CC
- Slightly better performance with new deep-learning-based classifier;
further
th
30 improvements
Rencontres under
de Blois – 05/06/2018 way
– S. Hallmann 6
Energy / zenith angle resolution
here: shower reconstruction
15 100
Reconstructed Energy [GeV]
Median zenith resolution [deg]
KM3NeT Preliminary
KM3NeT Preliminary LoI-9m 90
e & e CC
80 10-1
new
10 70
60
50
10-2
40
5
30
20
10-3
10
0
5 10 15 20 25 30
Neutrino energy [GeV] 0
0 10 20 30 40 50 60 70 80 90 100
True Energy [GeV]
- Median shower zenith angle - Energy resolution close to Gaussian
resolution ~5° @ 10 GeV - better than 30% in relevant range
- Resolution dominated by
intrinsic ν-e scattering angle*
*) “Intrinsic limits on resolutions in muon- and electron-neutrino charged-current events in the
KM3NeT/ORCA detector” / JHEP 2017 (2017), 8, arXiv:1612.05621
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 7
Known/Unknown neutrino parameters
Standard Model + 3ν framework
reasonably
well Currently not beyond...
determined established
Δm²12, |Δm²23|, absolute mass scale?, Dirac/Majorana?
θ12 θ23 θ13 sign(Δm²23)?, octant of θ23?, CP-Phase?
ORCA physics
programme
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 8
Known/Unknown neutrino parameters
Standard Model + 3ν framework
reasonably
well Currently not beyond...
determined established
not accessible
Δm²12, |Δm²23|, absolute mass scale?, Dirac/Majorana?
θ12 θ23 θ13 sign(Δm²23)?, octant of θ23?, CP-Phase?
= Neutrino Mass Hierarchy Possible
Main ORCA physics goal measurement with
future extensions?
High sensitivity to further Sensitivity to 3x3
ORCA physics unitarity through tau-
constrain current bounds programme
on atmospheric neutrino appearance
oscillation parameters Sensitivity to
- non-standard interactions
Other topics: - sterile neutrinos
- Sensitive to 80% of Galactic supernovae Competitive bounds on dark
- Earth tomography? matter for spin dependent
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 9
cross section
Measurement of oscillation parameters
- 90% CL measurement contours Δχ²-fit using Asimov dataset approach
for Δm²23 and sin²θ23
- Precision: Fitted systematics:
→ 2% in Δm²23 θ13, δCP, flux spectral tilt, ν / ν skew,
→ 5% in θ23 track-norm, shower-norm, NC-norm
combined track+shower energy-scale
Oscillation parameters: PDG2016
Truth assumption:
NH (fixed), δCP = 0 (fitted)
ORCA 3y sensitivity
SuperK (2015)
T2K (2015)
NOVA (2018)
IceCube (2017)
MINOS (2014)
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 10ντ appearance
- >3000 detected ντ events/year
oscillation - ντ events predominantly shower-like
probability
νμ →ντ
- Asimov dataset approach with Δχ²-fit
including systematics on
non-solar oscillation parameters,
flux spectral tilt, ν / ν skew
flavour normalisation terms
→ Rate constrained to within 10%
after 1 year
→ Weak constraints from other
experiments
non-
th
30 Rencontres de Blois – 05/06/2018 – S. Hallmann appearance unitarity 11ντ appearance - ντ appearance tests unitarity of the PMNS matrix and BSM theories → 20% deviation from unitarity can be detected with 5σ in 3 years → Confirm exclusion of non-appearance already with 2 months of data → Interesting to measure tau appearance + oscillation parameters (Δm²23 , sin²θ23) already during construction phase of ORCA 30th Rencontres de Blois – 05/06/2018 – S. Hallmann 12
Neutrino Mass Hierarchy (NMH)
- Measure event distributions in energy-zenith plane
- Oscillation patterns affected by matter effects
- FLUX + X-SECTION differences between ν and ν lead to NMH sensitivity
→ Need
large statistics
good energy + direction resolution
e + e (NH - IH) / NH + (NH - IH) / NH
30th Rencontres de Blois – 05/06/2018 – S. Hallmann Eresol = 25% resol = (mp/E)1/2 13Neutrino Mass Hierarchy (NMH)
Sensitivity to exclude wrong hierarchy Fitted systematics:
based on LLH-ratio test statistic using non-solar oscillation parameters,
toy experiments: flux spectral tilt, ν / ν skew,
track-norm, shower-norm, NC-norm
Oscillation parameters: PDG2016
true “normal” hierarchy true “inverted” hierarchy
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 14Sterile neutrinos 3+1 Atmospheric oscillation experiments have good sensitivity in Uτ4 mixing ORCA: Factor of two better sensitivity wrt. current limits from SK and IC after only 1 year of data taking (analysis based on LoI detector configuration) 30th Rencontres de Blois – 05/06/2018 – S. Hallmann 15
Sterile neutrinos: New ANTARES result
- ANTARES oscillation analysis presented at Neutrino2018
- 9 years of data (2007-2016)
- 7710 events selected in 2830 days livetime
- track channel only, Ereco from muon range
Included systematics:
3+1 model, Δm²41 > 0.5 eV²
• Unconstrained normalization for
neutrinos
• Normalization for atmospheric muons
• Prior from data
• exponential extrapolation into signal region
• Unconstrained spectral index
• Flux shape systematics from Barr et al.
• Implementation from IceCube
• Kindly provided by Th. Stuttard
• Cross section from Genie
• Leading effect MA
• Test MC with detector response
variation:
• 15% absorption length variations
• 10% PMT efficiencies variations
-> both effects well described by
30th Rencontres de Blois – 05/06/2018 – S. Hallmann normalization+spectral index 16Interesting possible extension:
„P2O“ Protvino2Orca Beam
Protvino U70 proton accelerator (Ep = 70 GeV, 8-15kW)
With possible upgrade to 450 kW:
→ 2-7 GeV neutrino beam (to be constructed)
→ P2O high statistics LBL experiment
Baseline 2590 km optimal Baseline:
→ First oscillation minimum νμ→νμ @ 5.1 GeV 2590 km
→ Matter resonance maximum νμ→νe @ 3.8 GeV
Sensitivity to mass hierarchy at least 5σ after 1 year of beam
for all combinations of oscillation parameters
σ contours of 4 test points
non-degenerate
KM3NeT/P2O
preliminary
Sensitivity to measure CP-phase
→ Exclusion of non CP violation
(0°/180°) possible for 35% of true CP
values at ~3σ CL after 6 years
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 17Construction status Main Cable, 2015 First ORCA string: 22/09/2017, Video: tiny.cc/OrcaDeployment Junction Box, Sept 2016 - Construction started, first data arrived in 2017 - Data-taking currently interrupted (replacement of deep sea part of main cable) - Production of detection lines continues - Deployment of 4 lines planned after summer 2018 in single sea operation 30th Rencontres de Blois – 05/06/2018 – S. Hallmann 18
Events observed with single line - a muon bundle (observed shortly - a typical event selected as neutrino after deployment) candidate 30th Rencontres de Blois – 05/06/2018 – S. Hallmann 19
First neutrino analysis
Uses 82 days of data taken with first ORCA line
Events in cos(θ)Conclusion
- KM3NeT/ORCA construction has started
- First atmospheric neutrino signal seen with one detection string
- End 2018: several detection strings operational
→ completion envisaged in 2021
- Main purpose: Determination of neutrino mass hierarchy
- Precise measurement atmospheric oscillation parameters
& tau appearance normalisation
+ rich physics programme beyond 3x3 neutrino oscillation studies
(dark matter, supernovae, sterile neutrinos, NSI)
- Interesting options for future extensions are investigated:
- Neutrino Beam from Protvino (“P2O”)
→ Fast determination of neutrino mass hierarchy
→ Sensitivity to CP violation
- Feasibility study of ~10x denser detector: “SuperORCA”
→ Measure CP violation? (Not covered in this talk)
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 21Backup
New developments with deep learning
OrcaNet [ http://github.com/ViaFerrata/OrcaNet ]:
- Event-type classifier based on deep Convolutional Neural Networks
- Given raw hit-information
instead of high level variables from reconstruction algorithms
- Work in progress, but already comparable performance to
Random Decision Forest
KM3NeT Preliminary
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 23NMH Fit – LLH Ratio test statistic 30th Rencontres de Blois – 05/06/2018 – S. Hallmann 24
Data/MC agreement first line 30th Rencontres de Blois – 05/06/2018 – S. Hallmann 25
Interesting possible extension:
P2O Protvino2Orca Beam
Accelerator complex at Protvino
currently operates at 8-15 kW 60d/year
→ Upgrade to 450 kW
→ 4x1020 p.o.t/year
would be feasible
(Fermilab→Nova: 700 kW,
6x1020 p.o.t/year)
Baseline: 2590 km, cos(θ)=-0.2
→ First oscillation minimum νμ→νμ @ 5.1 GeV ORCA is sensitive to
→ Matter resonance maximum νμ→νe @ 3.8 GeV this energy range
→ Gives non-degenerate sensitivity to
neutrino mass hierarchy and CP-phase
Oscillation probabilities νμ→νe
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 26Interesting possible extension:
P2O Protvino2Orca Beam
ORCA detector, 1year beam
→ Sensitivity to determine neutrino mass
hierarchy at least 5σ for all
combinations of oscillation parameters
σ contours of 4 test points
KM3NeT/P2O
preliminary
→ Sensitivity to measure CP-phase
→ Exclusion of non CP violation
(0°/180°) possible for 35% of true CP
values at ~3σ CL after 6 years
30th Rencontres de Blois – 05/06/2018 – S. Hallmann 27You can also read
