KM3NeT/ORCA: measuring neutrino oscillations and the Mass Hierarchy - PowerPoint PPT Presentation

KM3NeT/ORCA: measuring neutrino oscillations and the Mass Hierarchy in the Mediterranean Simon Bourret Laboratoire APC, CNRS & Université Paris-Diderot on behalf of the KM3NeT Collaboration XXVI International Workshop on Weak Interactions and Neutrinos Irvine, California, USA, 19-24 June 2017

KM3NeT objectives θ z detector § ARCA : Discover/Observe high-energy neutrino sources in the Universe ν à talk by A. Capone Wed. 21 (astroparticle session) § ORCA : Study ν properties, determine the Neutrino Mass Hierarchy and measure oscillation parameters P( ν x → ν μ ) for θ =130º - Mantle crossing P( ν x → ν μ ) for θ =180º - Mantle-core-mantle 1 1 IH NH ν µ à ν µ ν µ à ν µ 0.5 0.5 ν e à ν µ ν e à ν µ 0 0 1 10 1 10 5 5 E ν [GeV] E ν [GeV] WIN 2017 KM3NeT/ORCA - S. Bourret 2

The ORCA detector 3’’ PMT • 115 strings • 18 DOMs / str • 31 PMTs / DOM • Total: 64k PMTs • ~8 Mton instrumented (5.7) 43 cm 9 m ~ 2 0 0 m Optimized for MH sensitivity Eur. Phys. J. C 74, 3056 (2014) ~210 m WIN 2017 KM3NeT/ORCA - S. Bourret 3

Detector geometry § Vertical spacing optimized for NMH 400 ARCA/ORCA KM3NeT LoI: J. Phys. G 43 (2016) 0840 (1601.07459) 200 y [m] 0 9m 12m -200 MH sensitivity -400 True NH 6m -400 -200 0 200 400 x [m] True IH § Horizontal spacing adjusted to deployment requirements è new full MC simulation WIN 2017 KM3NeT/ORCA - S. Bourret 4

Event topologies: tracks (ARCA) ν µ CC “Track” ν WIN 2017 KM3NeT/ORCA - S. Bourret 5

Event topologies: cascades (ARCA) (ARCA) ν ν µ CC ν NC “Track” “Cascade” ν WIN 2017 KM3NeT/ORCA - S. Bourret 6

Updated performance: effective volume § New loosened trigger è increase of low-E efficiency § Adapted & improved both Track and Shower reconstructions § Particle ID model being refined § NMH & oscillation sensitivities not yet updated with these improvements electron channel muon channel 10 ] 3 Effective Volume [Mm KM3NeT Preliminary ν & ν CC KM3NeT preliminary e e 9 8 7 6 5 4 3 LoI-9m 2 new detector & new trigger/reco new detector & old trigger/reco 1 0 5 10 15 20 25 Neutrino Energy [GeV] WIN 2017 KM3NeT/ORCA - S. Bourret 7

Updated performance: zenith resolution § New loosened trigger è increase of low-E efficiency § Adapted & improved both Track and Shower reconstructions § Particle ID model being refined § NMH & oscillation sensitivities not yet updated with these improvements electron channel muon channel 15 Median zenith resolution [deg] KM3NeT preliminary KM3NeT Preliminary LoI-9m & CC ν ν e e new 10 5 0 5 10 15 20 25 30 Neutrino energy [GeV] WIN 2017 KM3NeT/ORCA - S. Bourret 8

Statistical analysis J. Phys. G 43 (2016) 0840 parameter true value distr. initial value/prior distr. treatment prior θ 23 [ � ] { 40 , 42 , . . . , 50 } uniform over [35 , 55] fitted no θ 13 [ � ] 8 . 42 µ = 8 . 42, σ = 0 . 26 fitted yes § Profile over 4 oscillation θ 12 [ � ] 34 µ = 34, σ = 1 fluct.* N/A ∆ M 2 [10 � 3 eV 2 ] & 5 syst. parameters µ = 2 . 4, σ = 0 . 05 µ = 2 . 4, σ = 0 . 05 fitted no ∆ m 2 [10 � 5 eV 2 ] 7.6 µ = 7 . 6, σ = 0 . 2 fluct.* N/A δ CP [ � ] { 0, ..., 360 } uniform over [0 , 360] fitted no overall flux factor 1 µ = 1, σ = 0 . 1 fitted yes NC scaling 1 µ = 1, σ = 0 . 05 fitted yes S NH = µ NH − µ IH ν / ν skew 0 µ = 0, σ = 0 . 03 fitted yes µ/e skew 0 µ = 0, σ = 0 . 05 fitted yes energy slope 0 µ = 0, σ = 0 . 05 fitted yes σ IH Table 1: Default parameter settings used for the LLR analysis. For θ 23 a total of seven initial values is tried: x + i × 5 � , where x is the randomly drawn value and i ∈ [ − 3 , − 2 , . . . , 3]. * θ 12 and δ m 2 are assigned a fixed value in the fit, randomly drawn from the initial value distribution. arbitrary units 0.18 § Generate pseudo-experiments and 0.16 NH IH 0.14 � � compute L NH / L IH LLR = log 0.12 0.1 § Median sensitivity ⇔ probability of 0.08 0.06 observing median LLR of wrong hierarchy µ IH µ NH 0.04 0.02 0 -15 -10 -5 0 5 10 15 LLR σ IH WIN 2017 KM3NeT/ORCA - S. Bourret 9

Sensitivity results (LoI detector) J. Phys. G 43 (2016) 0840 2 sin ( ) θ 23 0.4 0.45 0.5 0.55 0.6 8 ] σ NH, =0 Mass hierarchy significance [ δ ° 7 CP § ~ 3 σ MH sensitivity in 3 years IH , =0 δ ° CP 6 NH, δ =180 ° CP § The true value of δ cp has small but 5 IH , =180 δ ° CP non-negligible impact 4 3 2 1 (LoI - 9m spacing) KM3NeT preliminary 0 8 40 42 44 46 48 50 NH, = 42 θ ° 7 [degrees] 23 θ ] 23 σ IH, θ = 42 ° 23 Median Significance [ NH, = 48 6 θ ° 23 § The combination of NH and IH, = 48 θ ° 23 5 upper octant of θ 23 would 4 significantly improve sensitivity ( 5 σ in 3 years ) 3 2 § In the IH, sensitivity is mostly 1 independent of octant of θ 23 (LoI - 9m spacing) 2020 2021 2022 2023 2024 2025 Date WIN 2017 KM3NeT/ORCA - S. Bourret 10

Oscillation parameters measurement J. Phys. G 43 (2016) 0840 § Achieve 2-3% prec. in Δ m 2 32 and 4-10% in sin 2 θ 23 (3 years) § Competitive with LBL experiments projected sensitivity in 2020 § Early determination of the octant of θ 23 is feasible § Analysis based on Asimov T2K 2015 68% C.L. NH assumed T2K 2020 datasets NOvA 2020 § θ 12 , θ 13 and δ m 2 fixed § Other param. unconstrained § Energy scale uncertainty added (has no impact on NMH sens.) MINOS (LoI – 9m) ORCA 3 years (MH known) NH, δ CP = 0, maximal mixing assumed WIN 2017 KM3NeT/ORCA - S. Bourret 11

Oscillation parameters measurement J. Phys. G 43 (2016) 0840 § Achieve 2-3% prec. in Δ m 2 32 and 4-10% in sin 2 θ 23 (3 years) § Competitive with LBL experiments projected sensitivity in 2020 § Early determination of the octant of θ 23 is feasible KM3NeT preliminary (LoI - 9m) § Analysis based on Asimov datasets § θ 12 , θ 13 and δ m 2 fixed § Other param. unconstrained § Energy scale uncertainty added (has no impact on NMH sens.) 1 σ 2 σ MH known MH unknown NH assumed, δ CP = 0 WIN 2017 KM3NeT/ORCA - S. Bourret 12

Tau neutrino appearance § ν τ appearance tests PMNS unitarity and BSM theories § ~ 3k ν τ CC events/year with full ORCA § Rate constrained within ~10% in 1 year § Sensitivity with few strings is under study KM3NeT preliminary ç unitarity 1 σ 2 σ 3 σ 5 σ ç no appearance § analysis uses same PID as NMH (not optimised for ν τ ) ν / ν § prior on NC norm. (30%) and skew (10%) WIN 2017 KM3NeT/ORCA - S. Bourret 13

Light sterile neutrino § The dominant effect in ORCA of adding a eV scale sterile neutrino would be the suppression of ν µ è ν τ oscillation at ~20 GeV § With 1 year of data ORCA is sensitive to |U τ 4 | 2 values smaller than current limits set by SK § Fitted: 4 syst. + 2 osc. ( θ 23 , Δ M 2 ) § U e4 = 0 § Δ m 2 41 = 0.3 eV 2 WIN 2017 KM3NeT/ORCA - S. Bourret 14

Non-Standard Interactions § Current limits: à see e.g. talk by I. Mocioiu Tue. 20 ( ν session) Rept. Prog. Phys. 76, 044201 (2013) § With only 1 year of data, ORCA sensitive to NSI effects below these limits: § Fitted: 4 syst. + 2 osc. ( θ 23 , Δ M 2 ) § 95% C.L. in (| ε ee | , | ε e τ | , | ε ττ |) space à 2D projection for | ε ee | = 0 SK + K2K limits from arXiv:0506143 § WIN 2017 KM3NeT/ORCA - S. Bourret 15

Funding and timeline § 7 strings funded for ORCA (11 M € inc. infrastructure) § 2 strings deployment Sept. 17 1 st node: Sept 2016 1 st ORCA string ready Total ORCA cost: ~45 M € 7 Strings 115 Strings Operational Full Detector WIN 2017 MH Determination ORCA Construction 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 WIN 2017 KM3NeT/ORCA - S. Bourret 16

Summary § ORCA is being built in the Mediterranean sea to measure oscillations with atmospheric neutrinos: detector is to be completed by 2020 § Main goal is to determine the Neutrino Mass Hierarchy , with a sensitivity of >3 σ in 3 years of operation § ORCA will also improve measurements of other oscillation parameters such as Δ m 2 32 and θ 23 § Further physics potential: PMNS unitarity, sterile ν ’s, NSI … § More topics not adressed in this talk: DM detection, Earth tomography, supernovae … WIN 2017 KM3NeT/ORCA - S. Bourret 17