Global Picture Multiple sources Multiple detectors 18 July 2017 2 - PowerPoint PPT Presentation

Oscillation Measurements with KM3NeT-ORCA João Coelho APC Laboratory 18 July 2017 18 July 2017 1

arXiv:1611.01514 [hep-ph] Global Picture  Multiple sources  Multiple detectors 18 July 2017 2

Missing Pieces Is q 23 = p /4? Underlying symmetry?  Do neutrinos violate CP? ( d CP )   What is the mass ordering? (Mass Hierarchy) Normal Hierarchy Inverted Hierarchy same? d CP ? D m 2 32 < 0 ? 18 July 2017 3

One weird trick to measure the Mass Hierarchy… 18 July 2017 4

Matter Effects V H 0 18 July 2017 5

Resonances q 23 21 cos2 q 12 31 cos2 q 13 q 12 D m 2 q 13 D m 2 18 July 2017 6

Resonances q 23 NH q 12 q 13 IH 18 July 2017 7

Resonances q 23 ORCA JUNO ARCA q 12 DUNE q 13 NOvA T2K 18 July 2017 8

Atmospheric Neutrinos 18 July 2017 9

Atmospheric Neutrinos Neutrino Source mantle core Oscillations are resonant at certain energies E res ~ 7 GeV in Mantle E res ~ 3 GeV in Core Nue appearance at the surface 18 July 2017 10

Atmospheric Neutrinos  Resonance occurs for NH only for neutrinos mantle and vice versa for antineutrinos  Mantle crossing neutrinos provide core strongest signal for MH measurements P( ν μ → ν x ) for θ =130º 1 IH NH ν μ 0.5 Oscillations are resonant at certain energies ν e 0 E res ~ 7 GeV in Mantle 1 5 10 E res ~ 3 GeV in Core E ν [GeV] 18 July 2017 11

The Challenge q Z  Measure neutrino direction and energy  Search for oscillation patterns from matter effects  Sensitive to difference in patterns between NH and IH  Requires large statistics and good energy and direction res. 18 July 2017 12

KM3NeT Collaboration www.km3net.org 11 Countries >200 scientists >40 Institutions ARCA Site 18 July 2017 13

Main Objectives  ORCA : Determine the m 2 Mass Hierarchy (MH) Normal Hierarchy D m 2 32 > 0  ARCA : Discover/Observe high-energy neutrino sources in the universe Talk by A. Kouchner Thursday m 2 Inverted Hierarchy D m 2 32 < 0 18 July 2017 14

The ORCA Detector 2450m Depth • ~6 Mton instrumented • 115 strings • 18 DOMs / str • 31 PMTs / DOM • Total: 64k 3’’PMTs 43 cm 9 m Optimized for MH sensitivity ~210 m 18 July 2017 15

Trigger  Optical background mostly from 40 K decays in the water  Measured: 8 kHz uncorr., 340 Hz level-two coinc. / PMT [Eur. Phys. J. C 74, 3056 (2014)]  Look for coincidences in time and PMT direction to reduce trigger rate.  Causality further restricts space and time correlations for extra power.  Final trigger rate ~59 Hz , with 70% of events containing a cosmic ray muon . 40 K b - 40 Ca 40 Ca b - 40 K 40 K 40 K 40 Ca b - 18 July 2017 16

Trigger  Optical background mostly from 40 K decays in the water  Measured: 8 kHz uncorr., 340 Hz level-two coinc. / PMT [Eur. Phys. J. C 74, 3056 (2014)]  Look for coincidences in time and PMT direction to reduce trigger rate.  Causality further restricts space and time correlations for extra power.  Final trigger rate ~59 Hz , with 70% of events containing a cosmic ray muon . First ARCA lines show trigger clearly muon dominated. 18 July 2017 17

Measuring Neutrinos Shower-like Track-like 18 July 2017 18

Reconstruction 1) Start with a track or shower hypothesis 2) Use causality to perform a robust hit selection 3) Find vertex and direction that best match hit pattern 4) Estimate track range for computing track energy (0.24 GeV / m) 5) Estimate Shower energy and direction from hit distribution after initial fit to the vertex position and time Track Hypothesis Shower Hypothesis q C 18 July 2017 19

Reco Performance  Energy resolution: ~25% (Close to limit arXiv:1612.05621)  Angular resolution: Better than 10 degrees at relevant energies q Res. q Res. n e -CC n m -CC E Res. E Res. n e -CC n m -CC 18 July 2017 20

Event Selection  Events are classified through a Random Decision Forest (RDF)  At 10 GeV:  90% of n e -CC are shower-like  70% of n m -CC are track-like  Most atmospheric muons are removed by containment cuts 18 July 2017 21

Full Statistical Analysis Profile over 4 oscillation & 5 systematic parameters  Generate pseudo-experiments and compute NH IH  For each MH assumption, LLR distribution will peak at different values  Median sensitivity : probability of m NH m IH observing median LLR of wrong hierarchy for PEs generated with fixed true hierarchy s IH 18 July 2017 22

Sensitivity Results  ~3 s MH sensitivity in 3 years  The combination of NH and upper octant of q 23 would significantly improve sensitivity ( 5 s in 3 years )  The value of d cp has small but non- negligible impact on sensitivity  In the IH, sensitivity is mostly independent of octant of q 23  Best case scenario could achieve >5 s by 2022 (1.5 years) 18 July 2017 23

Other Parameters  High statistics and excellent resolution → Measure D m 2 32 and sin 2 q 23  Competitive with NOvA and T2K projected sensitivity in 2020  Achieve 2-3% prec. in D m 2 32 and 4-10% in sin 2 q 23 Normal Hierarchy T2K 2015 T2K 2020 68% C.L. NOvA 2020 MINOS KM3NeT 18 July 2017 24

Extended Models Arbitrary Perturbation Non-Standard Interactions (NSI) Sterile Neutrinos (3+N Flavours) 18 July 2017 25

Enhanced Matter Effects NSI ( e e t = 0.2) Steriles (“ Curr .” Limits) Visit https://goo.gl/CJyFoK for more 18 July 2017 26

Non-Standard Interactions  ORCA sensitive to NSI effects of order 10% of the Fermi int.  Direct bounds are more than 10x larger in some cases  ORCA improves over current atmospheric scale bounds  Limits competitive with global limits from oscillation * [1] JHEP 0908:090 (2009) [2] JHEP 1309:152 (2013) [3] KM3NeT-ORCA Preliminary 18 July 2017 27 *Phys. Rev. D 84, 113008 (2011)

Sterile Neutrinos  [1] PRD 85, 077301 (2012); PRL 117, 151801 (2016) Promising sensitivity in U t 4 mixing [2] J. J. Evans, Neutrino 2016; PRL 117, 151803 (2016)  [3] Phys. Rev. D 91, 052019 (2015) Factor of two better sensitivity than [4] PRL 117, 071801 (2016); arXiv:1702.05160 (2017) current limits from SK and IC [5] KM3NeT-ORCA Preliminary [6] Phys. Rev. D 64, 112007 (2001)  After only 1 year of data taking 18 July 2017 28

Earth tomography  ORCA is sensitive to the electron density N e while geophysics measure r m 1 s uncertainty after 10 years assuming NH:   5% in the whole mantle (c)  6% in the whole outer core (b) 10 year sensitivity including systematics Mantle NO IO Outer PREM model basis for r m core - - uniform Z/A rescaling in layer - Monte Carlo response & PID 18 July 2017 29

Tau neutrino appearance n t app. tests unitarity and new physics  ~ 3k n t CC events/year with full ORCA   Rate constrained within ~10% in 1 year  Sensitivity with few strings is under study New phys. Unitarity No app. - Monte Carlo response and PID - same PID as MH (not optimised for n t ) 18 July 2017 30

Simulation Update Performances based on temporary detector layout J. Phys. G 43 (2016) 084001 New set of simulations started Trigger + reconstruction + PID + background rejections Some new results here 18 July 2017 31 Accounts for technical constraints

New Geometry Design New Footprint From 6 Mton (LoI) to 8 Mton (accounts for technical constraints) 18 July 2017 32

Improvements at trigger level  Addition of a new trigger now: ONE local coincidence (L1) plus causally-connected hits in vicinity (do not have to be coincidences) before: cluster of causally-connected L1 hits (2 L0 hits on sam DOM) Keep bandwidth requirements: trigger rate from pure-noise smaller than irreducible trigger rate from to atmospheric muons. Increase of effective n e CC volume at low energies despite sparser detector 18 July 2017 33

Improvements in reconstructions  Reconstruction strategies adjusted for new trigger: allows for fainter events Tracks: - prefit based on a single local coincidence plus casually connected hits in the vicinity (for an assumed track direction) - Scan in all directions, with a step size of 5 degrees - Full fit procedure applied to 96 “best” reconstructed tracks Much higher efficiency w.r.t. the trigger (low E) - angular resolution unchanged 18 July 2017 34

Improvements in reconstructions  Reconstruction strategies adjusted for new trigger: allows for fainter events Showers: main changes in the hit selection (loosened) Now 20% faster turn-on and 40% larger plateau compared to LoI-9m with similar reconstruction resolutions Expect an increase in MH sensitivity and oscillation parameters, but a robust estimate requires a full chain processing (on going). 18 July 2017 35

Summary  ORCA is being built in the Mediterranean sea to measure oscillations with atmospheric neutrinos  Main goal is to determine the Neutrino Mass Hierarchy  ORCA will also improve measurements of other oscillation parameters such as D m 2 32 and q 23  Lots of potential for other searches: sterile neutrinos, NSI, earth tomography, tau neutrinos, etc.  MH could be determined by 2023  Stay tuned for updated sensitivities 18 July 2017 36

Thank you! 18 July 2017 37

Backup Slides 18 July 2017 38