Analysis of first KM3NeT/ORCA data J. Schumann July 29, 2019 FRANCI 2019, Erlangen
Overview • KM3NeT : Water Cherenkov detector in the Mediterranean Sea • Detector is split up and deployed at two sites: → ARCA Astroparticle research → ORCA Neutrino oscillation research Artist impression of the 8 Mton instrumented mass KM3NeT detector • Current project status: → Deployment for Phase-1 (7 DUs) → Four detection units (DU) installed and taking data ⇒ First data available → Data Analysis July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 2/18
μ - Detection Unit & Reconstruction • Detection Unit: 18 DOMs, 31 photomultipliers each • Dataset Livetime 1 DU → 82 days 2 DUs → 17 days • Event Reconstruction: → Maximum likelihood method for track ~9m hypothesis using PDFs generated from θ Zenith Monte-Carlo simulations ~30m z vertex • Task: ν μ → Search for neutrino candidates requires r vertex ~20m dedicated event selection July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 3/18
Analysis Details & Event Selection Cuts
μ - Reconstructed Events • Problem: → Event rate dominated by atmospheric down-going muons → Rate of ’up-going’, i.e. mis-reconstructed, muon events still ∼ 10 4 higher than actual neutrino event rate • up-going events → Neutrino events 10 5 10 4 Events nu (1DU) ×10 3 ~9m data (1DU) θ Zenith muon (1DU) 10 3 nu (2DUs) ×10 3 ~30m data (2DUs) z vertex muon (2DUs) 10 2 ν μ 1.00 0.75 0.50 0.25 0.00 0.25 0.50 0.75 1.00 r vertex cos( ) Zenith distribution of all reconstructed events July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 5/18
Event Topology • Event trigger: large clusters of causally connected detected photons at the PMTs (hit) • Search for hit patterns of up-going events • Identification of (spacial) characteristics for event selection Simulated atmospheric muon event Simulated neutrino event July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 6/18
Data / Monte-Carlo comparison • Data is in good agreement with Monte-Carlo simulations Triggered DOMs (No Event Selection) 10 6 muon muon data data 10 6 10 5 nu x 1.0e+04 nu x 1.0e+04 10 5 10 4 Events Events 10 4 10 3 10 3 10 2 10 2 0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 n n Number of triggered DOMs (2 DUs) Number of triggered DOMs (1 DU) Radial Vertex Distance (No Event Selection) 10 7 muon 10 7 data 10 6 nu x 1.0e+04 10 6 10 5 10 5 Events 10 4 Events 10 4 10 3 10 3 10 2 muon 10 2 data 10 1 nu x 1.0e+04 0 20 40 60 80 100 10 1 r vtx 0 20 40 60 80 100 Radial vertex distance (2 DUs) r vtx Radial vertex distance (1 DU) July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 7/18
Geometrical Cuts μ - • Require reconstructed tracks close to the DU(s) • Horizontal muon tracks below the DU(s) create (also) up-going patterns × 10 4 × 10 3 3.0 nu (1DU) ×1000 nu (1DU) ×1000 1.50 muon (1DU) muon (1DU) 2.5 nu (2DUs) ×1000 nu (2DUs) ×1000 1.25 2.0 muon (2DUs) muon (2DUs) 1.00 Events Events 1.5 0.75 1.0 0.50 0.5 0.25 ~9m 0.0 0.00 θ Zenith 0 50 100 150 200 0 20 40 60 80 100 r vtx z trg ~30m z vertex Mean height of tiggered hits Radial distance of the reco. ν μ r vertex vertex Cut: � z trg � > 40 m ~20m Cut: r vtx < 20 m July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 8/18
Likelihood / Reconstruction Cuts • Check likelihood value of best × 10 1 up-going solution nu (1DU) 4 muon (1DU) • Other cuts: nu (2DUs) muon (2DUs) 3 → Likelihood value difference Events between best up- and 2 down-going solution 1 • Possible improvements: 0 → Use likelihood value normalised 0 25 50 75 100 125 150 175 200 Q up to number of degrees of freedom Likelihood of best up-going solution Cut: Q up > 40 July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 9/18
Resulting Zenith Distribution Analysis Initial events ν Candidates (MC) Mis-reco. muons in MC Rate 1 . 4 × 10 7 17 ( 5 . 2 ) 1DU 1 0.2 / day 5 . 0 × 10 6 43 ( 1 . 4 ) 2DU 0 2.5 / day 2DU (min. muons) 5 . 0 × 10 6 81 ( 5 . 22 ) 0 4.8 / day Zenith (Neutrino Selection) 10 1 10 1 muon muon data data nu nu 10 0 10 0 Events Events 10 1 10 1 10 2 10 2 1.0 0.8 0.6 0.4 0.2 0.0 1.0 0.8 0.6 0.4 0.2 0.0 cos( ) cos( ) July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 10/18
Final Remarks / Outlook • Event reconstruction with one/two DUs → Neutrino identification possible → Features for Sparking PMTs and Bioluminesence effects needed • No blinding → Main goal: understanding the detector ⇒ Focus on geometrical cuts • Current status: → Preliminary Results → Start from other ongoing collaboration analysis (cross-check) → Most promising: Arrival time residual w.r.t. reco. hypothesis • Outlook: → Use also the four installed DUs → Development of (new) cut features on-going July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 11/18
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Backup
cos(Zenith)=0.563442000012 Run: 4919, EventID: 12281 200 150 z [m] 100 50 0 0 250 500 750 1000 1250 1500 1750 2000 Time [ns] 175 150 125 z [m] 100 Neutrino Candidate 75 50 100 50 0 50 100 150 200 Time residual [ns] cos(Zenith)=0.563442000012 Run: 4919, EventID: 12281 200 200 150 150 z [m] z [m] 100 100 50 50 0 0 0 250 500 750 1000 1250 1500 1750 2000 0 250 500 750 1000 1250 1500 1750 Time [ns] Time [ns] 175 175 150 150 125 125 z [m] z [m] 100 100 75 75 50 50 100 50 0 50 100 150 200 100 50 0 50 100 150 200 Time residual [ns] Time residual [ns] 200 150 Run: 4919, EventId: 12281, cos(Θ) = 0 . 56 z [m] 100 50 July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 14/18 0 0 250 500 750 1000 1250 1500 1750 Time [ns] 175 150 125 z [m] 100 75 50 100 50 0 50 100 150 200 Time residual [ns]
cos(Zenith)=0.194254508542 Run: 4897, EventID: 24439 200 150 z [m] 100 50 0 0 250 500 750 1000 1250 1500 1750 Time [ns] 150 z [m] 100 Reconstuction Hit Selection 50 100 50 0 50 100 150 200 Time residual [ns] cos(Zenith)=0.194254508542 Run: 4897, EventID: 24439 200 200 150 150 z [m] z [m] 100 100 50 50 0 0 0 250 500 750 1000 1250 1500 1750 0 500 1000 1500 2000 Time [ns] Time [ns] 150 150 z [m] z [m] 100 100 50 50 100 50 0 50 100 150 200 100 50 0 50 100 150 200 Time residual [ns] Time residual [ns] 200 150 Run: 4897, EventId: 24439, cos(Θ) = 0 . 19 z [m] 100 50 July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 15/18 0 0 500 1000 1500 2000 Time [ns] 150 z [m] 100 50 100 50 0 50 100 150 200 Time residual [ns]
cos(Zenith)=0.873935298157 Run: 5004, EventID: 22573 200 150 z [m] 100 50 0 0 250 500 750 1000 1250 1500 1750 2000 Time [ns] 175 150 125 z [m] 100 Sparking PMT 75 50 25 100 50 0 50 100 150 200 Time residual [ns] cos(Zenith)=0.873935298157 Run: 5004, EventID: 22573 200 200 150 150 z [m] z [m] 100 100 50 50 0 0 0 250 500 750 1000 1250 1500 1750 2000 0 200 400 600 800 1000 1200 1400 Time [ns] Time [ns] 175 175 150 150 125 125 z [m] z [m] 100 100 75 75 50 50 25 25 100 50 0 50 100 150 200 100 50 0 50 100 150 200 Time residual [ns] Time residual [ns] 200 150 Run: 5004, EventId: 22573, cos(Θ) = 0 . 87 z [m] 100 50 July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 16/18 0 0 200 400 600 800 1000 1200 1400 Time [ns] 175 150 125 z [m] 100 75 50 25 100 50 0 50 100 150 200 Time residual [ns]
cos(Zenith)=0.744312870382 Run: 4814, EventID: 7878 200 150 z [m] 100 50 0 400 600 800 1000 1200 1400 1600 1800 Time [ns] 175 150 125 z [m] 100 Bioluminesence 75 50 100 50 0 50 100 150 200 Time residual [ns] cos(Zenith)=0.744312870382 Run: 4814, EventID: 7878 200 200 150 150 z [m] z [m] 100 100 50 50 0 0 400 600 800 1000 1200 1400 1600 1800 0 500 1000 1500 2000 Time [ns] Time [ns] 175 175 150 150 125 z [m] z [m] 125 100 100 75 75 50 50 100 50 0 50 100 150 200 100 50 0 50 100 150 200 Time residual [ns] Time residual [ns] 200 150 Run: 4814, EventId: 7878, cos(Θ) = 0 . 74 z [m] 100 50 July 29, 2019 | Johannes Schumann | FRANCI19 | Analysis of first ORCA data 17/18 0 0 500 1000 1500 2000 Time [ns] 175 150 z [m] 125 100 75 50 100 50 0 50 100 150 200 Time residual [ns]
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