The NOvA neutrino experiment and its astrophysics program
Matthew Strait, for the NOvA collaboration
University of Minnesota, Twin Cities
February 22, 2021
Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 1 / 27 Introduction Outline
Overview of NuMI beam and NOvA detectors Neutrino oscillation results (rapidly) See more detail Wednesday 17:30: talk by Zoya Vallari Astrophysics
NOvA Far Detector
Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 2 / 27 Design Design Overview
Fermilab’s NuMI beam Near detector Observe unoscillated beam composition, energy Far detector observes: νµ → νµ νµ → νe ν¯µ → ν¯µ ν¯µ → ν¯e
NOvA Simulation
NOvA Far Detector νµ
POT νµ Off-axis → narrow 13 3 10 ν e 10
× ν spectrum at 2 GeV e 102 1st oscillation
/ GeV 5 10 maximum at 2 810 km 1
Neutrinos / m 10−1 0 5 10 15 20 Neutrino energy (GeV)
Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 3 / 27 Design Detector Technology
Two functionally identical detectors Segmented plastic and scintillator tracking calorimeter 63% active APD readout Near detector is 300 t, underground, 1 km from NuMI target Far detector is 14 kt, on the surface
32 pixel APD sees fiber pairs from 32 cells
Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 4 / 27 Design Event Topologies
1m
Proton Beam νμ + n → μ + p → 1m Muon
Michel e- Optimized for ν Charged Current μ EM showers Proton νe + n → e + p ∼6 samples per X Electron 0 Convolutional νe Charged Current neural net Proton ν + X → ν + X' classifier selects
π0 (→γγ) signal events
Neutral Current
Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 5 / 27 Results νµ Analysis
Far Detector Data: 2013–2020 — νµ disappearance Neutrino mode: 13.6 × 1020 POT Anti-neutrino mode: 12.5 × 1020 POT 211 events selected 105 events selected Background: 9.2 events Background: 2.1 events
ν-beam NOvA Preliminary ν-beam NOvA Preliminary
FD data FD data 20 10 2020 Best-fit 2020 Best-fit σ 1- syst. range 8 1-σ syst. range 15 Background Background 6 10 4 Events / 0.1 GeV Events / 0.1 GeV 5 2
0 1 1 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 Ratio to no osc. 0 Ratio to no osc. 0 0 1 2 3 4 5 0 1 2 3 4 5 Reconstructed neutrino energy (GeV) Reconstructed neutrino energy (GeV)
Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 6 / 27 Results νe Analysis
Far Detector Data — νe appearance
82 events in ν mode 33 events inν ¯ mode Background: 26.8 events Background: 14.0 events 1.0 wrong-sign (appearingν ¯e) 2.3 wrong-sign 22.7 other beam (intrinsic νe, νµ, ντ , 10.2 other beam neutral current) 1.6 cosmic 3.1 cosmic > 4σ electron anti-neutrino appearance
ν-beam NOvA Preliminary ν-beam NOvA Preliminary
30 Core only Core only FD data 15 FD data 2020 best-fit 2020 best-fit 1-σ syst range POT 1-σ syst range 20
POT-equiv Wrong sign bkg Wrong sign bkg 10
20 Total beam bkg Total beam bkg 20 × Cosmic bkg Cosmic bkg
10 10 ×
10 5 Events / 12.50 Events / 13.60 0 0 1 2 3 4 1 2 3 4 Reconstructed neutrino energy (GeV) Reconstructed neutrino energy (GeV)
Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 7 / 27 Results Combined
2 Combined Appearance/Disappearance Results — θ23, ∆m32
2 −3 2 ∆m32 = (2.41±0.07)×10 eV NOvA Preliminary (normal hierarchy)
NOvA FD 13.6×1020 POT equiv ν + 12.5×1020 POT ν Normal Hierarchy 90% CL 3 NOvA Preliminary NOvA MINOS+ 2020
) 2.5
3.0 T2K 2020 IceCube 2018 σ SK 2020 ) 2 2 1.5 eV -3 1 Normal hierarchy (10
2.5 Significance ( Inverted 2 32 0.5 hierarchy m
∆ 0 0.4 0.5 0.6 0.7 2θ sin 23
2.0 NOvA Best fit Slight preference for upper
0.4 0.5 0.6 octant, normal hierarchy 2θ 2 +0.04 sin 23 sin θ23 = 0.57−0.03
Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 8 / 27 Results Combined
Combined Appearance/Disappearance Results — Mass ordering, θ23, δCP
NOvA Preliminary 0.7 NOvA FD 13.6×1020 POT equiv ν + 12.5×1020 POT ν 5 NOvA Preliminary 0.6 NH Lower octant 23
) NH Upper octant θ σ 2 4 0.5 IH Lower octant
sin IH Upper octant 0.4 3
Normal hierarchy ≤1σ ≤2σ ≤3σ Best Fit 0.3 NH 2 0 π π 3π 2π 2 δ 2
CP Significance ( 1 NOvA Preliminary 0 0.7 0 π π 3π 2π 2 2 δCP 0.6 23 θ 2 0.5 All values of δ allowed sin 0.4 Prefer normal hierarchy by 1.0σ
≤1σ ≤2σ ≤3σ Best Fit Prefer upper octant by 1.2σ
Inverted hierarchy 0.3 IH 0 π π 3π 2π Exclude δ = π/2 inIH at > 3σ 2 δ 2 CP Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 9 / 27 Astrophysics Astrophysics
NOvA Far Detector
As a large fine-grained detector, the Far Detector supports a variety of astrophysical analyses Some benefit from the FD’s location on the surface Some can be done in spite of it Cosmic muon rate: 150 kHz Near Detector: 100 m underground — much smaller, but much quieter 36 Hz of cosmics
Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 10 / 27 Astrophysics Triggers for Astrophysics
10,752 FEBs (344,064 det. channels) FEB FEB FEB FEB FEB FEB FEB FEB FEB FEB 11,160 Front End Boards FEB FEB FEB FEB Shared Memory ARTDAQ Data Driven Triggers System DDT event stack DCM 1 ARTDAQ-1 ARTDAQ-2 ARTDAQ-N All data continuously Zero Suppressed Processor Processor Processor DCM 1 5 ms data at ½ - ⅔ MIP DCM 1 DCM 1 180 Data Concentrator Modules blocks digitized (6 - 8 MeV/cell) DCM 1 DCMs
/s Data Event builder
Buffered for ∼20 minutes Gb Buffer Trigger Recep on while trigger decisions are
Minimum Bias Data Slice Pointer Table 0.75 GB/S Stream made Ethernet 1 » Data Time Window Search COtS 140-200 Buffer Node Computers Data Beam triggers Buffer Nodes Buffer Nodes Buffer Nodes
Buffer Nodes Data Other external triggers Buffer Nodes Buffer Nodes 200 Buffer Nodes Data-driven triggers (3,200 Compute Cores)
Triggers request anywhere from 50 µs (e.g. cosmic showers) to 45 seconds (supernova) No dead time: triggers do not interfere with each other
Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 11 / 27 Astrophysics Cosmic Rays Cosmic ray multi-muon seasonal effect at the Near Detector
Well-known: underground cosmic rate higher in summer Less dense summer atmosphere → more π decay before interacting But we observe more multi-µ in winter Phys.Rev.D 99 (2019) 12, 122004 Effect larger with higher multiplicity No clear explanation
10 2.5 Multiple-muon data 20 8 Effective temperature data (ECMWF) 2
6 1.5 10 4 1 > (%) > (%) > (%) > (%) µ µ 2 0.5 eff 0 eff
0 0 M = 2 / R 2 0.5 R T T ∆ ∆ ∆ ∆ M = 4 −4 −1 −20 M = 5 −6 −1.5 M ≥ 6 −8 −2 −30 2015-01 2015-07 2016-01 2016-07 2017-01 2017-07 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Date (year-month) Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 12 / 27 Astrophysics Cosmic Rays Seasonal multi-muon effect in the Far Detector 0 1000 2000 3000 4000 5000 6000 500 0 x (cm) −500 NOvA Preliminary 1.25 Weekly R 500 µ 1.2 0 1000 2000 3000 4000 5000 6000 (Hz) z (cm) µ 1.1 NOvA - FNAL E929 R 3 103 Run: 23156 / 10 10 2 hits 102 hits 10 Event: 119763 / DDenergy 10 10 1 1 UTC Wed Jun 1, 2016 − − − − − 50 40 30 20 10 0 10 20 30 40 50 10 102 103 1.05 19:04:8.793091456 t (µsec) q (ADC) Study sample of muon showers with 1 multiplicity > 15 2016-01 2016-06 2016-11 2017-05 2017-09 2018-03 2018-07 Also observe winter maximum Simulation work underway to find explanation of effects in both Near and Far Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 13 / 27 Astrophysics Cosmic Rays Other Cosmic Ray Studies 1 Measurement of low-energy east-west asymmetry Caused by Earth’s B field 2 Short-term weather effects Known, but understudied 3 Solar flare correlation? Claimed by L3+C L3+C: 4 Measure muon rates above 100 TeV Resolve Baksan/IceCube discrepancy? Phys.Part.Nucl. 49 (2018) 4, 639 A&A 456, 351 Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 14 / 27 Astrophysics Cosmic Rays Discovery of ICARUS µ-Flux Excess (64±4° Zenith, and 179±9° Azimuth) in NOvA-ND, due to SBN-FD 24.8. - 3.9. 2015 10 5 -Flux Excess [%] µ 12. - 23.8. 2015 0 2015-04 2015-07 2015-10 2016-01 2016-04 2016-07 2016-10 2016-12 2017-04 Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 15 / 27 Astrophysics Monopoles Magnetic Monopole Search Search for a monopole component of cosmic rays in the Far Detector Large surface area — catch rare events On surface — sensitive to lighter monopoles that don’t reach far underground Signals: −2 If β & 10 : highly ionizing, like a charge of 68.5e −2 If β . 10 : slow track NOvA sensitive down to β ≈ 10−4 Simulation Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 16 / 27 Astrophysics Monopoles Magnetic Monopole Search Results 10−12 ) NOvA 1 − −13 (This work) sr 1 10 8 − > 5 × 10 GeV SLIM s 2 5 Slow monopole search: − > 10 GeV 10−14 95-day exposure: MACRO 10 − > 10 GeV Phys.Rev.D 103 (2021) 1, 012007 10 15 ∼2000 days of exposure (with −16 different detector conditions) to be 10 MACRO analyzed 16 10−17 > 10 GeV IceCube 6 Fast monopole search: in progress 90% C.L. flux limit (cm > 10 GeV −18 10 − 10−4 10 3 10−2 10−1 1 Monopole speed (β) Set mass limits in flux/speed space: NOvA has best limits in yellow region Background-free: limits scale linearly with exposure Expect to reach 4 × 10−16 cm−2s−1sr−1 for 3 × 10−4 < β < 0.8 ≈ MACRO limits across most of the plot, but extending to lower masses Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 17 / 27 Astrophysics Multimessenger Astronomy Supernova neutrinos Core collapse supernovae release 99% of NOvA is mostly sensitive toν ¯e : their energy in neutrinos At Galactic center: ∼ 10–60 MeV Far Near + Burst lasting 10s of seconds ν¯e + p → e + n 2163 46 12 12 ∗ Only one SN observed in neutrinos: 1987a νx + C → νx + C 393 9 12 − 12 νe + C → e + N 137 3 12 + 12 ν¯e + C → e + B 139 3 − − νx + e → νx + e 199 4 Primary signal: 1–7 hits from positron Neutron capture on 35Cl marginally visible Largest operating carbon-based detector Complementary to water/lead/argon detectors for constraining flavor content Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 18 / 27 Astrophysics Multimessenger Astronomy Far Detector: 5 ms cosmic data + SN simulation Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 19 / 27 Astrophysics Multimessenger Astronomy Supernova Trigger Remove muon tracks, activity near tracks Trigger covers half the galaxy Filter by supernova candidate cluster energy SNEWS alerts cover the rest Plan to also send triggers to SNEWS soon JCAP 10 (2020) 014 Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 20 / 27 Astrophysics Multimessenger Astronomy Can we read out Betelgeuse? This is 5 ms of everyday data: Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 21 / 27 Astrophysics Multimessenger Astronomy Simulated peak flux from Betelgeuse, 5 ms, cosmic tracks removed: Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 22 / 27 Astrophysics Multimessenger Astronomy Multimessenger search with gravitational waves NOvA receives triggers from LIGO/Virgo Save 45 s of continuous data around each gravitational wave candidate Same as for a supernova candidate Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 23 / 27 Astrophysics Multimessenger Astronomy General multimessenger search Any unusual activity coincident with gravitational waves? Looked between MeV, 100s of TeV None found PRD 101, 11 112006 Cosmic event with ∼ 2000 muons Not coincident with a gravitational wave event Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 24 / 27 Astrophysics Multimessenger Astronomy Search for supernova-like neutrinos coincident with gravitational waves 90% limits: 9.6, 27 M supernova Red: median case for triggered FD Most likely signal for NOvA would be supernova neutrinos New multivariate analysis improves cosmic rejection Reduces FD background from 450 Hz to 5 Hz S200213t 100 80 9.6, 27 M at 10 kpc 60 40 Events/live-second 20 0 10 20 30 40 Time since event (s) Searched using 75 LIGO/Virgo events No excesses found Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 25 / 27 Conclusions Conclusions Neutrino oscillations Broad astrophysics program Appearance ofν ¯e in aν ¯µ beam at > 4σ Made possible by trigger system, Inverted hierarchy, δ ≈ π/2 excluded at > 3σ complementary Near and Far Detectors See talk Wednesday 17:30 for more details More results and new analyses to come Matthew Strait (UMN) NOvA — Neutrino Telescopes 2021 February 22, 2021 26 / 27