NOvA Near Detector: Performance and Physics Hongyue Duyang For the NOvA collaboration 1 Οutline • Introduction to the NOvA near detector. • Rock-muon induced EM showers. • νe-CC inclusive cross-section measurement. • Coherent π0 cross-section measurement. • Neutrino-electron elastic scattering for absolute flux constraint. • Summary 2 Introduction • NOvA is a long-baseline neutrino experiment designed to measure νμ to νe oscillation. (See Adam Aurisano’s talk for the first result!) • The principal task of the NOvA near detector is to constrain systematics for oscillation measurement. • In addition, the NOvA near detector provides an excellent opportunity for the measurement of various neutrino interactions. • Neutrino interactions have their own physics, and are important for oscillation experiments to reduce systematics. • This talk will highlight some measurements using NOvA’s early data: • νe-CC inclusive cross-section measurement. • Coherent π0 cross-section measurement. • Neutrino-electron elastic scattering for absolute flux constraint. 3 The NOνA Near Detector NOνA Near Detector Construction NO�A NO�A Far Detector (Ash River, MN) MINOS Far Detector (Soudan, MN) A broad physics scope • • Detector construction and instrumentation0.3 kton, completed4.2mX4.2mX15.8m, Aug.Using ��→�e , � ͞ �→� ͞ e … ° Determine the � mass hierarchy ° Determine the � octant 2014 • 1 km from source, underground at Fermilab.23 ° Constrain �CP • PVC cells filled with liquid scintillatorUsing ��→�� , � ͞ .�→ � ͞ � … • Neutrinos observed within seconds of turning on! ° Precision measurements of 2 2 sin 2�23 and Dm 32. • Alternating planes of orthogonal (Exclude view. �23=�/4?) ° Over-constrain the atmos. sector Results (four oscillation channels) Also … ° Neutrino cross sections at the NO�A Near Detector ° Sterile neutrinos Bin to bin correlation matrix: ° Supernova neutrinos Fermilab ° Other exotica Ryan Patterson, Caltech • Low-Z, fine-grained (1 plane ~ 0.15X0), highly- active tracking calorimeter, optimized for EM shower reconstruction. Mass weight of detector component: C12 Cl35 H1 Near DetectorTi48 O16 Others 11 0.3 kton Jonathan M. Paley 66.8% 16.4% 10.5% 206 3.3%layers 2.6% 0.4% 4 cm ⨯ 6 cm 4 The measured inclusive cross section from Gargamelle, T2k, and NOvA as shown. There is also shown the predicted cross section for nue on carbon from GENIE. There is large correlation between the energy bins for NOvA results (see Top table). Our detector material is dominant by the carbon, chlorine, and hydrogen. 11/17 NuInt 2015 Xuebing Bu (Fermilab) 28 NuMI off-axis beam NO�A detectors are sited NuMI NuMI Beam Beam 14 mrad off the NuMI The NuMI Beam beam axis With the medium-energy NuMI tune, yields a narrow 2-GeV spectrum at the NO�A detectors ➔ Detectors are installed by being ➔ Detectorsoff beam are installed axis by being off beam axis on axis → Reduces NC and �e CC ➔ Narrow band beam peaked at 2 GeV backgrounds in the ➔ Narrow14 mrad band beam peaked at 2 GeV (NO➔ �NearA) maximum oscillation oscillation analyses ➔ Near ➔maximumReduced oscillation NC background while maintaining high � flux at 2 GeV. ➔ Reduced➔ Electron NC background neutrino flux counts ~1% � of total flux. ➔ Electron neutrino flux counts ~1% of total flux. Ryan Patterson, Caltech 7 Fermilab JETP, August 6, 2015 • Narrow11/17 NuInt 2015band neutrino beam peakXuebing Buat (Fermilab) ~2GeV. 5 11/17 •NuIntDominated 2015 by νμ (94%), withXuebing small Bu (Fermilab) contribution from νe (1%). 5 5 Near Detector: 10 �s of readout during NuMI beam pulse (color ⇒ time of hit)Neutrino Interaction in ND • Introduction to the NOvA near detector. • Rock-muon induced EM showers. • νe-CC inclusive cross-section measurement. • Coherent π0 cross-section measurement. • Neutrino-electron elastic scattering for absolute flux constraint. • Summary Ryan Patterson, Caltech 10µs of readout during16 NuMI beam pulse.Fermilab JETP, August 6, 2015 6 Οutline • Introduction to the NOvA near detector. • Rock-muon induced EM showers. • νe-CC inclusive cross-section measurement. • Coherent π0 cross-section measurement. • Neutrino-electron elastic scattering for absolute flux constraint. • Summary 7 Rock-Muon Induced EM Showers • Rock muons induce EM showers in the detector via bremsstrahlung radiation. • A muon-removal technique is developed to isolate those EM showers. • Provide a data-driven method to Check EM shower modeling and reconstruction for measurements involving EM showers. 8 Rock-Muon Induced EM Showers • Rock muons induced EM showers in the detector via bremsstrahlung radiation. • A muon-removal technique is developed to isolate those EM showers. • Provide a data-driven method to Check EM shower modeling and reconstruction for measurements involving EM showers. 9 ReconstructionEM Shower of shower Angular directions Resolution θshw - θμ (rad) • A “measured” angular resolution in data by comparing the 36 Jonathan M. Paley reconstructed EM shower direction to the muon direction. • The NOvA ND has good angular resolution (~0.02rad) for EM showers. • Important to measurements such as neutrino-electron elastic scattering and coherent π0 cross-section measurement. 10 Οutline • Introduction to the NOvA near detector. • Rock-muon induced EM showers. • νe-CC inclusive cross-section measurement. • Coherent π0 cross-section measurement. • Neutrino-electron elastic scattering for absolute flux constraint. • Summary 11 νe-CC Inclusive Cross-Sectionνe + A CC Interactions Measurement in the NOνA Near Detector NOνA Simulation 10 Full phase-space 1 50 p.o.t.) 8 21 /nucleon) 0.8 • Inclusive cross-section 2 40 - cm measurement: νe + N => Χ + e 6 CC flux -39 30 e 0.6 T2K ν flux ν from µ 10 e /50 MeV/10 • × There are very few electron NEUT νe prediction 2 0 0 ± ( 4 from KL, K , and K 20 GENIE νe prediction 0.4 S σ NEUT average neutrino cross section νe /cm 9 GENIE νe average CC 10 Gargamelle data Fraction of measurements at GeV scale. ν νe 10 2 × 0.2 T2K νe data T2K νµ data flux ( 0 0 e 0 1 2 3 4 5 6 7 8 9 10 ν 2 4 6 8 10 E (GeV) E (GeV) νe PRL 113, 241803 (2014) ν • Very limited world data • Beam electron neutrino interactions are irreducible backgrounds for the electron neutrino appearance analysis.• NOvA has a unique opportunity to make a clean measurement of ν • Measuring the electron neutrino inclusivee CC cross inclusive section, cross in sectionparticular in the 1 – 3 GeV energy region is important• Will restrict for long-baseline to 1-3 GeV range for the time being experiment, like DUNE. 24 Jonathan M. Paley 12 Event display νe-CCfor Inclusive nue candidate Cross-Section in Measurement data 11/17 NuIntThe 2015 signal events areXuebing νe-CC Bu (Fermilab) events with EM showers 32 induced by the electrons in the final state. 13 BDT output distributions BDT output distributions νe-CC Inclusive Cross-Section: Event Selection • Pre-selection cuts on fiducial, containment, shower length and energy, fraction of MIP hits, andLeft EM plot likelihood shows theapplied. shape distributions of BDT output for the nue CC signal and numu CC and NC background. • Build multi-variantLeft plot showsBoost D theecision shape Tree distributions (BDT) algorithm of BDT based output upon for shower the nue CC signal Right plot shows the BDT output distributions after event selection from data, properties to reduce background:and numu CC and NC background. Right plot shows thesignal BDT and output various distributions backgrounds. after event selection from data, • Fraction of MIP hitsAll in eventssub-leading are selected prong with preselection cuts. signal and various backgrounds. • 11/17Fraction NuInt 2015 of energy in ±4cmAll events transverseXuebing are selected Buroad (Fermilab) with preselection cuts. 13 • Maximal fraction of energy in 6-continuous planes •11/17Fraction NuInt 2015 of energy in first 10 planes Xuebing Bu (Fermilab) 13 • Fraction of energy in 2nd, 3rd and 4th plane. νe-CC: Rock Muon EM Showers 20 2.6 × 1020 POT NOνA Preliminary 2.6 × 10 POT NOνA Preliminary 0.3 Brem EM Data Brem EM Data 0.25 0.25 Brem EM MC Brem EM MC 0.2 0.2 νe MC νe MC 0.15 0.15 0.1 0.1 Fraction of Events Fraction of Events 0.05 0.05 0 0 1 1.5 2 0 200 400 600 Shower Energy (GeV) Shower Length (cm) 2.6 × 1020 POT NOνA Preliminary • Use rock muon EM showers to 2000 check EM shower modeling and Data BDT algorithm. 1500 MC 1000 • Good agreement between data Events and MC. 500 • Take the data/MC difference in −0.4 −0.2 0 0.2 0.4 selection efficiency as systematics. 1.5 1 0.5 Data / MC −0.4 −0.2 0 0.2 0.4 15 BDT output νe-CC: Background Normalization 2.6 × 1020 POT NOνA Preliminary 2.6 × 1020 POT NOνA Preliminary 1400 2500 Data Data CC νe 1200 CC νe 2000 ROCK + CC ROCK + CC νe 1000 νe NC NC 1500 800 CC νµ CC νµ Events Events 600 1000 400 500 200 0.4 0.45 0.5 0.55 0.6 0.65 0.7 −0.3 −0.25 −0.2 −0.15 −0.1 1.2 1 1 0.9 0.8 0.8 0.6 0.7 0.6 Data / Bkg 0.4 Data / Bkg 0.4 0.45 0.5 0.55 0.6 0.65 0.7 −0.3 −0.25 −0.2 −0.15 −0.1 Fraction of MIP hits BDT output • Use 2 Sideband samples for background normalization: • Fraction of MIP hits > 0.45. • BDT < -0.1 • MC over predict backgrounds: choose a normalization factor of 0.95±0.2. 16 νe-CC: Flux NOνA Simulation 1 • νe flux comes from muon and kaon decay 0.8 muon • Systematics from beam transport and kaon CC flux e 0.6 hadron production. ν • Use external data (MIPP and NA49) to 0.4 constraint the hadron production uncertainty.