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The NOvA Experiment

The NOvA Experiment. Ji Liu On behalf of the NOvA collaboration College of William and Mary APS April Meeting April 1, 2012. NOvA. L ong -baseline neutrino oscillation experiment currently under construction Off-axis neutrinos from NuMI beam

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The NOvA Experiment

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  1. The NOvA Experiment Ji Liu On behalf of the NOvA collaboration College of William and Mary APS April Meeting April 1, 2012

  2. NOvA • Long-baseline neutrino oscillation experiment currently under construction • Off-axis neutrinos from NuMI beam • Two identical mostly active liquid scintillator detectors • Near Detector: serves as a non-oscillation reference • Far Detector: measure oscillations • Primary goal: observe and study and • oscillations at the atmospheric oscillation length/energy. • Gives NOvA sensitivity to θ13 , mass hierarchy, δcp • Secondary goal: measure sin2θ23 and Δm232to better precision Far Detector 810 km Near Detector APS April Meeting -- Ji Liu

  3. Neutrino Oscillation Channels • Accelerator experiments looks for νe appearance • Oscillation probability depends on sin22θ13, sin2θ23, δcp and mass hierarchy • Probability can differ between and Δm2sol Δm2atm Δm2atm Δm2sol Normal Hierarchy Inverted Hierarchy APS April Meeting -- Ji Liu

  4. Detectors • Massive, 65% active Far Detector • 15 kton, 810 km from source • Functionally equivalent Near Detector • 220 ton, 1 km from source • Both have fine spatial resolution to distinguish νeand NC events • 0.15 X0 per layer PVC extrusion + Liquid Scintillator 63m Read out via WLS fiber to APD APS April Meeting -- Ji Liu

  5. MC Events in NOvA p+ μ e Beam Small shower from 2nd γ APS April Meeting -- Ji Liu Reject 995/1000 background events and achieve 26% efficiency

  6. Off-Axis Feature Both detectors will be sited 14 mrad off the NuMI beam axis. • Increase low-energy neutrino flux • Narrow energy spectra enhances background rejection • narrow band beam peaked at 2 GeV, well matched to peak oscillation probability APS April Meeting -- Ji Liu

  7. Sensitivity to Mass Hierarchy Normal Hierarchy Inverted Hierarchy Daya Bay results Daya Bay results Daya Bay results is assuming 2sin2(θ23) = 1 APS April Meeting -- Ji Liu

  8. Far Detector Construction First block in place ~ early June 2012 First block filled ~ Aug 2012 First block outfitted ~ Nov 2012 First Data ~ 1 yr. from now APS April Meeting -- Ji Liu

  9. Near Detector On the Surface (NDOS) • Near detector prototype constructed on the surface in Fall 2010 • Currently taking data from the NuMI& Booster neutrino beams Top View SideView • Physics goal of NDOS: • Study response of the detector to neutrinos • Investigate the cosmic ray background • Calibrate the detectors (Seen T. Kutnink’s talk for more details) Side View APS April Meeting -- Ji Liu

  10. Michel Electrons PRELIMINARY • Use for electro-magnetic energy calibration • Easy to identify by looking at the end of the muon tracks for late hits • Have average ~ 4 hits per event Here colors of the cellsrepresent time, green hits are 4 μslater than blue ones Michel e APS April Meeting -- Ji Liu

  11. Conclusion • NOvA is on track to make many important contributions to neutrino physics • Measurement of θ13 • Determination of mass hierarchy • More precise measurements of Δm2, sin2(2θ23) • Far detector construction is starting and will take its first data in ~ 1 year • Prototype detector has been running for one year • Studying calibration • Initial studies of neutrino interactions APS April Meeting -- Ji Liu

  12. Back-up Slides APS April Meeting -- Ji Liu

  13. Neutrinos Oscillation Channels • νe disappearance reactor experiments • Looking for νe disappearance • Probability depends on sin22θ13 and Δm2 • CHOOZ, Double-Chooz and Daya Bay Atmospheric L/E P( νe -> νe) Solar L/E L/E (km/MeV) APS April Meeting -- Ji Liu

  14. Neutrinos • Neutrinos have two sets of eigenstates • Weak eigenstates (νe, νμ, ντ) • Mass eigenstates (ν1, ν2, ν3) • Neutrinos oscillations come about because the weak eigenstates are rotated from the mass eigenstates. weak eigenstates mass eigenstates unitary mixing matrix APS April Meeting -- Ji Liu

  15. Neutrinos: What we know • Mixing angle: • Mass Hierarchy Mu -> e E -> mu, tao Mu-> tao Reactor + Solar, L/E~15 km/MeV atmospheric and accelerator, L/E~0.5 km/MeV Sin2(2θ13)= 0.092 ± 0.016(stat) ± 0.005(syst) Solar neutrinos: Atmospheric neutrinos: APS April Meeting -- Ji Liu

  16. Neutrinos: What we don’t know • Mass Hierarchy • CP violation phase is unconstrained Delta msol2 • Neutrino mass hierarchy • Individual mass of neutrino Delta matm2 Delta matm2 Delta msol2 APS April Meeting -- Ji Liu

  17. NOvA Features • Long baseline & Matter effects The neutrinos in the NuMI beam propagate through the earth and a coherent charged-current forward scattering of mu-e with electrons in the earth induces a significant change in the oscillation probabilities. These matter effects have opposite sign for neutrino and anti-neutrino and for the normal versus inverted neutrino mass ordering. • Optimized for the detection of both νμ→ νe and νμ → νe oscillations NOvA will split its running time equally between neutrino running and antineutrino running. It will make the sensitivity to seeing a signal less dependent on the value of δcpand the sign of Δm2and give NOvA the capability of measuring them. APS April Meeting -- Ji Liu

  18. Sensitivity to Mass Hierarchy Combing T2K Results Normal Hierarchy Inverted Hierarchy Daya Bay results Daya Bay results Daya Bay results is assuming 2sin2(θ23) = 1 APS April Meeting -- Ji Liu

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