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Neutrino oscillations: Perspective of long-baseline experiments

Neutrino oscillations: Perspective of long-baseline experiments. 522. Wilhelm and Else Heraeus-Seminar: Exploring the neutrino sky and fundamental particle physics on the Megaton scale Bad Honnef, Jan. 21, 2013 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A.

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Neutrino oscillations: Perspective of long-baseline experiments

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  1. Neutrino oscillations: Perspective of long-baseline experiments 522. Wilhelm and Else Heraeus-Seminar:Exploring the neutrino sky and fundamental particle physics on the Megaton scale Bad Honnef, Jan. 21, 2013Walter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAAAAA

  2. Contents • Introduction • Measurement of dCP:Experiments and phenomenology • The critical issue for large q13: Systematics? • Long-baseline alternatives with new technologies? • Comment on sterile neutrinos • Summary

  3. (short baseline) (also: T2K, Double Chooz, RENO)

  4. Consequences of large q13 • q13 to be well measured by Daya Bay • Mass hierarchy: 3s discovery for up to 40% of all dCP possible iff ProjectX, possiblyuntil 2025 • CP violation measurement extremely difficultNeed new facility! Huber, Lindner, Schwetz, Winter, 2009

  5. Mass hierarchy measurement? • Mass hierarchy discovery possible with atmospheric neutrinos? (liquid argon, HyperK, MEMPHYS, INO, PINGU, ORCA …) Barger et al, arXiv:1203.6012;IH more challenging Perhaps differentfacilities for MH and CPVproposed/discussed?  Talks by Smirnov (2), Resconi, Heijboer • NB: basically any new LBL experiment at design luminosity with E > 1 GeV and L >> 600 km can for all dCP measure the hierarchy in ne-nm transition (MSW effect)! • Alternative: medium-baseline reactor experiments, perhaps

  6. Measurement of dCP:Experiments and phenomenology

  7. Why is dCP interesting? sind • CP violationNecessary condition for successful baryogenesis (dynamical mechanism to create matter-antimatter asymmetry of the universe) thermal leptogenesis by decay of heavy see-saw partner? • Model buildinge.g. TBM sum rule: q12 = 35 + q13cosd (Antusch, King; Masina) • Need performance which is equally good for all dCP cosd Correction leadingto non-zero q13? Symmetrye.g. TBM, BM, …?

  8. Long-baseline oscillations • Antineutrinos:Problem: Earth matter violates CP, CPT explicitely! • Silver:Challenging (t threshold, many t decay channels, vertex res.) • Platinum, T-inv.: Works only for Superbeam + Beta beam (later) Large! (Cervera et al. 2000; Freund, Huber, Lindner, 2000; Akhmedov et al, 2004)

  9. Possible LBL neutrino sources There are three possibilities to artificially produce neutrinos • Beta decay: • Example: Nuclear reactors, Beta beams • Pion decay: • From accelerators: • Muon decay: • Muons produced by pion decays! Neutrino Factory Superbeam Muons,neutrinos Pions Neutrinos Protons Target Selection,focusing Decaytunnel Absorber

  10. Example: Neutrino FactoryInternational Design Study (IDS-NF) (Geer, 1997; de Rujula, Gavela, Hernandez, 1998; Cervera et al, 2000) • IDS-NF: Initiative from ~ 2007-2013 to present a design report, schedule, cost estimate, risk assessment for a neutrino factory • Vision? Staged approach towards high-energy frontier ( muon collider) Signal prop. sin22q13 Contamination  magnetized detector! Muons decay in straight sections of a storage ring PRELIMINARY

  11. The new paradigm: Precision?  Talk by Diwan C2P = LBNO:CERN-PyhäsalmiL~2300 km, 100kt liquid argon • CP violation performance represents only two possible values of dCP (0 and p) • Need new performance indicators, e. g. • Reveals that some experiments (narrow beam spectra!) strongly optimized for CPV Bands: q13 allowed ranges 1s (Coloma, Donini, Fernandez-Martinez, Hernandez, 2012)

  12. The critical issue for large q13:Systematics?

  13. Fluxes and cross sections: Superbeam, beta beam (illustrated) ? • Superbeam • Beta beam Near detector Appearance Fardetector Flux F1 Disappearance BB+SPL ? Near detector Appearance Fardetector Flux F2 Disappearance

  14. Fluxes and cross sections:Neutrino Factory (Tang, Winter, PRD 80, 053001, 2009) • Muon (anti)neutrino cross sections measured in self-consistent way • Fluxes in and fully correlated

  15. The big unknown: Systematics • New treatment needed • Use explicit near-far detector simulations • Use same knowledge for cross sections for all experiments • Define ranges for systematical errors: optimistic-default-conservative • Use identical framework for systematics implementation/correlations • Define reasonable ranges for experiment-dependent systematics: (Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

  16. Long-baseline options • Setup table + Daya Bay (Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

  17. Precision: Worldwide comparison (bands: systematics opt.-cons.) CKM phase The Neutrino Factoryis the only instrumentwhich can measure dCPwith a precision comparableto the quark sector NF10BB350WBBT2HK (Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

  18. Interesting alternatives • Comparison at default systematics: NF5 exhibitsstrong dependence on dCP (some dependence on binning!) BB100+SPL is the only setup comparable with NuFact (Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

  19. Critical impacts? Robust wrt systematics Main impact:Matter density uncertainty Neutrino Factory Operate in statistics-limited regimeExposure more important than near detector orsystematics  MICA? High-E superbeam QE ne X-sec critical:no self-consistent measurementTheory: ne/nm ratio?Experiment: nSTORM? Low-E (QE!) superbeam (Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

  20. Long-baseline alternatives with new technologies?

  21. Superbeam CERN-LENA? L ~ 2300 km (special thanks: Pilar Coloma) • Main impact factors: • Neutral current backgrounds versus efficiency • Fiducial volume (cost?) • To be studied? • Background migration(no migration matrices yet? NC backgrounds reconstructed in energy window of signal) • Combination with liquid argon? 100 kt liquid argon 100 kt LENA90% eff.10% NC 50 ktLENA90% eff.30% NC PRELIMINARY 50 kt LENA90% eff.10% NC 50 ktLENA50% eff.10% NC  Talks by Wurm, Hellgartner

  22. Beam to South Pole? (Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998) • Probability for L=11810 km (CERN/FNAL/JHF-South Pole) ! Param.enhance-ment Parametric enhancementthrough mantle-core-mantleprofile of the Earth.Unique physics potential! Core resonanceenergy Mantleresonanceenergy Naive L/E scalingdoes not apply! Thresholdeffects expected at: 2 GeV 4-5 GeV

  23. IceCube/DeepCore upgrades? • Fill in IceCube/DeepCore array with additional strings • Drive threshold to lower energies • PINGU (“Precision IceCube Next Generation Upgrade“): LOI in preparation • Modest cost ~30-50M$ (dep. on no. of strings) • Two season deployment anticipated: 2015/2016/2017 • A megaton-class detector at a few GeV (param. enhancement) • Further upgrades being discussed (MICA) (PINGU, 12/2012)  Talks by Kowalski

  24. Example:Low-intensity superbeam? • Use existing equipment (Fermilab main injector), new beam line • Here: use most conservative assumption NuMI beam, 1021 pot (total), neutrinos only[compare to LBNE: 22+22 1020 pot without Project X ~ factor four higher exposure than the one considered here](FERMILAB-PROPOSAL-0875, NUMI-L-714) • Low intensity may allow for shorter decay pipe(< 600M$ ?) • Advantage: Peaks in exactly the right energy range for the parametric enhancement/core effect Pem M. Bishai

  25. Mass hierarchy: Event rates (Daya Bay best-fit) PRELIMINARY >18s(stat. only)

  26. NuMI-like beam to PINGU? • Very robust mass hierarchy measurement (as long as either some energy resolution or control of systematics); no directional information needed GLoBES 2012 (Daya Bay best-fit; current parameter uncertainties, minimized over) PRELIMINARY All irreducible backgrounds included

  27. Potential for dCP? • Energy resolution prerequisite: PRELIMINARY NH L=11810 km

  28. Upgrade path towards dCP? • Measurement of dCP in principle possible, but challenging • Requires: • Electromagnetic shower ID (here: 1% mis-ID) • Energy resolution (here: 20% x E) • Volume upgrade(here: ~ factor two) • Project X • Performance and optimization of PINGU and MICA requires further study = LBNE + Project X! same beamto MICA? Tang, Winter, JHEP 1202 (2012) 028

  29. Matter density measurementExample: LBNE-like Superbeam • Precision ~ 0.5% (1s) on core density • Complementary to seismic waves Tang, Winter, JHEP 1202 (2012) 028 (Alan Jones, 1999)

  30. Comments on sterile neutrinos

  31. Evidence for sterile neutrinos? • LSND/MiniBooNE • Reactor+gallium anomalies • Global fits • Cosmology (MiniBooNE @ Neutrino 2012) (B. Fleming, TAUP 2011) (e. g. Kopp, Maltoni, Schwetz, 1103.4570)

  32. Example: 3+1 framework • Well known tension between appearance and disapp. data (appearance  disapp. in both channels) • Need one or more new experiments which can test • ne disappearance (Gallium, reactor anomalies) • nm disappearance (overconstrains 3+N frameworks) • ne-nm oscillations (LSND, MiniBooNE) • Neutrinos and antineutrinos separately (CP violation? Gallium vs reactor?) • QE electron neutrino and antineutrino cross sections (T2HK!) • Example: nSTORM - Neutrinos from STORed Muons(LOI: arXiv:1206.0294)can do it all!Summary of options: Appendix of white paper arXiv:1204.5379 MiniBooNE

  33. Conclusions • The precision measurement of dCP requires a new dedicated long-baseline experiment • Such an experiment can (typically) also measure the mass hierarchy; however, there are alternatives • The critical impact factors for dCP are: • Exposure (high-E superbeam) • Electron neutrino cross sections (low-E superbeam, beta beam) • Matter density uncertainty (Neutrino Factory) • Alternatives require further study. Examples: • Beam to South Pole (MICA?) • Beam to LENA

  34. BACKUP

  35. New performance indicator (Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

  36. Impact of implementation • Gray (eff. systematics, 0-10%) versus color (new): • More precise predictions for Neutrino Factory (bands: conservative – optimtistic, curves: default) • Systematic offset for T2HK, BB350 (QE ne cross sec. issue) (Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

  37. NuFact vs. BB+SPL Near detectorsnot so important ifdisappearance information from FDand three-flavor framework validException: NF5(main impact) (Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

  38. 90% CL, existing equipment 3s, Project X and T2K with proton driver, optimized neutrino-antineutrino run plan Mass hierarchy using existing equipment? Huber, Lindner, Schwetz, Winter, JHEP 11 (2009) 44

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