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Impact of large q 13 on long-baseline measurements at PINGU

Impact of large q 13 on long-baseline measurements at PINGU

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Impact of large q 13 on long-baseline measurements at PINGU

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  1. Impact of large q13 on long-baseline measurements at PINGU PINGU WorkshopErlangen university May 5, 2012Walter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAAAAA

  2. Contents • Introduction • Oscillation physics using a core-crossing baseline • Neutrino beam to PINGU: Beams and detector parameterization • Detector requirements for large q13 • Matter density measurement? • Summary

  3. ( ) ( ) ( ) = x x Three flavor mixing • Use same parameterization as for CKM matrix Pontecorvo-Maki-Nakagawa-Sakata matrix Potential CP violation ~ q13 (sij = sin qij cij = cos qij)

  4. q13 discovery 2012 • First evidence from T2K, Double Chooz • Discovery (~ 5s) independently (?)by Daya Bay, RENO Daya Bay 3s 1s error bars (from arXiv:1204.1249)

  5. Three flavors: Summary • Three flavors: 6 params(3 angles, one phase; 2 x Dm2) • Describes solar and atmospheric neutrino anomalies, as well as reactor antineutrino disapp.! MH? Atmosphericoscillations:Amplitude:q23Frequency: Dm312 Solaroscillations:Amplitude:q12Frequency: Dm212 Coupling: q13 (Super-K, 1998;Chooz, 1999; SNO 2001+2002; KamLAND 2002;Daya Bay, RENO 2012) Suppressed effect: dCP

  6. Consequences Huber, Lindner, Schwetz, Winter, 2009 • Parameter space for dCP starts to become constrained; MH/CPV difficult (need to exclude dCP=0 and p) • Need new facility!

  7. Mass hierarchy measurement? • Mass hierarchy [sgn(Dm2)] discovery possible with atmospheric neutrinos? (liquid argon, HyperK, MEMPHYS, INO, PINGU?, LENA?, …) Barger et al, arXiv:1203.6012;Smirnov‘s talk! Perhaps differentfacilities for MH and CPVproposed/discussed? • However: also long-baseline proposals! (LBNO: superbeam ~ 2200 km – LAGUNA design study; CERN-SuperK ~ 8870 km – Agarwalla, Hernandez, arXiv:1204.4217)

  8. Oscillation physics using a core-crossing baseline

  9. Matter profile of the Earth… as seen by a neutrino Core (PREM: Preliminary Reference Earth Model) Innercore

  10. Beams to PINGU? • Labs and potential detector locations (stars) in “deep underground“ laboratories: (Agarwalla, Huber, Tang, Winter, 2010) FNAL-PINGU: 11620 kmCERN-PINGU: 11810 kmRAL-PINGU: 12020 kmJHF-PINGU: 11370 km NEW? All these baselines cross the Earth‘s outer core!

  11. Matter effect (MSW) (Wolfenstein, 1978; Mikheyev, Smirnov, 1985) • Ordinary matter: electrons, but no m, t • Coherent forward scattering in matter: Net effect on electron flavor • Hamiltonian in matter (matrix form, flavor space): Y: electron fraction ~ 0.5 (electrons per nucleon)

  12. Parameter mapping (two flavors) • Oscillation probabilities invacuum:matter: Matter resonance: In this case: - Effective mixing maximal- Effective osc. frequency minimal For nm appearance, Dm312:- r ~ 4.7 g/cm3 (Earth’s mantle): Eres ~ 7 GeV- r ~ 10.8 g/cm3 (Earth’s outer core): Eres ~ 3 GeV  MH Resonance energy:

  13. Mantle-core-mantle profile (Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998) • Probability for CERN-PINGU (numerical) Coreresonanceenergy Challenge: Relative size of dCP-termssmaller forlonger L Mantleresonanceenergy Inter-ference Is thatpart useful? Thresholdeffects expected at: Beam energyand detector thresh. haveto pass these! 2 GeV 5 GeV 10 GeV

  14. Neutrino beam to PINGU? Beams and detector parameterization

  15. Possible 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

  16. Considered setups • Single baseline reference setups: • Idea: similar beam, but detector replaced by PINGU/MICA [need to cover ~ 2 – 5 GeV]: L [km] (for details: Tang, Winter, JHEP 1202 (2012) 028, arXiv:1110.5908; Sec. 3)

  17. Oscillation channels Want to study ne-nm oscillations • Beta beams: • In principle best choice for PINGU (need muon flavor ID only) • Superbeams: • Need (clean) electron flavor sample. Difficult? • Neutrino factory: • Need charge identification of m+ and m- (normally)

  18. PINGU fiducial volume? • In principle: Mton-size detector in relevant ranges: • Unclear how that evolves with cuts for flavor-ID etc. (background reduction); MICA even larger? • Use effective detector parameterization to study requirements: Eth, Veff, Eres Eres (DE) = x E Veff Eth (Tang, Winter, JHEP 1202 (2012) 028; Veff somewhat smaller than Jason‘s current results)

  19. Detector paramet.: mis-ID misID: fraction of events of a specific channelmis-identified as signal misIDtracks << misID <~ 1 ? (Tang, Winter, JHEP 1202 (2012) 028)

  20. Detector requirements for large q13

  21. Superbeam (misIDtracks = 0.01) • Mass hierarchy measurement very robust(even with largemisID and totalrates only possible) • Even with much smaller-scale beam? • Existing equipment, such as CNGS? NuMI? • CPV not promising (requires flavor mis-ID at the level of 1%, Veff > 5 Mt, Eres = 0.2 E or better) Fraction of dCP (Tang, Winter, JHEP 1202 (2012) 028)

  22. NuMI-like beam to PINGU? • Difference to atmospherics: can even live without energy resolution and cascade ID (NC and nt added)(if some track ID and systematics controlled) PRELIMINARY NuMI

  23. Beta beam • Similar results for mass hierarchy measurement (easy) • CPV not so promising: long L, asymmetric beam energies (at least in CERN-SPS limited case g~656 for 8B and g=390 for 8Li) although moderate detector requirements (misID ~ 0.001, Eth=2 GeV, Eres=50% E, Veff=5 Mt) (Tang, Winter, JHEP 1202 (2012) 028)

  24. Neutrino factory • No magnetic field, no charge identification • Need to disentangle Pem and Pmm by energy resolution: (from: Tang, Winter, JHEP 1202 (2012) 028; for non-magnetized detectors, see Huber, Schwetz, Phys. Lett. B669 (2008) 294) )

  25. nt contamination • Challenge:Reconstructed at lower energies!(Indumathi, Sinha, PRD 80 (2009) 113012; Donini, Gomez Cadenas, Meloni, JHEP 1102 (2011) 095) • Choose low enough Em to avoid nt • Need event migration matrices (from detector simulation) for reliable predictions! (neutral currents etc) (sin22q13=0.1) (Tang, Winter, JHEP 1202 (2012) 028)

  26. Precision measurements? … only if good enough energy resolution ~ 10% E and misID (cascades versus tracks) <~ 1% can be achieved! (Tang, Winter, JHEP 1202 (2012) 028)

  27. The BONUS program: Matter density measurement of the Earth‘s core?

  28. Example: Superbeam • Precision ~ 0.5% (1s) • Highly competitive to seismic waves (seismic shear waves cannot propagate in the liquid core!) (Tang, Winter, JHEP 1202 (2012) 028)

  29. Conclusions [my personal view] • Superbeams • Electron sample (cascades) probably contaminated by other flavors; therefore precision measurements unlikely • Interesting option: Use more or less existing equipment for a mass hierarchy measurement? (e.g. CNGS/MINOS with new beam line?) • Bonus: matter density measurement of Earth‘s core • Unique experiment as low-budget alternative to LBNE? • Neutrino factory • Energy resolution critical, since non-magnetized detector • Detector simulation needed to produce event migration matrices for reliable conclusions if Eres ~ 10% E achievable? • Beta beams • Intrinsically best-suited for PINGU/MICA: flavor-clean beam, requires muon neutrino flavor-ID • However: need high intensity, high energy 8B-8Li setups for reasonable sensitivities; there are better ways to build a beta beam for large q13 to do both MH+CPV

  30. Statement of PINGU collaboration needed now (or never)!?

  31. BACKUP

  32. Beams: Appearance channels (Cervera et al. 2000; Freund, Huber, Lindner, 2000; Akhmedov et al, 2004) • Antineutrinos: • Magic baseline:L~ 7500 km: Clean measurement of q13 (and mass hierarchy) for any energy, value of oscillation parameters!(Huber, Winter, 2003; Smirnov 2006)In combination with shorter baseline, a wide range of very long baseline will do! (Gandhi, Winter, 2006; Kopp, Ota, Winter, 2008)

  33. Quantification of performanceExample: CP violation discovery Best performanceclose to max. CPV (dCP = p/2 or 3p/2) Sensitive region as a function of trueq13 anddCP dCP values now stacked for each q13 No CPV discovery ifdCP too close to 0 or p No CPV discovery forall values of dCP 3s ~ Precision inquark sector! Read: If sin22q13=10-3, we expect a discovery for 80% of all values of dCP

  34. Effective volume • Difference Eth = 2 GeV, Veff=5 Mt to actual (energy-dependent) fiducial volume: (Tang, Winter, JHEP 1202 (2012) 028)

  35. VL baselines (1) Note: Pure baseline effect!A 1: Matter resonance Prop. To L2; compensated by flux prop. to 1/L2 (Factor 1)(Factor 2) (Factor 1)2 (Factor 2)2

  36. VL baselines (2) • Factor 1:Depends on energy; can be matter enhanced for long L; however: the longer L, the stronger change off the resonance • Factor 2:Always suppressed for longer L; zero at “magic baseline” (indep. of E, osc. Params) (Dm312 = 0.0025, r=4.3 g/cm3, normal hierarchy) • Factor 2 always suppresses CP and solar terms for very long baselines; note that these terms include 1/L2-dep.!