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Neutrino beam to PINGU?

Neutrino beam to PINGU?. BeyondDC workshop NIKHEF Amsterdam March 19-20, 2011 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Contents. Introduction: Neutrino oscillations Matter effects Physics with a very long baseline

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Neutrino beam to PINGU?

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  1. Neutrino beam to PINGU? BeyondDC workshopNIKHEF Amsterdam March 19-20, 2011Walter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAAAAA

  2. Contents • Introduction: Neutrino oscillations • Matter effects • Physics with a very long baseline • Beam options, detector requirements • PINGU as a far detector? • Summary

  3. Introduction:Neutrino oscillations

  4. Neutrino production/detection • Neutrinos are only produced and detected by the weak interaction: • The dilemma: One cannot assign a mass to the flavor states ne, nm, nt! Interaction with SU(2) symmetrypartner only Electron  electron neutrino neMuon  muon neutrino nmTau  Tau neutrino nt e, m, t ne, nm, nt W exchange particle(interaction) Production asflavor state

  5. Which mass do the ns habe? • There is a set of neutrinos n1, n2, n3, for which a mass can be assigned. • Mixture of flavor states: • Not unusual, know from the Standard Model for quarks • However, the mixings of the neutrinos are much larger! sin22q13=0.1, d=p/2

  6. ( ) ( ) ( ) = x x Three flavor mixing • Use same parameterization as for CKM matrix Pontecorvo-Maki-Nakagawa-Sakata matrix • If neutrinos are their own anti-particles (Majorana neutrinos) U  U diag(1,eia,eib)(do not enter neutrino oscillations) Potential CP violation ~ q13 (sij = sin qij cij = cos qij)

  7. Three active flavors: Masses • Two independent mass squared splittings, typically (solar) (atmospheric) • The third is given by • The (atmospheric) mass ordering (hierarchy) is unknown (normal or inverted) • The absolute neutrino massscale is unknown (< eV) 8 8 Normal Inverted

  8. Neutrino oscillations (two flavors) • If only two flavors: • Disappearance or survival probabilityAppearance probability Lower limit for neutrino mass!

  9. Three flavors: Simplified • What we know (qualitatively): • Hierarchy of mass splittings • Two mixing angles large, one (q13) small ~ 0? • One obtains then (in vacuum)

  10. Two flavor limits Two flavor limits by selection of frequency: • Atmospheric frequency: D31 ~ p/2 D21 << 1 • Solar frequency: D21 ~ p/2 D31 >> 1 averagesout Select sensitive termby choice of L/E! 0.5

  11. Example: MINOS • Running experiment in the US for the precision measurementof atmospheric parameters Beam line (Protons) Near detector: 980 t Far detector: 5400 t 735 km Source: MINOS

  12. Three flavors: Summary (Schwetz, Tortola, Valle, 2008-) • Three flavors: 6 params(3 angles, one phase; 2 x Dm2) • Describes solar and atmospheric neutrino anomalies! Atmosphericoscillations:Amplitude:q23Frequency: Dm312 Solaroscillations:Amplitude:q12Frequency: Dm212 Coupling: q13 (Super-K, 1998;Chooz, 1999; SNO 2001+2002; KamLAND 2002) Suppressed effect: dCP

  13. Most interesting quantitiesin the future? • The value of q13  Three-flavor effects • q13 sensitivity (exclusion limit if no signal) • q13 discovery reach/discovery potential • CP violation  Leptogenesis? • Mass ordering  Lepton flavor structure? • Deviation from tribimaximal mixings? • Deviations q23-p/4 • Deviations sin2q12 – 1/3 • In particular interesting in combination with q13=0! (Pascoli, Petcov, Riotto, hep-ph/0611338)

  14. 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

  15. Artificial 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. 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)

  17. Degeneracies Iso-probability curves • CP asymmetry(vacuum) suggests the use of neutrinos and antineutrinos • One discrete deg.remains in (q13,d)-plane(Burguet-Castell et al, 2001) • Additional degeneracies: (Barger, Marfatia, Whisnant, 2001) • Sign-degeneracy (Minakata, Nunokawa, 2001) • Octant degeneracy (Fogli, Lisi, 1996) b-beam/NF, n b-beam/NF, anti-n Best-fit

  18. Degeneracy resolution LBNE, T2KK, NF/BB@long L, … Monochromatic beam, Beta beam with different isotopes, WBB, … T2KK, magic baseline ~ 7500 km, SuperNOvA Neutrino factory, beta beam, Mton WC SB+BB CERN-Frejus, silver/platinum @ NF Reactor, atmospheric, astrophysical, … • Matter effects (sign-degeneracy) – long baseline, high E • Different beam energies or better energy resolution in detector • Second baseline • High statistics • Other channels • Other experimentclasses (many many authors, see e.g. ISS physics WG report, Euronu reports)

  19. Perspectives for CP violation Euronu report, arXiv:1005.3146 Will serve asreference setup(later in this talk) Generation 3?NuFactBB g>350 Generation 2?LBNET2HKT2KKSPL Generation 1:Double ChoozDaya BayT2KNOvA

  20. Matter effects

  21. 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)

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

  23. Beams to PINGU? • Labs/detector locations (stars) considered for Neutrino Factory: (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!

  24. 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 Resonance energy:

  25. Mantle-core-mantle profile (Parametric enhancement: Akhmedov, 1998; Petcov, 1998) • Probability for CERN-PINGU (numerical) Coreresonanceenergy Mantleresonanceenergy Inter-ference Is thatpart useful? Thresholdeffects expected at: Beam energyand detector thresh. haveto pass these! 2 GeV 5 GeV 10 GeV

  26. Baseline dependence Peak neutrino energy ~ 14 GeV Event rates (A.U.) • Comparison matter (solid) and vacuum (dashed) • Event rate (n, NH) hardly drops with L (Dm212  0) NH matter effect Vacuum, NH or IH NH matter effect Can a much larger detector mass compensatefor this disadvantage? (Freund, Lindner, Petcov, Romanino, 1999)

  27. Physics with a very long baseline

  28. Risk minimization • Complemenary mesurement (physics): measures q13, MH only • Insurance against anything (?)which can go wrong: • New physics • Systematics • Luminosity • Unfortunate part of parameter space (degeneracies – see before) • Risk minimizer! (Ribeiro et al, 2007)

  29. MSW effect, even for q13=0 • For long enough baselines, solar term large enough to verify MSW even for q13=0 (Winter, Phys. Lett. B613 (2005) 67)

  30. Neutrino geophysics? Source: Neutrino factory from Fermilab • Measurement of the density of the Earth‘s core at the level of 1% • Can PINGU be used? No other currently discussed option can do that! Outer coreshadow Inner coreshadow (Winter, Phys. Rev. D72 (2005) 037302) 1s,sin22q13=0.01

  31. Beam options, detector requirements

  32. Pions Neutrinos Protons Target Selection,focusing Decaytunnel Absorber Superbeam to PINGU? • Three problems: • Energy (need to pass 5 GeV or 10 GeV for MSW enhancement) • Electron neutrino flavor identification(cascades not flavor-clean) • Statistics. Example: LBNE (200kt WC)Disapp: 9700 (1300 km)  171 (11814 km)

  33. Neutrino factory – IDS-NF IDS-NF: • Initiative from ~ 2007-2013 to present a design report, schedule, cost estimate, risk assessment for a neutrino factory • Current status: Interim Design Report (2011)including details of how costing will be done ~ 7500 km ~ 4000 km

  34. Neutrino factory to PINGU? (Geer, 1997; de Rujula, Gavela, Hernandez, 1998; Cervera et al, 2000) • Main issue: charge identification (CID) • Typically requires magnetized detector • However: also no orpartial CID has beendiscussed in literature(Huber, Schwetz, 2008) • Then: energy resolutionimportant! • Use parametric resonance? Signal prop. sin22q13 Contamination (liquid argon, 1300km)

  35. Beta beams (CERN layout; Bouchez, Lindroos, Mezzetto, 2003; Lindroos, 2003; Mezzetto, 2003; Autin et al, 2003) (Zucchelli, 2002) • Key figure (any beta beam):Useful ion decays/year? • Often used “target values” (EURISOL):3 10186He decays/year1 101818Ne decays/year • Typical g ~ 100 – 150 (for CERN SPS) Prod.ring?  g Possible/recent modifications: • Higher g(Burguet-Castell et al, hep-ph/0312068) • Different isotope pairs leading to higher neutrino energies (same g) (http://ie.lbl.gov/toi) (C. Rubbia, et al, 2006)

  36. Beta beam to PINGU? • Flavor-clean ne beam • Flavor identification only for nm required(ne nm oscillation channel) • High enough energies, in principle, achievable for 8B, 8Li (high g) • High enough intensities, in principle, achievable with production ring technology?( FP7-funded Euronu design study) • Mainly discussed in context of upgraded CERN-SPS

  37. Isotopes compared • Example: Unoscillated spectrum for CERN-INO (India) • Total flux ~ Nbg2 (forward boost!)(Nb: useful ion decays) • Combine high statistics (CPV, He/Ne) with high E (MH, B/Li)? (E0 ~ 14 MeV) (E0 ~ 4 MeV) g (from Agarwalla, Choubey, Raychaudhuri, 2006) Peak En ~ g E0 Max. En ~ 2 g E0 (E0 >> me assumed;E0: endpoint energy)

  38. PINGU as a beta beam far detector?

  39. Reference setup (Choubey, Coloma, Donini, Fernandez-Martinez, 2009) • Reference setup: • 18Ne and 6He, g=350, to 500kt water Cherenkov detector at L=650 km • 8B and 8Li, g=656 and 390, to 50kt iron detector at L=7000 km • 1019 useful decay per year (all ions) • Considered as good compromisebetween mass hierarchy and CP violationmeasurements(see also Agarwalla, Choubey, Raychaudhuri, Winter, 2008) • Discussed in context with CERN-SPS upgr. • Theoretical idea pushing the technology

  40. What if one used PINGU as a second detector? Reference setup Ref. setupwithout 2nd baseline PINGU(aggressive):5 Mton fid. mass above2 GeV;50%*E energyresolution;10-5 flavor mis-ID Figs:JianTang (Cervera, Koskinen, Tang, Winter, work in progress)

  41. Detector requirements (1) • Flavor-misidentification (essentially probability to reconstruct a cascade from ne as muon track x fid. mass ne cascades/fid. mass muon tracks) • misID ~ 10-3 should be target

  42. Detector requirements (2) • Energy threshold (5 Mt above threshold) • 2 GeV optimal (core peak covered),5 GeV possibly tolerable,10 GeV beyond mantle resonance

  43. Detector requirements (3) • Energy resolution • Works, in principle, with total rates only • However, energy resolution helps • Need „migration matrix“ Eincident Ereconstr

  44. Detector requirements (4) • Fiducial mass • 1 Mt minimum • Higher masses have some impact

  45. Detector requirements (educated guess - summary) • For good sensitivities, need: • At least 1 Mton above 2 GeV • A few Mtons above 5 GeV • Some energy information • Contamination of muon track data sample with no more than a fraction of 10-3 of the cascades (NC and CC) from ne  Cuts?(for same fiducial volume/efficiency)

  46. Wish list • Fiducial mass muon tracks as a fct. of energy • Fiducial mass cascades as a function of energy, possibly separated by interaction type (CC, NC) and flavor • „Migration matrix“ Eincident Ereconstr • Probability to mis-ID cascade as muon track; or corresponding migration matrix (see GLoBES manual, Sec. 11.5, http://www.mpi-hd.mpg.de/personalhomes/globes/documentation.html)

  47. Summary • A very long baseline is a key component e.g. of a neutrino factory program or a high energy beta beam program • Interesting option to discuss the option to use PINGU as a far detector • Beam options: beta beam probably most promising. However: is there some possibility for (at least) some CID? – neutrino factory! • Energy threshold determined by MSW effect in Earth matter; oscillation physics with sub-GeV neutrinos? • Need input for more dedicated studies to establish the physics case

  48. BACKUP

  49. Neutrino oscillation probability Standard derivation N active, S sterile (not weakly interacting) flavors • Mixing of flavor states • Time evolution of mass state • Transition amplitude • Transition probability „quartic re-phasing invariant“

  50. Further simplifications • Ultrarelativistic approximations:L: baseline (distance source-detector) • Plus some manipulations: „mass squared difference“ F(L,E)=L/E „spectral dependence“ • For antineutrinos: U  U*

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