1. Impact of large  13 on long- baseline measurements at PINGU PINGU Workshop Erlangen university May 5, 2012 Walter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAA A A A

2. 2 Contents  Introduction  Oscillation physics using a core-crossing baseline  Neutrino beam to PINGU: Beams and detector parameterization  Detector requirements for large  13  Matter density measurement?  Summary

3. 3 Three flavor mixing  Use same parameterization as for CKM matrix Pontecorvo-Maki-Nakagawa-Sakata matrix ( ) ( ) ( ) =xx (s ij = sin  ij c ij = cos  ij ) Potential CP violation ~  13

4. 4  13 discovery 2012  First evidence from T2K, Double Chooz  Discovery (~ 5  ) independently (?) by Daya Bay, RENO (from arXiv:1204.1249) 1  error bars Daya Bay 3 

5. 5  Three flavors: 6 params (3 angles, one phase; 2 x  m 2 )  Describes solar and atmospheric neutrino anomalies, as well as reactor antineutrino disapp.! Three flavors: Summary Coupling :  13 Atmospheric oscillations: Amplitude:  23 Frequency :  m 31 2 Solar oscillations : Amplitude:  12 Frequency :  m 21 2 Suppressed effect :  CP (Super-K, 1998; Chooz, 1999; SNO 2001+2002; KamLAND 2002; Daya Bay, RENO 2012) MH?

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

7. 7 Mass hierarchy measurement?  Mass hierarchy [sgn(  m 2 )] discovery possible with atmospheric neutrinos? (liquid argon, HyperK, MEMPHYS, INO, PINGU?, LENA?, …) Barger et al, arXiv:1203.6012; Smirnov‘s talk!  However: also long-baseline proposals! (LBNO: superbeam ~ 2200 km – LAGUNA design study; CERN-SuperK ~ 8870 km – Agarwalla, Hernandez, arXiv:1204.4217) Perhaps different facilities for MH and CPV proposed/discussed?

8. Oscillation physics using a core-crossing baseline

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

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

11. 11 Matter effect (MSW)  Ordinary matter: electrons, but no ,   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) (Wolfenstein, 1978; Mikheyev, Smirnov, 1985)

12. 12 Parameter mapping (two flavors)  Oscillation probabilities in vacuum: matter: Matter resonance: In this case: - Effective mixing maximal - Effective osc. frequency minimal For  appearance,  m 31 2 : -  ~ 4.7 g/cm 3 (Earth’s mantle): E res ~ 7 GeV -  ~ 10.8 g/cm 3 (Earth’s outer core): E res ~ 3 GeV Resonance energy:  MH

13. 13 Mantle-core-mantle profile  Probability for CERN-PINGU (numerical) (Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998) Core resonance energy Mantle resonance energy Inter- ference Threshold effects expected at: 2 GeV5 GeV10 GeV Beam energy and detector thresh. have to pass these! Is that part useful? Challenge: Relative size of  CP -terms smaller for longer L

14. Neutrino beam to PINGU? Beams and detector parameterization

15. 15 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 Muons, neutrinos Possible neutrino sources Protons TargetSelection, focusing Pions Decay tunnel Absorber Neutrinos Superbeam

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

17. 17 Want to study e -  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  + and  - (normally) Oscillation channels

18. 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: E th, V eff, E res (Tang, Winter, JHEP 1202 (2012) 028; V eff somewhat smaller than Jason‘s current results) E th V eff E res (  E) =  E

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

20. Detector requirements for large  13

21. 21 Superbeam  Mass hierarchy measurement very robust (even with large misID and total rates 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%, V eff > 5 Mt, E res = 0.2 E or better) (Tang, Winter, JHEP 1202 (2012) 028) (misIDtracks = 0.01) Fraction of  CP

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

23. 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  ~656 for 8 B and  =390 for 8 Li) although moderate detector requirements (Tang, Winter, JHEP 1202 (2012) 028) (misID ~ 0.001, E th =2 GeV, E res =50% E, V eff =5 Mt)

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

25. 25  contamination  Challenge: Reconstructed at lower energies! (Indumathi, Sinha, PRD 80 (2009) 113012; Donini, Gomez Cadenas, Meloni, JHEP 1102 (2011) 095)  Choose low enough E  to avoid   Need event migration matrices (from detector simulation) for reliable predictions! (neutral currents etc) (sin 2 2  13 =0.1) (Tang, Winter, JHEP 1202 (2012) 028)

26. 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. 28 Example: Superbeam  Precision ~ 0.5% (1  )  Highly competitive to seismic waves (seismic shear waves cannot propagate in the liquid core!) (Tang, Winter, JHEP 1202 (2012) 028)

29. 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 E res ~ 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 8 B- 8 Li setups for reasonable sensitivities; there are better ways to build a beta beam for large  13 to do both MH+CPV

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

31. BACKUP

32. 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  13 (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. 33 Quantification of performance Example: CP violation discovery Sensitive region as a function of true  13 and  CP  CP values now stacked for each  13 Read: If sin 2 2  13 =10 -3, we expect a discovery for 80% of all values of  CP No CPV discovery if  CP too close to 0 or  No CPV discovery for all values of  CP 33 ~ Precision in quark sector! Best performance close to max. CPV (  CP =  /2 or 3  /2)

34. 34 Effective volume  Difference E th = 2 GeV, V eff =5 Mt to actual (energy-dependent) fiducial volume: (Tang, Winter, JHEP 1202 (2012) 028)

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

36. 36  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) VL baselines (2) (  m 31 2 = 0.0025,  =4.3 g/cm 3, normal hierarchy)  Factor 2 always suppresses CP and solar terms for very long baselines; note that these terms include 1/L 2 -dep.!