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A neutrino beam to IceCube/PINGU? (PINGU = “Precision IceCube Next-Generation Upgrade“). NPAC (Nuclear/Particle/Astro/Cosmo) Forum UW-Madison, USA May 15, 2012 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Contents. Introduction

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A neutrino beam to IceCube/PINGU? (PINGU = “Precision IceCube Next-Generation Upgrade“)


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    1. A neutrino beam to IceCube/PINGU?(PINGU = “Precision IceCube Next-Generation Upgrade“) NPAC (Nuclear/Particle/Astro/Cosmo) Forum UW-Madison, USA May 15, 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 • Comments on LBNE reconfiguration • 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. Mass spectrum/hierarchy • Specific models typically come together with specific MH prediction (e.g. textures are very different) • Good model discriminator (Albright, Chen, hep-ph/0608137) 8 8 Normal Inverted

    6. 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.! Solaroscillations:Amplitude:q12Frequency: Dm212 Atmosphericoscillations:Amplitude:q23Frequency: Dm312 Coupling: q13 (Super-K, 1998;Chooz, 1999; SNO 2001+2002; KamLAND 2002;Daya Bay, RENO 2012) Suppressed effect: dCP

    7. 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!

    8. 90% CL, existing equipment 3s, Project X and T2K with proton driver, optimized neutrino-antineutrino run plan Mass hierarchy discovery? Huber, Lindner, Schwetz, Winter, JHEP 11 (2009) 44

    9. 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;IH more challenging 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; South Pole: Dick et al, 2000)

    10. Oscillation physics using a core-crossing baseline

    11. What is PINGU? What is PINGU? 2012

    12. PINGU fiducial volume? • A few Mt fiducial mass for superbeam produced with FNAL main injector protons (120 GeV) LBNE-beam (Jason Koskinen)

    13. 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!

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

    15. 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)

    16. Parameter mapping • 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 ~ 6.4 GeV- r ~ 10.8 g/cm3 (Earth’s outer core): Eres ~ 2.8 GeV  MH Resonance energy:

    17. Mantle-core-mantle profile (Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998) • Probability for FNAL-PINGU (numerical) ! Inter-ference Parametric enhancementthrough mantle-core-mantleprofile of the Earth.Unique physics potential! Core resonanceenergy Mantleresonanceenergy Beam energyand detector threshold have to pass ~ 2 GeV!Naive L/E scalingdoes not apply! Thresholdeffects expected at: 2 GeV 4-5 GeV

    18. Neutrino beam to PINGU? Beams and detector parameterization

    19. 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

    20. 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)

    21. 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)

    22. 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 J. Koskinen ‘s current results)

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

    24. Detector requirements for large q13

    25. Superbeam (LBNE-like) (misIDtracks = 0.01) • Mass hierarchy measurement very robust(even with largemisID and totalrates only possible) Fraction of dCP (Tang, Winter, JHEP 1202 (2012) 028)

    26. Low-intensity alternative? • Use existing equipment, 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 allows for shorter decay pipe (rough estimate: ~ 100 m for 700kW beam) • Advantage: Peaks in exactly the right energy range for the parametric enhancement due to the Earth‘s core (Tang, Winter, JHEP 1202 (2012) 028)

    27. Detector parameterization • Challenges: • Electron flavor ID • Systematics (efficiency, flux normalization  near detector?) • Energy resolution • Make very (?) conservative assumptions here: • Fraction of mis-identified muon tracks (muon tracks may be too short to be distinguished from signal) ~ 20% • Irreducible backgrounds (zeroth order assumption!): • Intrinsic beam background • Neutral current cascades • nm nt cascades (hadronic and electromagnetic cascades indistinguishable) • Systematics uncorrelated between signal and background • No energy resolution (total rates only) (for details on parameterization: Tang, Winter, JHEP 1202 (2012) 028)

    28. Event rates (Daya Bay best-fit) PRELIMINARY >18s(stat. only)

    29. NuMI-like beam to PINGU? • Very robust mass hierarchy measurement (as long as either some energy resolution or control of systematics); track mis-identification maybe too conservative GLoBES 2012 (Daya Bay best-fit; current parameter uncertainties, marginalized over) PRELIMINARY All irreducible backgrounds included

    30. Probabilities: dCP-dependence • There is a rich dCP-phenomenology: PRELIMINARY NH (probably works for NH only!?)

    31. 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) • Maybe: volume upgrade(here: ~ factor two) • Project X • Performance and optimization of PINGU, and possible upgrades (MICA, …) require further study = LBNE + Project X! same beamto PINGU (Tang, Winter, JHEP 1202 (2012) 028)

    32. Beta beam • Similar results for mass hierarchy measurement (easy) • CPV less 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)

    33. 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) )

    34. 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)

    35. Matter density measurementExample: LBNE-like 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)

    36. LBNE reconfiguration (some personal comments) Thanks discussions with:A. de Gouvea, F. Halzen, J. Hylen, B. Kayser, J. Kopp, S. Parke, PINGU collaboration, …

    37. D ~ 600M$

    38. Landscape(before reconfiguration) • LBNE one out of many options to measure CPV • Can this reach be matched in a phased approach? • How can one define a truly unique experiment for <= 600M US$? • How would one react if T2HK happens? (P. Huber)

    39. Reconfiguration options?… or how to spend 600 M$ • New detector, existing beam line • MINOS site (L=735 km) • NOvA site (L=810 km) • New site? • New (smaller) detector, new beam line (~300 M$) • Smaller detector in Homestake (L=1300 km) • Surface detector at Homestake (L=1300 km) • New beam line (<= 550 M$?), (then) existing detector • PINGU (L=11620 km) • … Idea ~ 2 weeks old

    40. Best physics concept? NuMIbeam line Homestake, on-axis Newbeam line (Barger, Huber, Marfatia, Winter, PRD 76 (2007) 053005)

    41. Conclusion:LBNE – smaller version? • How many s does one need? • Combination of experiments tolerable as physics result? This is whatT2HKcannot do MH, 5s This is whatT2HKcan also do

    42. Conclusions: FNAL-PINGU? • FNAL-PINGU • Megaton-size ice detector as upgrade of DeepCore with lower threshold; very cost-efficient compared to liquid argon, water • Unique mass hierarchy measurement through parameteric enhancement; proton beams from main injector may just have right energy • In principle, MH even with counting experiment measurable (compared to MH determination using atmospheric neutrinos) • Challenges on beam side (questions from PINGU meeting): • Tilt of beam line – feasibility, cost? • Near detector necessary? Maybe not, if 10% systematics achievable … • Beam bunching (to reduce atmospheric backgrounds)? NB: very low exposure required for MH; shorter decay pipe, one horn only, …? • Perspectives • CP violation challenging (requires energy resolution, flavor identification), but not in principle excluded; needs further study on detector side • Measurement of Earth‘s core density, in principle, possible(Tang, Winter, JHEP 1202 (2012) 028) • Upgrades of PINGU discussed (MICA) • Truly unique and spectacular long-baseline experiment with no other alternative proposed doing similar physics!? The LBNE alternative if T2HK is going to be funded?

    43. BACKUP

    44. NOvA+INO (atm.)? MH, 3s (Blennow, Schwetz, arXiv:1203.3388)

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

    46. 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)

    47. 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

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

    49. 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

    50. 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.!