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Neutrino physics with IceCube DeepCore-PINGU … and comparison with alternatives

Neutrino physics with IceCube DeepCore-PINGU … and comparison with alternatives. TeVPA 2012 TIFR Mumbai, India Dec 10-14, 2012 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Contents. Introduction Oscillation physics with Earth matter effects

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Neutrino physics with IceCube DeepCore-PINGU … and comparison with alternatives

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  1. Neutrino physics with IceCube DeepCore-PINGU… and comparison with alternatives TeVPA 2012TIFR Mumbai, India Dec 10-14, 2012Walter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAAAAA

  2. Contents • Introduction • Oscillation physics with Earth matter effects • Mass hierarchy determination with PINGU • Neutrino beam to PINGU? • Atmospheric neutrinos • Comparison with alternatives, and outlook • Summary

  3. Atmospheric neutrino anomaly • The rate of neutrinos should be the same from below and above • But: About 50% missing from below • Neutrino change their flavor on the path from production to detection: Neutrino oscillations(Super-Kamiokande: “Evidence for oscillations of atmospheric neutrinos”, 1998)

  4. 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

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

  6. 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

  7. Oscillation physics withEarth matter effects

  8. Matter profile of the Earth… as seen by a neutrino Core (PREM: Preliminary Reference Earth Model) Innercore (not to scale)

  9. 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)

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

  11. Mantle-core-mantle profile (Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998) • Probability for L=11810 km (numerical) ! 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

  12. Mass hierarchy determination with PINGU

  13. What is PINGU?(“Precision IceCube Next Generation Upgrade“) • Fill in IceCube/DeepCore array with additional strings • Drive threshold to lower energies • LOI in preparation • Modest cost ~30-50M$ (dep. on no. of strings) • Two season deployment anticipated: 2015/2016/2017 (PINGU, 12/2012)

  14. PINGU fiducial volume? • A ~ Mt fiducial mass for superbeam produced with FNAL main injector protons (120 GeV) • Multi-Mt detector for E > 10 GeV atmospheric neutrinos • Fid. volume depends on trigger level (earlier Veff higher, which is used for following analyses!) (PINGU, 12/2012) LBNE-likebeam Atm. neutrinos

  15. Mass hierarchy measurement:statistical significance (illustrated) Source (spectrum, solid angle) Osc. effect (in matter) Detector mass Crosssection~ E x x x > 2 GeV Atmospheric neutrinosarXiv:1210.5154 > 5 GeV Measurement at threshold  application rather for future upgrades: MICA? BeamsM. Bishai Coreres.

  16. 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!

  17. Example:“Low-intensity“ superbeam? • 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 • Advantage: Peaks in exactly the right energy range for the parametric enhancement • Include all irreduciblebackgrounds (intrinsic beam, NC, hadronic cascades), 20% track mis-ID M. Bishai

  18. Event rates (for Veff 03/2012) PRELIMINARY >18s(stat. only)

  19. Mass hierarchy with a beam • Very robust mass hierarchy measurement (as long as either some energy resolution or control of systematics) GLoBES 2012 (Daya Bay best-fit; current parameter uncertainties included; based on Tang, Winter, JHEP 1202 (2012) 028 ) PRELIMINARY All irreducible backgrounds included

  20. Atmospheric neutrinos Akhmedov, Razzaque, Smirnov, 2012 • Neutrino source available “for free“ • Source not flavor-clean  different channels contribute and mask effect • Power law spectrum arXiv:1210.5154 • Many different baselines at once, weighted by solid angle • Detector: angular+energy resolution required! A. Smirnov

  21. Mass hierarchy with atmospheric neutrinos • Statistical significance depends on angular and energy resolution • About 3-10s likely for reasonable values • Final proof of principle will require event reconstruction techniques (in progress) Akhmedov, Razzaque, Smirnov, 2012

  22. Comparison with alternatives … and outlook

  23. Mass hierarchy • 3s, Project X and T2K with proton driver, optimized neutrino-antineutrino run plan • PINGU completed by beginning of 2017? • No “conventional“ atm. neutrino experiment could be built on a similar timescale or at a similar cost • Bottleneck: Cavern! Akhmedov, Razzaque, Smirnov, 2012; v5 PINGU2018-2020? 3s Huber, Lindner, Schwetz, Winter, JHEP 11 (2009) 44

  24. Probabilities: dCP-dependence • There is rich dCP-phenomenology: NH L=11810 km

  25. Upgrade path towards dCP? • Measurement of dCP in principle possible, but challenging • Wish list: • Electromagnetic shower ID (here: 1% mis-ID) • Energy resolution (here: 20% x E) • Maybe: volume upgrade(here: ~ factor two) • Project X • Currently being discussed in the context of further upgrades - MICA; requires further study • PINGU as R&D exp.? = LBNE + Project X! same beamto PINGU Tang, Winter, JHEP 1202 (2012) 028

  26. Matter density measurementExample: LBNE-like Superbeam • Precision ~ 0.5% (1s) on core density • Complementary to seismic waves (seismic shear waves cannot propagate in the liquid core!) from: Tang, Winter, JHEP 1202 (2012) 028;see also: Winter, PRD72 (2005) 037302; Gandhi, Winter, PRD75 (2007) 053002; Minakata, Uchinami, PRD 75 (2007) 073013

  27. Conclusions: 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 MSW effect in Earth matter • Atmospheric neutrinos: • Neutrino source for free, many different baselines • Requires energy and angular resolution (reconstruction work in progress) • PINGU to be the first experiment to discover the mass hierarchy at 3-5s? • Neutrino beam: • Requires dedicated source, with relatively low intensity • Proton beams from FNAL main injectior have just right energy to hit mantle-core-mantle parameteric enhancement region • Even possible as counting experiment, no angular resolution needed • Beyond PINGU: CPV and matter density measurements perhaps possible with beam to even denser array (MICA)?  PINGU as R&D experiment; worth further study! • Technology also being studied in water  ORCA

  28. BACKUP

  29. 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

  30. Detector paramet.: mis-ID misID: fraction of events of a specific channelmis-identified as signal 1.0? misIDtracks << misID <~ 1 ? (Tang, Winter, JHEP 1202 (2012) 028)

  31. Detector requirements Want to study ne-nm oscillations with different sources: • 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) q13, dCP q13, dCP q13, dCP

  32. Detector parameterization(low intensity superbeam) • 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)

  33. Measurement of dCP? • Many proposals for measuring CP violation with a neutrino beam • Require all a dedicated (new) detector + control of systematics Coloma, Huber, Kopp, Winter, 2012

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