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Neutrino Oscillation Measurements with IceCube and PINGU

Neutrino Oscillation Measurements with IceCube and PINGU. Alexander Kappes Particle physics seminar Physics Institute, University Bonn Bonn, June 27, 2013. Outline. Introduction to neutrino oscillations brief history what is neutrino oscillation? matter effects

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Neutrino Oscillation Measurements with IceCube and PINGU

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  1. Neutrino Oscillation Measurements with IceCube and PINGU • Alexander Kappes • Particle physics seminar • Physics Institute, University Bonn • Bonn, June 27, 2013

  2. Outline • Introduction to neutrino oscillations • brief history • what is neutrino oscillation? • matter effects • IceCube, DeepCore and neutrino oscillations • first measurements • future prospects • The PINGU low-energy extension • neutrino oscillation and mass hierarchy • current status of sensitivity studies to mass hierarchy Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  3. 1995 1988 Neutrino oscillations, a brief history • 1930: Wolfgang Pauli predicts neutrinos to solve mystery of continuous electron spectrum in radioactive decay→ weakly interacting particle with m ≪ me • 1956: Discovery of the electron neutrino by Cowan and Reins (reactor experiment) • 1957: First ideas on neutrino oscillations by Pontecorvo (ν ⟷ ν) • 1962: Discovery of the myon neutrino by Lederman, Schwarz and Steinberger(accelerator experiment) • late 1960s: Solar neutrino problem Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  4. The solar neutrino problem • Homestake experiment (1970‑1994)(Ray Davis and John Bahcall) • Purpose: detect and count neutrinos from nuclear fusion in Sun • Place: Homestate Gold Mine (South Dakota), 1500 m depth • Detector: 380 m3 perchloroethylene (37Cl + νe → 37Ar) • Result: only 1/3 of expected neutrinosbut Φ(νeB8) ∝ Tcore25 ! • Missing νe flux also seen by several other follow-up experiments (liquid → energy threshold) • Ga (pep): SAGE, GALLEX, GNO • H20 (8B): Kamiokande, SuperK • 2H20 (8B): SNO Homestake experiment Bahcall-Pinsonneault (2000) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  5. 2002 Koshiba and Davis Super-K, PRL (1998) Discovery of oscillations in atmospheric neutrinos • Super-Kamiokande experiment (1996 ‑ now) • Purpose: proton decay, solar and atmospheric neutrinos • Place: Mozumi Mine (Japan), 1000 m depth • Detector: 50 kton ultra-pure water • can detect both νeand νμ in MeV‑GeV range(interaction with nuclei or electrons in water) • allows direction reconstruction muon neutrinos Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  6. What is neutrino oscillation? cij = cos(θij), sij = sin(θij), δ = CP-violating phase … nothing special, typical quantum mechanical effect relating orthonormal vectors (U only real components; no CP violation; neutrinos Dirac type) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  7. P independent of sign of Δm2 ! Simple 2-flavor oscillation • Production of a νμ at t=0: Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  8. νe νμ ντ 3-flavor oscillation World-best fit values:(Fogli et al. (2012), arXiv:1205.5254) δm2 Δm2 θ13 θ12 δCP unconstrained Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  9. νe (p,n) νe νe νμ,τ (+) νe ; (−) νe Remark ( ) Effective parameters for 2-flavor mixing: (p,n) (p,n) (p,n) electron density Ne → νe e‑ νe νμ,τ W‑ + e‑ e‑ Z Z W e‑ e‑ e‑ e‑ e‑ νe Matter effects muon, tau neutrinos electron neutrinos Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  10. Effective parameters for 2-flavor mixing: Δm212 < 0 • Example: Neutrinos from the Sun • Propagation along smoothly decreasing density profile → at some point Ne = NeR • Effect is energy dependent ... Pee survival probability Δm212 > 0 Mikheyev, Smirnov, Wolfenstein Eν [MeV] Matter effects ‑ the MSW effect • ... and differs for Δm212 > (<) 0 !→ sign of Δm212 measured Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  11. castle-wall matter profile Neutrino traversing the Earth (∆m2/4E = 1.8 × 10-13 eV, sin2 2θ0 = 0.01, Θn = 11.5º) 0.6 0.4 P(νe → νμ,τ) earth density 0.2 P(νe → νμ,τ) 0 2 0.5 1.5 1 path length [Rearth] path length [a.u.] Matter effects ‑ parametric resonances • Occur in systems with periodically varyingdensity profile • In contrast to MSW effect, mixing NEVER has to become large along path ! • Periodic density change leads to continuous increase of P • Works also for “truncated” periodic profiles like Earth mantel→core→mantel transition Akhmedov (2000), hep-ph/9907435 Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  12. Neutrino Detection withNeutrino Telescopes Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  13. Time & position of hits Light intensity Energy μ trajectory → ν trajectory Detection principle muon νμ ν-nucleon interaction (νμ + N → μ + X) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  14. Current (planned) neutrino telescope projects Baikal (GVD) ANTARES (KM3NeT) IceCube Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  15. IceCube at the South Pole South Pole IceCube surface area

  16. The IceCube Observatory -1450 m -2450 m Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  17. Neutrino signatures in IceCube • Track-like: • Source: νμ CC interaction • Good angular resolution • Sensitive ≫ instrumented volume • Cascade-like: • Source: νe, νμ, ντ NC + νe CC interaction • Good energy resolution • Limited angular resolution • Sensitive ≈ instrumented volume • Composites: • Source: ντ CC + νμ CC inside instrumented volume • Challenging to reconstruct muon (data) cascade (data) tau (simulation) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  18. Neutrino Oscillations • in IceCube Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  19. IceCube Mena et al. PR D78 2008 α Neutrino oscillations in IceCube • Goal: measurement of atm. muon neutrino oscillationsMinimum for P(νμ→νμ)at ~25 GeV (L = Earth diameter) • IceCube energy threshold ~100 GeV(too few photons)→ higher sensor density with DeepCore • Instrumented volume: 10‑100 Mton • Average DOM density: 4× IceCube • Energy range: 10 GeV ‑ 100 GeV L = 2∙R∙cosα Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  20. μ μ νμ IceCube Coll., accepted by PRL First analysis (IC79) − Event selection • Selection of a low and high energy sample(only low-energy sample effected by oscillations) • In particular, low-energy sample effected by mis-reconstructed atmospheric muons→ suppression using IceCube veto and improved reconstruction (DeepCore) • High purity muon neutrino samples • low energy sample ~85%(main contamination νe) • high-energy sample ~95%(main contamination muons) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  21. Median zenith resolution (low-energies) Muon (neutrino) directional reconstruction (IC79) • Maximum likelihood reconstruction:comparison of expected and measured arrival time and # photons for each DOM • Low-energy sample: start and/or stopping point reconstructed • Angular resolutions: • high-energy sample: ≲ 2º • low-energy sample: 6º‑15º (zenith) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  22. Do we see neutrino oscillation in IC79? • Method: Combined χ2 of low- and high-energy sample in 2× 10 bins of cos θSystematics: DOM eff., ice model, rate norm., atm. flux model, νe norn., ν xsec • Results: • oscillations observed with more than 5σΔχ2 = 30 ≙ 5.6σ event rate [Hz] stat. errors kth sys. uncertainty IceCube Coll., accepted by PRL event rate [Hz] • best-fit: χ2 / n.d.f= 15.7 / 18 Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  23. Neutrino oscillation with high significance but not high precision yet • |Δm2| = [2.5 ± 0.5(stat) ± 0.3(sys)] 10-3 eV2 • sin2(2θ32) > 0.92 (68% CL) IceCube Coll., accepted by PRL Constraints on oscillation parameters (IC79) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  24. Future prospects (IC86) • Analysis of IC86 data • Energy information: • At low energies, tracks contained in IceCube volume (Ltrack ≈ E/GeV × 5 m) • Good correlation between Ltrack and energy • Designed to reduce effect ofice parameter uncertainties • 6 year of IceCube/DeepCore • Potential to become competitive with world-best measurements • Determination of θ23 octant (θ23 < or > 45º) via 3-flavor effects at 10-20 GeV requires better control of systematics effects IC86-2012 PRL results (IC79) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  25. PINGU − PRECISION ICECUBENEXT GENERATION UPGRADE Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  26. PINGU (5-10 MTon) From IceCube via DeepCore to PINGU IceCube (1 GTon) DeepCore (10-100 MTon) PINGU Instrumented volume: 5‑10 Mt Average DOM density: > 200×10‑6 m‑3 Energy range: 1 GeV ‑ 20 GeV → Precision measurement of oscillation parameters → Neutrino mass hierarchy → Dark Matter (WIMPs) → Supernovae (MeV neutrinos) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  27. m32 m22 m12 NH Δm322 > 0 IH Δm322 < 0 Δm322 m22 Δm212 m12 m32 m(νe) m(ντ) m(νμ) Neutrino mass hierarchy • Sign Δm212 known from MSW effect in Sun • Sign of Δm322 (atmospheric muon neutrinos) still unknownΔm322 > 0 → Normal hierarchy (NH)Δm322 < 0 → Inverted hierarchy (IH) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  28. Daya Bay True: NH True: IH 90% CL IH rejection with > 90%CL NH rejection with > 90%CL 90% CL Prakash, Raut & Sankar, arXiv:1201.6485 Neutrino mass hierarchy ‑ experiments of the next decade • Current experiments: • NOνA and T2K • νμ → νe appearance • Discrimination power depends on true value of δCP • Complete δCP coverage (90% CL) needs ≳ (10 yr T2K + 9 yr NOνA) • Future experiments: • Daya Bay II • Reactor experiment: P(νe→νe) • Requires (3σ after ~6 yr) Changgen Yang, NuMass 2013 Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  29. Maximum effect NH ↔ IH for θ=130ºat 7 GeV • For ν NH and IH approximately swappedRecap:→ effect cancels if detected N(ν) = N(ν) • Fortunately, flux(νatm) ≈ 1.3 × flux(νatm)and xsec(ν) ≈ 2 × xsec(ν) • ⟹ Count Nμ(E,θ) from νμ + N → μ + X and compare with NH / IH predictions Remark: neutrino telescopes inherently insensitive to ν ↔ ν Difference between NH and IH (νμ) Perfect resolution Akhmedov et al., arXiv:1205.7071 Neutrino mass hierarchy with neutrino telescopes • Oscillation pattern modified by matter effects in Earth(MSW effect + parametric resonances) • Effect differs for normal and inverted hierarchy(sign of Δm2changes) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  30. σθ = 23º σE = 4 GeV σθ = 15º σE = 3 GeV Perfect resolution σθ = 11º σE = 2 GeV Neutrino mass hierarchy with neutrino telescopes ΔN(IH‑NH) / √N(NH) [PINGU 1 yr, 10% sys.] • Target resolutions: ΔE/E < 40%, Δθ < 15º Akhmedov et al., arXiv:1205.7071 Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  31. Effect of systematic uncertainties on oscillation parameters • Inverting the hierarchy changes best-fit oscillation parameters ! • Example: just flipping the sign of Δm312 leads to large overestimationof Δχ2 ≈ ΔN(IH‑NH) / √N(NH) • Holds for all oscillation parametersbut with smaller impact Winter, arXiv1305.5539 Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  32. Possible PINGU layouts • 20‑40 additional strings with 60‑120 DOMs each • Horizontal string distance 10−25 m • Vertical DOM separation 2.5−5 m Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  33. Effective volumes and number of hit optical modules • Effective volume (20 PINGU strings) • Trigger condition: 3 hit pairs on neighboring DOMs • 20 hit required to account for selection/reconstruction efficiency • Veff several Megatons down to 4 GeV DeepCore DeepCore + PINGU • Number of hit optical modules • Neutrino energy: 9.3 GeVMuon energy: 4.8 GeV Cascade energy: 4.5 GeV • Hit modules:20 (DC) → ~50 (DC + PINGU) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  34. True: inverted hierarchy fit inverted hierarchy fit normal hierarchy best χ2IH best χ2NH Current status of studies • Reconstruction accuracy (fast algorithms adapted from DeepCore) • Zenith angle: 15º−8º (5 to 20 GeV) • Energy: 0.7 GeV + 0.2×Eν • Mass hierarchy extraction • Several approaches with differentfocuses under investigations • One of them: Δχ2 approach(includes systematics but no explicitbackground rejection) • calculate χ2 between pseudo data and NH and IH hypothesis • Δχ2 between best fit for NH and IHyields significance for rejection(here Δχ2 ≈ 12) more computationally expensive algorithmspromise improved performances Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  35. Current status of studies • Another approach: Unbinned likelihood • Uses 20 strings while assuming low signal efficiency • Resolutions approximated with Gaussians • Only limited inclusion of systematic effects Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  36. preliminary Preliminary range of sensitivity to mass hierarchy Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  37. Walter Winter, talk 2012 in Madison Accelerator Mantle NH Outer Core Inner Core IH significance PRELIMINARY PINGU 1021 PoT, no energy information true value of δCP Neutrino mass hierarchy with an accelerator beam to PINGU • Idea by Walter Winter(Tang & Winter arXiv:1110.5908) • Accelerator beam: νμ → νe appearance • Advantages: very long baseline (~12000 km) + strong matter effects in dense core • Capabilities w.r.t. δCP unclear yet • Would require • cascade identification • limited energy resolution, no directional information • limited beam power (current neutrino beams sufficient, e.g. NuMI) • but dedicated (steeply inclined) beam line 5 σ Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  38. Current timeline first set of cables/DOMs shipped to Pole design, manufacture and test hardware start data taking letter of intent 2013 2014 2015 2016 2017 2018 2019 2020 drill preparations finish deployment (20 strings) proposal to funding agencies first deployment PINGU timeline • Moderate timeline of ~10 years (data taking could start in 2017) • Overall low risk for construction and operation • Costs 35−60 M$ (20-40 strings) Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  39. Summary • Neutrino physics currently one of the most exciting areas in particle physics • Great perspectives for IceCube/PINGU in neutrino physics • first measurement of neutrino oscillation with high significance • potential for competing with world-best measurements in the future • PINGU low-energy extension currently under extensive study • measurement of neutrino mass hierarchy most fascinating perspective • first Monte Carlo based studies confirm potential to measure mass hierarchy within O(5) years of data taking • Letter of Intend and funding proposals planned until the end of the year The low-energy future of IceCube has just begone Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

  40. ~250 authors from 39 institutes in 10 countries Alexander Kappes | Teilchenphysikseminar, Bonn | 27.06.2013 |

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