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Beta beam scenarios … for neutrino oscillation physics

Beta beam scenarios … for neutrino oscillation physics. Beta beam meeting Aachen, Germany October 31-November 1, 2007 Walter Winter Universität Würzburg. Contents. Introduction: Neutrino oscillation physics with beta beams Beta beam scenarios Optimization of a green-field scenario

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Beta beam scenarios … for neutrino oscillation physics

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  1. Beta beam scenarios… for neutrino oscillation physics Beta beam meeting Aachen, Germany October 31-November 1, 2007Walter Winter Universität Würzburg

  2. Contents • Introduction: Neutrino oscillation physics with beta beams • Beta beam scenarios • Optimization of a green-field scenario • Using different isotopes • Physics case for a beta beam? • Summary Aachen 07 - Walter Winter

  3. Neutrino oscillations with two flavors Mixing and mass squared difference:na “disappearance”:nb “appearance”: ~Frequency Amplitude Baseline: Source - Detector Energy Aachen 07 - Walter Winter

  4. Picture of three-flavor oscillations Atmosphericoscillation:Amplitude: q23Frequency: Dm312 Solaroscillation:Amplitude: q12Frequency: Dm212 Sub-leading effect: dCP Coupling strength: q13 Magnitude of q13is key to “subleading” effects: • Mass hierarchy determination • CP violation Use ne transitions on atmospheric oscillation scale (“Oscillation maximum”) Aachen 07 - Walter Winter

  5. Matter effects in n-oscillations (MSW) • Ordinary matter contains electrons, but no m, t • Coherent forward scattering in matter has net effect on electron flavor because of CC (rel. phase shift) • Matter effects proportional to electron density and baseline • Hamiltonian in matter: (Wolfenstein, 1978; Mikheyev, Smirnov, 1985) Y: electron fraction ~ 0.5 (electrons per nucleon) Matter potential not CP-/CPT-invariant! Aachen 07 - Walter Winter

  6. Appearance channels: nmne • Complicated, but all interesting information there: q13, dCP, mass hierarchy (via A) Anti-nus (see e.g. Akhmedov, Johansson, Lindner, Ohlsson, Schwetz, 2004) Aachen 07 - Walter Winter

  7. The role of neutrinos+antineutrinos • CP asymmetry(vacuum)suggests the useof neutrinos andantineutrinos • One discrete deg.remains in (q13,d)-plane b-beam, n b-beam, anti-n Best-fit Aachen 07 - Walter Winter

  8. Often used performance indicators • Future experiment performance depends on (simulated) values implemented by nature • Often shown: Discovery reaches (q13, MH, CPV) as a function of these simulated values; mainly as a function of q13 and dCP • Sensitivity to q13: Largest value of q13, which cannot be distinguished from a simulated q13=0 • Corresponds to new exclusion limit if no signal • Marginalization over q13, dCP, mass hierarchy • Does not depend on simulated dCP Aachen 07 - Walter Winter

  9. Correlations and degeneracies • Connected (green) or disconnected (yellow) degenerate solutions (at a chosen CL) in parameter space • Discrete degeneracies – even if ns+anti-ns: (Barger, Marfatia, Whisnant, 2001)Intrinsic (d,q13)-degeneracy (Burguet-Castell et al, 2001)sgn-degeneracy (Minakata, Nunokawa, 2001)(q23,p/2-q23)-degeneracy (Fogli, Lisi, 1996) • Affect performance of appearance measurements. For example, q13 sensitivity: (Huber, Lindner, Winter, 2002; Huber, Lindner, Rolinec, Winter, 2006) Aachen 07 - Walter Winter

  10. Example for degeneracy resolution:“Magic baseline” (Huber, Winter, 2003) • Idea:Yellow term = 0 independent of E, oscillation parameters • Purpose: “Clean” measurement of q13 and mass hierarchy • Drawback: No dCP measurement at magic baseline • combine with shorter baseline Aachen 07 - Walter Winter

  11. Beta beam at very long baseline • Operate a beta beam at the magic baseline?(Agarwalla, Choubey, Raychaudhuri, 2006) • Use magnetized iron calorimeter as detectorCERN-ICAL (INO) ~ magic baseline • Authors use 8B and 8Li with rel. moderate g ~ 250 - 500 L~ 7000 – 9000 km bands Aachen 07 - Walter Winter

  12. Beta beam scenarios

  13. Motivation: Experiment classes For leading atm. params Signal prop. sin22q13 Contamination Aachen 07 - Walter Winter

  14. Original beta beam concept • Compared to superbeam: no intrinsic beam background • Compared to neutrino factory: no charge identification required • In principle, very interesting alternative concept! • Key figure (any beta beam):Useful ion decays/year? • Often used “standard values”:3 10186He decays/year1 101818Ne decays/year • Typical g ~ 100 – 150 (for CERN SPS) (Zucchelli, 2002) (CERN layout; Bouchez, Lindroos, Mezzetto, 2003; Lindroos, 2003; Mezzetto, 2003; Autin et al, 2003) Aachen 07 - Walter Winter

  15. Higher g beta beam Aachen 07 - Walter Winter

  16. Beta beam scenarios: He/Ne • “Low” gamma (g<150?) • Alternative to superbeam? Originally designed for CERN (SPS) • Water Cherenkov detector (see last slide; also: Volpe, 2003) • “Medium” gamma (150<g<300-350?) • Alternative to superbeam! Possible at upgraded SPS? • Usually: Water Cherenkov detector (Burguet-Castell et al, 2003+2005; Huber et al, 2005; Donini, Fernandez-Martinez, 2006) • “High” gamma (300-350<g<800?) • Specific physics case for that? Requires large accelerator (Tevatron-size) • Water Cherenkov detector or TASD or MID? (Burguet-Castell et al, 2003; Huber et al, 2005) • “Very high” gamma (g>800?) • Alternative to neutrino factory? Requires very large accelerator (LHC-size) • Detector technology other than water (TASD? MID?) (Burguet-Castell et al, 2003; Huber et al, 2005; Agarwalla et al, 2005+) Gamma determines neutrino energyand therefore detector technology!

  17. Example: CERN-Memphys(a superbeam-beta beam hybrid) Example: q13 discovery • Beta beam (g=100) plus4MW superbeam to 440 ktWC detector at Frejus site (L=130 km) • Effect of systematics smaller and absolute performance better than for T2HK • Antineutrino running not necessary because ne to nm(beta beam) and nm to ne(superbeam) channels present (see also: hep-ph/0703279) Sensitive region 10 years, 3sShading: systematics varied from 2% to 5% (Campagne, Maltoni, Mezzetto, Schwetz, 2006) Aachen 07 - Walter Winter

  18. Example: g=350 optimum at CERN? • Requires refurbished SPS (supercond. magnets) • Maximum doable at CERN? • L=730 km • For CPV an medium q13 even competitive to an optimized high-E NuFact (Burguet-Castell, Casper, Couce, Gomez-Cadenas, Hernandez, 2005; Fig. from Huber, Lindner, Rolinec, Winter, 2006) Aachen 07 - Walter Winter

  19. Green-field scenario

  20. Optimization of a green-field scenario • Use two different detector technologies: • 500 kt Water Cherenkov: Large mass, but poor energy resolution at high E (non-QE sample) • 50 kt NOvA-like TASD: Smaller mass, but very good energy resolution at high E • Assume specific isotopes: 6He, 18Ne, with 3 1018 (6He) and 1018 (18Ne) decays/yearfor 8 years (if simultaneous operation) • Main questions (this talk): • Which is the optimal gamma • What is the optimal baseline? • Which fraction neutrinos/antineutrinos is necessary? Aachen 07 - Walter Winter

  21. Scaling with g • Fix L/g=1.3 (~ 1st oscillation maximum) • The higher g, the better (modulo detector!) Our setups 1, 2, 3 (Huber, Lindner, Rolinec, Winter, 2005) Aachen 07 - Walter Winter

  22. Baseline optimization of a beta beam • Baseline optimization depends on performance indicatorand gamma setup:(Fig. from Huber, Lindner, Rolinec, Winter, 2005) • For lower gamma: Second osc. max. useful to resolve degs • For higher gamma: Degs reolved by improved statistics Aachen 07 - Walter Winter

  23. Neutrino-antineutrino balance • Balance calculate as fraction of running time;translates easily into balance of useful isotope decays (Fig. from Huber, Lindner, Rolinec, Winter, 2005) • Hardly imbalance as long as ~ 10% of the total running time present (~ 10%/50%=20% of orig. isotope decays) Aachen 07 - Walter Winter

  24. Comparison of setups (Huber, Lindner, Rolinec, Winter, 2005) 3s Aachen 07 - Walter Winter

  25. Using different isotopes

  26. Isotopes compared: Spectrum • Example: Unoscillated spectrum for CERN-INO • Total flux ~ Nbg2 (forward boost!) (Nb: useful ion decays) (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) Aachen 07 - Walter Winter

  27. Different isotopes: Some thoughts • Examples for isotopes • Want same neutrino energies(=same X-sections, L, physics):Peak energy ~ g E0, flux ~ Nbg2 Use high g and isotopes with small E0or low g and isotopes with large E0 for same total flux (exact for me/E0 << 1) • Example (table): Nb(B/Li) ~ 12 Nb(He/Ne) , g(He/Ne) ~ 3.5 g(B/Li) • NB: g: Accelerator dof versus Nb: ion source dofWhere is the cost/feasibility break-even point? (http://ie.lbl.gov/toi) Aachen 07 - Walter Winter

  28. L-g-optimization for MID: q13 sensitivity • Same luminosity, same detector! • Short baseline better for He/Ne,magic baseline for B/Li (in prep. with Agarwalla et al) Aachen 07 - Walter Winter

  29. A matter of luminosity? Short vs. long baseline Same physics for ~ 10 x luminosity (Agarwalla, Choubey, Raydchaudhuri, Winter, in prep.) Gamma increase: ~ 2.9-4.6 Aachen 07 - Walter Winter

  30. Even use alternating ions? • Alternating ionspossible degeneracyresolution strategyIdea: main statisticsat very differentneutrino energies!(Donini, Fernandez-Martinez, 2006) L=650 km (for other degeneracy studies: see, e.g. Donini, Fernandez-Martinez, Rigolin, 2004; Donini, Fernandez-Martinez, Migliozzi, Rigolin, 2004) Aachen 07 - Walter Winter

  31. Physics case

  32. Discussion: Physics case for a beta beam? • Can do q13, mass hierarchy, CPV measurements just as superbeam, neutrino factory; physics, in principle, similar • Cannot: • Measure leading atm. parameters very well • Be used for muon physics (such as a NF frontend!) • Be used as a muon collider frontend (NF?) • Be used for muon neutrino X-section measurement • Key questions: • Synergies with other non-oscillation measurements? • Cost/useful ion decays (BB) versus cost/useful muon decays (NF)? How do BB compare to superbeams? • Different isotopes versus different g? • Potential for non-standard physics? • Is there a seperate physics case for a beta beam? Aachen 07 - Walter Winter

  33. Separate physics case for a beta beam? • Blue: Superbeam upgrade based upon: lower effort • Green: Beta beam based upon: Good CPV reach, MH in most cases • Red: Neutrino factory (optimized) based upon: Good q13 reach Longer L (3s, Dm312=0.0022 eV2) Aachen 07 - Walter Winter

  34. Summary • Beta beam performance depends on isotope and g, which determine the physics reaches • The physics potential can be made similar to that of a NF or SB; therefore, for standard oscillation physics, it all comes down to a cost comparisonHowever: there might be a separate physics casefor intermediate sin22q13 • Isotope comparison master formulae:g(1) E0(1) = g(2) E0(2) , Nb(1)=Nb(2) (E0(1)/E0(2))2Accelerator effort versus ion source effort Aachen 07 - Walter Winter

  35. Beta beam vs. Superbeam vs. NuFact? • Lower g:Can easily compete with superbeam upgrades if properly optimized • Higher g:At least theoretically competitive to a neutrino factory • Challenges: • Can fluxes be reached? • Compare completely optimized accelerator strategies? (Fig. from Huber, Lindner, Rolinec, Winter, 2005) Aachen 07 - Walter Winter

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