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Optimization of a neutrino factory oscillation experiment

Optimization of a neutrino factory oscillation experiment. 3 rd ISS Meeting Rutherford Appleton Laboratory, UK April 25-27, 2006 Walter Winter Institute for Advanced Study, Princeton. Contents. Introduction Optimization summary: L-E m Improved detector summary Channel requirements

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Optimization of a neutrino factory oscillation experiment

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  1. Optimization of a neutrino factory oscillation experiment 3rd ISS MeetingRutherford Appleton Laboratory, UKApril 25-27, 2006 Walter Winter Institute for Advanced Study, Princeton

  2. Contents • Introduction • Optimization summary: L-Em • Improved detector summary • Channel requirements • Some phenomenology: Why are other channels useful? • Platinum • Silver • Where to concentrate the efforts? Synergies?How does the optimal neutrino factory look like? • Comparison to beta beams • Summary See my talk(s) at KEK andPatrick’s talk in Boston ISS RAL NuFact - Walter Winter

  3. Appearance channels • Complicated, but all interesting information there: q13, dCP, mass hierarchy (via A) (Cervera et al. 2000; Freund, Huber, Lindner, 2000; Freund, 2001) ISS RAL NuFact - Walter Winter

  4. Correlations and degeneracies • Connected (green) or disconnected (yellow) degenerate solutions (at a chosen CL) in parameter space • Affect performance of appearance measurements. For example, q13 sensitivity (Huber, Lindner, Winter, 2002) • Discrete degeneracies: (also: 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) ISS RAL NuFact - Walter Winter

  5. NF-Strategies to resolve degeneracies • Combine with “silver channels” ne -> nt (Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004) • Combine with “platinum channels” nm -> ne(sin22q13 > 10-3 ? Depends on BG-level!)(Boston workshop: Patrick’s talk) • Better detectors: Higher energy resolution, higher efficiencies atlow energies (CID!) (discussed at KEK, Boston) • Second NF baseline: “Magic baseline” (sin22q13 > 10-4)(Lipari, 2000; Burguet-Castell et al, 2001; Barger, Mafatia, Whisnant, 2002; Huber, Winter, 2003; others) • Other possibilities? How much doeswhat help? Where to concentratethe efforts? ISS RAL NuFact - Walter Winter

  6. Optimization of a neutrino factory 4 yr x 1.06 1021m+ decays + 4 yr x 1.06 1021m- decays Detector: 50 kt magnetized iron calorimeter ISS-values? 100 kt, 5+5 years running time = factor 2.36 luminosity increase for 1021 useful decays/year Most of the following work is done in collaboration with P. HuberM. LindnerM. Rolinec

  7. Optimization summary: L-Em • Example: q13 sensitivity relative to minimum in each plot (5s – new!) • “Magic baseline” good degeneracy resolver • L ~ 2000 – 4000 kmgood for statistics • Em > 40 GeV • At 5s very robust to • Threshold effects • Dm312 larger • Luminosity (Huber, Lindner, Rolinec, Winter, to appear) ISS RAL NuFact - Walter Winter

  8. CP violation and mass hierarchy • L ~ 3000 – 5000 km good for CP violation (large q13 : 1500 – 6000) • L > 6000 km necessary for mass hierarchy (if small q13) • Use 4000 and 7500 km (“magic baseline”) as standard baselines CP violation Mass hier. ISS RAL NuFact - Walter Winter

  9. Improved (golden) detector summary • Better energy resolution?Was: 0.15 x E (approximation) Improve to: ? • Lower appearance threshold?Was: 4 GeV, linearly climbing to maximum at 20 GeVImprove to: Max. already at 1 GeV? • CC/NC Backgrounds: Assume BG fraction b x E-2 such that ~ 5 x 10-6 integrated over spectrum (b ~ 10-3) • Background increases at low energies • Even if CID improved, NC background limits performance! (Fig. from Huber, Lindner, Winter, 2002; Gray curve from Cervera et al, 2000) (Cervera et al, 2000) ISS RAL NuFact - Walter Winter

  10. Improved detector: MH and CP violation • Improved detector would be excellent degeneracy resolver! • Also: Em = 20 GeV possible (while 50 GeV do not harm) Blue shading:Optimization potential: Golden* ISS RAL NuFact - Walter Winter

  11. Improved detector: Systematics Preliminary • CP violationmeasurement veryrobust with respectto systematics (signal normalization error) andBG level as long as b << 10-2 • Note that 20% BG uncertainty assumed Standard“improved” detector ISS RAL NuFact - Walter Winter

  12. Systematics: Leading atm. parameters Preliminary • For Dm312 systematics somewhat important Dashed:10% error onsolar params • Energy resolution important for leading atm. parameters • Systematics somewhat important for Dm312, but impact of solar input much larger ISS RAL NuFact - Walter Winter

  13. Channel requirements: Phenomenology Assume specific hierarchy • Antineutrinos: • Magic baseline: • Silver: • Platinum: (Akhmedov, Johansson, Lindner, Ohlsson, Schwetz, 2004) ISS RAL NuFact - Walter Winter

  14. Platinum channel • Changes sign of CP-odd term • Compare to antineutrinos: • Antineutrino channel without matter effect suppression/enhancement (dep. on hierarchy) • Support information on dCP for large q13? ISS RAL NuFact - Walter Winter

  15. Platinum channel: Assumptions • Electron detection properties are MINOS-like (NuMI note NuMI-L-714) • 2.5 GeV threshold • 40% efficiency • Energy resolution 0.15 x E • 1% BG from all neutral current events • 1% BG from charge identification • Fiducial detector mass: same as “golden” mass • Matter density uncertainty: Correlated with golden channel • If platinum is possible, use it in all “golden” detectors, such as for NuFact+NuFact@MB at both places! Limits the q13for which thischannel is useful! ISS RAL NuFact - Walter Winter

  16. Platinum channel: Results Preliminary Golden+Platinum Golden+Platinum Golden Golden BG-dominated • Good degeneracy resolver; especially for large q13! ISS RAL NuFact - Walter Winter

  17. Silver channel • Changes sign of CP-even and CP-odd terms • Here: we only test maximal mixing • Interesting for matter density correlation:2nd and 3rd terms fully correlated/anticorrelated with matter density uncertainty from 1st term(if same matter profile as golden channel) ISS RAL NuFact - Walter Winter

  18. Silver channel: Assumptions • Emulsion cloud chamber a la OPERA(Autiero et al, 2004) • Threshold starting at 2.5 GeV (Fig. 7, Autiero et al, 2004) • Energy resolution 0.20 x E (optimistic?) • 10 kt fiducial mass • Only neutrinos detected • Matter density uncertainty: Correlated with golden channel if at same baseline • Also: Test improved Silver* with 5 x Signal, 3 x BG(if all leptonic and hadronic t decay channels could be measured?) (Migliozzi, private communication) ISS RAL NuFact - Walter Winter

  19. Silver channel: Options • Which baseline? • Same as golden channel + correlated matter effect • Different from golden channel + uncorrelated matter effect (e.g., L=732 km) • Main results (qualitatively): • Muon energies should probably not be too low (higher tau production threshold!) • Silver channel hardly affects golden channel opt. • Correlated matter effect helps and makes 4000 + 4000 km attractive ISS RAL NuFact - Walter Winter

  20. Silver channel: Results and comparison Preliminary • Matter density correlation helps • Silver without upgrades not competitive to platinum • Silver* at “golden” baseline complementary to platinum Effect ofcorrelatedmatter effect ISS RAL NuFact - Walter Winter

  21. Better detector vs. new channels Preliminary • Better detector = increase reach by improved statistics/energy info • Different channel = resolve degs by complementary information ISS RAL NuFact - Walter Winter

  22. Overall picture: Comparison matrix ISS RAL NuFact - Walter Winter

  23. Comparison matrix: Explanations Synergies:Comparablestatistics Detector degree of freedom Directcomparison ofoptions at samebaseline Accelerator degree of freedom Overall effort Optimized detector, additional channel, or increased luminosity increase “detector effort” by oneBaseline: 4000 km, unless different one in index (MB=“Magic baseline”). Muon energy: 50 GeVStars: Improved golden detector; in any star option the muon energy is 20 GeV ISS RAL NuFact - Walter Winter

  24. “Simple” options • No surprises: L=4000 km good for CP violation,L=7500 km good for mass hierarchy • Beta beam very good for CP violation, but cannot measure mass hierarchy for small q13 ISS RAL NuFact - Walter Winter

  25. Synergies for detector effort “two” Compare with each other: If similar impact,concentrate on better one? (Thick curves: two baselines) • Synergies and optimal performance in “competing regions” for Golden*, Golden+Platinum, Golden+(Golden)MB • NEW: Magic baseline helps for large q13! Compare to (Golden)2L:If better in some region, real synergy effect! ISS RAL NuFact - Walter Winter

  26. Physics case: Large sin22q13 Discovery reaches for: • For large q13, only CP violation an issue • Beta beam best option even after optimization CP violation (3s) Mass hierarchy (3s) sin22q13 (5s) ISS RAL NuFact - Walter Winter

  27. Physics case: Interm. sin22q13 • “Typical” physics case for a neutrino factory!? • Improved detector and magic baseline sufficient to make physics case against beta beam for any performance indicator used here ISS RAL NuFact - Walter Winter

  28. Physics case: Small sin22q13 • Clear physics case for neutrino factory even with “moderate” improvements • Optimal reach for improved detector and magic baseline • Beta beam cannot determine masshierarchy ISS RAL NuFact - Walter Winter

  29. Where to concentrate the efforts? • Optimized NuFact: Measure mass hierarchy and CP violation almost down to sin22q13 = 10-5! (including all degeneracies, for maximal mixing, 3s) ISS RAL NuFact - Walter Winter

  30. Comparison to beta beams Preliminary Assumptions: • 2.9 10186He decays/year1.1 101818Ne decays/year at simultaneous operation for eight years(or double ion decays/year) • g=350, L=730 km, 500 kt WCMaximum at CERN?(Burguet-Castell et al, 2005) • g=1000, L=1300 km, 50 kt TASDHigh end. Optimal for CP violation(Huber, Lindner, Rolinec, Winter, 2005) • g=1000, L=2600 km, 50 kt TASDHigh end. Optimal for mass hierarchy(Huber, Lindner, Rolinec, Winter, 2005) • g=1000, L=1300 km + 2600 kmWhy not two baselines similar to NuFact? ISS RAL NuFact - Walter Winter

  31. Comparison to beta beams (2) Preliminary • NF good for q13 discovery, MH discovery and dCP for small q13 • Beta beam competitive for CP violation (large q13); But: Extreme effort to measure MH if q13 small could make physics case difficult! ISS RAL NuFact - Walter Winter

  32. Summary • Physics case for neutrino factory for small/intermediate sin22q13 established; no clear physics case for large q13 yet(baseline reopt. and reduced matter density uncertainties help somewhat …) • The optimal neutrino factory has (at least) • Two baselines with golden channel detectors • A golden detector as optimized as possible • Electron neutrino detection in all golden detectors • The silver channel could be interesting if • Improved efficiencies (more tau decay channels) • Correlated matter effects (put detector to golden baseline) • Specific physics case (non-maximal mixing, unitarity test etc.) ISS RAL NuFact - Walter Winter

  33. (Our) plans • Refine systematics/BG impact study • Check what one has to do for improved leading atm. parameter measurements • Re-check silver channel baseline optimization:732 km? Both at same baseline? Change ofoptimization? Muon energies? • Test impact of matter density uncertaintiesafter (correlated) platinum/silver channels • Possibly some work on large q13 case • Finish this analysis (writeup as paper) ISS RAL NuFact - Walter Winter

  34. Additional slides

  35. MINOS: Larger value of Dm312? • No qualitative changes in L-E-optimization,but improved absolute reaches! • Physics case for magic baseline even stronger • Example: 0.003 eV2 ISS RAL NuFact - Walter Winter

  36. Better detector: q13 sensitivity • High CL chosen (4s):avoid threshold effects(q13,dCP)-degeneracy affects sensitivity limitat L ~ 1500-5000 km • Better detector threshold:L=2000-3000 km most attractive q13-baseline “Magicbaseline” Preliminary ISS RAL NuFact - Walter Winter

  37. Better detector: Large q13 Preliminary • Both better Eres and threshold useful • Both better detector and smaller matter density uncertainty useful • Either or combination sufficient to compete with the superbeam upgrades (prel.) • Large Dr+better detector prefers shorter baselines (1000-2000km); Em small OK No dCP at Lmagic! ISS RAL NuFact - Walter Winter

  38. Better detector in L-E-space: q13 sens. • 3s sensitivity to sin22q13 Better Eres Better threshold Better Eres+thresh. Preliminary (Huber, Lindner, Rolinec, Winter, to appear) ISS RAL NuFact - Walter Winter

  39. Better detector in L-E-space: Large q13 • CP fraction for CP violation (3s):“Standard”“Optimal appearance”L=1000 km/Em=20 GeVpossible alternative? Preliminary (Huber, Lindner, Rolinec, Winter, to appear) ISS RAL NuFact - Walter Winter

  40. Silver channel: Optimal baseline? Preliminary • Correlated matter effect with LECC=4000 km better than any other baseline (except q13 sensitivity for L ~ 1500 km) ISS RAL NuFact - Walter Winter

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