1. Neutrino Factory and Beta Beam Experiment NO-VE 2006 Venice, Italy February 8, 2006 Walter Winter Institute for Advanced Study, Princeton

2. Feb. 8, 2006NOVE 2006 - Walter Winter2 Contents Introduction Introduction Neutrino factory Neutrino factory –Basics –Correlation and degeneracy resolution –ISS study: Current status –Optimization –“New physics” tests and other oscillation physics Beta beams Beta beams –Basics –Optimization –Comparison to neutrino factory Summary Summary

3. Feb. 8, 2006NOVE 2006 - Walter Winter3 Three-flavor oscillations: Requirements Coupling strength:  13 Atmospheric oscillation: Amplitude:  23 Frequency:  m 31 2 Solar oscillation: Amplitude:  12 Frequency:  m 21 2 Sub- leading effect:  CP Neutrino oscillation parameters (1  ):  m 21 2 ~ 8.2 10 -5 eV 2 +- 5% sin 2 2  12 ~ 0.83 +- 5% |  m 31 2 | ~ (2 – 2.5) 10 -3 eV 2 sin 2 2  23 ~ 1+- 7% sin 2 2     CP  Mass hierarchy? Neutrino oscillation parameters (1  ):  m 21 2 ~ 8.2 10 -5 eV 2 +- 5% sin 2 2  12 ~ 0.83 +- 5% |  m 31 2 | ~ (2 – 2.5) 10 -3 eV 2 sin 2 2  23 ~ 1+- 7% sin 2 2     CP  Mass hierarchy? (see e.g. Bahcall et al, hep-ph/0406294; Super-K, hep-ex/0501064; CHOOZ+solar papers) Key to subleading effects (CP violation, mass hierarchy)  13 Neutrino factory/ Beta Beam if  13 small!

4. Feb. 8, 2006NOVE 2006 - Walter Winter4 Timescales This talk: beyond next ten years! This talk: beyond next ten years!  Neutrino factory  Medium to high  beta beam But: Note that Beta Beams possible on different  scales  Timescale: 2025? (from: FNAL Proton Driver Study) Beta Beam? Depends on  !

5. Feb. 8, 2006NOVE 2006 - Walter Winter5 Neutrino factory Ultimate “high precision” instrument!? Ultimate “high precision” instrument!? Muon decays in straight sections of storage ring Muon decays in straight sections of storage ring Technical challenges: Target power, muon cooling, charge identification, maybe steep decay tunnels Technical challenges: Target power, muon cooling, charge identification, maybe steep decay tunnels (from: CERN Yellow Report ) p Target , K  Decays  -Accelerator  Cooling “Right sign” “Wrong sign” “Right sign” “Wrong sign” (Geer, 1997; de Rujula, Gavela, Hernandez, 1998; Cervera et al, 2000)

6. Feb. 8, 2006NOVE 2006 - Walter Winter6 Storage ring and “typical” params? Goal: ~ 10 21 useful muon decays/year. Two models: Goal: ~ 10 21 useful muon decays/year. Two models: Other “typical” parameters (high-E neutrino factory): E  = 50 GeV, L = 3,000 km (CP violation) Detector: 50 kt magnetized iron calorimeter (more ambitious: 100 kt, 10 years running time – ISS values) Operate two baselines in two polarities successively: 4 years x 10 21  + decays + 4 years x 10 21  - decays Operate two baselines in two polarities successively: 4 years x 10 21  + decays + 4 years x 10 21  - decays Operate one baseline in two polarities simultaneously: 8 years x 5 10 20  + decays + 8 years x 5 10 20  - decays Operate one baseline in two polarities simultaneously: 8 years x 5 10 20  + decays + 8 years x 5 10 20  - decays ++ --  + or  - “racetrack” (not to scale) “triangular”

7. Feb. 8, 2006NOVE 2006 - Walter Winter7 Appearance channels:  e  Complicated, but all interesting information there:  13,  CP, mass hierarchy (via A) (Cervera et al. 2000; Freund, Huber, Lindner, 2000; Freund, 2001)

8. Feb. 8, 2006NOVE 2006 - Walter Winter8 Correlations and degeneracies Connected (green) or disconnected (yellow) degenerate solutions (at a chosen CL) in parameter space Connected (green) or disconnected (yellow) degenerate solutions (at a chosen CL) in parameter space Affect performance of appearance measurements. For example,  13 sensitivity Affect performance of appearance measurements. For example,  13 sensitivity (Huber, Lindner, Winter, 2002) Discrete degeneracies: (also: Barger, Marfatia, Whisnant, 2001) Intrinsic ( ,  13 )-degeneracy (Burguet-Castell et al, 2001) sgn-degeneracy (Minakata, Nunokawa, 2001) (  23,  /2-  23 )-degeneracy (Fogli, Lisi, 1996) Discrete degeneracies: (also: Barger, Marfatia, Whisnant, 2001) Intrinsic ( ,  13 )-degeneracy (Burguet-Castell et al, 2001) sgn-degeneracy (Minakata, Nunokawa, 2001) (  23,  /2-  23 )-degeneracy (Fogli, Lisi, 1996)

9. Feb. 8, 2006NOVE 2006 - Walter Winter9 More correlations: Matter density For instance: Measure  CP with high precision for large  13 at L ~ 3 000 km For instance: Measure  CP with high precision for large  13 at L ~ 3 000 km 5% matter density uncertainty in mantle not acceptable for these measurements! Has to be of the order of 1% ( Figure from Ohlsson, Winter, 2003; see also: Koike, Sato, 1999; Jacobsson et al, 2001; Burguet-Castell et al, 2001; Geller, Hara, 2001; Shan, Young, Zhang, 2001; Fogli, Lettera, Lisi, 2001; Shan, Zhang, 2002; Huber, Lindner, Winter, 2002; Ota, Sato, 2002; Shan et al, 2003; Kozlovskaya, Peltoniemi, Sarkamo, 2003; others) Matter density uncertainties in 3D models ~ 5% (http://cfauvcs5.harvard.edu/lana/rem/mapview.htm)

10. Feb. 8, 2006NOVE 2006 - Walter Winter10 NF measurements: Performance indicators Matter of definition and hypothesis What indicator to use depends on purpose! Matter of definition and hypothesis What indicator to use depends on purpose! Examples (  CP only!) Examples (  CP only!) –Allowed region in  -  13 -plane Identify how much parameter space remains for specific hypotheses of simulated values –Sensitivity to max. CP violation  /2 or 3  /2 Can CP violation be detected for the hypothesis of max. CP violation? –Sensitivity to “any” CP violation For what fraction of CP violating values can CP violation be detected? (CP fraction plots!) –Precision of  How precisely can one measure  (only defined in the high precision limit, since  cyclic; also: not Gaussian!) –CP coverage How precisely can one measure  or what fraction of the parameter space can be excluded? Level of condensation, computation time True values: Few examples True values: Complete relevant space Purpose: Risk minimization Purpose: Looks like result

11. Feb. 8, 2006NOVE 2006 - Walter Winter11 NF measurements: Example  CP coverage Define: CP coverage = Fraction of all fit values of  which fit a chosen true  CP coverage <= 360 o Define: CP coverage = Fraction of all fit values of  which fit a chosen true  CP coverage <= 360 o CP scalingCP pattern  2 = 9, 4, 1; dashed: no degs) (Fig. from Huber, Lindner, Winter, hep-ph/0412199) True values of  and  13 affect topology! Degeneracies! True values of  and  13 affect topology! Degeneracies! But: Degeneracies not everywhere in param. space important But: Degeneracies not everywhere in param. space important Degeneracy problem even bigger than for max. CP violation!

12. Feb. 8, 2006NOVE 2006 - Walter Winter12 NF-Strategies to resolve degeneracies … depend on sin 2 2  13 ! Combine with superbeam upgrade ( sin 2 2  13 > 10 -3 ) (Burguet-Castell et al, 2002) Combine with superbeam upgrade ( sin 2 2  13 > 10 -3 ) (Burguet-Castell et al, 2002) Combine with “silver channels” e ->  ( sin 2 2  13 > 10 -3 ?) (Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004) Combine with “silver channels” e ->  ( sin 2 2  13 > 10 -3 ?) (Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004) Better detectors: Higher energy resolution, higher efficiencies at low energies (CID!) ( sin 2 2  13 > ?) (Will be important aspect in ISS study!) Better detectors: Higher energy resolution, higher efficiencies at low energies (CID!) ( sin 2 2  13 > ?) (Will be important aspect in ISS study!) Second NF baseline: “Magic baseline” ( sin 2 2  13 > 10 -4 ) (Lipari, 2000; Burguet-Castell et al, 2001; Barger, Mafatia, Whisnant, 2002; Huber, Winter, 2003; others) Second NF baseline: “Magic baseline” ( sin 2 2  13 > 10 -4 ) (Lipari, 2000; Burguet-Castell et al, 2001; Barger, Mafatia, Whisnant, 2002; Huber, Winter, 2003; others) Other possibilities? Other possibilities? (Fig. from Huber, Lindner, Winter, 2002) Intrinsic degeneracy disappears for better energy threshold! sin 2 2  13 =0.001

13. Feb. 8, 2006NOVE 2006 - Walter Winter13 Example: “Magic baseline” Idea: Yellow term = 0 independent of E, oscillation parameters Idea: Yellow term = 0 independent of E, oscillation parameters Purpose: “Clean” measurement of  13 and mass hierarchy Purpose: “Clean” measurement of  13 and mass hierarchy Drawback: No  CP measurement at magic baseline Drawback: No  CP measurement at magic baseline  combine with shorter baseline, such as L=3 000 km  13 -range: 10 -4 < sin 2 2  13 < 10 -2, where most problems with degeneracies are present  13 -range: 10 -4 < sin 2 2  13 < 10 -2, where most problems with degeneracies are present

14. Feb. 8, 2006NOVE 2006 - Walter Winter14 Unstable: Disappears for different parameter values Magic baseline:  13 sensitivity Use two-baseline space (L 1,L 2 ) with (25kt, 25kt) and compute  13 sensitivity including correlations and degeneracies: No CP violation measurement there! Optimal performance for all quantities: Animation in  13 -  CP -space: (Huber, Winter, 2003) sin 2 2  13  CP

15. Feb. 8, 2006NOVE 2006 - Walter Winter15 CP coverage and “real synergies” 3 000 km + 7 500 km versus all detector mass at 3 000 km (2L) 3 000 km + 7 500 km versus all detector mass at 3 000 km (2L) Magic baseline allows a risk-minimized measurement (unknown  ) Magic baseline allows a risk-minimized measurement (unknown  ) “Staged neutrino factory”: Option to add magic baseline later if in “bad” quadrants? “Staged neutrino factory”: Option to add magic baseline later if in “bad” quadrants? Any “extra” gain beyond a simple addition of statistics One baseline enough Two baselines necessary (Huber, Lindner, Winter, 2004)

16. Feb. 8, 2006NOVE 2006 - Walter Winter16 ISS study International scoping study of a future neutrino factory and super-beam facility Establish physics case for a facility (accelerator complex and detection systems) for a future long- baseline neutrino oscillation program Establish physics case for a facility (accelerator complex and detection systems) for a future long- baseline neutrino oscillation program “Define” requirements: Muon energy, baselines, channels, … “Define” requirements: Muon energy, baselines, channels, … Three working groups: Physics, accelerator, detector (Dornan; Blondel, Nagashima, Zisman; King, Long, Roberts, Yasuda; many others) Three working groups: Physics, accelerator, detector (Dornan; Blondel, Nagashima, Zisman; King, Long, Roberts, Yasuda; many others) Next plenary meeting: April 24-29, 2006 at RAL (UK) Next plenary meeting: April 24-29, 2006 at RAL (UK) Final written report: September 2006? Final written report: September 2006? More information: http://www.hep.ph.ic.ac.uk/iss/ More information: http://www.hep.ph.ic.ac.uk/iss/

17. Feb. 8, 2006NOVE 2006 - Walter Winter17 ISS issues: Physics cases? Examples (  13 only): Examples (  13 only): 1)Large  13 : sin 2 2  13 > 0.01 (Physics case for NuFact at all? vs. Superbeams?) 2)Small  13 : 10 -4 < sin 2 2  13 < 10 -2 (NuFact’s “golden age”?) 3)“Zero”  13 : sin 2 2  13 << 10 -4 (What physics can be done? What does that mean?) Maybe: Only build NF if T2K, Double Chooz etc. do not see a signal? Maybe: Only build NF if T2K, Double Chooz etc. do not see a signal? (Huber/POFPA report) Neutrino factory! (or higher gamma beta beam) Beta beam? Superbeam- Upgrade? -factory? 123

18. Feb. 8, 2006NOVE 2006 - Walter Winter18 ISS issues: Better detector? Better threshold (low-E efficiencies) helps for all measurements! Better threshold (low-E efficiencies) helps for all measurements! Better energy resolution helps somewhat Better energy resolution helps somewhat Better threshold (low-E efficiencies) helps for all measurements Better threshold (low-E efficiencies) helps for all measurements Better energy resolution helps somewhat Better energy resolution helps somewhat Better detector may be key component in large  13 discussion Better detector may be key component in large  13 discussion (Huber, Lindner, Rolinec, Winter, to appear)

19. Feb. 8, 2006NOVE 2006 - Walter Winter19 Physics case for  13 =0? Establish MSW effect for  13 =0 by solar oscillation (appearance prob.) L > 5,500 km (Winter, 2004) Determine mass hierarchy for  13 =0 (disappearance probability) L ~ 6,000 km (de Gouvea, Jenkins, Kayser, 2005; de Gouvea, Winter, 2005) Very long (>> 3,000 km) baseline important component of any such program! Theoretical:  13 =0 would be an important indicator for some symmetry!

20. Feb. 8, 2006NOVE 2006 - Walter Winter20 Optimization of a neutrino factory Example:  13 sensitivity relative to minimum in each plot (3  ) Example:  13 sensitivity relative to minimum in each plot (3  ) Important result: Since muon energy ~ $ 40 GeV enough?! Important result: Since muon energy ~ $ 40 GeV enough?! Threshold effects: Threshold effects: (Huber, Lindner, Rolinec, Winter, to appear; also: Freund, Huber, Lindner, 2001)

21. Feb. 8, 2006NOVE 2006 - Walter Winter21 Disappearance channels Disappearance information important to reduce errors on leading parameters (see e.g. Donini, Fernandez-Martinez, Rigolin, 2005; Donini, Fernandez-Martinez, Meloni, Rigolin, 2005) Disappearance information important to reduce errors on leading parameters (see e.g. Donini, Fernandez-Martinez, Rigolin, 2005; Donini, Fernandez-Martinez, Meloni, Rigolin, 2005) Idea: Use data sample without charge identification for disappearance, i.e., add right and wrong sign muon events Idea: Use data sample without charge identification for disappearance, i.e., add right and wrong sign muon events  Better efficiencies! (de Gouvea, Winter, 2005; Huber, Lindner, Rolinec, Winter, to appear) sin 2 2  13 = 0 (Fig. from Huber, Lindner, Winter, 2002) sin 2 2  13 precision

22. Feb. 8, 2006NOVE 2006 - Walter Winter22 Beyond three-flavor oscillations? Test unitarity and small ad-mixtures of “new physics” by:   detection P ee +P e  +P e  = 1? (Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004) 2. Neutral currents (hard, but harder than 1.?) (Barger, Geer, Whisnant, 2004) 3. Construction of unitarity triangles? (Xing, Zhang, 2004/2005) 4. Spectral signature for probability-level effects Example: Damping effects (Blennow, Ohlsson, Winter, hep-ph/0502147) 5. More complicated: Hamiltonian-level effects: Spectrum shifts (e.g., Blennow, Ohlsson, Winter, hep-ph/0508175) Example: Oscillation-NSI confusion theorem (Huber, Schwetz, Valle, 2002) Characteristic enhancement/ depletion in certain regions of spectrum while oscillation nodes remain unchanged Search for “new physics” motivated by many theoretical effects, such as neutrino decay, decoherence, search for steriles, LFV, extra dimenstions, …

23. Feb. 8, 2006NOVE 2006 - Walter Winter23 Other physics: Geophysics? Example: Measure inner core density  IC Per cent level precision not unrealistic Per cent level precision not unrealistic Survives unknown oscillation parameters Survives unknown oscillation parameters More recent discussions: Discriminate seismically degenerate geophysics models in mantle, test plum hypothesis etc.? More recent discussions: Discriminate seismically degenerate geophysics models in mantle, test plum hypothesis etc.? (Winter, 2005) BNL CERN JHF Inner core shadow sin 2 2  13 =0.01

24. Feb. 8, 2006NOVE 2006 - Walter Winter24 Beta beam Key figure (any beta beam): Useful ion decays/year? Key figure (any beta beam): Useful ion decays/year? “Standard values”: 3 10 18 6 He decays/year 1 10 18 18 Ne decays/year “Standard values”: 3 10 18 6 He decays/year 1 10 18 18 Ne decays/year  Can these be achieved? Typical gamma ~ 100 – 150 (for CERN SPS) Typical gamma ~ 100 – 150 (for CERN SPS) (CERN layout; Bouchez, Lindroos, Mezzetto, 2003; Lindroos, 2003; Mezzetto, 2003; Autin et al, 2003) Compared to superbeam: no intrinsic beam BG limiting the sin 2 2  13 sensitivity to > 10 -3 Compared to superbeam: no intrinsic beam BG limiting the sin 2 2  13 sensitivity to > 10 -3 Compared to neutrino factory: no charge identification required Compared to neutrino factory: no charge identification required  In principle, very interesting alternative concept! (Zucchelli, 2002)

25. 25 From very low to high gamma “Very low” gamma (  <150?) “Very low” gamma (  <150?) -Alternative to superbeam? -Originally designed for CERN (SPS) -Water Cherenkov detector (see before; also: Volpe, 2003) “Low” gamma (150<  <300-350?) “Low” gamma (150<  <300-350?) -Alternative to superbeam! -Possible at upgraded SPS? -Water Cherenkov detector (Burguet-Castell et al, 2004+2005; Huber et al, 2005) “Medium” gamma (300-350<  <800?) “Medium” gamma (300-350<  <800?) -Physics potential compared to effort? -Requires large accelerator (Tevatron-size) -Water Cherenkov detector or TASD or? (Burguet-Castell et al, 2004; Huber et al, 2005) “High” gamma (  >800?) “High” gamma (  >800?) -Alternative to neutrino factory? -Requires very large accelerator (LHC-size) -Detector technology other than water (TASD?) (Burguet-Castell et al, 2004; Huber et al, 2005; Agarwalla et al, 2005) (Fig. from Huber, Lindner, Rolinec, Winter, 2005) (for NOvA-like detector!) Gamma determines neutrino energy and therefore detector technology!

26. Feb. 8, 2006NOVE 2006 - Walter Winter26 Optimization of a beta beam Baseline optimization depends on goals and gamma: (Fig. from Huber, Lindner, Rolinec, Winter, 2005) Baseline optimization depends on goals and gamma: (Fig. from Huber, Lindner, Rolinec, Winter, 2005) For lower gamma: Second osc. max. useful to resolve degs For lower gamma: Second osc. max. useful to resolve degs Neutrino/antineutrino running: Have at least 10-20% of originally proposed flux! Neutrino/antineutrino running: Have at least 10-20% of originally proposed flux! (for other degeneracy studies: see, e.g. Donini, Fernandez-Martinez, Rigolin, 2004; Donini, Fernandez-Martinez, Migliozzi, Rigolin, 2004)

27. Feb. 8, 2006NOVE 2006 - Walter Winter27 Beta beam vs. Superbeam vs. NuFact? Lower  : Can easily compete with superbeam upgrades if properly optimized Lower  : Can easily compete with superbeam upgrades if properly optimized Higher  : At least theoretically competitive to a neutrino factory Higher  : At least theoretically competitive to a neutrino factory Challenges: Challenges: -Can fluxes be reached? -Compare completely optimized accelerator strategies? (Fig. from Huber, Lindner, Rolinec, Winter, 2005)

28. Feb. 8, 2006NOVE 2006 - Walter Winter28 Beta beam in ISS study (from talk given by Elena Couce on Jan. 24 at KEK) Use of Water Cherenkov detector Use of Water Cherenkov detector New efficiency and BG matrices for migration New efficiency and BG matrices for migration High gamma beta beam best alternative (even “low flux”) High gamma beta beam best alternative (even “low flux”) Two different options!

29. Feb. 8, 2006NOVE 2006 - Walter Winter29 What if  13 is large? Do we need a NuFact/ Beta beam program in this case? What if  13 is large? Do we need a NuFact/ Beta beam program in this case? NuFact: NuFact: –Feasibility of muon cooling, target power etc. (MICE, …) –Flexible storage ring concept for different physics scenarios? –Detector: Is there space for improvement? Beta beam: Beta beam: –Feasibility? Competitiveness? Price tag?  Probably depends on gamma! –Stored ions?  Answers from EURISOL design study? http://www.eurisol.org/ Summary: Key questions