Phenomenology of future LBL experiments … and the context with Euro WP6 IDS-NF + Euro plenary meeting at CERN March 25, 2009 Walter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAA A A A

2 Contents  Introduction to LBL phenomenology  Status of  Neutrino factory  Superbeams  Beta beams  Current Euro /IDS-NF issues  Performance indicators  Benchmark setups  Optimization/decision: Large versus small  13  Conclusions This talk: Only standard oscillation physics

Long baseline phenomenology

4 Channels of interest  Disappearance for  m 31 2,  23 :    NB: We expand in  Appearance for  13, CPV, MH:  Golden: e   (NF/BB) or    e  (SB) (e.g., De Rujula, Gavela, Hernandez, 1999; Cervera et al, 2000)  Silver: e   (NF – low statistics!?) (Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004)  Platinum:   e (NF: maybe in low-E NF) (see e.g. ISS physics working group report)  „Discovery“:    (OPERA, NF?) (e.g. Fernandez-Martinez et al, 2007; Donini et al, 2008) Neutral currents for new physics (e.g., Barger, Geer, Whisnant, 2004; MINOS, 2008)  31 =  m 31 2 L/(4E)

5 Appearance channels (Cervera et al. 2000; Freund, Huber, Lindner, 2000; Huber, Winter, 2003; Akhmedov et al, 2004)  Antineutrinos:  Magic baseline:  Silver:  Superbeams, Plat.:

6 Degeneracies  CP asymmetry (vacuum) suggests the use of neutrinos and antineutrinos Burguet-Castell et al, 2001)  One discrete deg. remains in (  13,  )-plane (Burguet-Castell et al, 2001)  Additional degeneracies: (Barger, Marfatia, Whisnant, 2001)  Sign-degeneracy (Minakata, Nunokawa, 2001)  Octant degeneracy (Fogli, Lisi, 1996) Best-fit  -beam,  -beam, anti- Iso-probability curves

7 Degeneracy resolution  Matter effects (sign- degeneracy) – long baseline, high E  Different beam energies or better energy resolution in detector  Second baseline  Good enough statistics  Other channels  Other experiment classes WBB FNAL-DUSEL, T2KK, L, … Monochromatic beam, Beta beam with different isotopes, WBB, … T2KK, magic baseline ~ 7500 km, SuperNOvA Neutrino factory, beta beam, Mton WC SB+BB CERN-Frejus, NF Reactor, atmospheric, astrophysical, … (many many authors, see e.g. ISS physics WG report)

Status of the neutrino factory

9 Neutrino factory – IDS-NF IDS-NF:  Initiative from ~ to present a design report, schedule, cost estimate, risk assessment for a neutrino factory  In Europe: Close connection to „Euro us“ proposal within the FP 07  In the US: „Muon collider task force“ ISS (Geer, 1997; de Rujula, Gavela, Hernandez, 1998; Cervera et al, 2000) Signal prop. sin 2 2  13 Contamination Muons decay in straight sections of a storage ring

10 Physics potential  Excellent  13, MH, CPV discovery reaches  About 10% full width error (3  ) on log 10 (sin 2 2  13 ) for sin 2 2  13 = (Gandhi, Winter, hep-ph/ , Fig. 6)  About degree full width error (3  ) on  CP for sin 2 2  13 = (Huber, Lindner, Winter, hep-ph/ , Fig. 7) But what does that mean? Cabibbo angle-precision (  C ~ 13 deg.)! Why is that relevant? Can be another feature of nontrivial QLC models: E.g. from specific texture+QLC-type assumptions: (  : model parameter) (Niehage, Winter, arXiv: ) (IDS-NF, 2008)

11 Low energy neutrino factory  „ Low cost“ version of a neutrino factory for moderately large  13 : E  ~ 4.12 GeV  Possible through magnetized TASD with low threshold (Geer, Mena, Pascoli, hep-ph/ ; Bross et al, arXiv: )

12 On near  Define near detectors including source/detector geometry:  Near detector limit: Beam smaller than detector  Far detector limit: Spectrum similar to FD  Systematics  X-Section (shape) errors (30%)  Flux normalization errors (2.5%)  BG normalization errors (20%) (Tang, Winter, arXiv: ) ~ND limit~FD limit

13 ND: Main results  Need two near detectors, especially for leading atmospheric parameters  Flux monitoring important for CPV (large  13 )  Near detectors not relevant for  13 discovery, MH  Systematical errors cancel if two neutrino factory baselines (even without ND) 30% XSec-errors, uncorrelated among all bins Use near detectors (Tang, Winter, arXiv: )

14 Impact of ND+new systematics (Tang, Winter, arXiv: ) IDS-NF systematics too conservative? CP violation, 3 

15 Low-E versus high-E NuFact  High-E reference: IDS-NF baseline 1.0  Low-E reference: Bross et al, arXiv: , decays*kt, 2% systematics errors (flux norm, BGs) (Tang, Winter, arXiv: )  High-E NuFact one to two orders of magnitude in  13 better

16 NF: Status and outlook  Characteristics:  Truly international effort  Green-field setup (no specific site)  High-E NuFact: Benchmark setup defined  Will evolve over time  Examples: MECC, Detector masses of far detectors  Open issues: „Low cost“ alternative? Benchmark setup for that?  Euro relationship: Results shared between IDS- NF (physics) and Euro ; Funding from Euro

Status of superbeams

18 Beam/Superbeam setups Characteristics: Possible projects depend on regional boundary conditions (e.g., geography, accelerator infrastructure) Setups: MINOS NO A (+ upgrades) WBB FNAL-DUSEL … Setups: CNGS CERN SPL-Frejus … Setups: T2K T2HK T2KK …

19 Superbeam upgrades: Examples  Exposure L: Detector mass [Mt] x Target power [MW] x Running time [10 7 s]  Bands: variation of systematical errors: 2%-5%-10%  „Typical“  CP, 3  (Barger, Huber, Marfatia, Winter, hep-ph/ , hep-ph/ ) discovery Nominal exposure 120 GeV protons

20 Luminosity scalings  If  13 found by next generation:  WBB and T2KK can measure CPV, MH  NuMI requires Lumi-upgrade (ProjectX?)  Systematics impact least for WBB; best physics concept? MH for sin 2 2  13 > 0.003

21 On-axis versus off-axis Example: NuMI-like beam  100kt liquid argon  CP =-  /2  CP =+  /2 sin 2 2  13 CP violationMass hierarchy (Barger et al, hep-ph/ ) Constraint from NuMI beam FNAL- DUSEL WBB Ash River OA, NOvA* Off-axis technology may not be necessary if the detector is good enough, i.e., has good BG rejection and good energy resolution! WC good enough??? On axis

22  L=130 km: CERN-Frejus  Interesting in combination with beta beam: Use T-inverted channels ( e   and   e ) to measure CPV  Problem: MH sensitivity, only comparable to T2HK Concerns of WP6 communicated to Euro CB in Feb 2008: „[...] It is well known that this setup has good possibilities to observe CP violation, however, due to the short baseline there will be no chance to determine the mass hierarchy. We believe that this is a very important measurement for a future neutrino facility, and will be one of the comparison criteria to be defined within this study. We want to point out very clearly that restricting the SB study only to the CERN-Frejus setup excludes this measurement from the very beginning. […]” European plan: CERN-MEMPHYS 22 (Campagne, Maltoni, Mezzetto, Schwetz, hep-ph/ ) LBL+ATM WBB FNAL-DUSEL (average)

23 SB: Status and outlook  Characteristics:  Projects driven by regional interests/boundary conditions  Projects attached to existing accelerator sites (mid term perspective)  Benchmark setups:  Partly defined (such as baselines, detectors etc)  Fuzzy assumptions on proton plans, running times, … (benchmark comparison difficult!)  Relationship to Euro : Only CERN-Frejus setup studied within Euro WP2  Concern raised by some WP6 members: European setup maybe „dead end“?

Status of beta beams

25 Original „benchmark“ setup!? More recent key modifications:  Higher  (Burguet-Castell et al, hep-ph/ )  Different isotope pairs leading to higher neutrino energies (same  ) ( ) (CERN layout; Bouchez, Lindroos, Mezzetto, 2003; Lindroos, 2003; Mezzetto, 2003; Autin et al, 2003) (Zucchelli, 2002) (C. Rubbia, et al, 2006)  Key figure (any beta beam): Useful ion decays/year?  Often used “standard values”: He decays/year Ne decays/year  Typical  ~ 100 – 150 (for CERN SPS)

26 Current status: A variety of ideas  “Classical” beta beams:  “Medium” gamma options (150 <  < ~350) -Alternative to superbeam! Possible at SPS (+ upgrades) -Usually: Water Cherenkov detector (for Ne/He) (Burguet-Castell et al, ; Huber et al, 2005; Donini, Fernandez-Martinez, 2006; Coloma et al, 2007; Winter, 2008)  “High” gamma options (  >> 350) -Require large accelerator (Tevatron or LHC-size) -Water Cherenkov detector or TASD or MID? (dep. on , isotopes  (Burguet-Castell et al, 2003; Huber et al, 2005; Agarwalla et al, 2005, 2006, 2007, 2008, 2008; Donini et al, 2006; Meloni et al, 2008)  Hybrids:  Beta beam + superbeam (CERN-Frejus: see before; Fermilab: see Jansson et al, 2007)  “Isotope cocktail” beta beams (alternating ions) (Donini, Fernandez-Martinez, 2006)  Classical beta beam + Electron capture beam (Bernabeu et al, 2009) ……

27 Stand-alone European version?  CERN-Gran Sasso or Boulby?  Example: CERN-Boulby, L=1050 km   =450 (SPS upgrade), 18 Ne only!  Red: usef. ions x kt x yr  Blue: 5x20 21 usef. ions x kt x yr 99% CL Mass hierarchy (Meloni, Mena, Orme, Palomares-Ruiz, Pascoli, arXiv: ) Problem: Antineutrino channel missing! (degs only partially resolved by spectrum) More later …

28 BB: Status and outlook  Characteristics:  Mostly European effort (so far)  Partly green-field, mostly CERN-based  Benchmark setup:  Often-used: SPS-based setup, sort of „benchmark“ in the literature (e.g. for useful number of ion decays)  Not up-to-date anymore wrt isotopes, , useful ion decays etc  Define new benchmark with the necessary requirements for WP4?  Relationship to Euro : Studied within WP4 (mostly source aspects)

Current Euro physics issues (some thoughts)

30 Performance indicators  Many performance indicators used in literature  What is the best way to present?  Fair comparison of whole parameter space or comparison at specific benchmark points?  WP6 will have to look into this (Pilar) Example:  13 discovery vs  13 sensitivity (Huber, Lindner, Schwetz, Winter, in prep.) Warning: If particular  CP chosen, any answer can be obtained!

31 Benchmark setups: Status  Do we need these? At the end, for a physics comparison, probably …  Can be used to define requirements for reasonable physics output (see, e.g., IDS-NF)  Maybe: More aggressive versus minimal version Example: ISS Plot  Neutrino factory:  Exists for high-E version  Not yet for low cost version  Superbeam:  Minimal version exists (apart from specific numbers)  More aggressive: Not defined  Beta beam:  Minimal version exists (apart from specific numbers)  More aggressive: Not defined (ISS, arXiv: )

32  Small  13 : Optimize  13, MH, and CPV discovery reaches in  13 direction  Large  13 : Optimize  13, MH, and CPV discovery reaches in (true)  CP direction ~ Precision!  What defines “large  13 ”? A Double Chooz, Day Bay, T2K, … discovery! Optimization of exps (3  m 31 2 = eV 2  Optimization for small  13 Optimization for large  13 T2KK Beta beam NuFact

33 Large  13 strategy  Assume that we know  13 (Ex: Double Chooz)  Minimum wish list easy to define:  5  independent confirmation of  13 > 0  3  mass hierarchy determination for any (true)  CP  3  CP violation determination for 80% (true)  CP ~ Cabibbo-angle precision as a benchmark! For any (true)  13 in 90% CL D-Chooz allowed range! (use available knowledge on  13 and risk-minimize)  What is the minimal effort (minimal cost) for that?  Use resources wisely! (arXiv: Sim. from hep-ph/ ; 1.5 yr far det yr both det.) (arXiv: ; Sim. from hep-ph/ ; 1.5 yr far det yr both det.)

34 Example: Minimal beta beam  Minimal effort =  One baseline only  Minimal   Minimal luminosity  Any L (green-field!)  Example: Optimize L-  for fixed Lumi:   as large as 350 may not even be necessary! (arXiv: ) Sensitivity for entire Double Chooz allowed range! 5yr x Ne and 5yr x He useful decays

35 Minimal beta beam at the CERN- SPS? (  fixed to maximum at SPS) (arXiv: ) (500 kt) CERN-Boulby CERN-LNGS CERN-Boulby CERN-LNGS Conclusions: - CERN-Boulby or CERN-LNGS might be OK at current SPS if ~ 5 times more isotope decays than original benchmark (production ring?) - CERN-Frejus has too short baseline for stand-alone beta beam

36 Small  13 strategy  Assume that Double Chooz … do not find  13  Minimum wish list:   discovery of  13 > 0  3  mass hierarchy determination  3  CP violation determination For as small as possible (true)  13  Two unknowns here:  For what fraction of (true)  CP ? One has to make a choice (e.g. max. CP violation, for 80% of all  CP, for 50%, …)  How small  13 is actually good enough?  Minimal effort is a matter of cost!  Maybe the physics case will be defined otherwise? ?

37 Connection to high-E frontier?

38 Conclusions  Current status:  Neutrino factory:  Strong collaboration with IDS-NF  High-E benchmark setup defined  „Low cost“ version further studied  Superbeams:  CERN-Frejus anticipated as benchmark  Has too little MH sensitivity, even if combined with atm. data (Issues: low energy, short baseline)  Beta beams:  SPS-based benchmark often used in literature  Probably not sufficient: Define more aggressive version with higher  or more isotope decays (production ring)?  Next steps?  Discuss performance indicators  Discuss if benchmarks needed for WP6  Connection to global perspective?  …

Backup

40 Long baseline experiments Contamination SourceProduction … and DetectionLimitationsL Beam, Super- beam Intrinsic beam BGs, systematics ,500 km ~ 0.5 – 5 GeV Neutrino factory Charge identification, NC BG ,500 km 2-25 GeV  -beam Source luminosity ,500 km 0.3 – 10 GeV For leading atm. params Signal prop. sin 2 2  13

41 IDS-NF baseline setup 1.0  Two decay rings  E  =25 GeV  5x10 20 useful muon decays per baseline (both polarities!)  Two baselines: ~ km  Two MIND, 50kt each  Currently: MECC at shorter baseline (

42 Two-baseline optim. revisited  Robust optimum for ~ km  Optimization even robust under non- standard physics (dashed curves) (Kopp, Ota, Winter, 2008)

43 Timescale for  13 discovery? (Huber, Kopp, Lindner, Rolinec, Winter, 2006)  Assume: Decision on future experiments made after some LHC running and next- generation experiments  Two examples:  ~ 2011: sin 2 2  13 > 0.04?  ~ 2015: sin 2 2  13 > 0.01? D

44 Example: CPV discovery … in (true) sin 2 2  13 and  CP Sensitive region as a function of true  13 and  CP  CP values now stacked for each  13 Read: If sin 2 2  13 =10 -3, we expect a discovery for 80% of all values of  CP No CPV discovery if  CP too close to 0 or  No CPV discovery for all values of  CP 33 Cabibbo-angle precision for  CP ~ 85%! Fraction 80% (3  ) corresponds to Cabibbo-angle precision at 2  BENCHMARK! Best performance close to max. CPV (  CP =  /2 or 3  /2)

45 Luminosity scaling for fixed L  What is the minimal LSF x  ?  (Ne,He): LSF = 1 possible (B,Li): LSF = 1 not sufficient  But: If LSF >= 5:  can be lower for (B,Li) than for (Ne,He), because MH measurement dominates there (requires energy!) (Winter, arXiv: ) (100kt) (500kt) only  < 150!

46 Minimal  beta beam (Winter, arXiv: )