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

2. This talk: Only standard oscillation physics
Contents
Introduction to LBL phenomenology
Status of
Neutrino factory
Superbeams
Beta beams
Current Euron/IDS-NF issues
Performance indicators
Benchmark setups
Optimization/decision: Large versus small q13
Conclusions
This talk: Only standard oscillation physics

3. Long baseline phenomenology

4. Channels of interest
Disappearance for Dm312, q23: nm  nm NB: We expand in
Appearance for q13, CPV, MH:
Golden: ne  nm (NF/BB) or nm  ne (SB) (e.g., De Rujula, Gavela, Hernandez, 1999; Cervera et al, 2000)
Silver: ne  nt (NF – low statistics!?) (Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004)
Platinum: nm  ne (NF: maybe in low-E NF) (see e.g. ISS physics working group report)
„Discovery“: nm  nt (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)
D31 = Dm312 L/(4E)

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

6. Iso-probability curves
Degeneracies
Iso-probability curves
CP asymmetry (vacuum) suggests the use of neutrinos and antineutrinos
One discrete deg. remains in (q13,d)-plane (Burguet-Castell et al, 2001)
Additional degeneracies: (Barger, Marfatia, Whisnant, 2001)
Sign-degeneracy (Minakata, Nunokawa, 2001)
Octant degeneracy (Fogli, Lisi, 1996)
b-beam, n
b-beam, anti-n
Best-fit

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)

8. Status of the neutrino factory

9. Neutrino factory – IDS-NF
(Geer, 1997; de Rujula, Gavela, Hernandez, 1998; Cervera et al, 2000)
Signal prop. sin22q13
Contamination
Muons decay in straight sections of a storage ring
IDS-NF:
Initiative from ~ to present a design report, schedule, cost estimate, risk assessment for a neutrino factory
In Europe: Close connection to „Euronus“ proposal within the FP 07
In the US: „Muon collider task force“
ISS

10. Physics potential Excellent q13, MH, CPV discovery reaches
(IDS-NF, 2008)
About 10% full width error (3s) on log10 (sin22q13) for sin22q13 = (Gandhi, Winter, hep-ph/ , Fig. 6)
About degree full width error (3s) on dCP for sin22q13 = (Huber, Lindner, Winter, hep-ph/ , Fig. 7) But what does that mean? Cabibbo angle-precision (qC ~ 13 deg.)! Why is that relevant? Can be another feature of nontrivial QLC models: E.g. from specific texture+QLC-type assumptions: (F: model parameter)
(Niehage, Winter, arXiv: )

11. Low energy neutrino factory
„Low cost“ version of a neutrino factory for moderately large q13: Em ~ 4.12 GeV
Possible through magnetized TASD with low threshold
(Geer, Mena, Pascoli, hep-ph/ ; Bross et al, arXiv: )

12. On near detectors@IDS-NF
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%)
~ND limit
~FD limit
(Tang, Winter, arXiv: )

13. ND: Main results
Need two near detectors, especially for leading atmospheric parameters
Flux monitoring important for CPV (large q13)
Near detectors not relevant for q13 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
CP violation, 3s
IDS-NF systematics too conservative?
(Tang, Winter, arXiv: )

15. Low-E versus high-E NuFact
High-E reference: IDS-NF baseline 1.0
Low-E reference: Bross et al, arXiv: , 1023 decays*kt, 2% systematics errors (flux norm, BGs)
High-E NuFact one to two orders of magnitude in q13 better
(Tang, Winter, arXiv: )

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?
Euron relationship: Results shared between IDS-NF (physics) and Euron; Funding from Euron

17. Status of superbeams

18. Beam/Superbeam setups
Characteristics: Possible projects depend on regional boundary conditions (e.g., geography, accelerator infrastructure)
Setups: MINOS NOnA (+ upgrades) WBB FNAL-DUSEL …
Setups: CNGS CERN SPL-Frejus …
Setups: T2K T2HK T2KK …

19. Superbeam upgrades: Examples
120 GeV protons
Exposure L: Detector mass [Mt] x Target power [MW] x Running time [107s]
Bands: variation of systematical errors: 2%-5%-10%
„Typical“ dCP, 3s
discovery
Nominal exposure
(Barger, Huber, Marfatia, Winter, hep-ph/ , hep-ph/ )

20. Luminosity scalings If q13 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 sin22q13 > 0.003

21. On-axis versus off-axis Example: NuMI-like beam  100kt liquid argon
sin22q13
CP violation
Mass hierarchy
FNAL-DUSEL WBB
dCP=-p/2
Ash River OA, NOvA*
Constraint from NuMI beam
dCP=+p/2
(Barger et al, hep-ph/ )
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???

22. European plan: CERN-MEMPHYS
L=130 km: CERN-Frejus
Interesting in combination with beta beam: Use T-inverted channels (ne  nm and nm  ne) to measure CPV
Problem: MH sensitivity, only comparable to T2HK Concerns of WP6 communicated to Euron 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. […]” 2s
LBL+ATM
WBB FNAL-DUSEL (average)
(Campagne, Maltoni, Mezzetto, Schwetz, hep-ph/ )

23. SB: Status and outlook Characteristics: Benchmark setups:
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 Euron: Only CERN-Frejus setup studied within Euron WP2
Concern raised by some WP6 members: European setup maybe „dead end“?

24. Status of beta beams

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

26. Current status: A variety of ideas
“Classical” beta beams:
“Medium” gamma options (150 < g < ~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 (g >> 350)
Require large accelerator (Tevatron or LHC-size)
Water Cherenkov detector or TASD or MID? (dep. on g, 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
g=450 (SPS upgrade), 18Ne only!
Red: 1021 usef. ions x kt x yr
Blue: 5x2021 usef. ions x kt x yr
Mass hierarchy
99% CL
Problem: Antineutrino channel missing! (degs only partially resolved by spectrum) More later …
99% CL
(Meloni, Mena, Orme, Palomares-Ruiz, Pascoli, arXiv: )

28. BB: Status and outlook Characteristics: Benchmark setup:
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, g, useful ion decays etc
Define new benchmark with the necessary requirements for WP4?
Relationship to Euron: Studied within WP4 (mostly source aspects)

29. Current Euron 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: q13 discovery vs q13 sensitivity (Huber, Lindner, Schwetz, Winter, in prep.)
Preliminary
Warning: If particular dCP 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:
(ISS, arXiv: )

32. Optimization of exps
Small q13: Optimize q13, MH, and CPV discovery reaches in q13 direction
Large q13: Optimize q13, MH, and CPV discovery reaches in (true) dCP direction ~ Precision!
What defines “large q13”? A Double Chooz, Day Bay, T2K, … discovery!
Beta beam
Optimization for large q13
NuFact
T2KK
Optimization for small q13
(3s, Dm312= eV2)

33. Large q13 strategy Assume that we know q13 (Ex: Double Chooz)
Minimum wish list easy to define:
5s independent confirmation of q13 > 0
3s mass hierarchy determination for any (true) dCP
3s CP violation determination for 80% (true) dCP ~ Cabibbo-angle precision as a benchmark!
For any (true) q13 in 90% CL D-Chooz allowed range! (use available knowledge on q13 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.)

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

35. Minimal beta beam at the CERN-SPS? (g fixed to maximum at SPS)
(500 kt)
CERN-Boulby
CERN-Boulby
CERN-LNGS
CERN-LNGS
(arXiv: )
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 q13 strategy Assume that Double Chooz … do not find q13
Minimum wish list:
3s-5s discovery of q13 > 0
3s mass hierarchy determination
3s CP violation determination
For as small as possible (true) q13
Two unknowns here:
For what fraction of (true) dCP? One has to make a choice (e.g. max. CP violation, for 80% of all dCP, for 50%, …)
How small q13 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: Next steps? Neutrino factory: Superbeams:
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 g or more isotope decays (production ring)?
Next steps?
Discuss performance indicators
Discuss if benchmarks needed for WP6
Connection to global perspective? …

39. Backup

40. Long baseline experiments
Source
Production … and Detection
Limitations L
<E>
Beam, Super-beam
Intrinsic beam BGs, systematics
100-2,500 km
~ 0.5 – 5 GeV
Neutrino factory
Charge identification, NC BG
700-7,500 km
2-25 GeV
b-beam
Source luminosity
100-7,500 km
0.3 – 10 GeV
For leading atm. params
Signal prop. sin22q13
Contamination

41. IDS-NF baseline setup 1.0 Two decay rings Em=25 GeV
5x1020 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 q13 discovery?
Assume: Decision on future experiments made after some LHC running and next-generation experiments
Two examples:
~ 2011: sin22q13 > 0.04?
~ 2015: sin22q13 > 0.01? D
(Huber, Kopp, Lindner, Rolinec, Winter, 2006)

44. Example: CPV discovery … in (true) sin22q13 and dCP
Best performance close to max. CPV (dCP = p/2 or 3p/2)
Sensitive region as a function of true q13 and dCP
dCP values now stacked for each q13
No CPV discovery if dCP too close to 0 or p
No CPV discovery for all values of dCP 3s
Cabibbo-angle precision for dCP ~ 85%! Fraction 80% (3s) corresponds to Cabibbo-angle precision at 2s BENCHMARK!
Read: If sin22q13=10-3, we expect a discovery for 80% of all values of dCP

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

46. Minimal g beta beam
(Winter, arXiv: )