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Neutrino oscillations: Perspective of long-baseline experiments. 522. Wilhelm and Else Heraeus-Seminar: Exploring the neutrino sky and fundamental particle physics on the Megaton scale Bad Honnef, Jan. 21, 2013 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. - PowerPoint PPT Presentation
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Neutrino oscillations: Perspective of long-baseline experiments
522. Wilhelm and Else Heraeus-Seminar:Exploring the neutrino sky and fundamental particle physics on the Megaton scale
Bad Honnef, Jan. 21, 2013
Walter WinterUniversität Würzburg
2
Contents
Introduction Measurement of CP:
Experiments and phenomenology The critical issue for large 13:
Systematics? Long-baseline alternatives with new
technologies? Comment on sterile neutrinos Summary
3
(also: T2K, Double Chooz, RENO)
(short baseline)
4
Consequences of large 13
13 to be well measured by Daya Bay
Mass hierarchy: 3 discovery for up to 40% of all CP possible iff ProjectX, possiblyuntil 2025
CP violation measurement extremely difficultNeed new facility!
Huber, Lindner, Schwetz, Winter, 2009
5
Mass hierarchy measurement?
Mass hierarchy discovery possible with atmospheric neutrinos? (liquid argon, HyperK, MEMPHYS, INO, PINGU, ORCA …)
Barger et al, arXiv:1203.6012;IH more challenging
NB: basically any new LBL experiment at design luminosity with E > 1 GeV and L >> 600 km can for all CP measure the hierarchy in e- transition (MSW effect)!
Alternative: medium-baseline reactor experiments, perhaps
Perhaps differentfacilities for MH and CPV
proposed/discussed?
Talks by Smirnov (2), Resconi, Heijboer
Measurement of CP:Experiments and phenomenology
7
Why is CP interesting?
CP violationNecessary condition for successful baryogenesis (dynamical mechanism to create matter-antimatter asymmetry of the universe) thermal leptogenesis by decay of heavy see-saw partner?
Model building
e.g. TBM sum rule: 12 = 35 + 13 cos(Antusch, King; Masina)
Need performance which is equally good for all CP
Symmetrye.g. TBM, BM, …?
Correction leadingto non-zero 13?
sin
cos
8
Antineutrinos: Problem: Earth matter violates CP, CPT explicitely!
Silver:Challenging ( threshold, many decay channels, vertex res.)
Platinum, T-inv.: Works only for Superbeam + Beta beam (later)
Long-baseline oscillations
(Cervera et al. 2000; Freund, Huber, Lindner, 2000; Akhmedov et al, 2004)
Large!
9
There are three possibilities to artificially produce neutrinos
Beta decay:Example: Nuclear reactors, Beta beams
Pion decay:From accelerators:
Muon decay:Muons produced by pion decays! Neutrino Factory
Muons,neutrinos
Possible LBL neutrino sources
Protons
Target Selection,focusing
Pions
Decaytunnel
Absorber
Neutrinos
Superbeam
10
Example: Neutrino FactoryInternational Design Study (IDS-NF)
IDS-NF: Initiative from ~ 2007-2013 to present a design report, schedule, cost estimate, risk assessment for a neutrino factory
Vision? Staged approach towards high-energy frontier ( muon collider)
(Geer, 1997; de Rujula, Gavela, Hernandez, 1998; Cervera et al, 2000)
Signal prop. sin2213
Contamination magnetized detector!
Muons decay in straight sections of a storage ring
11
The new paradigm: Precision?
CP violation performance represents only two possible values of CP (0 and )Need new performance
indicators, e. g.Reveals that
some experiments (narrow beam spectra!) strongly optimized for CPV (Coloma, Donini, Fernandez-Martinez,
Hernandez, 2012)
Bands: 13 allowed ranges
C2P = LBNO:CERN-PyhäsalmiL~2300 km, 100kt
liquid argon
1
Talk by Diwan
The critical issue for large 13:Systematics?
13
Fluxes and cross sections: Superbeam, beta beam (illustrated)
Superbeam
Beta beam
Near detector
Disappearance
Appearance Fardetector
Flux F1
Near detector
Disappearance
Appearance Fardetector
Flux F2
?
?BB+SPL
14
Fluxes and cross sections:Neutrino Factory
Muon (anti)neutrino cross sections measured in self-consistent way
Fluxes in and fully correlated
(Tang, Winter, PRD 80, 053001, 2009)
15
The big unknown: Systematics
New treatment needed Use explicit near-far detector
simulations Use same knowledge for
cross sections for all experiments Define ranges for systematical
errors: optimistic-default-conservative
Use identical framework for systematics implementation/correlations Define reasonable ranges for experiment-dependent systematics:
(Coloma, Huber, Kopp, Winter,
arXiv:1209.5973)
16
Long-baseline options
Setup table
(Coloma, Huber, Kopp, Winter, arXiv:1209.5973)
+ Daya Bay
17
Precision:
Worldwide comparison
CKM phase
(bands: systematics
opt.-cons.)
(Coloma, Huber, Kopp, Winter, arXiv:1209.5973)
The Neutrino Factoryis the only instrument
which can measure CP
with a precision comparableto the quark sector
NF10BB350WBBT2HK
18
Interesting alternatives
Comparison at default systematics:
(Coloma, Huber, Kopp, Winter, arXiv:1209.5973)
NF5 exhibitsstrong dependence on CP (some dependence on binning!)
BB100+SPL is the only setup comparable with NuFact
19
Critical impacts?
(Coloma, Huber, Kopp, Winter, arXiv:1209.5973)
Robust wrt systematics
Main impact:Matter density uncertainty
Operate in statistics-limited regime
Exposure more important than near detector orsystematics MICA?
Neutrino Factory
High-E superbeam
Low-E (QE!) superbeam
QE e X-sec critical:no self-consistent measurement
Theory: e/ ratio?Experiment: STORM?
Long-baseline alternatives with new technologies?
21
Superbeam CERN-LENA?
Main impact factors:Neutral current
backgrounds versus efficiency
Fiducial volume (cost?)
To be studied?Background
migration(no migration matrices yet? NC backgrounds reconstructed in energy window of signal)
Combination with liquid argon?
L ~ 2300 km
100 kt liquid argon
100 kt LENA
90% eff.10% NC
50 kt LENA
90% eff.10% NC
50 ktLENA
90% eff.30% NC
50 ktLENA
50% eff.10% NC
Talks by Wurm, Hellgartner
(special thanks: Pilar Coloma)
22
Beam to South Pole?
Probability for L=11810 km (CERN/FNAL/JHF-South Pole)
(Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998)
Core resonance
energy
Mantleresonance
energy
Param.enhance-
ment
Thresholdeffects
expected at:2 GeV 4-5 GeV
Naive L/E scalingdoes not apply!
Parametric enhancementthrough mantle-core-mantle
profile of the Earth.Unique physics potential!
!
23
IceCube/DeepCore upgrades?
Fill in IceCube/DeepCore array with additional strings Drive threshold to lower
energies
PINGU (“Precision IceCube Next Generation Upgrade“): LOI in preparation
Modest cost ~30-50M$ (dep. on no. of strings)
Two season deployment anticipated: 2015/2016/2017
A megaton-class detector at a few GeV (param. enhancement)
Further upgrades being discussed (MICA)
(PINGU, 12/2012) Talks by Kowalski
24
Example:
Low-intensity superbeam? Use existing equipment (Fermilab main injector),
new beam line Here: use most conservative assumption
NuMI beam, 1021 pot (total), neutrinos only[compare to LBNE: 22+22 1020 pot without Project X ~ factor four higher exposure than the one considered here] (FERMILAB-PROPOSAL-0875, NUMI-L-714)
Low intensity may allow for shorter decay pipe(< 600M$ ?)
Advantage: Peaks in exactly the right energy range for the parametric enhancement/core effect
M. Bishai
Pe
25
Mass hierarchy: Event rates
Normal hier. Inv. hierarchy
Signal 1560 54
Backgrounds: e beam (irreducible) 39 59
Track mis-ID (20%) 511 750
appearance (below production threshold!)
3 4
Neutral currents (irred.) 2479 2479
Total backgrounds 3032 3292
Total signal+backg. 4592 3346
(Daya Bay best-fit)
>18 (stat. only)
26
NuMI-like beam to PINGU?
Very robust mass hierarchy measurement (as long as either some energy resolution or control of systematics); no directional information needed
(Daya B
ay best-fit; current param
eter un
certainties, min
imized over)
GLoBES 2012
All irreducible backgrounds included
27
Potential for CP?
NH
L=11810 km
Energy resolution prerequisite:
28
Upgrade path towards CP?
Measurement of CP in principle possible, but challenging
Requires: Electromagnetic
shower ID (here: 1% mis-ID)
Energy resolution (here: 20% x E)
Volume upgrade(here: ~ factor two)
Project X Performance and
optimization of PINGU and MICA requires further study
= LBNE + Project X!
Tang, Winter, JHEP 1202 (2012) 028
same beamto MICA?
29
Matter density measurementExample: LBNE-like Superbeam
Precision ~ 0.5% (1) on core density
Complementary to seismic waves
Tang, Winter, JHEP 1202 (2012) 028(Alan Jones, 1999)
Comments on sterile neutrinos
31
Evidence for sterile neutrinos?
LSND/MiniBooNE Reactor+gallium anomalies
Global fits
Cosmology(M
iniB
ooN
E @
Neu
trin
o 20
12)
(B. F
lemin
g, TA
UP
2011)
(e. g. Kopp, Maltoni, Schwetz, 1103.4570)
32
Example: 3+1 framework
Well known tension between appearance and disapp. data (appearance disapp. in both channels)
Need one or more new experiments which can test e disappearance (Gallium, reactor anomalies) disappearance (overconstrains 3+N frameworks) e- oscillations (LSND, MiniBooNE) Neutrinos and antineutrinos separately (CP violation? Gallium vs reactor?) QE electron neutrino and antineutrino cross sections (T2HK!)
Example: STORM - Neutrinos from STORed Muons (LOI: arXiv:1206.0294) can do it all! Summary of options: Appendix of white paper arXiv:1204.5379
MiniBooNE
33
Conclusions
The precision measurement of CP requires a new dedicated long-baseline experiment
Such an experiment can (typically) also measure the mass hierarchy; however, there are alternatives
The critical impact factors for CP are: Exposure (high-E superbeam) Electron neutrino cross sections
(low-E superbeam, beta beam) Matter density uncertainty (Neutrino Factory)
Alternatives require further study. Examples: Beam to South Pole (MICA?) Beam to LENA
BACKUP
35
New performance indicator
(Coloma, Huber, Kopp, Winter, arXiv:1209.5973)
36
Impact of implementation Gray (eff. systematics, 0-10%) versus color (new):
More precise predictions for Neutrino Factory (bands: conservative – optimtistic, curves: default)
Systematic offset for T2HK, BB350 (QE e cross sec. issue)
(Coloma, Huber, Kopp, Winter, arXiv:1209.5973)
37
NuFact vs. BB+SPL
(Coloma, Huber, Kopp, Winter, arXiv:1209.5973)
Near detectorsnot so important if
disappearance information from FD
and three-flavor framework valid
Exception: NF5(main impact)
38
Mass hierarchy using existing equipment?
90% CL, existing equipment
3, Project X and T2K with proton driver, optimized neutrino-antineutrino run plan
Huber, Lindner, Schwetz, Winter, JHEP 11 (2009) 44
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