Post on 08-Jun-2020
transcript
Neutrino Oscillation Experiments
Pasquale MigliozziINFN - Napoli
Pasquale Migliozzi - INFN Napoli
Outline of the talk
The Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrixPresent experimental knowledge of the PMNS matrix
Atmospheric neutrinosSolar neutrinosAccelerator and reactor neutrinos
What is missing?Future projects
CERN-Gran Sasso (Europe) and NuMi (USA)JHF-SK (Japan) and NuMi off-axis (USA)Super Beams, Beta Beams and Neutrino Factories Conclusion
Pasquale Migliozzi - INFN Napoli
ilil U νν ∑=If neutrinos have mass:
ijijijij sandcwhere θθ sin,cos ==
τττ
µµµ
eee
li
cs
sc
iδecssccs
sc
UUUUUUUUU
U0
010
0
00
010
001
0
0
001
100
0
0
1313
1313
2323
23231212
1212
321
321
321
−⋅
−⋅
−⋅
−=
=
For three neutrinos (I assume that MiniBooNE will not confirm LSND because present datastrongly disfavor sterile neutrinos that would be compatible with LSND).
The PMNS leptonic mixing matrix
Similar to the CKM mixing matrix for quarks
Pasquale Migliozzi - INFN Napoli
τττ
µµµ
eee
li
cs
sc
iδecssccs
sc
UUUUUUUUU
U0
010
0
00
010
001
0
0
001
100
0
0
1313
1313
2323
23231212
1212
321
321
321
−⋅
−⋅
−⋅
−=
=
ilil U νν ∑=If neutrinos have mass:
For three neutrinos:
ijijijij sandcwhere θθ sin,cos ==
Three Angles
Pasquale Migliozzi - INFN Napoli
τττ
µµµ
eee
li
cs
sc
iδecssccs
sc
UUUUUUUUU
U0
010
0
00
010
001
0
0
001
100
0
0
1313
1313
2323
23231212
1212
321
321
321
−⋅
−⋅
−⋅
−=
=
ilil U νν ∑=If neutrinos have mass:
For three neutrinos:
ijijijij sandcwhere θθ sin,cos ==
CP violating phase!
Pasquale Migliozzi - INFN Napoli
Pasquale Migliozzi - INFN Napoli
∆mij2≡(mi
2-mj2) is in (eV/c2 )2
L is in km, and E is in GeV
Pasquale Migliozzi - INFN Napoli
NotationMixing parameters: U = U (θ12, θ13, θ23, δ) as for CKM matrix
Mass-gap parameters: M2 = ∆m212 , ± ∆m2
23
The absolute neutrino mass scale should be set by direct mass measurements:
• β-decay• 0ν2β-decay• “W-MAP”
Pasquale Migliozzi - INFN Napoli
So what do we have to measure?Three angles (θ12, θ13, θ23)Two mass differences (∆m2
12 (or δm2), ∆m223 (or ∆m2))
The sign of the mass difference ∆m2 (±∆m223)
One CP phase (δ)The source of atmospheric oscillations (detect τappearance)The absolute masse scaleAre neutrino Dirac or Majorana particles (or both)?Are there more - sterile - neutrinos?
All the underlined items can be studied with LBL experiments
Pasquale Migliozzi - INFN Napoli
Pasquale Migliozzi - INFN Napoli
The Super-Kamiokande detector50,000 ton water Cherenkov detector (22.5 kton fiducial volume)
Pasquale Migliozzi - INFN Napoli
SK data as function of the zenithal angle
MC expectations; Oscillation fit; data pointsPossible interpretation νµ → ντ
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K2K – the first LBL experiment
Results limited by systematic erroron the beam spectrum
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K2K energy spectrum
The value of ∆m2 determines
the oscillation minimum,
giving the maximum event rate
suppression
(GL Fogli, E. Lisi, A. Marrone and D. Montanino, hep-ph/0303064)
Pasquale Migliozzi - INFN Napoli
Solar Neutrinos
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Sudbury Neutrino Observatory
1700 tonnes InnerShielding H2O
1000 tonnes D2O
5300 tonnes Outer Shield H2O
12 m Diameter Acrylic Vessel
Support Structure for 9500 PMTs, 60% coverage
Urylon Liner andRadon Seal
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ν reactions in SNO
- Good measurement of νe energy spectrum- Weak directional sensitivity ∝ 1-1/3cos(θ)
- Both SK, SNO- Mainly sensitive to νe,, less to νµ and ντ- Strong directional sensitivity
ES -- +⇒+ eνeν x x
CC-eppd ++⇒+ν e
- νe ONLY
NCxx νν ++⇒+ npd
- Measure total 8B ν flux from the sun.
- Equal cross section for all ν types
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Physics Implication: Flavor Content
Strong evidence of flavor change
Φssm = 5.05+1.01-0.81 Φsno = 5.09+0.44
-0.43+0.46-0.43
Φµτ is5.3 σ from zero
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Impact of solar neutrinos
By combining the four solar experiments, only the large mixing angle solutions are seen to survive:
LOW: at lower δm2, with a long tail in the quasi-vacuum region
LMA: preferred by data, below the maximal mixing line
All solar neutrino experiments(Homestake, Gallex, SK, SNO)are fitted simultaneously
LOW
LMA
maximal mixing line
QUASIVACUUM
Cl+ Ga + SK + SNO (no CHOOZ)
δm2
(eV2 )
tan2θ12
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Reactor experimentsWhile atmospheric (SK) and K2K bounds on (∆m2
23, θ23) can be studied well in the 2ν approximation, a 3ν analysis is mandatory for reactor experiments:
Pee = Pee (∆m212, θ12, θ13, ∆m2
23) survival νe probabilityReactor Reactor
In practice, ∆m223 is marginalized away in the χ2 construction,
by adding the “atmospheric + K2K” likelihood
Therefore, “solar and reactor” data are linked through the parameters
(∆m212, θ12, θ13)
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The KamLand experiment
180 km
300
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The KamLAND dataThe KamLAND total rate singles LMA out
The KamLAND spectrum fixes the LMA sub-structure:
Above the analysis threshold (2.6 MeV) the “bulk” of the spectrum (first 4 bins above threshold) seems more suppressed than the “tail”
Pasquale Migliozzi - INFN Napoli
Ratio of Measured to Expected νe Flux from Reactor Neutrino Experiments
Continuous line is the expected value for ∆m2 = 5.5x10-5eV2 sin22θ12=0.833
G.Fogli et al., PR D66, 010001-406, (2002)
Pasquale Migliozzi - INFN Napoli
Impact of solar and reactor neutrinos
maximal mixing line
LMA - II
LMA - I
δm2
(eV2 )
sin2θ12
Taking LMA-I as the reference solution, we can extract the following ±1σ estimate for the relevant solar 3ν parameters:
LMA-I solution (~1σ) δm2 ≈ (7.3 ± 0.8)x 10-5 eV2
sin2 θ12 ≈ 0.315 ± 0.035sin2 θ13 ≤ 0.017
This is one of the conditions to fulfilled to make CP detectable in the leptonic sector
Pasquale Migliozzi - INFN Napoli
What still we have to measure?Three angles (θ12, θ13, θ23)Two mass differences (∆m2
12, ∆m223)
The sign of the mass difference ∆m2 (±∆m223)
One CP phase (δ)The source of atmospheric oscillations (detect τappearance)The absolute masse scaleAre neutrino Dirac or Majorana particles (or both)?Are there more - sterile - neutrinos?
All the underlined items can be studied with LBL experiments
DiscoveryPrecision meas.
Pasquale Migliozzi - INFN Napoli
1st
gen.
2nd
gen.
3rd
gen.
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Goals of 1st generation of Long Baseline Experiments
Confront emerging picture with precision dataconfirm oscillation hypothesis:
must measure/know E & L precisely to see oscillations in L/Epin down oscillation parameters (with 10% precision)
demonstrate νµ ντ is dominant mode:Tau appearance ! (CNGS direct, MINOS NC/CC)
Look for new phenomenaevidence for non-zero θ13 → detection of νe appearancetest for possible CPT violation?etc. etc.
Pasquale Migliozzi - INFN Napoli
Close detector
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The NuMi beam
Low energy beam: less flux, but better match to ∆m223
Still plenty of events: ~ 5000 νµ CC events in 2 yrs
Protons120 GeV
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Expected Neutrino Energy Distributions in 2 years
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1st Supermodule (1/2 detector) done, the 2nd one is being commissioned
Meanwhile first magnetizeddata on atmospheric ν
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Summary of MINOS
Data-taking with NuMI beam will begin early 2005Far & Near detector on schedule, Far det. already complete (detector very stable: < 1 ns timing drifts, ~ 1% pulse height drifts) Calibration detector running & data analysis will be completemuch progress on NuMI: civil & technical components
By 2007, they will provide a precise measurementsoscillation parameters: νµ ντ case;(NC/CC ratio for mode id)search for subdominant νµ νe (discussed later)
Also ~ 24 kiloton-year exposure to atm. ν’senergy, direction resolution competitive on νµ ντ
1st direct search for CPT non-cons. (νµ νµ vs νµ νµ)
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The CNGS neutrino beam
ICARUS
The beam will
start i
n may 2006
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CNGS beam layout at CERN site.
Progress in the civil engineering work: excavation completed concreting started
CNGS commissioning: May 2006
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Nominal ν beam (Nov. 2000)
Shared SPS operation
200 days/year
4.5x1019 pot / year
Average νµ energy 17 GeV
5 year run
Expected interactions in 1kton detector
~ 18000 νµ NC+CC
~ 80 ντ CCat ∆m2
23 = 2.5x10-3 eV2 and full mixing
The CNGS and the expected number of events
Limiting factor for θ13 search:νe + anti-νe beam contamination ~0.87%
An updated CNGS with a flux 1.5 more intense than the one approved in 2000 is now considered as the baseline option
Pasquale Migliozzi - INFN Napoli
d
d
p
p
Ionization electrons paths
Drift
ionizing track
Ionization electrons drift (msec) over large distances (meters) in a volume of highly purified liquid Argon (0.1 ppb of O2) under the action of an E field. With a set of wire grids (traversed by the electronsin ~ 2-3 µs) one can realize a massive, continuously sensitive electronic “bubble chamber”.
The ICARUS working principle
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≈300‘000 kg LAr= T300
ICARUS T600 (1 half-module out of 2)
ICARUS T600 (1 half-module out of 2)
Pasquale Migliozzi - INFN Napoli
18 m
1.5 m
1.5 m
Left
Cha
mbe
rRi
ght
Cham
ber
Cathode
Long longitudinal muon track crossing the cathode plane
Track Length = 18.2 m
3D ViewTop View
dE/dx = 2.1 MeV/cm
3-D reconstruction of the long track3-D reconstruction of the long track
dE/dx distribution along the trackdE/dx distribution along the track
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νµ →ντ oscillations
Analysis of the electron sampleExploit the small intrinsic νe contamination of the beam (0.8% of νµ CC)Exploit the unique e/π0 separation
Statistical excess visible before cuts ⇒ this is the main reason for performing this experiment at long baseline !
At ∆m223=3.5x10-3 eV2 165 τ → e events are expected
Main background from charged current interactions of νe in the beam 700 events are expected
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τ→e search: 3D likelihood
3 variablesEvisible, PT
miss, ρl≡PTlep/(PT
lep+ PThad+PT
miss)Exploit correlation between them
LS ([Evisible, PTmiss, ρl]) (signal)
LB ([Evisible, PTmiss, ρl]) (νe CC back)
Discrimination given by
5 T600 modules, 5 years CNGS (4.5 x 1019 p.o.t./year)
0
5
10
15
20
25
30
35
40
-2 0 2 4 6 8 10lnλ
Eve
nts
/12
kto
n x
yea
r
νe CC + ντ CC
νe CC
ντ CC, τ→ e
Overflow→
lnλ ≡L([Evisible, PTmiss, ρl]) = Ls / LB
lnλ
Vertex cuts applied
A simple analysis approach: a likelihood method based on 3 variables
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νµ→ ντ appearance search summary
Super-Kamiokande: 1.6 < ∆m2 < 4.0 at 90% C.L.
T3000 detector (2.35 kton active, 1.5 kton fiducial)Integrated pots = 2.25 x1020
Several decay channels are exploited (golden channel = electron)(Low) backgrounds measured in situ (control samples)High sensitivity to signal, and oscillation parameters determination
(these numbers have to be multiplied by a factor 1.5)
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The Emulsion Cloud Chamber (ECC)
Emulsions for tracking, passive material astarget
Established technique charmed “X-particle” first observed
in cosmic rays (1971)DONUT/FNAL beam-dump experiment: 7 ντ
observed (2000)
< µm space res. mass
Pb
ντ
1 mm
Emulsion layers
track segments
Experience with emulsions and/or ντ searches :E531, CHORUS, NOMAD and DONUT
∆m2 = O (10-3 eV2 ) → Mtarget ~ 2 kton
modular structure (“bricks”): basic performance is preservedlarge detector → sensitivity, complexityrequired: “industrial” emulsions, fast automatic scanning
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Event reconstruction with an ECCHigh precision tracking (δx < 1µm ; δθ < 1mrad)
Kink decay topologyElectron and γ/π0 identification
Energy measurement Multiple Coulomb ScatteringTrack counting (calorimetric measurement)
Ionization (dE/dx meas.)π/µ separation e/π0 separation
Topological and kinematical analysis event by event
5X0
( ~
½br
ick)
1 mm
5 cm
ECC exposure at CERN-PS
0 1-1 mm
mm
0
10
3020
40
-2
π0
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Cell structure; exploited τ decay channels and topologies
“Long” decayskink angle θkink > 20 mrad
τ → e Progr. Rep. 1999
τ → µ Progr. Rep. 1999
τ → h (nπ0) Proposal 2000
+ ρ search Status Rep. 2001
“Short” decaysimpact parameter I.P. > 5 to 20 µm
τ → e Proposal 2000
τ → µ Status Rep. 2001
kink
θkink
Long decays
Pb(1 mm)
plastic base
I.P.
Short decays
emulsion layers
Pb(1 mm)
An optimized channel by channelanalysis is in progress. Ready by summer
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Backgrounds for the νµ→ ντ search
Charm productionCross-section and charmed fractions based on neutrino data
Large angle µ scatteringRate of µ scattering off lead estimated by using
MC simulation including nuclear form factors(cross-checked with NOMAD data)
data from 7.3 GeV/c µ scattering off copper
µ scanned in the CHORUS emulsionsScattering off lead of µ (p= 6-10 GeV/c) experimentally studied by the Collaboration. Results in agreement with expectations
Hadron reinteractions with kink topologythe present estimate is based on a FLUKA simulationconsistent with preliminary results from dedicated experiments
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Aim at the evidence of ντ appearance after a few years of data taking
0.6750.419.810.3With possible improvements
1.0643.817.29.0Final DesignCNGSx1.5 *)
Backsignal(∆m2 = 4.0 x 10-3 eV2)
signal(∆m2 = 2.5 x 10-3 eV2)
signal(∆m2 = 1.8 x 10-3 eV2)
Expected number of eventsfull mixing; 5 years run @ 4.5x1019 pot / year
*) An updated CNGS with a flux 1.5 more intense than the one approved in 1999 is now considered as the baseline option
Pasquale Migliozzi - INFN Napoli
The detector construction is in progress
νµ → νe search with OPERA(interesting by product)
A similar analysis can also be performed with the ICARUS detector
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Backgrounds for the νµ → νe search
π0 identified as electrons produced in νµ NC and νµ CC with the µ not identifiedνe beam contamination (main background)τ → e from νµ→ ντ oscillations (strongly reduced thanks to the capability in detecting decay topologies)
In the following we assume a three family mixing scenario with θ23 = 45º
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OPERA sensitivity to θ13
By fitting simultaneously the Ee, missing pT and Evis distributionswe got the sensitivity at 90%
2.5x10-3 eV2
0.05
5years data taking
Pasquale Migliozzi - INFN Napoli
Summary of the CNGS project
Construction of CNGS is well underway. The tunnel excavation is complete. The remaining construction work is on schedule (Beam starts by mid 2006)The ICARUS and OPERA experiments will permit
An unambiguous direct evidence of τ appearance in a νµbeamA measurement of ∆m2
23 at 10-20%Extend sensitivity for small νµ→νe mixings (competitive with other experiments)
The construction of the detectors is in progress and it is planned to be completed by mid 2006
Pasquale Migliozzi - INFN Napoli
Goals of 2nd generation of Long Baseline Experiments
Precision measurement of PMNS matrix elementssin22θ23 with 1% accuracy
∆m223 with few% accuracy
Discovery (if not done by 1st generation experiments) and measure non-zero θ13
They could give the 1st evidence of 3-flavor mixingIn case of non-zero θ13 precision measurement1st step to CP measurement
NB If θ13< 1° impossible to assess CP violation in the leptonic sector. The other condition to make CP in the leptonic sector detectable has been fulfilled by KamLAND (LMA solution)
Pasquale Migliozzi - INFN Napoli
JHF-Super-KamiokandeNeutrino Experiment
~1GeV ν beam
Kamioka JAERI(Tokai)
0.75MW 50 GeV PS( conventional ν beam)
Super-K: 22.5 kt
Plan to start in 2008-9
JHF 0.75MW + Super-Kamiokande
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JHF FacilityConstruction2001~2006 (approved)
8 bunches/~5µs3.3x1014proton/pulse3.94 (3.64) sec cycle1yr ≡ 1021 POT (130 days)
ν beam-linebudget request submitted
Near detectors (280m,2km)
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νµ
OA2°
Osc. Prob.=sin2(1.27∆m2L/Eν)
∆m2=3x10-3eV2
L=295km
osc
.max
.
Off Axis Beam(ref.: BNL-E889 Proposal) θTargetHorns
Decay Pipe
Super-K.
Quasi Monochromatic Beamx2~3 intense than NBB
Statistics at SK(OAB2deg, 1yr,22.5kt)~4500 νµ tot ~3000 νµ CC νe ~0.2% at νµ peak ~102 x (K2K)
Tuned at oscillation maximum
Oscillation probablity
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Detectors
Muon monitors @ ~140mSpill-by-spill monitoring of beam direction
First Front detector @280mNeutrino intensity/direction
Second Front Detector @ ~2kmAlmost same Eν spectrum as for SKWater Cherenkov can work
Far detector @ 295kmSuper-Kamiokande (50kt) 0
200
400
600
800
1000
1200
1400
1600
1800
x 10 3
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Eν (GeV)
1.5km
295km
0.28km
Neutrino spectra at diff. dist
dominant syst. in K2K
p π ν
140m0m 280m 2 km 295 km
Pasquale Migliozzi - INFN Napoli
Eν reconstruction in water Cerenkov
Assume CC Quasi Elastic (QE) reaction
µµµ
µµν θcos
22
pEmmEm
EN
N
+−
−=µ
p
ccQE
inelasticνµ + n → µ + p
+nπ
νµ + n → µ + p
ν
(Eµ , pµ)
beam energy
ccQEcc-inelastic
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Measurement of sin2 2θ23-∆m223
δ(sin22θ23)~0.01 δ(∆m223)~<1×10-4
δ(∆m
232
)
True ∆m232 (eV2)
OAB-2degree,5yr
δ(si
n2 2θ 2
3)
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sin22θ13 from νe appearance
Off axis 2 deg, 5 years
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NuMI Off-AxisTwo possible sites
Closer site, in MinnesotaAbout 711 km from FermilabClose to Soudan LaboratoryUnused former mineUtilities availableFlexible regarding exact location
Further site, in Canada, along Trans-Canada highway
About 985 km from FermilabThere are two possibilities:
About 3 km to the west, south of Stewart LodgeAbout 2 km to the east, at the gravel pit site, near compressor station
Pasquale Migliozzi - INFN Napoli
θ13 sensitivity
How the sensitivity to θ13 depends on the CP phase?In case of null results, what we can say about
future (JHF-HK, Neutrino Factory) expts?
Pasquale Migliozzi - INFN Napoli
Oscillation probability( )[ ]
( )( ) ( )[ ]
( )( ) ( )[ ]
( )( )
( ) ( ) 4321
2
122
2322
13
13
2
2
232
132
ˆ
ˆsin2sincos
ˆ1
ˆ1sinˆ
ˆsincoscossin
ˆ1
ˆ1sinˆ
ˆsinsinsinsin
ˆ1
ˆ1sinsin2sin
OOOO
P
CP
CP
e
+++≡
∆+
−∆−∆
∆+
−∆−∆
∆
−
∆−≅→
δδ
θθα
δξθα
δξθα
θθνν µ
2AA
AA
AA
AA
AAA
A
m
12
231
221
θξ
α
∝
∆∆
=mm
effects Matter ∝A
νν for for
+
−
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Oi terms in osc. prob. vs θ13
JHF CNGS
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Several observations
The first and the forth terms are independent of the CP violating parameter δIf θ13 is very small (≤ 1o) the second term (subdominant oscillation) competes with 1stFor small θ13, the CP terms are proportional to θ13; the first (non-CP term) to θ13
2
The CP violating terms grow with decreasing Eν (for a given L)There is a strong correlation between different parametersCP violation is observable only if all angles ≠ 0
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θ13 issue
The measurement of θ13 is made complicated by the fact that oscillation probability is affected by matter effects and possible CP violationBecause of this, there is not a unique mathematical relationship between oscillation probability and θ13
Especially for low values of θ13, sensitivity of an experiment to seeing νµ→νe depends very much on δSeveral experiments with different conditions and with both ν and ν will be necessary to disentangle these effectsθ13 needs to be sufficiently large if one is to have a chance to investigate CP violation in ν sector
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Accelerator expts. sensitivity vs δCP (1)
There are δCP values forwhich the sensitivity on θ13is even better than the one compute in the 2-flavor approximation (δCP=0).
Notice the different behaviour on ∆m2 of theCNGS sensitivity⇒ Possible measurementof the sign of ∆m2
31?
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Conclusion in case of null resultThe measurement of θ13 is made complicated by the fact that oscillation probability is affected by matter effects and possible CP violationThe sensitivity of JHF-SK/NUMI off axis is comparable with the one of the CNGS program for high values of α and for certain values of δCP.
Of course, an additional anti-ν runwould help in increasing the sensitivity of JHF-SK for large values of α.
Another possibility is to perform a pureθ13 measurement with reactors (H.Minakata et al. hep-ph/0211111)
From G.L. Fogli et al. hep-ph/0212127
If νµ → νe is observed
In the following: assume ICARUS and OPERA taking data from 2006 on
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CNGS at the start-up of JHF-SK
3 years data taking at the CNGSSensitivity: sin22θ13 < 0.035 @ 90% C.L. (a factor 4 better than CHOOZ)
Indication (90% C.L) of νe appearance if θ13 > 7°
(10.+3.7-4.4)°13.7°5.6°10°
(7.5+3.9-6.3)°11.4°1.2°7.5°
---7.0°---5.0°
---5.8°---2.5°
---5.5°---1°
θ13|maxθ13|minθ13|true90% C.L. allowed region
∆m2<0 ∆m2>0
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Allowed regions for JHF (5 years) + CNGS (8years)θ13=5° θ13=10°
∆m2<0 ∆m2>0 ∆m2<0 ∆m2>0
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Conclusion in case νe appearance is observed
If θ13 > 7°, CNGS could give a first indication of νeappearance after three years data taking The CNGS is an off-peak beam, therefore it has a different pattern from JHF-SK ⇒ they can be used in synergyAfter the completion of the approved CNGS program, one could continue the data taking
CNGS (8y) + JHF-SK(5y) could measure θ13 with 20% accuracy and constrain δCP
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Goals of 3rd generation of Long Baseline Experiments
Precision measurement of PMNS matrix elementsDiscovery and measure non-zero δCP, and determine the mass hierarchy (if not done by 2st generation experiments)
several experiments with different running conditions will be required in order to disentangle the true solution from degenerate solutions
NB If θ13< 1° impossible to assess CP violation in theleptonic sector. However, correlation effects could mimic small θ13 I.e. :
δCP is positive and very large → giving up JHF-HK and Neutrino Factory would be a tremendous mistake because after an anti-ν run one would have a “monumental” signal
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Super-JHF(4MW)+Hyper-K(1Mt)
~1,000 kt
Candidate site in Kamioka
Good for atm. νproton decay
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1. Produce a radioactive ion with a short beta-decay lifetime
2. Accelerate the ion in a conventional way (PS) to “high” energy
3. Store the ion in a decay ring with straight sections.
4. By its β-decay, νe (νe) will be produced.
- SINGLE flavour (νe )- Known spectrum/intensity- Focussed (1/γ) - Low energy (Eν = 580 MeV)
The “quality factor” QF=γ/Ecms (Nint ∝ γ/ Ecms) is bigger than in a conventional neutrino factory. In addition, ion production and collection is easier. Then, 500000X more time to accelerate.
Muons:γ~500Ecms~34 MeVQF~15
6He Beta-:γ~150Ecms~1.9 MeVQF~79
18Ne Beta+:γ~250Ecms~1.86 MeVQF~135
The β beam
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Neutrino Factories
The ultimate tool for probing neutrino oscillation, based on muon decays (NOT π DECAY !!!)
Enormous luminosityExceptional purityPerfect knowledge of spectrumFlavor of initial neutrino tagged by charge
Caveats:Technical challenges to muonaccelerationCost
• Proton drivers
• Targetry
• Particle production measurements
• RF manipulation
• Cooling
• Muon acceleration
Pasquale Migliozzi - INFN Napoli
µ+ → e++ νµ +νe
νµ → µ−
νµ→ µ+Oscillate
Wrong Sign muons
1016p/s
3 1020 νe/yr3 1020 νµ/yr
0.9 1021 µ/yr
77
Advantages of Muon Storage RingBoth νe and νµ species in beam:
A way to get well understood, high-intensity source of νe’s
νe→ντ or νe→νµ
High intensity allows:Probe small mixing angles
Long distancesStart to see earth matter effects for oscillations involving νe’s Reach solar neutrino region with accelerator beams
Pasquale Migliozzi - INFN Napoli
δ = 90º 99% C.L. Curves
Physics reach of β beams etc
Pasquale Migliozzi - INFN Napoli
Conclusion
Neutrino Physics appears to be an exciting field for many years to comeIn the short period (less than 10 years) LBL experiments like CNGS,NuMI and JHF
will measure some of the PMNS matrix elements (∆m213, sin2θ23) with a per
cent accuracywill determine unambiguously the source of the atmospheric neutrino deficit (τ appearance)have a good opportunity to observe for the first time the mixing angle θ13 ( ≥2º)
In the long term period, most likely several experiments with different running conditions will be required in order to disentangle the true solution from degenerate solutions and extract δCP and the mass hierarchy