Tópicos Avançados de Física de Partículas e Astropatrículas · Tópicos Avançados de Física...
Transcript of Tópicos Avançados de Física de Partículas e Astropatrículas · Tópicos Avançados de Física...
NEUTRINO OSCILATIONS
Tópicos Avançados deFísica de Partículas
e Astropatrículas
Sofia Andringa, LIP ([email protected]) Novembro 2016
Discovery withNatural Sources
Confirmation w/human-made
High precisionexperiments
oscillationsand mass
closing thecircle of 3
open questions
What are neutrinos? elementary particles, like electrons, but with neutral electrical charge* “undetectable” particles keeping energy conservation in decays
have only nuclear weak interactions
* mean free path of 10¹ m in water⁹* 1 of 10¹ interact in 1m of water⁹
detected 25 years after first proposal
(Z,A) –> (Z+1,A) + M(Z,A) = M(Z+1,A) + E
n –> p + e + v ⁻
Electron kinetic energy (MeV)
Inte
nsity
in e
lect
rons
3 types of neutrinosEletron neutrino (1956)
Muon neutrino (1962)
Tau neutrino (2000)
Lepton Universalitychecked at LEP
Same NC interaction for all neutrino; CC needs E > lepton mass(also more interactions fore with electrons in dense matter)
neutrinos and weak interaction
sources of neutrinos
Main nuclear fusion process in the Sun is
2e + 4p -> ⁻⁴He + 2 + 27 MeV
From measured luminosity:~ 60 billion / (cm² s)
First counting experiments:
³ Cl -> ³ Ar (E>0.8 MeV) : 0.34 x SSM⁷ ⁷[only secondary processes]
⁷¹Ga -> ¹Ge (E>0.2 KeV) : 0.58 x SSM⁷[including main fusion process]
the solar neutrino problem
the Super Kamiokande detector50,000 ton water Cherenkov detector
11,000 PMT 50 cm (+ 2 000 PMTs in OD)
1000m underground
in Mozumi mine,
Kamioka, Japan39m
42
m
Succeeds to KamiokaNDE detector which saw SN1987A
solar, atmospheric and beam neutrinos in SK since 1996
SKI 1996-2001 SKII 2002-2005 (half coverage)SKIII 2006-2008 (full coverage)SKIV 2009-now (new electronics)Solar + Atmospheric + K2K + T2K
the Super Kamiokande detector
from Nature @ Super Kamiokande500 days + nights exposure
Flux lower than Solar e
compatible with SNO's results
higher energy but lower fluxe ~ 2 in all directions
Solar e@ MeV
Atmospherice e
@ GeV
identifying electrons and muons
l l = e, Kinematics of e/ give energy and direction
no charge measurement
first measurement of oscillations
expected from cosmic ray fluxesconfirmed by electron measurements
fit with 1 - sin²2 sin²(1.27 m² L/E)
1 10 100 1000 km
@GeV
first measurement of oscillations
No time to change Fast change
1 - sin²2 sin²(1.27 m² L/E)maximal amplitude atL ~ 500 km / E ~ 1 GeV
new results
1 10 100 1000 km
@GeV
vacuum oscillations: 2 case1. Flavor states as a function of mass states – rotation matrix in 2. Time evolution for each mass state – Schrödinger equation
3. Same energy (E) at production – Taylor expansion around m~04. Probability to find different flavor – function of time, E, m,
from Nature @ Super Kamiokande500 days + nights exposure
Flux lower than Solar e
compatible with SNO's results
higher energy but lower fluxe ~ 2 in all directions
Solar e@ MeV
Atmospherice e
@ GeV
from the Sun @ SNOSudbury Neutrino Observatory: 1 kton of (salted) heavy water, viewed by 9000 PMTs
Electron-scattering + e -> + eas in H2O: 0.50 x SSM
Charged Currents + d(p,n) -> e + p + ponly e: 0.35 x SSM
Neutral Currents + d(p,n) -> + p + nall x: 1.00 x SSM
Sudbury Neutrino Observatory is a (Salted) Heavy Water Detector:
CC measure electron neutrinos; NC measure all neutrino types
CC / NC / ES / backgrounds
CC / NC = 0.35 ! NC/Solar Model = 1.00 !--> electron neutrinos oscillate and arrive as other neutrino types
1st “neutrino appearance”!Confirmation of Solar Model!
from the Sun @ SNO
- only electron neutrinos can be produced in nuclear fusion- but different neutrino types detected upon arrival at Earth* most neutrinos leave the Sun is the same effective mass state * the “survival probability” depends on neutrino energy/solar density
the solar neutrino problem solution
For propagation, only energy and mass are relevantFor interaction, only the energy and flavor are relevant
(E, M)E²=P²+M² = (Mx²-My²)/E
VeVV
oscillations and mass
Each mass has a combination of different interaction flavorsand each flavor has a combination of the different masses
(interaction in matter can be seen as inducing an effective mass)
L = c.Time
Mx and My
at productionand detection
L = c.Time
Discovery withNatural Sources
Confirmation w/human-made
High precisionexperiments
oscillationsand mass
closing thecircle of 3
open questions
flavor change + L/E dependence => mass
* Fix large propagation Length to see oscillation pattern in Energy
* First experimental discoveries of neutrinos used artificial sourcesNuclear reactor's e =/= Particle accelerator's
Nuclear fission (& fusion) @ MeV Pion production & decay@ GeV
K2K – 250 km from KEK to Kamioka
~10² protons on target between 1999 and 2004⁰(pion, kaon production in target studied at CERN)
muon neutrinos from positive pion decays,energy spectrum similar to the atmospheric one
The first Long Base Line experiment, 250 km from KEK to Kamioka
K2K, near detectors at KEK
Flux at 250 m much larger than at 250 km!!
Check muon neutrino beam (and contamination)Measure the resulting /e and other particlesStudy neutrino interactions (and nuclear effects)
K2K, near detectors at KEK
Flux at 250 m much larger than at 250 km!!
Check muon neutrino beam (and contamination)Measure the resulting /e and other particlesStudy neutrino interactions (and nuclear effects)
interactions @ 1 GeV
K2K
(Quasi)Elastic to Deep Inelasticp, , p / n, many , ...
1ktT, SK see mostly , e, , ...⁰
CC protons measured in ND detectors production in charged/neutral currents
(Quasi-)elastic interactions dominate
Needed for energy and direction in SK
n (N)
confirmation of oscillationspulsed beam events selectedwith neutrino time of flight:
107 seen for 150.9 expected (if there was no oscillation)
Oscillation pattern in E spectrum
location of the minimum m²flux reduction from sin²2
1 - sin²2 sin²(1.27 m² L/E)
@ 250 m@ 250 km
“atmospheric” oscillations
2010
Oscillations confirmed: beam disappearance compatible with in cosmic rays
1 - sin²2 sin²(1.27 m² L/E)
- fixed Length, selected Energies
- pure beams and near detectors
- measurements on interactions
2010 MINOS, magnetizedFar (+ Near) Detector730 km (E ~ 3 GeV),also atmospheric
“atmospheric” oscillationsOscillations confirmed: beam disappearance compatible with in cosmic rays
Precise L/E to measure phase; large fluxes to measure amplitude
1 - sin²2 sin²(1.27 m² L/E)
“atmospheric” oscillations
beam disappearance ~
~ beam disappearance
Very precise |m2|
Maximal mixing!?
and sharelarge % of m2, m3
e has more m1, m2
( )
T2K – from Tokay to Kamioka
Optimal beam energy for oscillation and resolution0.6 GeV 2.5º off-axis from parent direction
Reduce beam contaminationEnhance quasi-elastic interactions
disappearance
e appearence
On-axis and off-axis ND280m detector complex
selecting muon neutrinos1 Cherenkov ring e-like / -like late decay e signal
Neutrino energy position x,y position z,R
selecting electron neutrinos1 Cherenkov ring e-like / -like
late decay e signal
visible energy
neutrino energy not ⁰
recent results from T2KNeutrino mode446 from beam120
28 e (5 from beam)
not visible
and
e appearance!
Anti-neutrino mode
more difficult beam,and less statistics
compatible w/
e lacking statistics
Discovery withNatural Sources
Confirmation w/human-made
High precisionexperiments
oscillationsand mass
closing thecircle of 3
open questions
flavor change + L/E dependence => mass
* Fix large propagation Length to see oscillation pattern in Energy
* First experimental discoveries of neutrinos used artificial sourcesNuclear reactor's e =/= Particle accelerator's
Nuclear fission (& fusion) @ MeV Pion production & decay@ GeV
KamLANDLiquid scintillator Anti- Detectorin the old KamiokaNDE cavern
50% of all reactors in Japan 150km - 250km of Kamioka
calibration
OD
1 kton LSballoon
PMTsand buffer oil
e + p -> e + n⁺- only electron anti-nu- coincidence tagging
KamLAND measurementsDiscovery of geo-neutrinos!
solving the Solar Neutrino Problemopens the way to study natural sources
(ex: Borexino does solar + geo)
still backgrounds at low energy several purification campaigns
e + p -> e + n⁺- only electron anti-nu- coincidence tagging
Oscillations by KamLANDAmplitude sin²2 fixed by NaturePhase sin²(1.27 m² L/E) [eV²] [km]/[GeV]
maximized for =(1+2k) /2
m² for e disappearance ~ 10 ² ⁻ m² for disappearancelarge but non maximal mixing => different oscillation parameters
for different mass combinations
“solar” oscillationsSolar oscillations enhanced by matter effects in the SunConfirmed by vacuum oscillations of reactor in the Earth
Vacuum L/E signature gives best result on |m²|
Oscillation parameters arecompatible for and
Two very complementary independent measurements
P = 1 - sin²(2).x sin² (1.27 L/E.m²/x)x(2,m²,electron density)
Matter effects in the Sun, break degeneracy in /m²
closing the circle on 3 neutrinosOscillation frequencies depend of squared mass differencesOscillation amplitudes depend on similarity of mass mixing in each flavor
3 flavors of neutrinos ( & anti-neutrinos ) for 3 mass values
Sun
solar oscillations (12)m²~10 eV², ⁻⁵ ~30º
Reactor
Cosmic rays &Accelerators
atmospheric oscillations (23)m²~10 ³ eV², ⁻ ~45ºsmall oscillations (13)
m²~10 ³ eV², ⁻ <10º
E ~ MeV E ~ GeV
+ Tau identification onlyat very high energy
Needs very high fluxes
1 km / 100 km 250 km250 km / 700 km
Daya Bay in China1, 2, 4 .... in total 8 neutrino detectors
All very precisely equal at different distances from
large nuclear reactor cores
Oscillations
New mixing angle much smaller than solar/atmospheric mixing(small number of e in T2K's )
2 methods to tag neutrons
Daya Bay + RENO + DChooz
Atmospheric Solar
Juno
directly see pattern of subdominant oscillations?
The challenge is energy resolution
m12 + m23
Mass HierarchyJUNO
Discovery withNatural Sources
Confirmation w/human-made
High precisionexperiments
oscillationsand mass
closing thecircle of 3
open questions
* Seen L/E pattern for three sets of neutrino oscillation parameters * Can not use simplified two-neutrino oscillation formula anymore
e
1 0 00 c23 s23
0 -s23 c23
c13 0 s13 e⁻i
0 1 0-s13 ei0 c13
c12 s12 0 -s12 c12 0 0 0 1
m² = 7.5 + 0.2 x 10 eV²⁻⁵Solar = 30º-35º
m²| = 2.24 + 0.06 x10 ³ eV²⁻Atmospheric= 40º-50º <~ 10º & =?
Matrix values range 0.15 – 0.85, 1%-6% uncertainty
m²
m²|
Largest angle is 45º Largest angle is 13ºHaving 3 mixing angles allows for CP-violation (GIM mechanism)
|Ue1| |Ue2| |Ue3||U1| |U2| |U3||U1| |U2| |U3|
0.82 0.55 0.150.35 0.70 0.610.44 0.45 0.77
|Vud| |Vus| |Vub||Vcd| |Vcs| |Vcb||V td| |V ts| |V tb|
0.97 0.23 0.000.23 0.97 0.040.01 0.04 1.00[ ] [ ]
Pontecorvo-Maki- Cabibbo-Kobayashi--Nakagawa-Sakata -Maskawa
Mixing matrices: Neutrinos and Quarks
Hints of CP violation in T2K
H.A. Tanaka, T2K @ Neutrino 2016
1 relevant phase2 mixing angles
3 mixing angles
matter effectschange up to 10%
odd CP phase change up to 30%
Joining disappearance + appearance+ neutrino and anti-neutrino beams+ the results from other experiments
Can neutrinos help to explainmatter/anti-matter asymmetry?