Neutrino PhysicsNeutrino PhysicsCaren Hagner
Universität Hamburg
Caren Hagner
Universität Hamburg
Part 1: Neutrino oscillation in vacuum
Introduction: neutrino mass, mixing and oscillation
Atmospheric neutrinos and accelerator neutrinos
Part 1: Neutrino oscillation in vacuum
Introduction: neutrino mass, mixing and oscillation
Atmospheric neutrinos and accelerator neutrinos
Some Historical RemarksSome Historical Remarks
• 1930: neutrino postulated by Pauli (massless, neutral)
• 1956: neutrino ve detected by Reines and Cowan
• 1957: Wu discovered parity violation in weak interaction
• 1958: Goldhaber experiment neutrinos are left handed anti-neutrinos right handed
• 1930: neutrino postulated by Pauli (massless, neutral)
• 1956: neutrino ve detected by Reines and Cowan
• 1957: Wu discovered parity violation in weak interaction
• 1958: Goldhaber experiment neutrinos are left handed anti-neutrinos right handed
nepve
3 Neutrino Flavors3 Neutrino Flavors
• 1960: B. Pontecorvo and M. Schwartz proposed neutrino beam (from accelerated protons) → discovery of vμ at AGS in Brookhaven by Ledermann, Schwartz and Steinberger
• LEP measurement of Z0 decay width:→ 3 active neutrino flavors (mv < 80 GeV): Nv = 3.00±0.06 ve, vμ, vτ
• 2000: vτ detected by DONUT experiment
• 1960: B. Pontecorvo and M. Schwartz proposed neutrino beam (from accelerated protons) → discovery of vμ at AGS in Brookhaven by Ledermann, Schwartz and Steinberger
• LEP measurement of Z0 decay width:→ 3 active neutrino flavors (mv < 80 GeV): Nv = 3.00±0.06 ve, vμ, vτ
• 2000: vτ detected by DONUT experiment
Neutrinos in the Standard ModelNeutrinos in the Standard Model
LLLb
t
s
c
d
u
LLL
e
e
RRRRRR btscdu ,,,,, RRRe ,,
• No right handed neutrinos
• Neutrinos are massless
• Le, Lμ, Lτ conserved
• No right handed neutrinos
• Neutrinos are massless
• Le, Lμ, Lτ conserved
??
Super-Kamiokande
atmospheric neutrinosaccelerator neutrinos
JAPANKamLAND
reactor neutrinos
JAPANCANADA
solar neutrinos
SNO
Important experimental results in recent years
ve→vμ,τ
OscillationΔm2 ≈ 8·10-5 eV2
vμ→v,(s)
Oscillation Δm2 ≈ 2·10-3 eV2
Neutrino Oscillations were observed→ Neutrinos have mass!
Neutrino Oscillations are a consequence of
neutrino mass and mixing
Neutrino Oscillations are a consequence of
neutrino mass and mixing
What is neutrino mixing? → compare to quark CKM mixingWhat is neutrino mixing? → compare to quark CKM mixing
b
t
s
c
d
u
ee
Quark and Lepton Mixing:Eigenstates of weak interaction ≠ Eigenstates of mass
bsd ,, bsd ,, bsd ,,
mass eigenstates
mass eigenstates 321 ,, 321 ,, 321 ,,
Quark - Mixing
Neutrino - Mixing
b
s
d
VVV
VVV
VVV
b
s
d
tbtstd
cbcscd
ubusud
Quark-Mixing Quark-Mixing
Cabbibo-Kobayashi-Maskawa (CKM) Matrix
• 3 mixing angles
• 1 phase: ei
CP-violation
BELLE, BABAR,CLEO,…
in precision measurement phase
b
t
s
c
d
u
b
t
s
c
d
u
b
s
d
VVV
VVV
VVV
b
s
d
tbtstd
cbcscd
ubusud
Hierarchy in Quark MixingHierarchy in Quark Mixing
• of masses: md « ms « mb
• of mixing angles: s12 = λ, s23 ≈ λ2, s13 ≈ λ3
• of masses: md « ms « mb
• of mixing angles: s12 = λ, s23 ≈ λ2, s13 ≈ λ3
b
s
d
cs
sc
ces
esc
cs
sc
b
s
d
i
i
100
0
0
0
010
0
0
0
001
'
'
'
1212
1212
1313
1313
2323
2323
Neutrino mass and mixingNeutrino mass and mixing
Neutrino mixing!Neutrino mixing!
3
2
1
321
321
321
UUU
UUU
UUU eeee
3 massive neutrinos: ν1, ν2, ν3 with masses: m1,m2,m3
Flavor-Eigenstates ve,vμ,vτ ≠ Mass-EigenstatesFlavor-Eigenstates ve,vμ,vτ ≠ Mass-Eigenstates
Historical remarkHistorical remark
• 1957-58: B. Pontecorvo proposed neutrino oscillations(because only ve was known, he thought of v ↔ anti-v)
• 1962 Maki, Nakagawa, Sakatadescribed the 2 flavor mixing and discussed neutrino flavor transition
• 1967 full discussion of 2 flavor mixing,possibility of solar neutrino oscillations,question of sterile neutrinos by B. Pontecorvo
• 1957-58: B. Pontecorvo proposed neutrino oscillations(because only ve was known, he thought of v ↔ anti-v)
• 1962 Maki, Nakagawa, Sakatadescribed the 2 flavor mixing and discussed neutrino flavor transition
• 1967 full discussion of 2 flavor mixing,possibility of solar neutrino oscillations,question of sterile neutrinos by B. Pontecorvo
Parametrization of Neutrino MixingParametrization of Neutrino Mixing
3
2
1
132313231223121323122312
132313231223121323122312
1313121312
21
21
21
][
][
iiii
iiii
iiie
ecceescsscesccss
ecseesssccessccs
eesecscc
Pontecorvo-Maki-Nakagawa-Sakata (PMNS) Matrix: • 3 Mixing angles: θ12, θ23, θ13
• 1 Dirac-Phase (CP violating): δ
Pontecorvo-Maki-Nakagawa-Sakata (PMNS) Matrix: • 3 Mixing angles: θ12, θ23, θ13
• 1 Dirac-Phase (CP violating): δ
If neutrinos are Majorana particles:• 2 additional Majorana-Phases (CPV): α1, α2
3
2
1
1212
1212
1313
1313
2323
2323
100
0
0
0
010
0
0
0
001
cs
sc
ces
esc
cs
sci
ie
θsolθ13, δθatm
Neutrino mixing anglesNeutrino mixing angles
v1
v2
v3
ve
vμ
vτ
θ12θ12ve
vμ
vτ
θ13
θ12
vτ
vμ
ve
θ23
θ13ve
vμ
vτ
3
2
1
1212
1212
1313
1313
2323
2323
100
0
0
0
010
0
0
0
001
cs
sc
ces
esc
cs
sci
ie
Solar and reactor experiments
θ12: 29o - 39oθ13<13o, δ ?
Unknown (CHOOZ)
Θ23: 34o - 58o
Atmospheric and accelerator
Neutrino OscillationsNeutrino Oscillations
3
2
2323
2323
cossin
sincos
Flavor eigenstates vμ, vτ Mass eigenstates v2,v3 with m2, m3
W
vμ
μ
source createsflavor-eigenstates
vτ
W
τ
p,n hadrons
detector seesflavor-eigenstates
v2
v3
propagation determined bymass-eigenstates
23,2
23,23,2 mpE
slightly different frequencies→ phase difference changes
General derivation of oscillation formula:
3
1kkk vUv
α = e, μ, τ
k = 1, 2, 3
kv neutrinos with negative helicity, mass mk, momentum pand energy
p
mpmpE k
kk 2
222
ktiE
k vetv k)(
3
1
*)(k
ktiE
k vUeUtv k
3
1
)(k
ktiE
k veUtv k now change to flavor base
→
vvA is the amplitude for the transition vα→ vβ at time t
General derivation of oscillation formula:
23
1
*2
)(
kk
tiEkvvvv UeUtAP k
ji
ijjjii
ji
ijjjiivv
E
LmUUUU
E
LmUUUUP
2sin)(2
4sin)(4
2**
22**
3
1
*
kkkUU using and
222jkkj mmm
2 Flavor Neutrino Oscillations2 Flavor Neutrino Oscillations
23
22
2 mmm 23
22
2 mmm
oszL
xP
223
2 sin)2(sin)(
Oscillation probability
)eV (in
GeV) (in48.2km) in(
22m
ELosz
)eV (in
GeV) (in48.2km) in(
22m
ELosz
Pro
babili
ty t
o fi
nd
vτ
Distance x in Losz
Losz, Δm2 sin2(2θ)
Pro
babili
ty t
o fi
nd
vμ
oszL
xP
223
2 sin)2(sin1)(
Survival probability
appearance
disappearance
Primary cosmic ray
N
N
K
π
π
μ
ν
π
#(vμ) / #(ve) ≈ 2
atmospheric neutrinos
Atmospheric Neutrino HistoryAtmospheric Neutrino History
•In less than two decades, atmospheric neutrinos have gone from being “anomalous” to being one of our main tools for theexploration of the lepton sector.
• 1980s – 1990s: Skepticism was rampant!• “Neutrino experiments are hard!”• “Cosmic ray experiments are hard!”• “Oscillation experiments are hard!”
•In less than two decades, atmospheric neutrinos have gone from being “anomalous” to being one of our main tools for theexploration of the lepton sector.
• 1980s – 1990s: Skepticism was rampant!• “Neutrino experiments are hard!”• “Cosmic ray experiments are hard!”• “Oscillation experiments are hard!”
Oscillation of atmospheric neutrinosOscillation of atmospheric neutrinos
]GeV[
]km[]eV[27.1sin2sin)(
2222
E
LmP atm
atmx
L ≈ 20 km
L ≈ 13000 km
atmosphericneutrinos:
Ev in GeV range
Oscillation probabilityvaries with zenith angle θ θ
Super-Kamiokande
• solar neutrinos (8B ve few MeV)
• atmospheric neutrinos (vμ, ve few GeV)
• K2K accelerator neutrinos (vμ 1 GeV)
• start ~2009: T2K off-axis super neutrino beam
electron event
myon event
50kt H2O
12000 PMTs12000 PMTs
Super-Kamiokande
SuperK – atmospheric neutrinosSuperK – atmospheric neutrinos
e–like events μ–like events
without oscillationoscillation (best fit)
data
νe
e
νμ
μ
Atmospheric neutrinos:Analysis neutrino oscillation (full SK-I data set)
Atmospheric neutrinos:Analysis neutrino oscillation (full SK-I data set)
Confirmed by MACRO, SOUDAN
E.Kearns Neutrino2004
Analysis of eventswith high L/E resolution
First evidence of oscillation pattern? First evidence of oscillation pattern?
Oscillation dip!(?)
“EVIDENCE FOR AN OSCILLATORY SIGNATURE IN ATMOSPHERIC NEUTRINO OSCILLATION.”Super-Kamiokande Apr 2004., Submitted to Phys.Rev.Lett., hep-ex/0404034
“EVIDENCE FOR AN OSCILLATORY SIGNATURE IN ATMOSPHERIC NEUTRINO OSCILLATION.”Super-Kamiokande Apr 2004., Submitted to Phys.Rev.Lett., hep-ex/0404034
• oscillation
• decay
• decoherence
from L/E analysisfrom L/E analysis
Super-Kamiokande: Accident 2001Super-Kamiokande: Accident 2001
Accident Nov 21, 2001:~7000 of 12000 PMT’simploded in chain reaction
Neutrino beamsNeutrino beams
ProtonBeam
TargetFocusingDevices
Decay Pipe
Beam Dump
,K
few 100 GeV
few GeV
Beam composition (typical example):
• dominantly vμ
• contamination from vμ (≈6%), ve (≈0.7%), ve (≈0.2%)
• vτ ≲ 10-6
Beam composition (typical example):
• dominantly vμ
• contamination from vμ (≈6%), ve (≈0.7%), ve (≈0.2%)
• vτ ≲ 10-6
250km
K2K
The K2K experiment
Muon range
detector
K2K-I Mar.1999 ~ Jul.2001near neutrino detectors
39m
41.4
m
Super-Kamiokande I
Outer detector
Inner detector
1885 8” PMTs
11146 20” PMTs
K2K-II Dec.2002~Upgrade of near neutrino detectors
•Removed Lead Glass detector•Installed SciBar and Electron
Catcher (Oct.2003~)
Super-Kamiokande II
K2K accelerator experimentK2K accelerator experimentNear
Detector1 ton
KEK
300m250km
νμ, <Eν>= 1.3 GeV
νμ, <Eν>= 1.3 GeV
Super-Kfar detector
50 kton
Goal: 1.0×1020 POT = 200 neutrino events in SKGoal: 1.0×1020 POT = 200 neutrino events in SK
Data (06/1999 – 02/2004): 8.9·1019 POT events in “Far Detector” :expected without oscillation:
Data (06/1999 – 02/2004): 8.9·1019 POT events in “Far Detector” :expected without oscillation:
1086.110.109.150
Probability for no oscillation: <0.01%Neutrino oscillation confirmed with 3.9σ!
)eV (in
GeV) (in48.2km) in(
22m
ELosz
First hint for typical deformation of energy spectrum First hint for typical deformation of energy spectrum
without oscillationbest fit oscillation