Post on 17-Jan-2016
Neutrino properties, Neutrino properties, oscillations, present statusoscillations, present status
Gaston WilquetIIHE - Université Libre de Bruxelles
1
Urs Fest, Bern, 21/1/2011
2
A very brief history of the neutrinosA very brief history of the neutrinos
Neutrino MixingNeutrino Mixing
Neutrino nature: Dirac or Majorana particle? Neutrino-less Neutrino nature: Dirac or Majorana particle? Neutrino-less -decay-decay
Direct mass measurementsDirect mass measurements
Neutrino oscillations – phenomenologyNeutrino oscillations – phenomenology
First evidences of neutrino oscillations: a selectionFirst evidences of neutrino oscillations: a selection
Observation of neutrino oscillations at reactors and accelerators: a selectionObservation of neutrino oscillations at reactors and accelerators: a selection
Near future (current decade) as conclusionsNear future (current decade) as conclusions
I shall not talk about the OPERA experiment: see next talk by Henri PessardI shall not talk about the OPERA experiment: see next talk by Henri Pessard
Contents
A very brief history of the A very brief history of the neutrinosneutrinos
3
Pierre Becquerel (1886) discovers radioactivityErnest Rutherford (1897) identifies and radioactivityJ.J.Thomson and others (1897) discover electron
Pierre and Marie Curie (1902) show that -rays are electrons
40K 40Ca + e-
Lise Maitner and Otto Hahn and James Chadwick (1914) measure the -rays energy spectrum: incompatible with 2-body decay. Angular momentum is not conserved.
C.D. Ellis et W.A. Wooster (1927) and Lise Meitner and W. Orthman (1930) do a calorimetric measurement of the total energy released in the radium E (210Bi) decay: incompatible with 2-body decay and with 3-body decay involving a -ray
Niels Bohr and others contemplates the possibility that energy-momentum is not conserved in decays
From the discovery of radioactivity to the “energy crisis”
4
Letter from Pauli retained by a ball in Zurich to the “Gruppe der Radioaktiven” in meeting in Tübingen
“Invention” of the neutrino and the weak interaction formalism
Wolfgang Pauli “invents” the neutrino (1930): the Columbus egg-decay is a 3-body decay involving a “neutron”: light spin ½ neutral particle
Enrico Fermi (1933) names the “neutrino” and develops the -decay theory – the base of the electroweak theory in the Standard Model
James Chadwick had discovered the neutron in 1932
Local 4-fermions current-current interaction based on the 4-spinor Dirac description of Fermions
n p
e ee
FG
5
Enrico Fermi (1933) offers a case of champagne to whom will detect the first neutrino.
Hans Bethe and Rudolf Peierls (1934)
Mean free path of moderate energy in lead: tens to thousands ly
Fred Reines et Clyde Cowan (1953-56-58) detect the first neutrino interactions at Savannah River nuclear power plant
1010N eN
The experimental discovery of the neutrino
6
13
0.5
.8
prompt 2- coincidence from annhilation on
delayed 's from capture by "neutronphage" nuclei (Cadmium) - known
's detected by scintilators and P
ee
three
shEp e n E MeV
keV e e
n E
MeV
M tubes
0.511keV
100 200 s
Ray Davis et al. (1955-58) confirm the difference neutrino/antineutrino
37
37 37 50
4000
Radiochemical experiments days
Working principle suggested by Bruno Pontecorvo
tested with cosmic rays by Ray Davis
of carbon tetrachloride exposed to Brookhave
e ArCl Ar e
l
:No count above backgroun
n
d
reactor
n e p
Neutrino, antineutrino and neutrino families
-
Highest energy proton beam
sp N D X
X
13
0
3 10
'
-
Interaction-decay chain
or or se
N X
e
s
Bruno Pontecorvo (1959):electron and muon have different partners e and Leon Lederman, Melvin Schwartz, Jack Steinberger at al (1962) discover the
+BNL beam decays
e
N X
N e X
DONuT Collaboration (2001) observes the at Fermilab
7
Neutrino MixingNeutrino Mixing
8
Neutrinos exist in 3 different flavours (familes, types)
is produced in CC weak interaction of lepton
If neutrinos are massive and mass eigenstates are not degenerated
a pr
: , ,e
iori mixing between :
flavour eigenstates
mass eigenstates
(6) parameters 3mixing angles
Dirac (Majorana)
3
11,
2 3 23
1,
, ,
1, 3
4
1, ,
1
k
k kek
kk
e
k
U
U eU
(3)phases
Extension to 4 mass eigenstates straightforward
Additionnal light flavour eigenstates are sterile :
active neutrino with = from invisible width at LEP02 2.9841 0.0084ZN m M Z
Mixing matrix
9
PMNS parameterization of mixing matrixBruno Pontecorvo (1957) -
Ziro Maki, Masami Nakagawa, Shoichi Sakata (1962)
10
Neutrino nature:Neutrino nature:Dirac or Majorana particle?Dirac or Majorana particle?
Neutrino-less Neutrino-less -decay-decay
11
The Standard Model Weyl neutrino
• Tsung Dao Lee and Chen Nin Yang (1956) predict P violation in weak interactions
• Chien Shiung Wu et al. (1957) observe maximum P violation in -decay
• Maurice Goldhaber et al. (1958) measure the neutrino helicity
() are fully polarized: h = -1/2 (+1/2)
Massless neutrinos may not be overtaken by Lorentz transformation
The massless and differ by an invariant observable: h
12
and are also distinguished by a conserved quantum number:
Lepton nu
SM described by a chiral field
State ( ) an
mber
hilit
and, 1 , 1
l lL
l l
L l L v l
n p p n
p n n p
LH
ated (created) by field has -1/2 (+1/2)lL h
Charged leptons: conserved:
are conserved independently
6
12
10
, , 10e
L BR e
L L L BR e e e
State ( ) anhilitated (created) by field is linear sperposi
is no more invariant and c
tion of and
But state ( state) enters into su
annot distinguish and
per s
po it
-1 / 2 1/ 2
1/ 2 1/ 2
l l lL h
h
h
h h
Ap
io
pa
n wi
rent
th weigh
conservation of artefact of violation and sm
t
allness f ?
o
610m
n p p n
p n
m
E
n p
L P
Massive neutrinos: Dirac or Majorana ?
Dirac neutrinos: and distinguished by
described by Dirac spinors (almost) like other fermions
field is sterile: no coupling to bosons
Small mass implies very weak coupling
1( 1)
,
10
R
L
RH W Z
to boson13 H
Majorana neutrinos are their own antiparticle
See-Saw mechanisms to explain smallness of the mass
very heavy partners new physics at GUT scale,
leptogenesis to explain violation and
1510m GeV
CP
matter/antimatter asymmetry13
14
Dirac vs. Majorana? Neutrino-less -decay
© LHEP website
76 ,2 211/ 2
( , ) ( , 2) 2 2
(1.77 0.01 0.12) 10
2nd order SM weak interaction predicted M. Goeppert-Mayer (1935)
observed in a dozen nuclei:
e
Ge
A Z A Z e
T y
7633 As
7632Ge
2.04 Q MeV7634Se
, ) ( , 2) 2
2 forbidden for Dirac neutrinos
A Z A Z e
L
2
1 20 01 2
3 32 2
1, 1,
0 25 100% known to
e
e
k
e
ek k ekk
ik
k
mT M
m
m U m U m
M
e
Moscow-Heidelberg experiment at Gran Sasso: semi-conductor
Only - very disputed - claim of a discovery in 2001:
Cuoricino experiment at Gran Sasso: crystals bol
0 2.99 251/ 2 0.501.19 10 0.2 0.6
eT y m eV
ometers 130
0 241/ 2
130 2
3.0 10 0.19 0.68 @ 90% . .e
T Xe e
T y m eV C L
e
4 crystals
Direct mass measurementsDirect mass measurements
15
Very high energy resolution & counting rateVery low background
iif ~ of total counts131 2 10m eV
e effective mass - electron energy spectrum in Tritium -decay
16
220
0
2 2
1
0
32
0 ( )
0
0 0
( ) ( )
if
for
e
e
effe
e
e
e
eff
effek
ee e e
e
kk
E E
E Max E m
x
m
x
dN E E p E E E Ed
m
U m
E
m
offset 2
e
effm
0m
1m eV
e effective mass - status of Tritium experiments
Both experiments have reached their intrinsic limit of sensitivity
Troitsk gaseous T2-source Mainz frozen T2-source
at 2 2
2005 : 2.3 95%
0.6 2.2 2.1
e
e
eff
eff
m eV CL
m eV
at 2 2
1999 : 2.5 95%
1.9 3.4 2.3
e
e
eff
eff
m eV CL
m eV
Magnetic adiabatic electron collimation followed by an electrostatic filter
17
Neutrino oscillations Neutrino oscillations phenomenologyphenomenology
18
Neutrino propagation in vacuum: Neutrino oscillation
Assume created with momentum at in CC interaction of
Flavour eigenstates propagate as superposition of mass eigensates with different phases:
3
1
0
0
-0
k kk
kk k
p t
| ν U | ν
ν
iE t| ν t U e | ν
Mixings define
Oscillation termMaximum probability
as 23
1
2 21,3* * 2
*
0
/
2
[ ] [ ]( ( ) ( )) 4 sin 1.27
[ ]
2
kk k
k
kjj k j k
j k
j k
L
L E
m E p p m
E
m eV L kmP U U U U
E GeV
U U U
Null if CP conserved
Oscillation term
parameters:
mixing angles
CP phase
+
2 21,3*
2
2 2 2 2 2 221 32 31
/
6
[ ] [ ] 3sin 2.54
[ ] 1
2
kjj k
j k
kj k j
L E
m eV L kmU
E GeV
m
m m m m m m
not sensitive to diagonal Majorana CP violation phases
oscillation experiment cannot distinguish Dirac - Majorana
19
NC :
CC :
Collusion between and may lead to
mixing
Forward elastic scattering plane
angle in m
wave exp w
t
h
a
it
, ,
0
,
2
-
,
2
, , , ,
,
| 1 | 10
,
e
e e
e e
e
m
Vi px e iE
e u d e u dn n n
e e
tE
E
n n
m N
e
ter very different from in vacuum
in vacuum and at Sun centre are different mass eigenstates supe
= number
r
dens
positions
ity
2
2
22 2 2
sin 2tan 2 2
cos 2 2
cos 2 sin
m CC F e eCC
m CC
mV G N N e
m E V
m m E V m
22
Flavour transition caused by matter effects
20
If varies "slowly enough": MSW (Mikheyev, Smirnov, Wolfenstein) effect:
created at large is mass eigenstates superposition different from vacuum
propagate adiabatically from large
e
e m
i e
N
N
N
to vacuum superposition of mass eigenstates
remains unchanged during propagarion
superposition reaching vacuum is different from
Adiabaticity condition depends on 2, , , ,
i m
e em E N N
In vacuum:
Matter effects allow distinguishing between and or fix
2
2
sin 2
90 sgn
oscP
m
Neutrinos oscillation: what we know in 2010 ?
e
All results compatible with
- Compatible with full mixing
- Large mixings between and / in and
- Compatible with
_
2 2 5 221 2 1
2 2 3 231
2 2 231 32 21
1 2
7 10
2.5 10
30
sol
atm
m m eV m m
m m eV
m m m
e 3
- Absolute mass scale ?
from spectrum in
- Mass hierarchy?
strong
or inverte
n
d
or degenera
o
c
in
y ?
21
3 3
1 2 3
3 1,2
1, ,3
3
2
2.3
0, 8 , 50
0, 50
2
: sin 2 0.12
e
effee
m eV E H He e
m m meV m meV
m m meV
m eV
e- component in ? CP violation ?
- Dirac or Majorana neutrino?3
21
e
2 5 2 221 7 10 solm eV m
0
2m
2 0.3 0.35 0.35
3 ? 0.5 0.5
1 0.7 .15 .15
2 2 3 231 32
2
2.5 10| | | |
atm
m m eV
m
2 3 232
3 3 -
2.5 10
2.3 : e
m eV
eV H He e
Normal hierarchy
2 5 2 221 7 10 solm eV m
0
2 3 232
3 3 -
2.5 10
2.3 : e
m eV
eV H He e
2m
2
3 ? 0.5 0.5
0.3 0.35 0.35
1 0.7 .15 .152 2 3 231 32
2
2.5 10| | | |
atm
m m eV
m
Inverted hierarchy
2 5 2 221 7 10 solm eV m
0
2m
2 0.3 0.35 0.35
3 ? 0.5 0.5
1 0.7 .15 .15
2 2 3 231 32
2
2.5 10| | | |
atm
m m eV
m
2 eV2
Degeneracy
First evidences of neutrino First evidences of neutrino oscillations: a selectionoscillations: a selection
22
First evidences: atmospheric and solar neutrinos
First experimental indications of neutrino oscillations were incidental.
Experiments designed to study the interior of the Sun (Ray Davis at Homestake mine in 1968 …) and cosmic rays through interactions in the atmosphere (IMB at Morton mine in 1986 …) using neutrinos as messengers.
(Almost) all evidences based on disappearance: deficit in flux of a neutrino flavour measured at distant point the from its source.
Evidences first confirmed by several experiments using natural neutrinos sources. Astrophysical and instrumental explanations of the deficits progressively abandoned.
Undisputed interpretation as neutrino oscillation dates from about a decade:
• Atmospheric neutrinos (…Kamiokande, Super-Kamiokande-1998…)
• Solar neutrinos (Homestake,… Kamiokande, Super-Kamiokande, SNO-2002…)
23
Pioneers: Ray Davis: Homestake radiochemical experiment, first solar neutrino detectionMasatoshi Koshiba: first large water Cerenkov experiment Kamiokande – solar and atmospheric neutrinos
Atmospheric neutrinos : Super-Kamiokande 1996-2005
Events topology discrimination based on the shapes of the Cerenkov rings
Not obvious but -like -like separation100% /e
muon600 MeV
Sharp ring
electron500 MeV
Fuzzy ring
50 11 200
2700
ktons of highly purified water seen by PM tubes
Under of rocks in Mozumi mine, Kamioka, Japanmwe
24
N X
N X
e
e
N e X
N e X
p
e
20 km
13 000 km
p
e
,2
,e e
v v
v v
Super-Kamiokande results arXiv:hep-ex/0501064
25
e
Measured -like flux agrees with model expectations for every and
decouples for probed by
Measured -like flux is largely depleted and depletion oscillates in
larg
d
e - mix
omain2
/L
L
E
e E
m L E
ing for probed by domain2m L E
2 2
2
1
2 3 223
[ ] [ ]sin 1.27
[ ]
500
2.5 10
kjm eV L km
E GeV
Lkm GeV
E
m eV
data
MC no oscillation
Events observed/predicted
Best fit to
data
Numbers of events
like like
sin2 sin2
m2 32
(eV
2 )
m2 32
(eV
2 )Super-Kamiokande results arXiv:hep-ex/01002.3471
2
2e 3
2
Best fits:
sin full - mixing
sin no component in
sin at
23
2 3 2
13
13
0.50
2.1 10
0.
0.04 90% . .
m eV
C L
2 5 2 221 7 10 solm eV m
2m
2 0.3 0.35 0.35
3 ? 0.5 0.5
1 0.7 .15 .15
2 2 3 231 32
2
2.5 10| | | |
atm
m m eV
m
e
26
20 1
1
6 10 1 2%
3 1.8
e
known to
e
elec
e e
thresh
P GW
s
E MeV E MeV
p e n
0.511keV
5t17t9
0t
3 2 3 223
(8.5 ) 998 1114
3 10 2.5 10
(0.09%)
twin reactors @ and
5 tons -doped liquid scintillatior
GW L m
E MeVm eV
L m
Gd
spectrum measured
spectrum expectede
e
ER
E
E
2 2 3 213 31
1.010 0.028( ) 0.027 ( )
sin 2 0.13 90% . . 2.5 10
eNo disappearance
at for
R stat syst
C L m eV
CHOOZ reactor experiment: confirms that no e in 3
27
Detector : liquid scintillator vessel doped with high neutron capture cross-section
Solar neutrinos: measured event rates vs. SSM predictions (Bahcall and Pinsonneault)
0.34 / 0.59
e
e
Experim
flu
ents sensitive
x defici
to CC only
:
:
tmeas pred
N e X
e
No sensible astrophysical or
instrumental explanation to
disappearance except oscillation.
28
4
10 -2 -1
4 2 2 26.73 0.6
6.5 10
Sun fusion reactor Hans Bethe (1930's), William Fowler (1950's)
Solar flux at Earth level: ep e He MeV E E MeV
cm s
29
Solar neutrinos: SNO 2002 results
, , , ,
9500
6000 . . .
1 ktons of highly purified heavy water seen by PM tubes
Under of rocks in Creighton mine, Sudbury, Canada
Sensitive to NC: e e
m w e
d p n
SNO NC
0.35CC CCmeas e model e
NC NCmeas model e
v v
v v
Proof of the appearance of active-like neutrinos of flavour different from
However not identified as : ,,
e
CCthresh
v
v v E E v
n vacuum: assume
remember that and have same
In the Sun core:
large
I 12 13
2 212 1 12 2
1 2
, 1 2
2
12 2
2
tan 0.44 0
: cos sin
0.7 0.3
: 0.3 0.7
sin 2tan 2
cos 2 2 2
0 2 cos 2 tan 2
e
NC
m
F e
e CC
V V
m
m E G N
N E V m
created as
emerges from Sun in vacuum as
are created in the Sun core in nu
If adiabatic transi
clear f
tion
usi
satisfie
d:
2
2
2 22 12 , 12
,
0 2
( ) (0)exp / 0.1
: cos sin
0. 0.7 3
m m
e
e
e
e
e
eN x N x R
on reactions
A mixture of and propagates in the vacuum between Sun and Earth
Fraction of surviving varies with
,e
e E
Solar neutrinos results explained by matter effects
30
adiabatic
2 0.10 0.1012 0.07 0.06tan 0.44
Observation of neutrino Observation of neutrino oscillations at reactors and oscillations at reactors and accelerators: a selectionaccelerators: a selection
31
What about oscillation experiments at accelerators and nuclear reactors?
2 2m eV
2sin 2
410
10
Until late 1990’s• No theoretical prediction• Theoretical prejudice: small mixing c.f. quarks• Hot dark matter models: large m > 10 eV → large m2
Acceleratorexperiments
From ~2000: U and m2 known with reasonable precision:Design experiments for specific L/E & oscillation channel.
32
Probing atmospheric neutrinos solution: disappearance or its appearance into at accelerators
2 2 3 2
... :
10 10100
Beams: many or focus/defocus to choose or
multi Long Baseline experiments
Near detector: Beam flux, composition and energy spectru
several
p N
E GeVm eV
L km
m before oscillation takes place
Far detector: flux and energy spectrum and compare with no oscillation extrapolationCC
K2K : KEK to Kamioka LBL experiment (1999-2004) / 1.3 / 250 Far detector: Super-KamiokandeE L GeV km
Visible energy
-like events
No oscillation
Best fit
112
151
4.3
9
Small statistics:
- events observed
- events exp
No oscillation scena
ected if no oscillatio
rio excluded at
n
33
MINOS : the LBL experiment @ Fermilab NuMI beam (2005)Two similar detectors: segmented magnetized iron calorimeters:
- magnetized iron slabs
- planes of plastic scintillator strips read by WLS fibres and PM
Near detecto
tubes
r: at
Far det
0.98 1.04ktons L kmector: at in Soudan mine, Minnnesota
Beam spectrum centered on
5.4 733
2 5
ktons L km
GeV
Ratio of data to expected for no oscillations
E GeV
2 0.11 3 231 0.08
231
2.35 10
sin 2 0.91 90% . .
@
m eV
C L
P. Vahle, Neutrino 2010
34
35
Probing solar neutrinos solution:e disappearance at nuclear reactors
2 4 5 210 1010
1- 2
0
%
e
Long Baseline experiments
Flux and energy spectrum at source known at level
Detector a la CHOOZ: doped liquid scintillator vessel
3
-
E MeVm eV
L km
p e n
liquid scintillator
PM tubes
1000
2100
tons
KamLAND LBL experiment at Kamioka 13 m diameter balloon
0 180 is the flux weighted average
distances to reactors
L kmKamLAND results
Expect 2179±89 events from reactors
+ 276±23 backgrounds
Observe 1609 events.
Oscillation pattern observed
36
2 0.21 5 221 0.21
2 0.0612 0.05
7.59 10
tan 0.47
KamLAND + Solar best fit assuming CPT: e e
m eV
arXiv:hep-ex/0801.4589
Common fit to KamLAND and solar neutrinos results
Near future (current decade) Near future (current decade) as conclusionsas conclusions
37
We know with good precision the few we knew
e
@ full mixing
large mixing
2 0.21 5 221 0.21
2 2 0.11 3 232 31 0.08
231
2 0.0612 0.05
7.59 10
2.35 10
sin 2 0.91 90% . .
tan 0.47 /
m eV
m m eV
C L
38
e
Absolute mass scale ?
- Sign of Mass hierarchy?
normal
or inverted
- at
component in ?
- ? violation ?
231
1 2 3
3 1,2
213
3
2.3
0, 8 , 50
0, 50
sin 2 0.13 90% . .
e
eff
CP
m eV
m
m m meV m meV
m m meV
C L
CP
- Dirac or Majorana neutrino ?
2 5 2 221 7 10 solm eV m
0
2m
2 0.3 0.35 0.35
3 ? 0.5 0.5
1 0.7 .15.15
2 2 3 231 32
2
2.5 10| | | |
atm
m m eV
m
2 3 232
3 3 -
2.5 10
2.3 : e
m eV
eV H He e
e
Observations made with natural neutrinos sources confirmed with manmade neutrinos sources and measurements improved
A lot that we do not know 10 years later
Oscillation: Why will it be difficult and maybe very difficult ?
13
231
1%
: sin
sgn :
e
e
13
Oscillation at accelerators: appearance in beam in LBL experiments
irreducible contamination in beam
: It all depends how small it is
violation
understandi
CPiCP e
m
231, ,sgn13
ng matter effects in Earth in LBL experiment
Correlations and intrinsic ambiguities between CP m
232
20 -100
,23
First generation of Super-beams:
factor on neutrinos flux
Principle: Near / Far detectors
Considerable improvement on m
sin 2 213 =0.25
sin 2 213 =0.09
sin 2 213 =0.17
2 800
E L
GeV km
○ CP=0▼ CP= ● CP=▲ CP=3/2
231 0m 231 0m
39
T2K (Tokai to Kamioka) experiment
First event in Super-K on 24 February 2010
Sensitivity after 5 years
0.6 295E L GeV km
Oscillation experiments at accelerators Strong correlation13 CP
2.4×
10-3
0.004 – 0.02
NOA experiment at Fermi Lab
far and near detector:
Liquid scintillator tracker/calorimeter
Take profit that and have different
matter effects to explore
Sensitivity after 6 years (3 +
231
2 810
15 220
sgn
E L GeV km
kton kton
m
3 )
Full lines for realistic fluxes
2 -3 231 2.4 10m eV
Strong correlation13 CP
0.005 – 0.013
More? Ask
40
Search for disappearance with detectors "a la CHOOZ"
Near and far detectors to overcome precision on flux knowledge
Limitation: systematic after 4 - 5 years data taking
1- 2%e
Oscillation experiments at reactors
East Reactor
West Reactor
351 m465 m
1115 m998 m
Double-CHOOZ
Twin reactors:
far detector: 2010
near detector: 2011-2012
Sensitivity in 2014:2
13si
8.5
1
1
n 2 0.03@ 90% . .
thG
C L
W
Daya Bay, China
twin reactors of
far detectors: 2011
near detector: 2010-2011
Sensitivity in 2014:2
13sin 2
3 2.9
4
2
0.01@ 9 . .
2
0%
th
C L
GW
41
Direct mass and 0-decay : why will it be very difficult ?
Katrin Tritium experiment - Karlsruhe
Sensitivity: factor improvement factor on
Measure at if
20.2 : 10 100
0 5 0.35
e e
e e
eff eff
eff eff
m eV m
m m eV
Degen
erat
e m
asse
s
2910 y
2510 y0-decay experiments
Inverted hierarchy: resolution
Factor improvement on best resolutions
Normal hierarchy: resolution
Beyond current reach of kn
A dozen projects in years 2011-2020
EXO -
own tech
niques
136
10
20 - 50
1
meV
me
Xe
V
Xenon TPC - aims at resolution10 50 meV
More? Ask
42
Ten years of collaboration with
Before doing physics with the OPERA detector from 2008, we built together the OPERA Target Tracker between 2000 and 2007
Scientific knowledgeWisdomKindnessPerpetual smile
In particular with
43
Scientific knowledgeWisdomKindnessPerpetual smile
Thank you, U
rs
44