Neutrino Physics Caren Hagner Universität Hamburg Caren Hagner Universität Hamburg Part 3:...
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Transcript of Neutrino Physics Caren Hagner Universität Hamburg Caren Hagner Universität Hamburg Part 3:...
Neutrino PhysicsNeutrino PhysicsCaren Hagner
Universität Hamburg
Caren Hagner
Universität Hamburg
Part 3: Absolute neutrino mass Introduction beta decay double beta decay
Part 3: Absolute neutrino mass Introduction beta decay double beta decay
Evidence for Neutrino Oscillations:Evidence for Neutrino Oscillations:
Neutrino oscillations were observed in 2 regions:
• Solar neutrinos and reactor neutrinosve → vμ,τ with Δm2 ≈ 8·10-5 eV2, large mixing
• Atmospheric neutrinos and accelerator neutrinosvμ → vτ,(s) mit Δm2 ≈ 2·10-3 eV2, maximal mixing
• LSND? Anti-vμ → Anti-ve with Δm2 ≈ 1 eV2
(Tested by MiniBooNE)
Neutrino oscillations were observed in 2 regions:
• Solar neutrinos and reactor neutrinosve → vμ,τ with Δm2 ≈ 8·10-5 eV2, large mixing
• Atmospheric neutrinos and accelerator neutrinosvμ → vτ,(s) mit Δm2 ≈ 2·10-3 eV2, maximal mixing
• LSND? Anti-vμ → Anti-ve with Δm2 ≈ 1 eV2
(Tested by MiniBooNE)
Neutrinos have mass! mlightest v ?
(3)(3)
Nature of Neutrino Mass I
Neutrino fields v(x) with mass m are described by the Dirac equation: 0)()( xvmi
The left-handed and right-handed components are:
)(2
1)( 5 xvxvL
)(
2
1)( 5 xvxvR
This leads to a system of two coupled equations:
0 RL mvvi 0 LR mvvi
With m=0 one obtains the decoupled Weyl equations: 0, RLvi
From Goldhaber experiment one knows that vL is realized.With m=0 there is no need to have vR. Therefore there were no vR in the Standard Model.
4 component spinor
2 components each
Dirac mass term..chvvmL LRD
Dirac Mass Term
The neutrino mass term in L could have exactly the same formas the mass term of the quarks and charged leptons:
LvRvm
Must add vR (right handed SU(2) singlets) to standard model!Problem: When the mechanism is the same, why are the masses so small?
mt = 174.3 ± 5.1 GeV; mb = (4.0-4.5) GeV;mτ = 1776.99 ± 0.29 MeV; m3 < 2eV
Lepton number is conserved!
Footnote: A Lorentz invariant mass term must link a chirally left-handed field with a chirally right handed field
Majorana ParticlesBecause neutrinos carry no electric charge(and no color charge), there is the possibility: particle ≡ anti-particle
Majorana particle
particleanti-particle (charge conjugate field):
Tc C M
cM for a Majorana particle:
But what about experiments?
Anti-neutrinos(reactor):
Neutrinos (solar):
-3737 eArCl ev-3737 eArCl ev
observed!
not observed!
There are two different states per flavorbut the difference could be due to left-handed and right-handed states!
-3737 eArCl eRv
-3737 eArCl eLv
Majorana Mass Term
Lcc
R vv )()( Note that
is a left-handed field
Rcc
L vv )()( and is a right-handed field
Footnote: A Lorentz invariant mass term must link a chirally left-handed field with a chirally right handed field
cLLLc
LL
M vvvvm
LL
)()(2
Let’s try
vL
left handed field
(vL)c
right handed field
mL
ok!
cRRRc
RR
M vvvvm
LR
)()(2
works too!
Lepton number violation!
cLLLc
LL
M vvvvm
LL
)()(2
cRRRc
RR
M vvvvm
LR
)()(2
112 LM mLL
222 RM mLR
cLL vv )(1 c
RR vv )(2 Construct the Majorana fields:
c)( 2,12,1
Eigenstates of the interaction: vL and vRMass eigenstates: Φ1 (mass mL), Φ2 (mass mR)
Dirac-Majorana Mass Term
h.c. )(
)(,2
R
cL
RD
DLcRLDM
v
v
mm
mmvvL
mass matrix M
mass term for each flavor:
In order to obtain the mass eigenstates one must diagonalize M:
2
1
0
0~m
mMUUMfind unitary U
with
cossin
sincosU with
LR
D
mm
m
22tan
with the mass eigenstates:
c
R
L
L
L
v
vU
v
v
)(2
1
and mass eigenvalues:
222,1 4)()(
2
1DRLLR mmmmmm
What if…1. mL = mR = 0: pure Dirac case θ = 45, m1=m2=mD. 2 degenerate Majorana states can be combined to form 1 Dirac state.
2. mD = 0: pure Majorana case θ = 0, m1=mL m2=mR
3. mR≫ mD, mL= 0: seesaw model θ = mD/mR≪ 1
,2
1R
D
m
mm Rmm 2
per neutrino flavor: one very light Majorana neutrino v1L = vL
one very heavy Majorana neutrino v2L = (vR)cmD of the order of lepton masses, mR reflects scale of new physics⇒ explains small neutrino masses!
mR
mD
Lower Limit of Neutrino MassLower Limit of Neutrino Mass
Super-K (atmospheric neutrinos): m2
atm = 2.5 × 10-3 eV2
m(νi) ≥ 0.05 eV
Super-K (atmospheric neutrinos): m2
atm = 2.5 × 10-3 eV2
m(νi) ≥ 0.05 eV
This sets the energy scalefor mass search!
This sets the energy scalefor mass search!
Which mass hierarchy?
v1
v2Δmsolar
v3
Δmat
m
inverted hierarchy
v3
v1
v2Δmsolar
Δmat
m
normal hierarchy
0.05 eV
- Lightest neutrino mass not known
- Δm2atm < 0 or >0 ?
?0
v3v1 v2
≲ 2 eV
quasi-degenerate
0
Neutrino Mass Measurements Strategies
cosmology &structure formation
D.N. Spergel et al: m < 0.69 eV (95%CL)S.W. Allen et al: m = 0.56 eV (best fit)
0 decay:
NEMO3
76Ge @ LNGS ´90-´03(71.7 kg×y)
|mee|=0.44+0.13-0.2 eV
2
SuperK, SNO, OMNIS + grav.waves: potential for ~1eV sensitivity?
astrophysics: supernova time of flight measurements
?3H
187Re
β decay kinematics:- Microcalorimeters- MAC-E spectrometers
<m>e < 2eV
β-decay
udd
udu
n p
W-
e-
ve
q = 2/3 - 1/3 -1/3 = 0
q = 2/3 + 2/3 -1/3 = 1
evepn
eve )1ZA,()ZA,(
Total kinetic energy Q≈ maximal kinetic energy of electron
Tritium β-Decay: Mainz/TroitskTritium β-Decay: Mainz/Troitsk
e -33 eHe H e -33 eHe H
222i
iei mUm
E0 = 18.6 keV
dN/dE = K × F(E,Z) × p × Etot × (E0-Ee) × [ (E0-Ee)2 – m2 ]1/2
Problem: All experiments measured negative Δm2!
Only recently solved by electrostatic spectrometers with electrostatic spectrometers with MAC-E filter MAC-E filter
principle of an electrostatic filter withprinciple of an electrostatic filter withmagnetic adiabatic collimation (MAC-E)magnetic adiabatic collimation (MAC-E)
adiabatic magnetic guiding of ´s along field lines in stray B-field of s.c. solenoids:Bmax = 6 TBmin = 3×10-4 T
energy analysis bystatic retarding E-fieldwith varying strength:
high pass filter withintegral transmissionfor E>qU
results from the MAINZ experimentresults from the MAINZ experiment
CL%95eV2.2eV1.22.22.1 22
mm
Mainz Data (1998,1999,2001)
KATRIN Main Spectrometer stainless steel vessel (Ø=10m & l=22m) on HV potential minimisation of bg UHV: p ≤ 10-11 mbar
„massless“ inner electrode system
UHV requirements:outgassing < 10-13 mbar l/sinner surface ~ 800m2
volume to pump ~ 1500m3
Ziel:eV20.0
m
Commissioning 2008
187187Re Re -decay: -decay: -calorimeters-calorimeters
MIBETA experiment(Milano, Como, Trento)array of 10 AgReO4 crystals
M.Sisti et al, NIM A520(2004)125A.Nucciotti et al, NIM A520(2004)148C. Arnaboldi et al, PRL 91, 16802 (2003)
E0 = 2.46 keV
Top ~ 70-100mK
free fit parameters:
endpoint energy
m2
spectrum normal.
pile-up amplitude
background level
187187Re Re decay decay -calorimeters -calorimeters Kurie plot of 6.2 ×106 187Re decay events above 700 eV
fit range: 0.9 to 4 keV
fit function
m2 = -112 ± 207 ± 90 eV2
m < 15 eV (90%CL) (2 eV in 2007?)
dN/dE = K × F(E,Z) × p × Etot × (E0-Ee) × [ (E0-Ee)2 – m2 ]1/2
Double-beta decayDouble-beta decay2 - decay
u e -
d
d
e -W
u
e
eW
0 - decay
e -
e -
d
du
u
W
We e
Lepton number violationΔL = 2
Lepton number violationΔL = 2
Summenenergie der Elektronen (E/Q)
Neutrinoless Double Beta DecayNeutrinoless Double Beta Decay
d
d
u
u
e
eW
W
n
n
p
p
v = v
0v Double Beta Decay:
(A,Z) (A,Z+2) + 2e- neutrino anti-neutrinoneutrino anti-neutrino
Majorana-neutrino:Majorana-neutrino:
only forMajorana-neutrino
andmV > 0!
Neutrinoless Double Beta DecayNeutrinoless Double Beta Decay
3
1
2
ieiiUmm
Effective neutrino mass in 0νββ-decay:
22
02
20
0010
2/1 ),(][
vF
A
VGT mM
g
gMZEGT
222 i
eii Umm
Compare to β-decay:
Phase space factor Transition matrix
element
Effective neutrino mass
3
2
1
132313231223121323122312
132313231223121323122312
1313121312
21
21
21
][
][
iiii
iiii
iiie
ecceescsscesccss
ecseesssccessccs
eesecscc
Dirac CP-PhaseDirac CP-Phase
Majorana CP-PhasesMajorana CP-Phases
Complex phases in the mixing matrixComplex phases in the mixing matrix
21 233
222
211
3
1
2
ie
iee
ieii eUmeUmUmUmm
Cancellation possible!
0v Doppel-Beta Experimente: Ergebnisse0v Doppel-Beta Experimente: Ergebnisse
CL) (90% eV 35.0
mHeidelberg-Moskau Collaboration, Eur.Phys.J. A12 (2001) 147
IGEX Collaboration, hep-ex/0202026, Phys. Rev. C59 (1999) 2108
2.1 × 1023 0.85 – 2.1
all 90%CLall 90%CL
HM-K
IGEX
Jedoch: ein Teil der HdM Kollaboration veröffentlicht Evidenz für 0v Doppel-Beta Zerfall!
Jedoch: ein Teil der HdM Kollaboration veröffentlicht Evidenz für 0v Doppel-Beta Zerfall!
(Q = 2039 keV für 76Ge Doppel-Beta Zerfall)
?
Zukunft: Heidelberg Ge Initiative (MPIK Heidelberg)Zukunft: Heidelberg Ge Initiative (MPIK Heidelberg)
Phase I: 20kg angereichertes (86%) 76Ge, vgl. HDMPhase II: 100 kgJahre, 0.1 – 0.3 eVPhase III: O(1t) angereichertes 76Ge, 10meV
Phase I: 20kg angereichertes (86%) 76Ge, vgl. HDMPhase II: 100 kgJahre, 0.1 – 0.3 eVPhase III: O(1t) angereichertes 76Ge, 10meV
CUORICINOCUORICINO
11 modules, 4 detector each,crystal dimension 5x5x5 cm3
crystal mass 790 g
4 x 11 x 0.79 = 34.76 kg of TeO2
2 modules, 9 detector each,crystal dimension 3x3x6 cm3
crystal mass 330 g
9 x 2 x 0.33 = 5.94 kg of TeO2
2v Doppelbeta mit 130Te (Q=2529 keV)
18 crystals 3x3x6 cm3 + 44 crystals 5x5x5 cm340.7 kg of TeO2
Start in 2003
Suche nach 0v Doppelbeta:T 1/2 0v (130Te) > 7.5 x 1023 y <mv> < 0.3 - 1. 6 eV
2v Doppelbeta mit 130Te (Q=2529 keV)
18 crystals 3x3x6 cm3 + 44 crystals 5x5x5 cm340.7 kg of TeO2
Start in 2003
Suche nach 0v Doppelbeta:T 1/2 0v (130Te) > 7.5 x 1023 y <mv> < 0.3 - 1. 6 eV
array of 988 bolometersgrouped in 19 colums with 13 flours of 4 crystals
750 kg TeO2
=> 600 kg Te
= 203 kg 130Te
IL PROGETTO CUOREIL PROGETTO CUORE
3 m
4 m
B (25 G)
20 sectorsSource: 10 kg of isotopes cylindrical, S = 20 m2, e ~ 60 mg/cm2
Tracking detector: drift wire chamber operating in Geiger mode (6180 cells)Gas: He + 4% ethyl alcohol + 1% Ar + 0.1% H2O
Calorimeter: 1940 plastic scintillators coupled to low radioactivity PMTs
Magnetic field: 25 GaussGamma shield: Pure Iron (e = 18 cm)Neutron shield: 30 cm water (ext. wall)
40 cm wood (top and bottom) (since march 2004: water boron)
Able to identify e, e, and
The NEMO3 detector Fréjus Underground Laboratory : 4800 m.w.e.
Drift distance
100Mo foil100Mo foil
Transverse view Longitudinal view
Run Number: 2040Event Number: 9732Date: 2003-03-20
Geiger plasmalongitudinalpropagation
Scintillator + PMT
Deposited energy: E1+E2= 2088 keVInternal hypothesis: (t)mes –(t)theo = 0.22 nsCommon vertex: (vertex) = 2.1 mm
Vertexemission
(vertex)// = 5.7 mm
Vertexemission
Transverse view Longitudinal view
Run Number: 2040Event Number: 9732Date: 2003-03-20
Criteria to select events:• 2 tracks with charge < 0• 2 PMT, each > 200 keV• PMT-Track association • Common vertex
• Internal hypothesis (external event rejection)• No other isolated PMT ( rejection)• No delayed track (214Bi rejection)
events selection in NEMO-3
Typical 2 event observed from 100Mo
100Mo 6.914 kg Q= 3034 keV
decay isotopes in NEMO-3 detector
82Se 0.932 kg Q= 2995 keV
116Cd 405 g Q= 2805 keV
96Zr 9.4 g Q= 3350 keV
150Nd 37.0 g Q= 3367 keV
Cu 621 g
48Ca 7.0 g Q= 4272 keV
natTe 491 g
130Te 454 g Q= 2529 keV
measurement
External bkg measurement
search (All the enriched isotopes produced in Russia)
100Mo likelihood analysis
Ec1+Ec2 (keV)
Data
Monte-Carlo
RadonMonte-Carlo
100Mo 6914 g
216.4 days4.10 kg.y
PRELIMINARY
Xavier Sarazin for the NEMO-3 Collaboration Neutrino 2004 Paris 14-19 June 2004
DataMonte-CarloRadonMonte-CarloT1/2 = 3.5 1023
100Mo 6914 g
216.4 days4.10 kg.y
Ec1+Ec2 (keV)
Previous limit V-A: T1/2() > 5.5 1022 y (Elegant V, Ejiri et al., 2001)
V-A: T1/2() > 3.5 1023 y (90% C.L.)
-Log
(Lik
elih
ood)
x NNtot
<mv>ee < 0.7 – 1.2 eV