Transcript Neutrino Mass and Mixing - Home | Boston University Physics

Neutrino Mass and
Mixing
David Sinclair
Carleton University
PIC2004
Outline
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History of neutrino mass and mixing
Recent results and current status
Future Prospects
History
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Original proposal by Pauli, Fermi
– Neutrino mass must be small
– Only 1 neutrino proposed so no mixing
Mass Measurements
b Decay
Mn=0
Mn>0
Electron Energy
Neutrino Mass from Tritium Decay
Neutrino Mixing
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Pontecorvo suggested (late 50’s) that
neutrinos would oscillate by analogy
with K0
When Davis showed deficit of solar
neutrinos, oscillation again raised as a
possible solution
This solution not popular until MSW
Neutrino Vacuum
Oscillation
Pe  1  sin 2 sin (m L / 4E)
2
2
2
MSW Effect
ne
Mass
nm
Electron Density
Implications of neutrino
oscillations
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ne, nm, nt are not mass eigenstates
Mass states are n1, n2, and n3
Lepton number not conserved
Theoretical Biases
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Mixings would be small
(comparable to Cabibbo mixing)
SeeSaw model suggests
Mn   Mq
2
Using the oscillation framework:
If neutrinos have mass:
n l  Uli n i
For three neutrinos:
 U e1 U e 2 U e3 
Maki-Nakagawa-Sakata-Pontecorvo matrix


U li  U μ1 U μ 2 U μ 3 
U

(Double b Decay)
 τ1 U τ 2 U τ 3 
0
0  1 0
0   c13 0 s13   1
0
0 
 c12 s12 0   1

 
 
 
 

i 2 / 2
   s12 c12 0    0 c23 s23    0 1
0  0
1 0 0 e
0 
 0
0 1   0  s23 c23   0 0 e  iδ    s13 0 c13   0
0
ei 3 / 2i 

Solar
Atmospheric
CP Violating Phase
Reactor...
where cij  cos  ij , and sij  sin  ij
Full neutrino mixing matrix
Majorana Phases
Recent Results
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Neutrino mass from cosmology
WMAP, 2DF
m1+m2+m3< 1 eV
Evidence for Neutrino
Oscillation - Atmospheric
Definitive Data from SK
Evidence for Oscillations
Solar
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Chlorine experiment sees ¼ SSM flux
Gallium experiments see ½ SSM flux
Kamiokande sees ½ SSM flux
Definitive data - SNO
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Heavy water Cerenkov detector
Measure ne flux with CC reaction
Measure total n flux with NC reaction
CC
NC
SNO
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1000 Tonnes of D2O
12 M Acrylic vessel
10,000 phototubes
8000 Tonnes of pure light
water
2000 m deep in Mine
World’s largest deep
cavern
All materials very pure
3 Phases of SNO
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1) Run with pure Heavy Water
2) Add 0.2% NaCl to enhance NC
detection
3) Remove NaCl, add Neutral Current
Detectors (NCDs)
Each phase is approx. 2 years
Salt – Pure D2O
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Constrained
Not Constrained
Pure D2O
Salt
Neutrino parameters from
Solar experiments (ne)
Evidence for Oscillation
Reactor Neutrinos
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Short distance searches (CHOOZ, Palo
Verde etc) have been negative
Kamland provides definitive
demonstration
Where are we
5
m  8.2  0.6  10 eV
2
12
Sin 212  0.82  0.05
2
3
m  2.1 10 eV
2
23
Sin 2 23  1.02
2
Sin 213  .36
2
2
2
Neutrino-less double beta
decay
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Nice data on 2 neutrino decay from
NEMO
Nice cryogenic techniques
Tantalizing results from Germanium
Mass of Neutrinos
Normal
Inverted
Double-beta effective mass constrained by oscillation data
NEMO
Xavier Sarazin for the NEMO-3 Collaboration
Neutrino 2004 Paris 14-19 June 2004
bb decay isotopes in NEMO-3 detector
bb2n measurement
116Cd
405 g
Qbb = 2805 keV
96Zr
9.4 g
Qbb = 3350 keV
150Nd
37.0 g
Qbb = 3367 keV
48Ca
7.0 g
Qbb = 4272 keV
130Te
454 g
Qbb = 2529 keV
100Mo
6.914 kg
Qbb = 3034 keV
82Se
Qbb = 2995 keV
bb0n search
Xavier Sarazin for the NEMO-3 Collaboration
0.932 kg
natTe
491 g
Cu
621 g
External bkg
measurement
(All the enriched isotopes produced in Russia)
Neutrino 2004 Paris 14-19 June 2004
2b2n preliminary results for other nuclei
NEMO-3
82Se
932 g
241.5 days
2385 events
S/B = 3.3
• Data
bb2n
simulation
Background subtracted
82Se
116Cd
T1/2 = 10.3  0.2 (stat)  1.0 (syst)  1019 y
if SSD T1/2 = 2.8  0.1 (stat)  0.3 (syst)  1019 y
if HSD T1/2 = 3.05  0.1 (stat)  0.3 (syst)  1019 y
150Nd
T1/2 = 9.7  0.7 (stat)  1.0 (syst)  1018 y
96Zr
T1/2 = 2.0  0.3 (stat)  0.2 (syst)  1019 y
E1+E2 (keV)
NEMO-3
116Cd
405 g
168.4 days
1371 events
S/B = 7.5
NEMO-3
150Nd
37 g
168.4 days
449 events
S/B = 2.8
NEMO-3
96Zr
5.3 g
168.4 days
72 events
S/B = 0.9
Data
Data
Data
bb2n
simulation
bb2n
simulation
bb2n
simulation
E1+E2 (MeV)
Xavier Sarazin for the NEMO-3 Collaboration
E1+E2 (MeV)
E1+E2 (MeV)
Neutrino 2004 Paris 14-19 June 2004
Experimental approach - CUORE
Thermal detectors
heat bath
Source = detector
(calorimetric)
e-
Thermal sensor
absorber
crystal
e-
Incident
particle
Resolution of the 5x5x5 cm3 (~
760 g ) crystals
:
@ 46 keV
@ 0.351 MeV
@ 0.911 MeV
@ 2.615 MeV
@ 5.407 MeV
210Po
 line
Counts
0.8 keV FWHM
1.4 keV FWHM
2.1 keV FWHM
2.6 keV FWHM
3.2 keV FWHM
(the best  spectrometer ever
realized)
Energy [keV]
The Future
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Determine 13
– New Reactor experiments
– Long baseline
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Are masses Majorana or Dirac
– Double beta decay
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Is CP violated
– Superbeams
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Sterile neutrinos?
– Miniboone
The Future Looks Very
Exciting
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Many new experiments taking data or
about to start
Precision measurements of MNSP
matrix
Look for CP violation
Neutrino astrophysics