neutrino masses and oscillations neutrino masses and oscillations triumphs and challenges r. d....
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NEUTRINO MASSES AND NEUTRINO MASSES AND OSCILLATIONSOSCILLATIONS
Triumphs and Challenges
R. D. McKeownCaltech
OutlineOutline
• Historical introduction• Neutrino Oscillations
Vacuum OscillationsMatter Oscillations
• Neutrino Masses
• The Near Future
• Outlook
1869
Historical Perspective
UP CHARM TOP
DOWN STRANGE BOTTOM
ELECTRON
e
MUON
TAU
1913
???1 2 3
New “Periodic Table”
Discovery of the Neutrino – 1956
F. Reines, Nobel Lecture, 1995
EarlyHistory
• 1936- discovery of the muon (I. Rabi: Who ordered that ??)
• 1950’s - discovery of ’s at nuclear reactors
• 1958 – B. Pontecorvo proposes neutrino oscillations
• 60’s and 70’s – were studied with accelerator experiments e ≠
"All you have to do is imagine something that does practically nothing. You can use your son-in-law as a prototype."
More Recent History
• 1968 – 1st solar anomaly evidence
• 1980’s – new interest in neutrino masses and oscillations:
’s as dark matter??
• 1980-present: the quest for neutrino oscillations
• 1998 Super-Kamiokande obtains first evidence for neutrino oscillations
Two Generation Model
1.24
(Pe minimum)
Length & Energy Scales
E= 1 GeV, m2=10-3 eV2 , L = 1240 km Super-K!!
1.24
(Pe minimum)
30 kton H20 Cherenkov 11000 20” PMT’s
Super-Kamiokande Results
Neutrino Oscillation Interpretation
K2K, MINOS
> 0.001
Length & Energy Scales
E= 1 GeV, m2=10-3 eV2 , L = 1240 km
E= 1 MeV, m2=10-3 eV2 , L = 1.2 km
Super-K
Chooz,Palo Verde
1.24
(Pe minimum)
Reactor Neutrino Experiments
• e from n-rich fission products• detection via inverse beta decay (e+pe++n)• Measure flux and energy spectrum• Variety of distances L= 10-1000 m
Precise Measurements
Flux and Energy Spectrum ~1-2 %
Early Reactor Oscillation Searches
103
Distance (m)
Enter
• Long Baseline (180 km)• Calibrated source(s)• Large detector (1 kton)• Deep underground (2700 mwe)
Length & Energy Scales
E= 1 GeV, m2=10-3 eV2 , L = 1240 km
E= 1 MeV, m2=10-3 eV2 , L = 1.2 km
E= 1 MeV, m2=10-5 eV2 , L = 125 km
Super-K
Chooz,Palo Verde
1.24
(Pe minimum)
Stat
istic
al e
rror
s on
ly
Designed to test solar neutrino
oscillation parameters
on Earth (!)KamLAND has a much
longer baselinethan previous
(reactor) experiments
Only a few places in the World could hostOnly a few places in the World could hostan experiment like KamLAND…an experiment like KamLAND…
KamLAND usesthe entire Japanese
nuclear powerindustry as a
long baseline source
Kashiwazaki
Takahama
Ohi
Narrow base
line
Narrow base
line
range:
range:
85.3% of signal h
as
85.3% of signal h
as
140 km < L <
344
140 km < L <
344
kmkmThe total electric power produced “as a The total electric power produced “as a by-product” of the by-product” of the ’s is:’s is:
•~60 GW or...~60 GW or...•~4% of the world’s manmade power or…~4% of the world’s manmade power or…•~20% of the world’s nuclear power~20% of the world’s nuclear power
Spectrum Distortion
KamLAND Detector
1879
1000 Ton
(Cosmic veto)
(135 m)
- R- Rprompt, delayedprompt, delayed < 5.5 m < 5.5 m
- - ΔΔRRe-ne-n < 2 m < 2 m
- 0.5 - 0.5 μμs < s < ΔΔTTe-ne-n < 1 ms < 1 ms
- 1.8 MeV < E1.8 MeV < Edelayeddelayed < 2.6 MeV < 2.6 MeV
- 2.6 MeV < E2.6 MeV < Epromptprompt < 8.5 MeV < 8.5 MeV
Tagging efficiency 89.8%Tagging efficiency 89.8%
… …In addition:In addition:
- 2s veto for showering/bad 2s veto for showering/bad μμ
- 2s veto in a R = 3m tube along track2s veto in a R = 3m tube along track
Dead-time 9.7%Dead-time 9.7%
Selecting antineutrinos, ESelecting antineutrinos, Epromptprompt>2.6MeV>2.6MeV
(543.7 ton)(543.7 ton)
5.5 m5.5 mfiducial cutfiducial cut
Balloon edgeBalloon edge
Ratio of Measured and Expected e Flux from Reactor Neutrino Experiments
Solar : m2 = 5.5x10-5 eV2
sin2 2 = 0.833
G.Fogli et al., PR D66, 010001-406,(2002)
Measurement of Energy Spectrum
Oscillation Effect
KamLAND best fit : m2 = 7.9 x 10-5 eV2
tan2= 0.45
Solar Neutrino Energy Spectrum
More missing neutrinos…
Neutrino Oscillations?
Rorbit
“Just So ??? “
Length & Energy Scales
E= 1 GeV, m2=10-3 eV2 , L = 1240 km
E= 1 MeV, m2=10-3 eV2 , L = 1.2 km
E= 1 MeV, m2=10-5 eV2 , L = 125 km
Super-K
Chooz,Palo Verde
1.24
(Pe minimum)
E= 1 MeV, m2=10-11 eV2 , L = 108 km
Matter Enhanced Oscillation (MSW)Mikheyev, Smirnov, Wolfenstein
Enter SNO…e + d p + p + e- ( CC )
x + d p + n + x ( NC )x + e- x + e- ( ES )
• Neutrino Mixing• Neutrino Masses• Flavor Oscillations
+
Combined fit with solar neutrino data
m2=7.9+0.6-0.5x10-5 eV2
tan2=0.40+0.10-0.07
Open circles: combined best fitClosed circles: experimental data
RECENT NEWSMiniBOONE refutes LSND!
LSND ruled out at 98% confidence
Maki – Nakagawa – Sakata Matrix
Future ReactorExperiment!
CP violation
Why so different???Why so different???
<
New “Periodic Table”
L R mD
mD M
LR
m mD
2
MmD
“Seesaw mechanism”
M
The Mass PuzzleThe Mass Puzzle
Why haven’t we seen R?Extra Dimension
• All charged particles are on a 3-brane• Right-handed neutrinos SM gauge singlet
Can propagate in the “bulk”• Makes neutrino mass small
(Arkani-Hamed, Dimopoulos, Dvali, March-Russell;Dienes, Dudas, Gherghetta)
• Barbieri-Strumia: SN1987A constraint“Warped” extra dimension (Grossman, Neubert)
or more than one extra dimensions• Or SUSY breaking
(Arkani-Hamed, Hall, HM, Smith, Weiner;
Arkani-Hamed, Kaplan, HM, Nomura) (From H.Murayama)
• Baseline ~2km
• More powerful reactors
• Multiple detectors → measure ratio
The Quest for 13
at the Daya Bay
Nuclear Power Plant
• 4 reactor cores, 11.6 GW
• 2 more cores in 2011, 5.8 GW
• Mountains provide overburden to shield cosmic-ray backgrounds
Daya Bay nuclear power plant
DYB NPP region
Location and surroundings
55 km
Experiment Layout
Detector modules
• Three zone modular structure: I. target: Gd-loaded scintillator
II. g-catcher: normal scintillator
III. Buffer shielding: oil
• Reflector at top and bottom• 192 8”PMT/module• Photocathode coverage: 5.6 % 12%(with reflector)
20 t Gd-LS
LSoil
Target: 20 t, 1.6mg-catcher: 20t, 45cmBuffer: 40t, 45cm
Sensitivity to Sin22q13
• Experiment construction: 2008-2010• Start acquiring data: 2010• 3 years running
90% CL, 3 years
Goals for the future
• Establish 13 non-zero
• Measure CP violation
• Determine mass hierarchy
Also: Majorana or Dirac Sterile species?
e Appearance
CP violation
matter
T2K- From Tokai To Kamioka
Mass hierarchy (+/-)
L = 810 km
NOA - New Fermilab Proposal
Parameters Consistent with a1% and 4% e oscillation probability
NOA(5 yr )
Daya Bay
CP
normal
inverted
Daya Bay will complement NOA
FNALto Homestake
Neutrino Factory -- CERN layout
e+ e
_
interacts
giving
oscillates e
interacts giving
WRONG SIGN MUON
1016p/s
1.2 1014 s =1.2 1021 yr
3 1020 eyr
3 1020 yr
0.9 1021 yr
Beta Beams
Other Future StudiesOther Future Studies
• Double beta decay (m<0.1 eV)(Majorana only!)
• Direct measurements (m< 1 eV) (KATRIN)
• Cosmological Input (m<0.2 eV) (Planck satellite)
My prediction:My prediction:We will measure:
• neutrino mass hierarchy
• CP violation in mixing
And know the role of ’s in• particle physics
• cosmology
All in time for Keh-Fei’s 70All in time for Keh-Fei’s 70thth !! !!