Transcript NEUTRINO MASSES AND OSCILLATIONS Triumphs and Challenges

NEUTRINO MASSES AND
OSCILLATIONS
Triumphs and Challenges
R. D. McKeown
Caltech
Outline
•
•
Historical introduction
Neutrino Oscillations
Vacuum Oscillations
Matter Oscillations
• Neutrino Masses
• The Near Future
• Outlook
Historical Perspective
1913
1869
UP
CHARM
TOP
DOWN
STRANGE
BOTTOM
ELECTRON
MUON
TAU
nne 1
nnm2
nn3t
???
New “Periodic Table”
Discovery of the Neutrino – 1956
F. Reines, Nobel Lecture, 1995
Early
History
• 1936- discovery of the muon
(I. Rabi: Who ordered that ??)
• 1950’s - discovery of n’s at nuclear
reactors
• 1958 – B. Pontecorvo proposes neutrino
oscillations
• 60’s and 70’s – n were studied with
accelerator experiments ne ≠ nm
"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 n anomaly evidence
•
1980’s – new interest in neutrino masses and
oscillations:
n’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 g
minimum)
Length & Energy Scales
1.24
(Pe gminimum)
En= 1 GeV, Dm2=10-3 eV2 , L = 1240 km
Super-K!!
30 kton H20 Cherenkov
11000 20” PMT’s
Super-Kamiokande Results
Neutrino Oscillation
Interpretation
Wn > 0.001
g K2K, MINOS
Length & Energy Scales
1.24
(Pe gminimum)
En= 1 GeV, Dm2=10-3 eV2 , L = 1240 km
Super-K
En= 1 MeV, Dm2=10-3 eV2 , L = 1.2 km
Chooz,
Palo Verde
Reactor Neutrino Experiments
• ne from n-rich fission products
• detection via inverse beta decay (ne+pge++n)
• Measure flux and energy spectrum
• Variety of distances L= 10-1000 m
Precise Measurements
Flux and Energy Spectrum g
~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
1.24
(Pe gminimum)
En= 1 GeV, Dm2=10-3 eV2 , L = 1240 km
Super-K
En= 1 MeV, Dm2=10-3 eV2 , L = 1.2 km
Chooz,
Palo Verde
En= 1 MeV, Dm2=10-5 eV2 , L = 125 km
Designed to
test solar neutrino
oscillation parameters
on Earth (!)
KamLAND has a much
longer baseline
than previous
(reactor) experiments
Only a few places in the World could host
an experiment like KamLAND…
Kashiwazaki
Takahama
Ohi
KamLAND uses
the entire Japanese
nuclear power
industry as a
longbaseline source
The total electric power produced “as a
by-product” of the n’s is:
•~60 GW or...
•~4% of the world’s manmade power or…
•~20% of the world’s nuclear power
Spectrum Distortion
KamLAND Detector
1000 Ton
(135 mm)
1879
(Cosmic veto)
Selecting antineutrinos, Eprompt>2.6MeV
- Rprompt, delayed < 5.5 m (543.7 ton)
- ΔRe-n < 2 m
5.5 m
fiducial cut
- 0.5 μs < ΔTe-n < 1 ms
- 1.8 MeV < Edelayed < 2.6 MeV
- 2.6 MeV < Eprompt < 8.5 MeV
Tagging efficiency 89.8%
…In addition:
- 2s veto for showering/bad μ
- 2s veto in a R = 3m tube along track
Dead-time 9.7%
Balloon edge
Ratio of Measured and Expected ne Flux
from Reactor Neutrino Experiments
Solar n:
Dm2 = 5.5x10-5 eV2
sin2 2Q = 0.833
G.Fogli et al., PR
D66, 010001-406,
(2002)
Measurement of Energy Spectrum
Oscillation Effect
KamLAND best fit :
Dm2 = 7.9 x 10-5 eV2
tan2q = 0.45
Solar Neutrino Energy Spectrum
More missing neutrinos…
Neutrino Oscillations?
Rorbit
“Just So ??? “
Length & Energy Scales
1.24
(Pe gminimum)
En= 1 GeV, Dm2=10-3 eV2 , L = 1240 km
Super-K
En= 1 MeV, Dm2=10-3 eV2 , L = 1.2 km
Chooz,
Palo Verde
En= 1 MeV, Dm2=10-5 eV2 , L = 125 km
En= 1 MeV, Dm2=10-11 eV2 , L = 108 km
Matter Enhanced Oscillation (MSW)
Mikheyev, Smirnov, Wolfenstein
n2
n1
Enter SNO…
ne + d g p + p + e- ( CC )
nx + d g p + n + nx ( NC )
nx + e- g nx + e- ( ES )
+
• Neutrino Mixing
• Neutrino Masses
• Flavor Oscillations
Combined fit with solar
neutrino data
Dm2=7.9+0.6-0.5x10-5 eV2
tan2q=0.40+0.10-0.07
Open circles: combined best fit
Closed circles: experimental data
RECENT NEWS
MiniBOONE refutes LSND!
LSND ruled out
at 98% confidence
Maki – Nakagawa – Sakata Matrix
Future Reactor
Experiment!
CP violation
<
Why so different???
New “Periodic Table”
The Mass Puzzle
“Seesaw mechanism”
n L

n R 
 mD
mD   n L 
 
M  n R
mD2
mn 
 mD
M
M
Why haven’t we seen nR?
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)
The Quest for q13
at the
Daya Bay
Nuclear Power Plant
• Baseline ~2km
• More powerful reactors
• Multiple detectors → measure ratio
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
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
20 t
Gd-LS
• Reflector at top and bottom
• 192 8”PMT/module
• Photocathode coverage:
5.6 %  12%(with reflector)
Target: 20 t, 1.6m
g-catcher: 20t, 45cm
Buffer: 40t, 45cm
LS
oil
Sensitivity to Sin22q13
90% CL, 3 years
• Experiment construction: 2008-2010
• Start acquiring data: 2010
• 3 years running
Goals for the future
• Establish q13 non-zero
• Measure CP violation
• Determine mass hierarchy
Also: Majorana or Dirac
Sterile species?
ne Appearance
T2K- From Tokai To
Kamioka
Mass hierarchy (+/-)
CP violation
matter
NOnA - New Fermilab Proposal
L = 810 km
Parameters Consistent with a
1% and 4% nmne oscillation probability
Daya Bay will complement NOnA
normal
Daya Bay
inverted d
CP
NOnA
(5 yr n)
FNALto Homestake
Neutrino Factory -- CERN layout
1016p/
s
1.2 1014 m/s =1.2 1021 m/yr
0.9 1021 m/yr
3 1020 ne/yr
3 1020 nm/yr
m+  e+ ne
oscillates ne 
_
nm
nm
interacts giving mWRONG SIGN MUON
interacts
giving m+
Beta Beams
Other 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:
We will measure:
• neutrino
• CP
mass hierarchy
violation in n mixing
And know the role of n’s in
• particle physics
• cosmology
All in time for Keh-Fei’s 70th !!