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 !! !!