Solar Neutrinos & Homestake or Something new under the Sun

Solar Neutrinos & Homestakeor

Something new under the Sun

Kevin T. Lesko

Lawrence Berkeley National Laboratory

Berkeley, CA

20 January 2004 Kevin Lesko2

Why are Solar Neutrinos in the News?

• Discoveries about neutrinos• Key, Critical Piece of the Universe we

understand very little about• Neutrinos have Mass (as much all the stars)• Mix between different species (neutrinos

are complicated)• 30 year old problem (missing neutrinos)

solved!


• “…to see into the interior of a star and thus verify directly the hypothesis of nuclear energy generation in stars.”Phys. Rev. Lett. 12, 300 (1964); Phys. Rev. Lett. 12, 303 (1964)

Bahcall and Davis

4p --> 4He + 2e + 2e+

+ ~25 MeV

p + e- + p 2H + e

2H + p 3He +

3He + 4He 7Be +

7Be + e- 7Li + e

7Li + p 4He + 4He

7Be + p 8B + 8B 8Be* + e+ + e

8Be* 4He + 4He3He + p 4He + e+ + e

3He + 3He 4He + 2p

p + p 2H + e+ + e

85% 15%

0.02%

p-p Chain

Solar Neutrinos


Solar Neutrino Experiments (pre-SNO)Experiment Depth

(m.w.e.)Target Reaction Threshold

(MeV)Homestake 4900 615 tons of C2Cl4 e+

37Cl 37Ar+e 0.814SAGE 4700 60 tons metallic Ga e+

71Ga 71Ge+e 0.233Gallex + GNO 3300 30.3 tons GaCl3-HCl e+

71Ga 71Ge+e 0.233Kamiokande 2700 3 kt H2O

680 t fiducial volumee+ee +e 7.5

Super-Kamiokande

2700 55 kt H2O22.5 kt fiducial volume

e+ee +e 5.5

Homestake (S Dakota, USA)

Super-Kamiokande (Japan)

SAGE (Baksan, Russia)

GALLEX (Gran Sasso, Italy)

Only e directly observed


The Solar Neutrino Problem

• Subsequent 35 years have seen 5 experiments, all measure a deficiency of solar neutrinos

Either

Solar Models are Incomplete or

Incorrect

Or

Neutrinos Undergo Flavor Changing

Oscillations


Example of Two Flavor Oscillations

1.0

0.8

0.6

0.4

0.2

0.0

Pro

babilt

y

76543210

x/osc

e

In the example here, sin2 is 0.7. One can solve for values of and m2 which produce fluxes consistent with measured fluxes on Earth.

In general, oscillations could explain the missing s

The Sudbury Neutrino Observatory

• Charged Currente+de-+p+p just one flavor of

• Elastic Scattering

x+e-x+e-

• Neutral Current x+dx+n+p

All flavors of

Large

Deep

Clean

Sensitive


Neutrino Appearance Experiment!

SSM: BPBAstrophy J 555, 990 2001

e (106 cm-2 s-1)

(

106 c

m-2 s

-1)

SSM

NC

SNO

NC

SNO

CC

SNO

ES


What does this mean?

• Neutrinos are massive, solved SNP• Confirmed Solar Model• Neutrinos mix

– But not like quarks

– Strong Evidence for MSW effects

• Found some of the dark matter– As much mass as all luminous matter

• New physics– Neutrinos are a new physics frontier

– SNO + KamLAND are a beachheads

e

Ue1 Ue2 Ue3

U1 U2 U3

U1 U2 U 3

1

2

3


Are we done? • Absolute mass, what is the mass of a neutrino?• How many neutrinos are there? 3 or more?

– Sterile neutrinos?

• Are neutrinos their own anti-particle or not?– Neutrinoless double beta decay?

• Understanding the full mixing of neutrinos?– Precision Measurements of parameters– 13 of particular interest

• CP violation in Leptons?• Extend the Standard Model• Hints for new symmetries & understanding origins of

mass

No!


Physics using the Sun

• Oscillation Parameter 12

Are there only 3 neutrinos?

How do the neutrinos relate to each other?

Why do they mix in the unusual fashion they do?

• Magnetic Moments

Learn more about the neutrino’s fundamental properties

• Solar Physics

Learn precisely how the Sun works

• Input to other experiments


Next Generation Solar Neutrino Experiments

Low energy (pp) neutrino experiment:• E> 50 keV• Well known • ES, CC expts• neutrino b

• solar physics


Connection to HomestakeFurther experiments are needed to understand neutrinos,

some of these require:

• Even better shielding from backgrounds (deeper, cleaner, better controlled environments)

• Better known sources of neutrinos (Sun is still an excellent source, and it is still free)

• Even more difficult experiments

But a National Facility helps ALL these experiments


Why should you (we) care?

• Not for Spin-offs - they are great, but not the real reason to do science

• Not just because Japan/Europe are doing it - we should listen and watch, but guide ourselves

• To understand the world/nature/universe • To ask why and be able to seek and find the

answer • Education, next generation benefits from new

tools, new ideas, better understanding of nature • To be able to compete in the next century

(science and technology)


Why should we care?• Often big discoveries, big steps in new

fields or at the overlap of fields - neutrinos are a good example of this

• Economic sense - share site, technology, rather than having redundant sites

• Tremendous synergism between experiments and fields not previously explored


QuickTime™ and a

Photo CD Decompressor

are needed to use this picture

QuickTime™ and a

Photo CD Decompressor

are needed to use this picture

Backup slides



KamLAND usesthe entire Japanesenuclear powerindustry as aLong-baseline source

Why Kamioka?

KamLAND

80% of flux frombaselines 140 to 210 km

Kashiwazaki

Takahama

Ohi


Solar Neutrinos in the News• 2002 Nobel Physics Prize: Koshiba + Davis

(Sweden)• 2003 Fermi Prize: Davis + Bahcall (US)• 2003 Herzberg Prize: MacDonald (Canada)• 2003 Rutherford Prize: Wark (England)• Sudbury Neutrino Observatory

– Top 2 discoveries in 2002– Top 3 cited papers in all physics in 2003– Generally heralded as proof of new physics


Neutrino Physics - Solar

Sudbury Neutrino Observatory - Canada

5 appearance experiment flavor changingSSM Confirmation/ SNP SolutionNew Physics Hitoshi Murayama

Documents

Solar Neutrinos & Homestake or Something new under the Sun