1. Solar Neutrinos & Homestake or Something new under the Sun Kevin T. Lesko Lawrence Berkeley National Laboratory Berkeley, CA

2. 20 January 2004Kevin Lesko 2 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!

3. 20 January 2004Kevin Lesko 3 “…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 --> 4 He + 2 e + 2e + + ~25 MeV p + e - + p 2 H + e 2 H + p 3 He +  3 He + 4 He 7 Be +  7 Be + e - 7 Li + e 7 Li + p 4 He + 4 He 7 Be + p 8 B +  8 B 8 Be* + e + + e 8 Be* 4 He + 4 He 3 He + p 4 He + e + + e 3 He + 3 He 4 He + 2p p + p 2 H + e + + e 85% 15% 0.02% p-p Chain Solar Neutrinos

4. 20 January 2004Kevin Lesko 4 Solar Neutrino Experiments (pre-SNO) Homestake (S Dakota, USA) Super-Kamiokande (Japan) SAGE (Baksan, Russia) GALLEX (Gran Sasso, Italy) Only e directly observed

5. 20 January 2004Kevin Lesko 5 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

6. 20 January 2004Kevin Lesko 6 Example of Two Flavor Oscillations 1.0 0.8 0.6 0.4 0.2 0.0 Probabilty 76543210 x/ osc  e In the example here, sin 2  is 0.7. One can solve for values of  and  m 2 which produce fluxes consistent with measured fluxes on Earth. In general, oscillations could explain the missing s

7. The Sudbury Neutrino Observatory Charged Current e +d  e - +p+p just one flavor of Elastic Scattering x +e -  x +e - Neutral Current x +d  x +n+p All flavors of Large Deep Clean Sensitive

8. 20 January 2004Kevin Lesko 8 Neutrino Appearance Experiment! SSM: BPB Astrophy J 555, 990 2001  e (10 6 cm -2 s -1 )   (10 6 cm -2 s -1 )

9. 20 January 2004Kevin Lesko 9 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

10. 20 January 2004Kevin Lesko 10 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!

11. 20 January 2004Kevin Lesko 11 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

12. 20 January 2004Kevin Lesko 12 Next Generation Solar Neutrino Experiments Low energy (pp) neutrino experiment: E  > 50 keV Well known  ES, CC expts neutrino  b solar physics

13. 20 January 2004Kevin Lesko 13 Connection to Homestake Further 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

14. 20 January 2004Kevin Lesko 14 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)

15. 20 January 2004Kevin Lesko 15 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

16. 20 January 2004Kevin Lesko 16 Backup slides

17. 20 January 2004Kevin Lesko 17

18. 20 January 2004Kevin Lesko 18 KamLAND uses the entire Japanese nuclear power industry as a Long-baseline source Why Kamioka? KamLAND 80% of flux from baselines 140 to 210 km Kashiwazaki Takahama Ohi

20. 20 January 2004Kevin Lesko 20 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

21. 20 January 2004Kevin Lesko 21 Neutrino Physics - Solar Sudbury Neutrino Observatory - Canada 5  appearance experiment flavor changing SSM Confirmation/ SNP Solution New Physics Hitoshi Murayama