Science

1. Science Underground

2. The early periodic table

3. The structure of matter 1869 - Mendeleyev – grouped elements by atomic weights

4. The structure of matter (cont.) • This lead eventually to a deeper understanding Eventually this led to Our current picture of the atom and nucleus

5. What are fundamental particles? • We keep finding smaller and smaller things

6. History of the search for fundamental particles • Proton and electron • These were known to make up the atom • The neutron was discovered • Neutrons were found to decay • They decayed into protons and electrons • But in the decay it looked like something was missing • In 1930 Pauli postulated a unseen neutral particle • In 1933 Fermi named it the “neutrino” (little neutral one)

7. neutrino How do we know about things we can’t see? Two Body Particle Decay Three Body Decay

8. Our current view of the structure of matter

9. Charge +2/3 -2/3 -1/3 +1/3 _ _ _ Anti-Quarks _ _ _ Heavier Heavier The Quark Model – nuclear & heavy particles • Proton (+1) is uud 2/3+2/3-1/3=1 • Neutron (0) is udd 2/3-1/3-1/3=0 • p+ (Pion +1) is ud 2/3+1/3=1 • k+ (kayon +1)is us 2/3+1/3=1 This model explained all existing nuclear particles and predicted all other “legal” combinations

10. Table of Baryons

11. Anti-leptons Heavier Heavier Leptons – the light ones Charge 0 | 0 -1 | +1 positron Leptons are believed to be fundamental and have no internal structure The number of leptons is conserved (i.e. you can only create lepton- anti-lepton pairs) Neutrinos are neutral and nearly massless

12. Our current view of underlying structure of matter The Standard Model

13. A Major Puzzle – Matter/Antimatter Asymmetry • Quarks can only be created in quark – antiquark pairs (like leptons) • This means protons can only be created in P P pairs • Electrons can only be created in electron - positron pairs • However, the world we live in is made up of protons and neutrons and electrons – not their antiparticles. • There is strong evidence that this is true everywhere in the Universe. • So how did this imbalance arise in the early Universe?

14. Neutrinos They only interact weakly If they have mass at all – it is very small Why do we care about neutrinos? • They may be small, but there sure are a lot of them! • 300 million in every cubic meter of the Universe left over from the Big Bang • with even a small mass they could be most of the mass in the Universe!

15. Facts about Neutrinos • Neutrinos are only weakly interacting • 40 billion neutrinos continuously hit every cm2 on earth from the Sun (24hrs/day) • Interaction length is ~1 light-year of steel • 1 out of 100 billion interact going through the Earth

16. n Does the neutrino have mass? Because its mass is so small it’s difficult to measure directly!

17. Indirect Measurement of Neutrino Mass • If neutrinos have different masses they can transform from one type to another as they move • If they have different masses – it means they have mass

18. =Electron n =Muon n n1 n2 n1 n2 Muonn Electronn Neutrino Oscillations

19. m- e- electron ne muon nm How do we see neutrinos?

20. How do we see particles? • Most particles have electric charge • Charged particles knock electrons out of atoms • As other electrons fall in the atoms emit light • The light from your TV is from electrons hitting the screen • In a sense we are “seeing” electrons

21. Cherenkov Radiation When a charged particle moves through transparent media faster than speed of light in that media. Cherenkov radiation Cone of light

22. Cherenkov Radiation

23. Super-Kamiokande

24. Md Undergraduate Students at Super-K 16%7.2% 16%7.2%

25. Detecting neutrinos Cherenkov ring on the wall Electron or muon track The pattern tells us the energy and type of particle We can easily tell muons from electrons

26. Telling particles apart Muon Electron

27. What did this experiment tell us? • Super-K told us that neutrinos oscillate from one type to another • This means neutrinos have mass • but we still don’t know exactly how much • It, in combination with two other experiments, SNO and Kamland, helped to solve the solar neutrino problem that Ray Davis first found here in Homestake and for which he won the 2002 Nobel Prize

28. Why go underground? What we are looking for happens above ground - but there is too much background to see it!

29. Extensive Air Shower Development

30. Why go deep? • Muons are background • At sea level 100 m2/s • At 8000’ underground 50 m2/yr • Homestake provides a reduction of a factor ~60 million • This reduction allows us to look at very rare phenomena

31. Why build an underground lab? • There is compelling science to be done underground • We need to answer fundamental questions about the nature of the Universe • There are important questions in geology and microbiology • There are issues of national defense • There is no general purpose lab at any substantial depth in the U.S. • There is a deep lab in Canada • There is a general purpose lab in Italy • We have an outstanding opportunity to build the premier underground laboratory in the world here in South Dakota

32. Science Underground • Dark Matter – Marvin Marshak • Proton Decay – Al Mann • Neutrino Physics – Ken Lande • Neutrinos from the Sun – Kevin Lesko • Neutrinoless Double Beta Decay – John Wilkerson • National Security Underground – Harry Miley • Geo-Science – Bill Roggenthen