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What Are Neutrinos Anyway and What Is All This Fuss About?

What Are Neutrinos Anyway and What Is All This Fuss About?. College of Applied Sciences Colloquium January 16, 2002. Randy Johnson Physics Department. New York Times. May 7, 1996. June 5, 1998. June 19, 2001. What are Neutrinos?. Physics ‘s First Principle.

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What Are Neutrinos Anyway and What Is All This Fuss About?

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  1. What Are Neutrinos Anywayand What Is All This Fuss About? College of Applied Sciences Colloquium January 16, 2002 Randy Johnson Physics Department College of Applied Sciences Colloquium

  2. New York Times May 7, 1996 June 5, 1998 June 19, 2001 College of Applied Sciences Colloquium

  3. What are Neutrinos? College of Applied Sciences Colloquium

  4. Physics ‘s First Principle Conservation of Energy and Momentum • Galileo and Newton – Mechanical Energy • Joule – Heat • Maxwell – Light • Einstein – Mass College of Applied Sciences Colloquium

  5. Events Beta Decay e- He3 H3 e- Energy The Energy Crisis Radioactive Decays Alpha Decay Events Th234 U238 a a Energy College of Applied Sciences Colloquium

  6. Invention of the Neutrino Wolfgang Pauli’s Desperate Remedy – the Neutron College of Applied Sciences Colloquium

  7. p n e- Recognition of the Neutrino Fermi Theory of Weak Interactions Pauli’s neutron becomes Fermi’s neutrino Interaction similar to electromagnetism but much weaker College of Applied Sciences Colloquium

  8. Strong Make nuclei Make atoms E&M Weak “Fundamental” Particles Def: Smallest particles that make up matter Fundamental particles 1930’s style • Proton • Neutron • Electron • Neutrino College of Applied Sciences Colloquium

  9. 1949 Yukawa Potential and the Strong Force 1935 Particle exchange model of the strong force: Mpc2 150 MeV College of Applied Sciences Colloquium

  10. 1950 Search for the Pion with Unexpected Results p Mpc2 = 139 MeV Mmc2 = 105 MeV I. Rabi “Who ordered that?” College of Applied Sciences Colloquium

  11. Elementary Particles1950’s Style Hadrons • Baryons: proton, neutron, lambda, … • Mesons: 3 pion, 4 kaons, 2 etas, … Leptons • Electron, muon • Neutrino College of Applied Sciences Colloquium

  12. 1995 Discovery of the Neutrino 1955 – Savannah River Reactor 1013n/cm2/sec 3 reactions/hr Reines and Cowan at Hartford Reactor College of Applied Sciences Colloquium

  13. 1969 Murray Gell-Mann and the Invention of Quarks Three quarks for Muster Mark Proton: Pion: u u u d d d u Quarks are equivalent s College of Applied Sciences Colloquium

  14. 1988 Muon’s Have Their Own Neutrino Steinberger 1962 Schwartz Ledermann College of Applied Sciences Colloquium

  15. 1976 Discovery of the Charm QuarkThe November Revolution 1974 Everyone believes in quarks! Richter Ting with data College of Applied Sciences Colloquium

  16. 1995 Perl’s Discovery of the Tau Meson m+ 1975 n n t+ e+ e- t- n m- n Again – missing energy! College of Applied Sciences Colloquium

  17. Discovery of the Tau Neutrino Photographic Emulsion Fermilab DONUT 2000 Four events seen College of Applied Sciences Colloquium

  18. Elementary Particles 2000 Style Open questions: • Why the families? • What is mass? • What’s next? College of Applied Sciences Colloquium

  19. Neutrinos from the Sun Basic energy generation in sun: ne Light from sun was generated 1,000,000 years ago ne ne Neutrinos were generated 9 minutes ago! College of Applied Sciences Colloquium

  20. First Solar Neutrino Experiment 615 tons C2Cl4 Detection: Ray Davis + Auger electron Production Rate: 1.5 atoms/day (SSM) College of Applied Sciences Colloquium

  21. Biggest Solar Neutrino Experiment n Super-K g e g College of Applied Sciences Colloquium

  22. Neutrino Picture of the Sun Angle from Solar Direction Events Super-K data cos q College of Applied Sciences Colloquium

  23. Results from All Solar Neutrino Experiments College of Applied Sciences Colloquium

  24. SNO vs. Super-K SNO’s or Super-K’s Elastic Scattering SNO’s Charged Current Reaction College of Applied Sciences Colloquium

  25. Lost Neutrinos are Found College of Applied Sciences Colloquium

  26. Young’s Double Slit Experiment Light interferes with itself. How Can Neutrinos Change Type? Magic of Quantum Mechanics College of Applied Sciences Colloquium

  27. Neutrino Oscillations If: • Neutrinos have mass; and • If they can interact with each other. Then: Pe Pm College of Applied Sciences Colloquium

  28. Other Indications of Neutrino Mass No Direct Evidence Other Oscillation Evidence LSND Experiment Super-K Cosmic Rays College of Applied Sciences Colloquium

  29. So Who Cares? Everything in the Universe Cares! Our universe was once very, very hot! It is now very cold! T = 2.7o K = ~.0003 eV College of Applied Sciences Colloquium

  30. Cosmic Microwave Background Clumps are seeds of galaxies But not enough matter to make clumps clump! COBE Satellite data College of Applied Sciences Colloquium

  31. Neutrinos and Cosmology Microwave background represents about a billion photons/m3 Should be 3 times as many neutrinos! If they have mass, they could give the extra matter that is needed to seed galaxy formation. Wild speculation, but we may be here because of neutrinos have mass! And that is what the fuss is about! College of Applied Sciences Colloquium

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