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The Troublesome Kid An introductory course on neutrino physics (III)

The Troublesome Kid An introductory course on neutrino physics (III). J.J. Gómez-Cadenas IFIC-Valencia Summer Student School CERN, July,2006. A man sits in a deep mine baby sitting a tank of cleaning fluid. He says he can count solar neutrinos…. Solar neutrinos. The chlorine experiment.

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The Troublesome Kid An introductory course on neutrino physics (III)

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  1. The Troublesome KidAn introductory course on neutrino physics (III) J.J. Gómez-Cadenas IFIC-Valencia Summer Student School CERN, July,2006

  2. A man sits in a deep mine baby sitting a tank of cleaning fluid He says he can count solar neutrinos…

  3. Solar neutrinos

  4. The chlorine experiment Cl3725% of all natural chlorine Inverse beta decay (0.86 Mev threshold) Cl37+nAr37+e- Ar is chemically very different from Chlorine. An inert gas that can be eventually removed from chlorine. It is radioactive and reverts to Cl37 emitting an Auger electron

  5. The hero in the mine Only a few atoms of Ar37 per run! Concept: Count the atoms of Ar37 produced by neutrinos 380 000 liters of C2Cl4 (a cleaning fluid) deep inside Homestake mine to shield from natural radiation (a Olympic swimming pool) Let Argon-37 accumulate from 1 to 3 months. Flush with He gas to remove Ar from fluid. Let the Ar condensate in a 77 K charcoal trap. Collect and purify Ar. Count the number of Auger electrons from Ar37

  6. 37Cl(ne,e)37Ar (Ethr = 813 keV) KshellEC t = 50.5 d 37Cl + 2.82 keV (Auger e-, X) Chlorine by numbers Expects 8.2 SNU1.8 Observs 2.56 SNU0.23

  7. The solar neutrino problem • Also called “paradox”, “dilemma”, “puzzle” and other nice words that showed that every body (secretly) believed that: • Davis (Chlorine experiment) was wrong • Bahcall (The solar model) was wrong Or, more likely: Both were wrong!

  8. 71Ga(ne,e)71Ge (Ethr = 233 keV) K,L shellEC t = 16.5 d 71Ga + 10 keV, 1 keV (Auger e-, X) Gallium experiments Expects 127 SNU12 Observs 68.1 SNU3.75

  9. What does a neutrino in water?

  10. Water detectors: Concept

  11. Water detectors: Concept

  12. Super Kamiokande

  13. The eyes of Super-Kamiokande

  14. Super-Kamiokande solar results

  15. A neutrino picture of the sun Super-K observation Neutrinos come from the sun indeed!

  16. Super-Kamiokande by numbers

  17. The solar neutrino problem after Super Kamiokande So Davis was not wrong after all!

  18. SNO

  19. SNO detector

  20. Signals in SNO

  21. ES NC CC SNO observations

  22. The solar neutrino problem So the sun is shining the expected number of neutrinos but many of them are nm and/or nt! Not only Davis, but also Bahcall was right!

  23. Atmospheric neutrinos

  24. Atmospheric flux prediction • Ingredientes: • Primary proton flux • Hadronic production models • Hadron propagation (geomagnetic effects)

  25. Zenith angle measures n path lengt Notice: Three decades of path length from O(104) to O(10) km.

  26. Super-K sees also atmospheric neutrinos

  27. The atmospheric neutrino problem

  28. Energy dependence Effect depends no only on the path length but also on the energy

  29. Solar & Atmospheric neutrino problems • The combination of all solar neutrino experiments (before SNO) implied that solar neutrinos were disappearing between production (in the sun core) and detection in the earth. • SNO shows that the sun is shining the expected n flux but most of them are nm and/or nt • The zenith dependence observed by Super-Kamiokande experiment showed that nm (but not ne) produced in the atmosphere were also disappearing. The effect depends on the zenith angle, that is on the neutrino path length, between production and detection and on the energy

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