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SUPER -KAMIOKANDE

SUPER -KAMIOKANDE. Kamiokande = Kamioka Nucleon Decay Experiment. Topics of Discussion. Detector Super-Kamiokande Solar neutrinos Results. Properties of Super-K. A Large Water Cherenkov Detector for Cosmic Particles Size: Cylinder of 41.4m (Height) x 39,9m (Diameter)

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SUPER -KAMIOKANDE

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  1. SUPER -KAMIOKANDE Kamiokande = Kamioka Nucleon Decay Experiment

  2. Topics of Discussion • Detector Super-Kamiokande • Solar neutrinos • Results

  3. Properties of Super-K • A Large Water Cherenkov Detector for Cosmic Particles • Size: Cylinder of 41.4m (Height) x 39,9m (Diameter) • Weight: 50,000 tons of pure Water • Number of Photomultipier Tubes: 11,200

  4. Photomultplier Tube

  5. How does S-K detect? The PMTs collect the pale blue light called Cherenkov light which is emitted by particles travelling faster as light in the water

  6. Cherenkovlight wavefront Compare : shock wave of supersonic airplanes c0 = speed of light in vacuum Cherenkov radiation See http://webphysics.davidson.edu/applets/applets.html for a nice illustration

  7. The picture above shows an incoming 1063 MeV neutrino which strikes a free proton at rest and produces a 1032 MeV muon. Different colors are related to time, blue shows the muon, green the electron of the muon decay.

  8. Advantages of S-K • The direction the neutrino came from can be determined • The time of the neutrino’s arrival can be determined • The energy of the electron gives a rough estimate of the neutrino energy

  9. Time of neutrino’s arrival • It is possible to search for day/night or seasonal variations

  10. Direction of neutrino • One can provide solid evidence that the neutrinos are actually coming from the sun

  11. Estimate of neutrino Energy It is possible to distinguish neutrinos from different reaction chains in the sun So, where and how are neutrinos produced?

  12. Solar fusion 1 • Basic process in sun and most stars – fusion of hydrogen(protons) into helium First step is combination of two protons 11H + 11H 21H + e+ +e p ne n then e

  13. Solar fusion 2 The cross-section for this process is very small at average proton energies in the core of the sun, however there is a huge number of protons available to react. Deuterons so produced fuse with protons: 21H + 11H 32H + 

  14. Solar fusion 3 • In our sun 3He is most likely to react with another 3He nucleus. 32He + 32He 42He + 2 11H +  • The complete process is given by: 4 11H 42He +2 e+ +2 e + • This process is known as the proton-proton cycle or the ‘PPI chain’.

  15. Solar fusion 4 • PPII : 32He + 42He  74Be +  74Be + e-73Li + e 73Li + 11H 2 42He • PPIII: 32He + 42He  74Be +  74Be + 11H  84Be + e+ + e 84Be  2 42He

  16. Solar neutrinos • Neutrinos are ‘ghost ‘-particles which merely interact, they are the only known type of particle that can escape from the sun’s core bringing direct information about the solar interior

  17. Solar neutrinos 2 • Neutrinos are difficult to detect and measure • Neutrinos produced in different branches carry away different amounts of energy and momentum – detector design has to take account

  18. Solar neutrinos at S-K • Super Kamiokande uses elastic scattering of neutrinos from electrons • Cherenkov radiation emitted by the electron is detected  e

  19. ne e Overview

  20. http://www.pc.uci.edu/~tomba/sk/tscan/solar

  21. Theory versus experiment

  22. All five blue bars, according to various experiments, show significantly less values than the model predictions: the discrepancy is approximately a factor oftwo

  23. Additional Result of S-K • S-K observes a significant difference between the numbers of neutrinos coming up through the ground as went down on the other side • A possible explanation is neutrino conversion takes place in matter – called Mikheyev-Smirnov-Wolfenstein effect

  24. Additional Result of S-K • Super-K has found evidence of the transformation of muon type neutrinos to something else, probabely tau type neutrinos (neutrino oscillations). • This is taken as strong evidence that neutrinos have a small, but finite mass.

  25. What This Means • Neutrino oscillations is today the most promising of the proposed solutions to the solar neutrino problem

  26. Solar neutrino research was undertaken to test stellar evolution • Unexpectedly one found evidence for new neutrino physics • More experiments are needed to understand neutrino oscillation phenomena

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