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Neutrino Oscillations Michiel Bosma

Neutrino Oscillations Michiel Bosma. Why study neutrino oscillations ? What are neutrino oscillations ? How could one detect them ? Have neutrino oscillations been found to exist ?. Why study neutrino oscillations ?. It might partially solve the dark matter problem since:.

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Neutrino Oscillations Michiel Bosma

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  1. Neutrino Oscillations Michiel Bosma • Why study neutrino oscillations ? • What are neutrino oscillations ? • How could one detect them ? • Have neutrino oscillations been found to exist ?

  2. Why study neutrino oscillations ? It might partially solve the dark matter problem since: • Huge amounts of neutrinos exist • Neutrino oscillations imply a nonzero neutrino rest mass • Even a tiny neutrino rest mass contributes enormously to the total mass in the universe

  3. And there’s also the solar neutrino problem: Lots of neutrinos are produced in the sun through the following reactions : Normalized flux Neutrino energy (MeV) p + p  2H + e+ + e 1 0.42 0.08 0.862 7Be + e-  7Li + e 0.0001 14 8B  8Be + e+ + e But only roughly 2/3 of the expected neutrinos are measured on earth !

  4. What are neutrino oscillations? Consider our neutrinos as mixed states : e = cos 1 + sin 2  = -sin 1 + cos 2 These neutrinos will develop in space - time as follows: | k(x,t) = | k(0,0) exp[i(pkx - Ekt)] where Ek is given by (pk2 + mk2)1/2 ,which we can approximate for relativistic particles as the neutrino by pk + mk2/2pk Since we wouldn’t like the states to go spatially out of synchronization we must demand p1= p2=p Combining the above, we arrive at: | k(x,t) = | k(0,0) exp(-imk2t/2p)

  5. If we further define m2 = m22 - m12 we arrive at the following expressions for the chances of finding either a e or a  : P(e  e ) = 1 - sin2(2) sin2(m2t / 4p) P(e   ) = sin2(2) sin2(m2t / 4p) Or, if we introduce L = t and  = 4p / m2 : P(e  e ) = 1 - sin2(2) sin2(L / ) P(e   ) = sin2(2) sin2(L / )

  6. How to detect neutrino oscillations ? First of all: fill a huge underground area with lots of fluid There are specific detectors, which use reactions like: e + 37Cl  37Ar + e- Davis e + 71Ga71Ge + e- GALLEX Or more general ones,which use: k + n  p + k- Super-Kamiokande e + d  2p + e- SNO (Charged Current) k + d  p + n + k SNO (Neutral Current, d-Breakup) k + e-  k + e- SNO,Super-K (Elastic Scattering) where k = e, ,  e-, -, - are measured by means of Cherenkov-radiation

  7. How Cherenkov-radiation detection works

  8. The different regions in which the experiments measure

  9. Results Super-Kamiokande concluded that atmosferic neutrinos oscillate    , and placed some limits on sin22 and m2 KAMLand also placed some limits on sin22 and m2 KAM-Land The SNO experiment has observed neutrino oscillations and can solve the solar neutrino problem with their data Super-Kamiokande 

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