Big World of Small Neutrinos

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Big World of Small Neutrinos

• Hitoshi Murayama
• LBL NSD/PD Colloquium
• May 15, 2002

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Neutrinos in the Standard Model
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Puzzle with Beta Spectrum

• Three-types of radioactivity a, b, g
• Both a, g discrete spectrum because
• Ea, g Ei Ef
• But b spectrum continuous

• F. A. Scott, Phys. Rev. 48, 391 (1935)

Bohr At the present stage of atomic theory,
however, we may say that we have no argument,
either empirical or theoretical, for upholding
the energy principle in the case of b-ray
disintegrations
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Three Kinds of Neutrinos

• There are three

• And no more

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Neutrinos are Left-handed
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Evidence for Neutrino Mass
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Super-Kamiokande (SuperK)

• Kamioka Mine in central Japan
• 1000m underground
• 50kt water
• Inner Detector
• 11,200 PMTs
• Outer Detector
• 2,000 PMTs

Michael Smy
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SuperKamiokaNDENucleon Decay Experiment

• p?ep0, Kn, etc
• So far not seen
• Atmospheric neutrino main background

• Cosmic rays isotropic
• Atmospheric neutrino up-down symmetric

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A half of nm lost!
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Survival Probability
p1 GeV/c, sin2 2q1 Dm23?103(eV/c2)2
Half of the up-going ones get lost
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More to come
250km

• 81?8 events if no oscillation
• 56 events observed
• MINOS (IL ? MN) 2005

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Public Interest in Neutrinos
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Solar Neutrinos
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How the Sun burns

• The Sun emits light because nuclear fusion
  produces a lot of energy

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We dont get enough
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Josh Klein, Lepton Photon 2001
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SNO comes to the rescue

• Charged Currentne
• Neutral Current nenmnt
• 5.3s difference
• ? nm,t are coming from the Sun!

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Wrong Neutrinos

• Only ne produced in the Sun
• Wrong Neutrinos nm,t are coming from the Sun!
• Somehow some of ne were converted to nm,t on
  their way from the Suns core to the detector
• ? neutrino oscillation!

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Dark Side of Neutrino Oscillation

• Traditional parameterization of neutrino
  oscillation in terms of (Dm2, sin22q) covers only
  a half of the parameter space
• (de Gouvêa, Friedland, HM)
• Convention n2 heavier than n1
• Vary q from 0 to 90
• sin22q covers 0 to 45
• Light side (0 to 45) and Dark Side (45 to 90 )
• To cover 0?? q ? 90?? use tan2 q

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March 2002
April 2002 with SNO
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What Next?

• Can we convincingly verify oscillation with
  man-made neutrinos?
• Hard for low Dm2
• To probe LMA, need L100km, 1kt
• Need low En, high Fn
• Use neutrinos from nuclear reactors

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Location, Location, Location