Neutrino Physics - Lecture 5

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Neutrino Physics - Lecture 5

• Steve Elliott
• LANL Staff Member
• UNM Adjunct Professor
• 505-665-0068, elliotts_at_lanl.gov

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Lecture 5 Outline

• Finish Solar Neutrinos
• Neutrinos from the Atmosphere
• The neutrinos
• Past experiments
• What we know and what we want to learn

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The hierarchy question
Normal
Inverted
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The Dark Side of solar neutrinos
Two flavors are involved in solar neutrino
oscillations. ?e and a linear combination of ???
and ??.
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The Dark Side of solar neutrinos II
For ?lt?/4, ?1 is mostly ?e. But for ? ?/2 -
?? ?/4, ?1 is mostly ???. Thus, although
oscillations in a vacuum cannot distinguish
between ? and ?, matter oscillations can.
That is cos2? changes sign.
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Solar Neutrino Resultsthere is no dark side
Early fit to solar neutrino data. Note solution
space for tan?gt1.
Phys.Lett. B490 (2000) 125
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The addition of KamLAND
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Whats left to do?

• Is our model of neutrino mixing and oscillation
  complete, or are there other mechanisms at work?
• Without luminosity constraint, pp and 7Be fluxes
  poorly known.
• With constraint, 7Be is still poorly known.
• Is nuclear fusion the only source of the Suns
  energy and is it steady state?
• What is the correct hierarchial ordering of the
  neutrino masses?

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Non-Standard Interactions and New Properties

• Do neutrinos have non-standard interactions?
• Are there unexpected properties?
• Non-standard interactions of neutrinos with
  matter would lead to modifications of matter
  effects in oscillations.
• NSI on order of 10-30 of SM weak interaction are
  possible and compatible with accelerator and
  oscillation data.
• Such large effects would affect solar neutrino
  data. Since NSI must mimic SM behavior in the
  matter dominated region, but be small in the
  vacuum region, the transition region is a good
  place to look.

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The Vacuum-matter transition
About 2 MeV
hep-ph/0305159

• This classic LMA oscillation probability curve
  might be altered by NSI.

Vacuum
Matter
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Future Solar Neutrino Experiments
Experiment Target Reaction Threshold
Borexino 300 t liq. Scint. ES 250 keV
KamLAND 600 t liq scint. ES 250 keV
LENS 60 t In load in scint CC
HERON 68 m3 LHe ES 45 keV
CLEAN 40 t liq. Ne ES 35 keV
MOON Few t of 100Mo CC 168 keV
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Future Experiments
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Atmospheric NeutrinosUp vs. Down
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IMB and Kamiokande

• Previous large water Cherenkov detectors
• Built to look for proton decay, atmospheric
  neutrinos are a significant background hence
  lots of study
• Kamiokande was able to lower threshold to see
  solar neutrinos
• Saw SN1987A, but not pdk
• Statistically weak indication of atmospheric
  neutrino oscillations
• Led to plan for Very Large SuperK

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SuperK

• 1000 m underground
• 50,000 tons of water
• 12,000 pmts

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Results
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L/E analysis (Ishitsuka NOON 2004)
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L/E results
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Maximal mixing and the future
If sin2?13 is different than 0, Earth matter
effects can resonantly enhance the subdominate
transitions depending on the sign of ?m232.
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Future Experiments
Experiment Target Status
SuperK 50 kt water Continue on
SNO 1 kt heavy water Just completed
MINOS Iron magnetized calorimeter Operating
INO 30-50kt magnetized tracking calorimeter proposal
UNO/HyperK Mt class water proposal
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SNO is small but deep