Neutrino Physics - Lecture 6

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Neutrino Physics - Lecture 6

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

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Lecture 6 Outline

• Reactor Neutrinos (Many slides from Bob Mckeown)
• The neutrinos
• Past experiments
• What we know and what we want to learn

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Reactor Experiments

• CHOOZ, Palo Verde
• Double CHOOZ, Daya Bay
• Texono
• Neutrino magnetic moment
• Coherent scattering

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Anti-?e Disappearance
Dominant ?12 Oscillation
P(?e??e)
Distance (m)
Subdominant ?13 Oscillation
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q13
hep-ph/0309130
90, 95, 99 CL
Chooz
?m232 from SK atmospheric
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Neutrino Oscillation Studies with Nuclear
Reactors

• ne from n-rich fission products
• detection via inverse beta decay (nepgen)
• Measure flux and energy spectrum
• Improve detectors, reduce background
• Variety of distances L 10m-250km

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Detection Signal

• Coincidence signal detect
• Prompt e annihilation g
  EnEpromptEn0.8 MeV
• Delayed n capture 180 ms capture time

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KamLAND uses the entire Japanese nuclear
power industry as a longbaseline source
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Ratio of Measured and Expected ?e Flux from
Reactor Neutrino Experiments
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Measurement of Energy Spectrum
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KamLAND best fit Dm2 7.9 x 10-5 eV2 tan2q
0.45
KamLAND fixes mass Solar fixes angle
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Geoneutrinos
Two estimates of total power dissipated by
Earth 44.2 1 TW 30 1 TW 19 TW is
estimated to be due to radiogenic sources, 84
due to Th/U decay, some mantle studies imply it
might be larger.
Nature 436, 499
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New Reactor Proposals
Daya Bay, China
KASKA

• 1.5 km baseline
• Deeper/bigger
• Near/Far

Braidwood, Il
Chooz, France
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Detector Design Studies
horizontal cylinder
horizontal cylinder
spherical
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Daya Bay

• Each detector
• Inner zone 20 tons Gd-doped LS
• Defined by acylic
• Outer zone just LS
• Outermost zone just mineral oil
• 224 pmts
• Sin2?13 0.008
• Constr. 2007
• Data start 2009

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Double Chooz

• Sin2?13 0.022-0.030
• Data 2008
• Daya Bay and Double Chooz have similar concepts
  for LS

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New Properties

• Unexpected new neutrino properties
• CPT invariance violation
• Equivalence principle violation
• Lorentz violation
• Would appear as oscillation effects but with a
  departure from the classic oscillation wavelength
  energy dependence
• Mass varying neutrinos
• Dark energy scale 2 meV is similar to scale of
  neutrino mass splitting (9 meV)2
• Might be observable in oscillation, ???
  experiments

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Magnetic Moments

• Do neutrinos have magnetic moments?
• Dirac neutrinos can posses static moments
• Majorana neutrinos can possess transition moments
• SM predicts very small value 3x10-19(m?/eV)?B
• Present limits lt9x10-11?B
• Measurements hard because the possible EM and
  known WI contributions are similar in magnitude.
• Astrophysical constraints in addition to
  reactor/accelerator limits. Beta beams and
  tritium sources have also been proposed.

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Electron elastic scattering experiments

• Neutrino elastic scattering cross sections scale
  as E2?, whereas the ?B interaction are mostly
  energy independent. Thus the EM cross section may
  dominate at low energies.
• Reactor neutrino experiments are the best to
  date. Most recent TEXONO expt. in Taiwan

PR D75 (2007) 012001
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Coherent nuclear scattering experiments

• 1 MeV neutrino with 10-10?B scattered on a NZ
  spin 0 nucleus has

J.Phys.Conf.Ser. 39 (2006) 266
Spin contributions enhance SM cross section. For
N?Z, isospin dependent terms contribute. High A
nuclei have low recoil energies. Like ES, largest
ratio is for low recoil energy