Neutrino astronomy Hubert Reeves 2011 11...
Transcript of Neutrino astronomy Hubert Reeves 2011 11...
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Neutrino astronomy Hubert Reeves 2011 11 09 •
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Structure of atoms
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1932 Discovery of neutrons Chadwick .
• An isolated neutron disintegrates in 20 minutes
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1932 Discovery of the neutron .
• Life time: twenty minutes• Disintegrates in one proton and one electron • neutron
=»
proton+electron
• But : problem !
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Energyandmomentumare notconserved!!!
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Energy
is
not conserved
!!!, also
momentum
,
• Lavoisier 1795 • «
Nothing can be lost and nothing can be
created
»
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Wolfgang Pauli
Suppose the existence of a new particle
With no electric charge
With very feeble interactions with other particles .
The «
neutrino
»
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• The neutrino carries the missing energy and momentum
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Neutrinos are detected in 1965 Generated by neutron
disintegrations In nuclear reactors
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Average neutrino population ( per cubic meter of space)
•• The most
abundant
particle
in the cosmos !
.
• Neutrinos: =450 millions • Photons := 400 millions • Electrons , protons : = 1 .
•
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Large spectrum of energies
From mev to GevSunSupernovae Cosmic rays Earth Cosmology
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Twelve
varieties
of neutrinos
• Neutrinos and antineutrinos
• Three «
flavors
»
• neutrino –e• neutrino –mu• neutrino –tau•• Two spins (up and down)
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Feeble interaction of neutrinos with other particles.
• Disadvantage : difficult to detect their presence
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A sheet
of paper
is
enough
to shade
a flux of photons
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To screen
a flux of neutrinos : a screen
of lead
of many
light-years• .
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Neutrino telescopes
Hundred of thousands tons
of detecting liquid
are needed
to register a few neutrinos per second
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Thousands of Cerenkof detectors
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Feeble
interaction of neutrinos with other
particles
• Advantage : they may come from opaque locations:
• Stellar centers• Galactic nuclei • Earth interior •
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Neutrino detection program
• Auscultation of darkest spots • Supernovae interior mechanisms• Origin of gamma ray bursts• Test of the Big Bang and earliest universe• Test of fundamental physics theories •
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Sun
Light come from the surface,
Neutrinos come from the center .
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UV come from the surface
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Photons diffuse
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Neutrinos come directly from the center
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Origin of solar energy ?
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Transformation of hydrogen in helium
4protons =
»1 Helium + 4 neutrinos
Origin of solar energy
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Transformation of hydrogen in helium
Fifteen millions of degree
Neutrinos are emitted from the nuclear reactions .
Origin of solar energy
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Solar neutrinos
detected in 1962 in a mine of South Dakota
• Ron Davis•
Confirm the nuclear origin of solar (stellar) energy
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Neutrino luminosity of Sun
• Neutrinos : 5 % • Photons : 95 %• Sixty billions of neutrinos cross our body each
second
• . .
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Neutrino luminosity of Sun
• Neutrinos : 5 % • Photons : 95 %• Sixty billions of neutrinos cross our body each
second
• Our body emits a few tens of neutrinos per second (depending upon our weight)
• . .
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Neutrino luminosity of Sun
• Neutrinos : 5 % • Photons : 95 %• Sixty billions of neutrinos cross our body each
second
• Our body emits a few tens of neutrinos per second (depending upon our weight!!!)
• . .
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The neutrinic sun does not set
• Detectable all night • No eclipse !
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Matter and antimatter
For each
particle
there
exist
an antiparticle
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• Is the Sun made of matter or antimatter?
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• Northerh Lights : eV photons from interaction of solar wind ( protons) with earth atmosphere show that the solar surfac is made of matter.
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• Northerh Lights : eV photons from interaction of solar wind ( protons) with earth atmosphere show that the Sun is made of matter.
• If the sun was made of antimatter, we would get gamma rays of hundred Mev , from protons and antiprotons , resulting in pion decays
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Solar core ?
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The sun
emits
large fluxes neutrinos and very
small
amount
antineutrinos
• the solar core is made of matter
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Forty years of solar neutrino observations. Neutrnos
cross the Sun in three
seconds
The photons take
a million years
to diffuse
Tne
neutrinos are (almost) instant monitor of the solar
interior
The photos give
million year
averages
.
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•Confirm the nuclear source of solar( stellar)
energy
Solar neutrinos
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Solar 11 year cycle Number of sunspots
since 1960
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NUMBER of sunspot
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• No variation with the 11 year cycle
The solar neutrino flux is constant
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•Confirm the nuclear source of solar( stellar)
energy
The neutrino flux is only one third of solar model predictions ;
Why ?
Solar neutrinos
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There are three
neutrino flavors
1)
neutrino électronic
(e)
2)
neutrino muonic
(mu)
3)
neutrino tauic
(tau)
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Sun emits only e-neutrinos
• Detectors detect only e–neutrinos• Why only one third?
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Neutrinos can change flavors « oscillate) (as the pokemons ! )
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Neutrino oscillation
km
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Neutrino oscillation
• Can be measured through long base-line studies
USA : Soudan –Chicago , Japan Kamiokande
Europe ; Cern-
Gran Sasso 730 km
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Oscllation of MeV e –neutrinoafter one hundred Km 100- km
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From the Sudbury Observatory
The Sun emits only e-neutrinos
They oscillate in the path
Only one third e-neutrinos arrive at earth .!
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Problem
• To oscillate must be massive • The neutrino were first assumed to be
massless.
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Neutrino masses
• Around one eV • One millionth of the electron mass.•• Solar studies gives new physics!!
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Neutrino velocity
• Slightly lower than light (from Special Relativity)
• But Cern Gran Sasso experiment.2x10-5 faster than lignt .
Problem with Crab nebula observations 10-9
accuracy between lignt and neutrino velocity)
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All stars emit neutrinos
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Neutrino emission by hotter stars
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Fractional neutrino fluxes
• Solar : 5 % • Red Giants + de 50% • Supernovae : 99.99 %
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On feb 23 , 1987 at 10h00
• A supernova in the Large Magellanic Cloud • 160 million light-years from Earth • Brighy as 30 million sun for a few hours
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Courbe de lumière de 1987a
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A few neutrinos are detected
tthree hours
before
the photons
Why?
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Photon diffuse !
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• L( neutrinos) =3x1053 erg/sec • = 3x1019L ( solar photon ) • = 3x108 galaxies!
Supenova luminosity
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Neutrinos in cosmology
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Fossil radiation of neutrinos
• The Big Bang theory predicts the existence of a thermal radiation of neutrinos witu cosmic temperature= 1.86 degree .
• Energy of milli-eV (meV) . Not detectable with present technologies
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Visible matter in the universe
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Energy
spectrum
of Fossil
Radiation
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Dark matter and energy.
• Only 5 % of the cosmic density is visible ( emission of photons)
• 20% is dark matter • 75% is dark energy
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Could
dark
matter
be
composed
of neutrinos?
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Could
dark
matter
be
composed
of neutrinos ?
No .
They have masses smaller than 2 eV
Hence a cosmic density of 2 % !
Nevertheles they contain as much energy density as all stars !!
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Matter antimater enigma
• Big Bang =»
high temperature
• Thermal equilibrium • Matter population=antimatter population • Annihilation during cooling• Only light should be left.
We exist!!! .
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Matter
and antimatter
in the early universe
• A Above
10-13 K• Populations were
strctly
equal
• Below
10-13K
• : addition of one matter
particle
surplus for each 109
particles
and antiparticles
• Later
: annihilation
• Antimatter
disappear• Only
matter
and lignt
remain
• . •
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Neutrino Cosmic Densities .
• Observed mass of neutrinos <
3 eV ( tritium decay) :
• Population = 450 cm-3
• 0.6x10-3
< neutrino density ) < 0.02
• Dark matter = 0,20 • Would require a mass > 10 eV
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Influence of electron
density
on propagation of neutrinos
(MSW)effectNégligible for (E(nu) 5MeV
Oscillation depends upon electron densities
()
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MSW effect on solar neutrinos
• Varies with neutrino energy • At (0.862 MeV) on the line emission of Be-7 • Surviving fraction = f(Be-7) = 56%
On B-8, ( E< 14 Mev)
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Surviv;ng fraction f(B-8) = 35 %
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Oscillation of atmospheric neutrinos
Created by atmospheric collisions of cosmic rays
• Oscillates through the earth volume
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NEUTRINOS 2006
2006
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Antares detector in the sea close to Toulon
• Screened by whole earth
• No detection at november 2011 • Problem ?
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Crab Nebula 4 july 1054
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• Résultat : léger excès de matière (1/1000,000,000!)
• Annihilations et …reliquat de matière: nous! • Trop élevé
pour provenir du secteur des
quarks Suffisant dans celui des neutrinos?
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La vie des étoiles: Transformation de masse en énergie . E =Δmc2
Vecteurs: gravité
et nucléaire.
Emission : photons et neutrinos .
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Neutrino astronomy�Hubert Reeves 2011 11 09 Structure of atoms 1932 Discovery of neutrons �Chadwick .1932 Discovery of the neutron . Energy is not conserved !!!,�also momentum ,Diapositive numéro 7Wolfgang Pauli Diapositive numéro 9 Diapositive numéro 11Diapositive numéro 12 Average neutrino population ( per cubic meter of space) Diapositive numéro 14Diapositive numéro 15Twelve varieties of neutrinos � �Feeble interaction of neutrinos with other particles.A sheet of paper is enough to shade a flux of photons ���To screen a flux of neutrinos : �a screen of lead� of many light-years � Neutrino telescopes Diapositive numéro 21Diapositive numéro 22Feeble interaction of neutrinos with other particles �Neutrino detection program Sun Diapositive numéro 26Diapositive numéro 27Diapositive numéro 28Origin of solar energy ? Origin of solar energy Origin of solar energy Solar neutrinos Diapositive numéro 33Diapositive numéro 34Diapositive numéro 35Neutrino luminosity of Sun Neutrino luminosity of Sun Neutrino luminosity of Sun The neutrinic sun does not set Diapositive numéro 40Diapositive numéro 41Matter and antimatter Diapositive numéro 43Diapositive numéro 44 Solar core ? The sun emits large fluxes neutrinos and very small amount antineutrinos Forty years of solar neutrino observations. Solar neutrinos Diapositive numéro 51Solar 11 year cycle �Number of sunspots � since 1960 Diapositive numéro 53Diapositive numéro 54The solar neutrino flux is constant Solar neutrinos There are three neutrino flavors Sun emits only e-neutrinosNeutrinos can change flavors �« oscillate)�(as the pokemons ! ) Neutrino oscillation Neutrino oscillation Diapositive numéro 62Diapositive numéro 63Diapositive numéro 64 From the Sudbury Observatory Problem Neutrino masses Neutrino velocity All stars emit neutrinos Neutrino emission by hotter starsFractional neutrino fluxes Diapositive numéro 72On feb 23 , 1987 at 10h00 Diapositive numéro 74Diapositive numéro 75Courbe de lumière de 1987a A few neutrinos are detected tthree hours before the photons Diapositive numéro 78Diapositive numéro 79Supenova luminosity Neutrinos in cosmology Fossil radiation of neutrinos Diapositive numéro 83Energy spectrum of Fossil RadiationDiapositive numéro 85Dark matter and energy.Diapositive numéro 87Could dark matter be composed of neutrinos? Could dark matter be composed of neutrinos ? Matter antimater enigma Matter and antimatter in the early universe Neutrino Cosmic Densities . Influence of electron density on propagation of neutrinos (MSW)effect MSW effect on solar neutrinos Oscillation of atmospheric neutrinos Diapositive numéro 96NEUTRINOS 2006Antares detector �in the sea close to Toulon Diapositive numéro 99Diapositive numéro 100Diapositive numéro 101Diapositive numéro 102Diapositive numéro 103La vie des étoiles: Transformation de masse en énergie . E =mc2Diapositive numéro 105