Neutrino astronomy Hubert Reeves 2011 11 09 •

Structure of atoms

1932 Discovery of neutrons Chadwick .

• An isolated neutron disintegrates in 20 minutes

1932 Discovery of the neutron .

• Life time: twenty minutes• Disintegrates in one proton and one electron • neutron

=»

proton+electron

• But : problem !

Energyandmomentumare notconserved!!!

Energy

is

not conserved

!!!, also

momentum

,

• Lavoisier 1795 • «

Nothing can be lost and nothing can be

created

»

Wolfgang Pauli

Suppose the existence of a new particle

With no electric charge

With very feeble interactions with other particles .

The «

neutrino

»

• The neutrino carries the missing energy and momentum

Neutrinos are detected in 1965 Generated by neutron

disintegrations In nuclear reactors

Average neutrino population ( per cubic meter of space)

•• The most

abundant

particle

in the cosmos !

.

• Neutrinos: =450 millions • Photons := 400 millions • Electrons , protons : = 1 .

•

Large spectrum of energies

From mev to GevSunSupernovae Cosmic rays Earth Cosmology

Twelve

varieties

of neutrinos

• Neutrinos and antineutrinos

• Three «

flavors

»

• neutrino –e• neutrino –mu• neutrino –tau•• Two spins (up and down)

Feeble interaction of neutrinos with other particles.

• Disadvantage : difficult to detect their presence

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

Hundred of thousands tons

of detecting liquid

are needed

to register a few neutrinos per second

Thousands of Cerenkof detectors

Feeble

interaction of neutrinos with other

particles

• Advantage : they may come from opaque locations:

• Stellar centers• Galactic nuclei • Earth interior •

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 •

Sun

Light come from the surface,

Neutrinos come from the center .

UV come from the surface

Photons diffuse

Neutrinos come directly from the center

Origin of solar energy ?

Transformation of hydrogen in helium

4protons =

»1 Helium + 4 neutrinos

Origin of solar energy

Transformation of hydrogen in helium

Fifteen millions of degree

Neutrinos are emitted from the nuclear reactions .

Origin of solar energy

Solar neutrinos

detected in 1962 in a mine of South Dakota

• Ron Davis•

Confirm the nuclear origin of solar (stellar) energy

Neutrino luminosity of Sun

• Neutrinos : 5 % • Photons : 95 %• Sixty billions of neutrinos cross our body each

second

• . .

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)

• . .

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!!!)

• . .

The neutrinic sun does not set

• Detectable all night • No eclipse !

Matter and antimatter

For each

particle

there

exist

an antiparticle

• Is the Sun made of matter or antimatter?

• Northerh Lights : eV photons from interaction of solar wind ( protons) with earth atmosphere show that the solar surfac is made of matter.

• 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

Solar core ?

The sun

emits

large fluxes neutrinos and very

small

amount

antineutrinos

• the solar core is made of matter

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

.

•Confirm the nuclear source of solar( stellar)

energy

Solar neutrinos

Solar 11 year cycle Number of sunspots

since 1960

NUMBER of sunspot

• No variation with the 11 year cycle

The solar neutrino flux is constant

•Confirm the nuclear source of solar( stellar)

energy

The neutrino flux is only one third of solar model predictions ;

Why ?

Solar neutrinos

There are three

neutrino flavors

1)

neutrino électronic

(e)

2)

neutrino muonic

(mu)

3)

neutrino tauic

(tau)

Sun emits only e-neutrinos

• Detectors detect only e–neutrinos• Why only one third?

Neutrinos can change flavors « oscillate) (as the pokemons ! )

Neutrino oscillation

km

Neutrino oscillation

• Can be measured through long base-line studies

USA : Soudan –Chicago , Japan Kamiokande

Europe ; Cern-

Gran Sasso 730 km

Oscllation of MeV e –neutrinoafter one hundred Km 100- km

From the Sudbury Observatory

The Sun emits only e-neutrinos

They oscillate in the path

Only one third e-neutrinos arrive at earth .!

Problem

• To oscillate must be massive • The neutrino were first assumed to be

massless.

Neutrino masses

• Around one eV • One millionth of the electron mass.•• Solar studies gives new physics!!

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)

All stars emit neutrinos

Neutrino emission by hotter stars

Fractional neutrino fluxes

• Solar : 5 % • Red Giants + de 50% • Supernovae : 99.99 %

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

Courbe de lumière de 1987a

A few neutrinos are detected

tthree hours

before

the photons

Why?

Photon diffuse !

• L( neutrinos) =3x1053 erg/sec • = 3x1019L ( solar photon ) • = 3x108 galaxies!

Supenova luminosity

Neutrinos in cosmology

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

Visible matter in the universe

Energy

spectrum

of Fossil

Radiation

Dark matter and energy.

• Only 5 % of the cosmic density is visible ( emission of photons)

• 20% is dark matter • 75% is dark energy

Could

dark

matter

be

composed

of neutrinos?

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 !!

Matter antimater enigma

• Big Bang =»

high temperature

• Thermal equilibrium • Matter population=antimatter population • Annihilation during cooling• Only light should be left.

We exist!!! .

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

• . •

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

Influence of electron

density

on propagation of neutrinos

(MSW)effectNégligible for (E(nu) 5MeV

Oscillation depends upon electron densities

()

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)

-

Surviv;ng fraction f(B-8) = 35 %

Oscillation of atmospheric neutrinos

Created by atmospheric collisions of cosmic rays

• Oscillates through the earth volume

•

NEUTRINOS 2006

2006

Antares detector in the sea close to Toulon

• Screened by whole earth

• No detection at november 2011 • Problem ?

Crab Nebula 4 july 1054

• 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?

La vie des étoiles: Transformation de masse en énergie . E =Δmc2

Vecteurs: gravité

et nucléaire.

Emission : photons et neutrinos .

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