Dear Radioactive Ladies and Gentlemen. SCENE. 1. Th

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THE NEUTRINO PARTICLE HOW TO LEARN A
GREAT DEAL BY OBSERVING NOTHING A DRAMA
in Four Acts and a Dozen Scenes Haim Harari
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Act I BEFORE PRE-HISTORY
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SCENE 1
Looking Back in Time
The edge of the universe

The beginning of the universe
Studying the beginning of the universe
Distant observations
?
"Conventional" astronomy Visible light and other
kinds of radiation "Obstacles" Clouds,
the atmosphere Avoiding "background" A Dark
night, no background radiation
The detector must observe the desired radiation,
not the undesired one.
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SCENE 2
Darkness
The beginning of the universe Complete
darkness Outer Space Complete darkness Most
matter in every galaxy Invisible and dark Most
matter in the universe Invisible and dark Most
energy in the universe Invisible and dark
The universe is "flat" and its total mass is
known 70 - Dark energy 25 - Dark matter, mostly
unknown 4 - Free Hydrogen and Helium 0.5 -
Stars
Understanding the universe and its creation
requires an intensive study of the invisible
dark matter and energy
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SCENE 3
The Inside story
Light and other radiation, come to us
from the surface
of a star What happens inside the sun?
What happens inside a star, when it is born?
When it develops? When it explodes?
The temperature on the surface of the sun
thousands of degrees. The temperature inside
the sun millions of
degrees. Understanding the secrets of the suns
requires looking inside the sun Understanding the
secrets of a star requires an "inside photograph"
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Act II A TERRIBLE TALE ABOUT AN
INVISIBLE PARTICLE
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SCENE 1
Dear Radioactive Ladies and Gentlemen
b decay
e-
A1 ? A2 e-
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SCENE 1
Dear Radioactive Ladies and Gentlemen
b decay
e-
e-
e-
e-
N1 ? N2 e-
The electron energy Always the same?
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SCENE 1
Dear Radioactive Ladies and Gentlemen
The electron energy Always the same?
Experiment Not at all. Every time a different
energy Some energy is always missing Someone is
"stealing" energy
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SCENE 1
Dear Radioactive Ladies and Gentlemen
b decay
n
e-
e-
e-
e-
N1 ? N2 e- n
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SCENE 1
Dear Radioactive Ladies and Gentlemen
b decay
n
e-
e-
e-
e-
n
n
p
p
e-
n ? p e- n
n
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SCENE 2
The Secret of the Sun
What is the source of energy of the sun? Burning
conventional fuel? The mass is sufficient for
thousands of years. But the sun exists billions
of years.
WE NEED A PROCESS, WHICH IS A MILLION TIMES
"STRONGER !
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SCENE 2
The Secret of the Sun
A nuclear "fire" inside the sun All nuclear
processes in the sun emit neutrinos the life
story of every star is related to similar
processes
Creating the heavy chemical elements
Hans Bethe
p n e, n
We must Look into the center of the sun
Look into the center of the star
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SCENE 3
Catching the thief
Pauli "I did a terrible thing. I postulated a
particle, which cannot be discovered"
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When 10 neutrinos pass through Earth, only one
hits something.
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SCENE 3
Catching the Thief
Detector
Reactor
Reines-Cowan 1956
THE THIEF HAS BEEN CAUGHT!
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Act III "WHO ORDERED THAT?"
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SCENE 1
And what would you like for dessert?
1935 The Elementary Particles
p, n, e-, n
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SCENE 1
And what would you like for dessert?
1935 The elementary particles
p, n, e-, n
A comedy of errors Yukawa predicted
1935 Anderson-Nedermayer discovered 1937 The
celebration started and ended 1945 Powel
discovered the Yukawa particle Anderson-Nedermayer
remained with a shocking discovery
m 200 times heavier than the electron, but
identical to it in all other properties
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SCENE 1
And what would you like for dessert?
And the neutrino?
The electron comes with a neutrino m is also
created with a neutrino Are these neutrinos
identical?
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SCENE 2
The November Revolution
11/11/1974 An indirect observation of an
additional quark c Completing the "second
generation" of building blocks
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SCENE 3
Reincarnation
Does the neutrino have a mass? If so, it
is tiny Theory There is a good
reason for a tiny mass, no
explanation for a zero mass.
n1 n2 n3
ne nm nt
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SCENE 3
Reincarnation
Example ne Emitted from the sun. On its
way to us, converts into nm nm Emitted from an
accelerator. On its way to detector converts
into nt Conclusion Neutrino oscillations
non-vanishing neutrino masses First
experiments in accelerators and nuclear reactors

negative results!
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Act IV WE SEE NOTHING Therefore EVERYTHING
IS CLEAR
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SCENE 1
Underground Astronomy
What is happening inside the sun? Who can escape
from the center of the sun and reach us on
earth? Where can we "catch" a neutrino"
Everywhere ! Where is the minimal "background"?
Deep underground How do you catch neutrinos?
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SCENE 1
Underground Astronomy
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SCENE 1
Underground Astronomy
Kamiokande
n n ? e p
5000 tons water
e
Super-luminary "Boom"
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SCENE 2
What did the fourth guest get for dessert?
Davis et al Number of neutrinos arriving from
the sun is only one third of the expected
number Kirsten, Dostrovsky et al About half of
the expected number Koshiba et al About half of
the expected number
Koshiba et al The ratio between the types of
neutrinos in cosmic radiation is also different
from the expected ratio.
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SCENE 2
What did the fourth guest get for dessert?
Conclusion Neutrino mixing and neutrino
oscillations!!! The neutrinos have tiny masses!
nt nm ne
- 50 meV - 8 meV - Lighter
And the fourth guest also received something he
did not order!
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SCENE 3
A voyage into the darkness

• The birth of a neutrino astronomy,
• performed underground
• Understanding processes inside the sun
• Understanding star explosions (Supernova)
• Studying neutrino properties
• Neutrinos are approximately 0.5 of the universe
  mass.
• In every cubic centimeter of the universe there
  are
• 400 photons and 110 neutrinos of each of the
  three kinds.

The challenge Understanding the dark matter and
the dark energy
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Epilog
The tiniest and most elusive particle plays a
crucial role in creating the universe
We observe the inside of a star and study the
darkness of the universe, by going underground !
"Neutrino physics is largely the art of learning
a great deal by observing nothing"
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