THE NEUTRINO PARTICLE:

HOW TO LEARN A GREAT DEAL

BY OBSERVING NOTHING

A DRAMA

in Four Acts

and a Dozen Scenes

Haim Harari

THE NEUTRINO PARTICLE:

HOW TO LEARN A GREAT DEAL

BY OBSERVING NOTHING

A DRAMA

in Four Acts

and a Dozen Scenes

Haim Harari

Act I

BEFOREPRE-HISTORY

Act I

BEFOREPRE-HISTORY

Looking Back in Time Looking Back in Time

The detector must observe the desired radiation, not the undesired one.

SCENE

1

The edge of the universe

Studying the beginning of the universe

The beginning of the universe

Distant observations

"Conventional" astronomy: Visible light and other kinds of radiation"Obstacles": Clouds, the atmosphereAvoiding "background": A Dark night, no background radiation

=

DarknessDarkness

The universe is "flat" and its total mass is known70% - Dark energy25% - Dark matter, mostly unknown 4% - Free Hydrogen and Helium0.5% - Stars

SCENE

2

The beginning of the universe Complete darknessOuter Space Complete darknessMost matter in every galaxy Invisible and darkMost matter in the universe Invisible and darkMost energy in the universe Invisible and dark

Understanding the universe and its creation requires an intensive study of the invisible dark matter and energy

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 Inside storyThe Inside story

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 sunUnderstanding the secrets of a star requires an "inside photograph"

SCENE

3

Act II

A “TERRIBLE” TALE

ABOUT

AN INVISIBLE PARTICLE

Act II

A “TERRIBLE” TALE

ABOUT

AN INVISIBLE PARTICLE

A1 A2 + e-

e-

decay

Dear Radioactive Ladies and GentlemenDear Radioactive Ladies and GentlemenSCENE

1

N1 N2 + e-

e-e-

e-

e-

The electron energy:Always the same?

Dear Radioactive Ladies and GentlemenDear Radioactive Ladies and GentlemenSCENE

1

decay

Dear Radioactive Ladies and GentlemenDear Radioactive Ladies and GentlemenSCENE

1

The electron energy: Always the same?

Experiment: Not at all.Every time a different energySome energy is always missing

Someone is "stealing" energy

The Neutrino: Dark, invisible, penetrating, elusive, massless (?)

Neutrino

N1 N2 + e- +

e-e-

e-

e-

Dear Radioactive Ladies and GentlemenDear Radioactive Ladies and GentlemenSCENE

1

decay

n p + e- +

np

np

e-

e-

e-

e-

e-

decay

Dear Radioactive Ladies and GentlemenDear Radioactive Ladies and GentlemenSCENE

1

WE NEED A PROCESS, WHICH IS A MILLION TIMES "STRONGER“ !WE NEED A PROCESS, WHICH IS A MILLION TIMES "STRONGER“ !

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.

SCENE

2 The Secret of the SunThe Secret of the Sun

A nuclear "fire" inside the sun

All nuclear processes in the sun emit neutrinosthe life story of every star is related to similar processes

Creating the heavy chemical elements

p ne,

Hans Bethe

We must: Look into the center of the sun Look into the center of the star

SCENE

2 The Secret of the SunThe Secret of the Sun

Nevertheless:

+n e- + p

When 10 neutrinos pass through Earth, only one hits something.

SCENE

3 Catching the thiefCatching the thief

Pauli: "I did a terrible thing.I postulated a particle,which cannot be discovered"

16

Reines-Cowan 1956 THE THIEF HAS BEEN CAUGHT!

SCENE

3 Catching the ThiefCatching the Thief

DetectorReactor

Act III

"WHO ORDERED THAT?"

Act III

"WHO ORDERED THAT?"

p, n, e-, 1935: The Elementary Particles

SCENE

1 And what would you like for dessert?And what would you like for dessert?

A comedy of errorsYukawa predicted 1935Anderson-Nedermayer discovered 1937The celebration started … and ended 1945Powel discovered the Yukawa particleAnderson-Nedermayer remained with a shocking discovery

p, n, e-, 1935: The elementary particles

SCENE

1 And what would you like for dessert?And what would you like for dessert?

– 200 times heavier than the

electron,but identical to it in all other properties

Meanwhile: Dozens of new particles All are made out of quarks

Ordinary matter

Heavy matter s -

u d e- e

e

The first neutrino beam in an acceleratorA proof that there are two distinct kindsof neutrinos

Schwarz Lederman Steinberge

SCENE

1 And what would you like for dessert?And what would you like for dessert?

And the neutrino? The electron comes with a neutrino

is also created with a neutrinoAre these neutrinos identical?

11/11/1974

An indirect observation of an additional quark cCompleting the "second generation" of building blocks

SCENE

2 The November RevolutionThe November Revolution

u d e e

c s

t b

First generation

Second generation

Third generation No more!

The standardmodel

t b

Within a year

Discovery of the third "brother" of the electronPredicting the third neutrinoPredicting the "third generation" of quarks

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.

e

No reason for an identity between the two classifications

Mixing and oscillations are expectedA three-way schizophrenia

SCENE

3 ReincarnationReincarnation

Example:

e Emitted from the sun.

On its way to us, converts into

Emitted from an accelerator.

On its way to detector converts into

Conclusion:Neutrino oscillations non-vanishing neutrino massesFirst experiments in accelerators and nuclear reactors –

negative results!

SCENE

3 ReincarnationReincarnation

Act IV

WE SEE NOTHING

Therefore

EVERYTHING IS CLEAR

Act IV

WE SEE NOTHING

Therefore

EVERYTHING IS CLEAR

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 undergroundHow do you catch neutrinos?

SCENE

1 Underground AstronomyUnderground Astronomy

Gae + Ge71

Gallex

30 tons

400 tons of cleaning fluid

Cle + A37

Homestake

SCENE

1 Underground AstronomyUnderground Astronomy

e

+ n e + pKamiokande

5000 tons water

SCENE

1 Underground AstronomyUnderground Astronomy

Super-luminary"Boom"

Koshiba et al: The ratio between the types of neutrinos in cosmic radiation is also different from the expected ratio.

SCENE

2 What did the fourth guest get for dessert?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 numberKirsten, Dostrovsky et al: About half of the expected numberKoshiba et al: About half of the expected number

Conclusion: Neutrino mixing and neutrino oscillations!!!The neutrinos have tiny masses!

eAnd the fourth

guest also received something he did

not order!

SCENE

2 What did the fourth guest get for dessert?What did the fourth guest get for dessert?

- 50 meV

- 8 meV

- Lighter

The challenge: Understanding the dark matter and the dark energy

The birth of a neutrino astronomy, performed underground

1. Understanding processes inside the sun2. Understanding star explosions (Supernova)3. 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.

SCENE

3 A voyage into the darknessA voyage into the darkness

"Neutrino physics is largely the art of learning a great deal by

observing nothing"

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 !

EpilogEpilog