THE NEUTRINO PARTICLE: HOW TO LEARN A GREAT DEAL BY OBSERVING NOTHING A DRAMA

2. THE NEUTRINO PARTICLE: HOW TO LEARN A GREAT DEAL BY OBSERVING NOTHING A DRAMA in Four Acts and a Dozen Scenes Haim Harari

3. Act I BEFORE PRE-HISTORY

4. SCENE 1 Looking Back in Time The edge of the universe = The beginning of the universe Distant observations Studying the beginning of the universe  "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.

5. 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

6. 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"

7. Act II A “TERRIBLE” TALE ABOUT AN INVISIBLE PARTICLE

8. SCENE 1 Dear Radioactive Ladies and Gentlemen bdecay e- A1 A2 + e-

9. SCENE 1 Dear Radioactive Ladies and Gentlemen bdecay e- e- e- e- N1 N2 + e- The electron energy: Always the same?

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

11. SCENE 1 Dear Radioactive Ladies and Gentlemen bdecay n e- e- e- e- N1 N2 + e- +n

12. SCENE 1 Dear Radioactive Ladies and Gentlemen bdecay n e- e- e- e- n n p p e- n n  p + e- +n

13. 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“ !

14. 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 Hans Bethe Creating the heavy chemical elements p n e, n We must: Look into the center of the sun Look into the center of the star

15. Nevertheless: n n+n  e- + p SCENE 3 Catching the thief Pauli:"I did a terrible thing. I postulated a particle, which cannot be discovered" 16 When 10 neutrinos pass through Earth, only one hits something.

16. SCENE 3 Catching the Thief Reactor Detector Reines-Cowan 1956 THE THIEF HAS BEEN CAUGHT!

17. Act III "WHO ORDERED THAT?"

18. SCENE 1 And what would you like for dessert? 1935: The Elementary Particles p, n, e-,n

19. 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

20. Schwarz Lederman Steinberge The first neutrino beam in an accelerator A proof that there are two distinct kinds of neutrinos ne , nm • Meanwhile:Dozens of new particles • All are made out of quarks ude-ne Ordinary matter Heavy matter sm-nm 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?

21. Within a year Discovery of the third "brother" of the electron Predicting the third neutrino Predicting the "third generation" of quarks t nt t b The standard model u d ene csmnm First generation Second generation Third generation t bt nt No more! SCENE 2 The November Revolution 11/11/1974 An indirect observation of an additional quark c Completing the "second generation" of building blocks

22. No reason for an identity between the two classifications Mixing and oscillations are expected A three-way schizophrenia SCENE 3 Reincarnation Does the neutrinohave 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

23. SCENE 3 Reincarnation Example: neEmitted from the sun. On its way to us, converts intonm nmEmitted from an accelerator. On its way to detector converts intont Conclusion: Neutrino oscillations non-vanishing neutrino masses First experiments in accelerators and nuclear reactors – negative results!

24. Act IV WE SEE NOTHING Therefore EVERYTHING IS CLEAR

25. 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?

26. Homestake n + Cl37 e +A37 400 tons of cleaning fluid Gallex n + Ga71 e +Ge71 30 tons SCENE 1 Underground Astronomy

27. SCENE 1 Underground Astronomy Kamiokande n+ n  e + p 5000 tons water e Super-luminary "Boom"

28. 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.

29. 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!

30. 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

31. 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"