1. Neutrinos Highlights and Heroes An „Appetizer“ for the lecture Neutrinos in Physics and Astrophysics Christian Spiering, DESY Zeuthen

2. Content First Lecture (1) 1) From the postulate to the discovery  Wolfgang Pauli, eccentric theoretician, becomes father of the neutrino  Enrico Fermi, universalist, formulates the theory of weak interactions  Fred Reines, restless experimentalist, discovers the neutrino  Bruno Pontecorvo suggests two neutrino species which are discovered by Lederman, Steinberger and Schwarz

3. Content First Lecture (2) 2) From Pontecorvo’s idea to the Nobel Prize 2015  Bruno Pontecorvo (“Mr. Neutrino”) develops the idea of oscillations … and predicts a deficit of solar neutrinos!  … which is observed by Raymond Davis and later by Kamiokande  Mikheev, Smirnov and Wolfenstein: Matter oscillations  Art Mc Donald proves the oscillation of solar neutrinos  Atmospheric neutrinos in the 1980s: deficit or no deficit?  Takaaki Kajita proves the oscillation of atmospheric neutrinos  Nobel Prize 2015 to McDonald and Kajita

4. Content Second Lecture Neutrinos from heaven  Raymond Davis detects solar neutrinos in USA – but much less than calculated.  Masatoshi Koshiba detects solar neutrinos in Japan – but also less than expected  Vladimir Gavrin and Till Kirsten with SAGE and GALLEX: It’s not the solar model which is wrong!  A centennial day: Feb 23, 1987: neutrinos from a Supernova  Neutrinos and Supernovae  Facts and emotions: the interpretation of supernova SN1987A  From Moisej Markov to Francis Halzen: catching neutrinos at highest energy.

6. A little prehistory  1896: Henri Becquerel discovers radioactivity (by chance!)  1897-98: Ernest Rutherford distinguishes  and  -radiation  1900: Paul Villard identifies  -radiation (not deflected by magnetic fields!)  ~ 1900: Pierre & Marie Curie, Becquerel and others identify  -radiation as electrons  1908: Rutherford and Hans Geiger identify  -radiation as He nuclei Penetration of ,  and  radiation

7. A little prehistory  1911/1913 The Rutherford-Bohr model of the atom: positive nuclei + electrons which can move only on quantized orbits  Early 1920s: Widely accepted assumption: the nucleus consists of protons and electrons

8. The puzzle Gamma spectrum: lines Alpha spectrum: lines Beta spectrum Why continuous???

9. The puzzle  Lise Meitner and Otto Hahn (since 1907): Why are beta spectra continuous?  Many measurements, many contradictory results (continuum vs. lines), many debates (Meitner, Charles Ellis, James Chadwick, Rutherford and others)  Mid of the 1920s: no way out – the beta spectrum is continuous!

10. The puzzle If beta decay goes like nucleus A  nucleus A‘ + electron why don‘t we see a line spectrum? Expected for 2-particle final state

11. The puzzle If beta decay goes like nucleus A  nucleus A‘ + electron why don‘t we see a line spectrum? Expected for 2-particle final state Niels Bohr: Energy conservation only for an ensemble of interactions, not for individual interactions ? (i.e. just another surprise of quantum mechanics)

12. 1930: start of the story Wolfgang Pauli: nucleus A  nucleus A‘ + electron + „neutron“ Expected for 2-particle final state - neutral - spin ½ - mass < electron mass - weakly interacting

13. Wolfgang Pauli, the eccentric theoretician  Born 1900 in Vienna.  1918-22: study of physics in Munich (with Sommerfeld). PhD 1922  1923: 237-page article about theory of relativity for Enzyklopädie der mathematischen Wissenschaften  Göttingen, Kopenhagen. 1923 -1928: Professor in Hamburg, from 1928 on in Zurich  1924: exclusion principle ("Pauli principle“)  Eminent role in development of quantum theory (Pauli was often called "conscience of physics“). Sharp, sarcastic, arrogant. - „Ganz falsch!!“ (utterly wrong!). - - Once, on an unclear paper: “It is not even wrong!”not even wrong

14. Wolfgang Pauli, the eccentric theoretician  1930, postulate of the neutrino (named 1933 by Enrico Fermi).  1931: nervous breakdown, relation to C.G Jung, later work on parapsychology and psychoanalysis  Liked to spend evenings in night bars  Rarely started working before 12 o’clock  The “Pauli effect”: something is breaking if he comes close  1935: short visit at Princeton, again from 1940-49, then back to Zurich  1945: Physics Nobel price for the exclusion principle  1958, Pauli dies in Zurich from cancer (in a room with number 137!)

15. The famous Pauli Letter from Dec. 4, 1930 … to Lise Meitner and a Meeting of German Physicists in Tübingen: Pauli did not come because he preferred to visit a dancing ball in Zurich!

16. The famous Pauli Letter from Dec. 4, 1930 … to Lise Meitner and a Meeting of German Physicists in Tübingen:

17. Fermi,  -decay and the neutrino  1932: James Chadwick discovers the neutron  A few months later, Dmitry Ivanenko and Werner Heisenberg independently propose that the neutron is a component of nuclei.  Pauli: mixed feelings – since this cannot be „his“ neutron.  1933: Fermi invents the name Neutrino (ital.: the small neutral)  1932/33: Fermi develops a theory of  -decay (which is not accepted by NATURE -- „too far from reality“ -- and then published in „Nuovo Cimento“ and „Zeitschrift für Physik“ (1933)

18. Enrico Fermi: „architect of the nuclear age“  Born in Roma 1901  Studies Physics in Pisa. PhD 1922  1926 professor of theoretical physics at Roma university: Fermi-Dirac statistics, Fermi’s golden rule, Fermi resonance, …  1931-33: theory of beta decay, invents the name neutrino  1934: discovers induced radioactivity by bombarding a nuclear target with neutrons, the first step to nuclear chain reactions  Nobel price in 1938 for induced radioactivity and discovery of transuranic elements. At this occasion, he emigrates from the fascist government of Italy, becomes professor at Columbia University, USA.  Constructs first atomic reactor in Chicago (becoming critical in Dec. 1942) and then works until 1945 at Los Alamos.  1945: director of the new Institute of Nuclear Physics of Chicago.  Dies 1954 from cancer

19. Fermi‘s idea for measuring mass of the neutrino

20. … and the modern experiments m( e ) = 20 eV m( e ) = 0 eV Electron Energy (keV) Present limit : m( e ) < 2.2 eV (Moscow, Mainz) Future: KATRIN (Karlsruhe)

21. … and the modern experiments Present limit : m( e ) < 2.2 eV (Moscow, Mainz) Future: KATRIN (Karlsruhe) Sensitivity to m( e ) ~ 0.2 eV

22. Desperately small cross section of neutrinos 1934: Hans Bethe and Rudolf Peierls show that the interaction cross section of neutrinos should be extremely small: billions of times smaller than that of electrons. At a few MeV: Peierls Bethe Bethe was also a precursor in the understanding of the origin of sun's light and of the models that predict the solar neutrinos flux.

23. Fred Reines, restless experimentalist and discoverer of the neutrino

27. Frederick Reines  Born in 1918 in Paterson, New Jersey (parents had been emigrated from Russia)  Gifted school-boy experimenter, sings in chorus and for some time even considers to start a professional singing career  PhD in 1944, New York University (Theoretical Physics)  1944 – 1959: Los Alamos Laboratory, work on Manhattan project, theory of blast waves  1951: sabbatical year – start with work on neutrinos  1956: discovery of the neutrino (more precisely: electron anti-neutrinos)  1959 – 1966: Case Institute of Technology  Works of double beta decay, electron lifetime, proton decay  Discovery of atmospheric neutrinos in a mine in South Africa

28. Frederick Reines  1966 – 1998: Univ. of California, Irvine  1973: one of the founders of the DUMAND project (the grandfather experiment of the Baikal neutrino telescope and IceCube)  1980s: One of the principal investigators of the IMB underground detector to search for proton decay  1990s: developing Alzheimer disease  1995: Nobel Prize for the discovery of the neutrino  1998: dies on August 26

29. Reines‘ first idea to detect neutrinos … … from the explosion of a nuclear bomb !

30. But then: Nucelar reactors as source 1953: Hanford Reactor 1955: much stronger military reactor in Savannah River Fred Reines Clyde Cowan Fred Reines Clyde Cowan

31. First attempt: Hanford detector Anti-Electron Neutrinos from Hanford Nuclear Reactor 3 Gammas in coincidence p n Cd   

32. photo- multipliers scintillator CdCl solved in water Savannah River experiment: the principle

33. Savannah River: Discovery 1956 The detector A neutrino signature Nobel Prize 1995

35. Pauli‘s answer to Reines

36. Bruno Pontecorvo (1959) Is there a second neutrino?

37. Bruno Pontecorvo  Born 1913 in Pisa, Italy  1929: starts study of Engineering at University Pisa but changes to Physics at University Rome in 1931  Becomes member of Fermi‘s group, takes part in the experiments with slow neutrons and induced radioactivity (1934)  Fermi: „… scientifically one of the brightest men to whom I have come into contact in my scientific career“  1936: moves to Paris to work with the Frederic and Irene Joliot-Curie. Many socialist friends.  Goes to USA (no return to Italy because of racial laws against jews)  Works for oil company and develops method of oil logging with the help of slow neutrons

38. Bruno Pontecorvo  Not taken to the Manhattan project because of his communist connections  1943: work in Canada on reactor design, new particle detectors, muon decay and cosmic rays  1946: proposes radio-chemical method for detection of neutrinos which later led to discovery of solar neutrinos (Nobel Prize for Ray Davis in 2002)  1948: moves to Harwell (England), Nuclear Physics Division  August 1950: After a holiday in Italy, Pontecorvo disappears, together with his family (as it turns out later, to the USSR)  Pontecorvo a master spy??? But he had no or limited access to secret objects and to secret information!  1951-55: experiments at the Dubna accelerator

39. Bruno Pontecorvo  1956: Dubna becomes International Institute and Pontecorvo becomes internationally visible again.  1957/58: first ideas on neutrino oscillations  1959: proposal how to test the existence of a second neutrino (muon neutrino)  1962: Discovery of  by Lederman, Schwartz and Steinberger (Nobel Prize 1988)  1969—1975: Present formulation of neutrino mixing and oscillations. Predicts solar neutrino deficit.  1993: Pontecorvo dies in Dubna  Epilogue: The 2015 Nobel Prize goes to Art McDonald and Takaaki Kajita for the final confirmation of neutrino oscillations, almost 23 years after Pontecorvo‘s dead …

40. Bruno Pontecorvo Marianne, Gil and Bruno Pontecorvo, 1940

41. Bruno Pontecorvo 1955

42. Bruno Pontecorvo

45. Pontecorvo and the muon neutrino  Beta-decay : n  p + e - + anti-  Pion decay:    +  Muon-decay (Pontecorvo and Hinks 1946):  -  e - + 2 neutrino-like particles ( + anti- ?)  Similar coupling constants for both processes (same force!)  Not observed:  -  e - +   … but this process should occur due to occasional annihilation + anti-     are there 2 neutrino types with different quantum numbers, e and , so that muon decay reads like  -  e - +  + anti- e ?

46. p    Accelerator  -decay:    +  Target  -absorber Bruno Pontecorvo (Dubna) Leon Lederman, Melvin Schwartz, Jack Steinberger (Brookhaven) neutrino beam

47. Bruno Pontecorvo (Dubna) Leon Lederman, Melvin Schwartz, Jack Steinberger (Brookhaven) If the muon neutrino interacts and is different from the electron neutrino, it should produce muons, not electrons:  + nucleus   + something

48. The Brookhaven experiment Nobel Prize 1988

49. The Bookhaven experiment Nobel Prize 1988

50. And finally: discovery of the third neutrino Slide taken from Karsten Heeger

53. Content First Lecture (2) 2) From Pontecorvo’s idea to the Nobel Prize 2015  Bruno Pontecorvo (“Mr. Neutrino”) develops the idea of oscillations … and predicts a deficit of solar neutrinos!  … which is observed by Raymond Davis and later by Kamiokande  Mikheev, Smirnov and Wolfenstein: Matter oscillations  Art Mc Donald proves the oscillation of solar neutrinos  Atmospheric neutrinos in the 1980s: deficit or no deficit?  Takaaki Kajita proves the oscillations of atmospheric neutrinos  Nobel Prize 2015 to McDonald and Kajita

54. Oscillations 1957 - 62  1957: Inspired by a paper of Gell-Mann and Pais who suggest K 0  anti-K 0 oscillations, Pontecorvo speculates about the possibility of oscillations of the kind  anti-  1958: there are rumors that Reines have observed (at a reactor) the process  which is only possible with neutrinos (not anti-neutrinos) … or the lepton number is not conserved !

55.  1958: This rumor was another motivation for Pontecorvo to speculate about  anti- oscillations  1962 (muon neutrino was discovered meanwhile) Z. Maki, M. Nakagawa, S. Sakata: Oscillations 1957 - 62

57.  1967: Pontecorvo proposes neutrino oscillations of the kind e lefthanded  anti- e lefthanded  Since only lefthanded and righthanded anti- take part in weak interactions, 50% of the neutrinos „disappear“  Pontecorvo predicts a corresponding deficit for solar neutrinos!  1969: Pontecorvo and Gribov consider e   oscillations and describe the time evolution of orginally pure weak eigenstates Neutrino oscillations 1967-76

58. L

59.  = mixing angle  m² = |m 1 ² - m 2 ²|, E = energy, L = distance L Neutrino oscillations 1967-76

60.  1976: Pontecorvo and Samoil Bilenky formulate neutrino mixing in full analogy to quark mixing, using only Dirac neutrinos (no Majorana neutrinos) Neutrino oscillations 1967-76

61. Matter Oscillations (MSW effect) Stanislav Mikheev and Alexei Smirnov, independently Lincoln Wolfenstein, find the mechanism of matter oscillations … or „resonant oscillations“ (when a neutrino passes through a region with a certain electron density - dependent on  m and E )

62. Solar neutrinos and the MSW effect electron neutrino tau neutrino muon neutrino

63. Formulation for 3 neutrinos

64. Solar Neutrinos and Oscillations  1970s: Raymond Davis detects solar neutrinos with his Chlor-Argon experiment, but only only 1/3 of the expected flux  1980s: Masatoshi Koshiba measures 50% of the expected flux with the water detector Kamiokande  THE DEFICIT IS REAL  1990s: Vladimir Gavrin with the SAGE detector and Till Kisten with the GALLEX detector (both Gallium-Germanium) measure lowest energy neutrinos, again with a deficit  THE DEFICIT IS NOT DUE TO A WRONG SOLAR MODEL  Art Mac Donald with his SNO experiment confirms that the number of all neutrino types is as expected  THE DEFICIT IS NOT DUE TO DECAYING NEUTRÌNOS …..BUT TO NEUTRINO OSCILLATIONS Nobel Prize 2015 details see next lecture

65. C. Spie ring MG- 11, Berli n cosmic proton ≈15 km π+π+  + e+e+ e   „Atmospheric“ Neutrinos

66. Atmospheric neutrinos  Detected 1965 by two groups at almost the same time:  Fred Reines and his CWI group in a South African mine  KGF group in the India Kolar Gold Field mine  1979: The Baksan Underground Scintillation Telescope starts operation and starts measuring atmospheric neutrinos

67. Water Cherenkov Detectors KAMIOKAIMB Japan, 3 kt Ohio, 8 kt  area = 120 m²  area = 400 m²

68. KAMIOKAIMB Japan, 3 kt Ohio, 8 kt Water Cherenkov Detectors

69. Fréjus NUSEX Soudan-I/II (France 1984-88) (France 1982-88) (USA 1981-90-2001) 700t Fe/flash chambers 130t Fe/streamer tubes 770t Fe/drift tubes 90 m² 10m² 10/100 m² Iron Sandwich Detectors

70. Puzzles …. and the Solution  1980s: IMB and Kamiokande see a deficit of atmospheric muon neutrinos, the sandwich detectors do not see it.  1990s:  Two ~ 1000 m² detectors start operation: MACRO and Super-Kamiokande

71. Puzzles …. and the Solution  1980s: IMB and Kamiokande see a deficit of atmospheric muon neutrinos, the sandwich detectors do not  1990s:  Two ~ 1000 m² detectors start operation: MACRO and Super-Kamiokande  Both detectors see a deficit, with the significance increasing over the years  1998: Super-Kamiokande announces detection of atmospheric neutrino oscillations in a press release.  The spokesman of Super-K was Totsuka, but the postdoc who has been doing the analysis was Nobel Prize 2015

73. Events vs. L/E in IceCube-DeepCore Muon neutrino survival probability Vertically upward Horizontal  Earth cosmic ray L

74. Neutrino oscillations at reactors and accelerators  1980s and 1990s: Many experiments at reactors and accelerators searched for a deficit of measured anti-electron neutrinos (reactors) or for disappearence/appearence of neutrinos of a special flavor at accelerators.  In the last 10 years:  The oscillation parameters deduced from solar neutrinos are confirmed by reactor experiments  The oscillation parameters deduced from atmospheric neutrinos are confirmed by accelerator experiments

75. Oscillation parameters, present values Still unknown:  mass hierarchy  octant of  23  CP violating phase

76. Nobel Prize for Physics 2015 The Nobel Prize in Physics 2015 was awarded jointly to Takaaki Kajita and Arthur B. McDonald "for the discovery of neutrino oscillations, which shows that neutrinos have mass"

77. END OF THE FIRST „APPETIZER“ LECTURE