Neutrinos Highlights and Heroes An „Appetizer“ for the lecture Neutrinos in Physics and...

NeutrinosHighlights and HeroesAn „Appetizer“ for the lectureNeutrinos in Physics and Astrophysics

Christian Spiering, DESY Zeuthen

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


2) From Pontecorvo’s idea to the Nobel Prize 2015Bruno 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

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.

LECTURE 1

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

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

The puzzle

Gamma spectrum: lines Alpha spectrum: lines

Beta spectrum Why continuous???

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!

The puzzleIf beta decay goes like

nucleus A nucleus A‘ + electronwhy don‘t we see a line spectrum?

Expected for 2-particle final state

The puzzleIf beta decay goes like

nucleus A nucleus A‘ + electronwhy don‘t we see a line spectrum?


Niels Bohr:Energy conservation only for an ensemble of interactions, not for individual interactions ?(i.e. just another surprise of quantum mechanics)

1930: start of the storyWolfgang Pauli:

nucleus A nucleus A‘ + electron + „neutron“


- neutral- spin ½- mass < electron mass- weakly interacting

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!”

https://en.wikipedia.org/wiki/Not_even_wrong

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!)

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!

The famous Pauli Letter from Dec. 4, 1930

… to Lise Meitner and a Meeting of German Physicists in Tübingen:

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)

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

Fermi‘s idea for measuring mass of the neutrino

… 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)

… and the modern experiments

Present limit : m(e) < 2.2 eV(Moscow, Mainz)

Future: KATRIN (Karlsruhe)

Sensitivity to m(e) ~ 0.2 eV

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.

No chance ever to detect neutrinos?

Fred Reines, restless experimentalist and discoverer of the neutrino

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

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

Reines‘ first idea to detect neutrinos …

… from the explosion of a nuclear bomb !

But then: Nucelar reactors as source

1953: Hanford Reactor 1955: much stronger military

reactor in Savannah River

Fred Reines

Clyde CowanFred Reines

Clyde Cowan

First attempt: Hanford detector

Anti-Electron Neutrinosfrom Hanford Nuclear Reactor

3 Gammasin coincidence

𝝂𝐞 p

n Cd

e+¿ ¿e−

g

g

g

photo-multipliers

scintillator

CdCl solvedin water

Savannah River experiment: the principle

Savannah River: Discovery 1956

The detector

A neutrino signature

Nobel Prize 1995

Pauli‘s answer to Reines

„Everything comes to him who knows how to wait.“

Bruno Pontecorvo (1959)

Is there a second neutrino?

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

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

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 …

Bruno Pontecorvo

Marianne, Gil and Bruno Pontecorvo, 1940

Bruno Pontecorvo

1955

https://it.wikipedia.org/wiki/File:Pontecorvo.jpg

Bruno Pontecorvo

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 ?

p

Accelerator

-decay: +

Target-absorber

Bruno Pontecorvo (Dubna) Leon Lederman, Melvin Schwartz, Jack Steinberger (Brookhaven)

neutrino beam

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

The Brookhaven experiment

Nobel Prize 1988

The Bookhaven experiment

Nobel Prize 1988

And finally: discovery of the third neutrino

Slide taken from Karsten Heeger

If they have mass, these neutrinos can transform to each other:

Neutrino Oscillations


2) From Pontecorvo’s idea to the Nobel Prize 2015Bruno 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

Oscillations 1957 - 62

1957: Inspired by a paper of Gell-Mann and Pais who suggest K0 anti-K0 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 !

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:



mass eigenstates weak eigenstates

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

L


)E

LΔm.(θ)νP(ν eμ

222 271sin2sin

= mixing angle m² = |m1² - m2²|, E = energy, L = distance

L


1976: Pontecorvo and Samoil Bilenky formulate neutrino mixing in full analogy to quark mixing, using only Dirac neutrinos (no Majorana neutrinos)


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 )

Solar neutrinos and the MSW effect

electron neutrino

tau neutrino

muon neutrino

Formulation for 3 neutrinos

3 mixing angles , , , , 1 CP-violating phase

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

C. Spierin

gMG-11, Berlin

cosmicproton

≈15 km

π+

+

e+

e

„Atmospheric“ Neutrinos

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

Water Cherenkov Detectors

KAMIOKA IMBJapan, 3 kt Ohio, 8 kt

marea = 120 m²

marea = 400 m²

KAMIOKA IMBJapan, 3 kt Ohio, 8 kt

Water Cherenkov Detectors

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

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

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

Takaaki Kajita

Events vs. L/E in IceCube-DeepCore

Muon neutrino survival probability

Vertically upward

Horizontal

q

nEarth

cosmicray

L

)E

LΔm.(θ)νP(ν eμ

222 271sin2sin

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 experimentsThe oscillation parameters deduced from atmospheric neutrinos

are confirmed by accelerator experiments

Oscillation parameters, present values

5.33

eV105.7

12

25221

m

45

eV104.2

23

23232

m

5.813

Still unknown:

mass hierarchy

octant of 23

CP violating phase

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"

END OF THE FIRST

„APPETIZER“ LECTURE

Neutrinos Highlights and Heroes An „Appetizer“ for the lecture Neutrinos in Physics and...

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