B.Pontecorvo: life and ideas

M.G. SapozhnikovJoint Institute for Nuclear Research, Dubna

• Pontecorvo Selected Scientific Works. Recollections on B.Pontecorvo.Edited by S.M.Bilenky, T.D.Blokhintseva, I.G.Pokrovskaya and M.G.Sapozhnikov. Societa Italiana di Fisica, 1997.

• Russian edition, two volumes, series "Classics of Science" of Russian Academy of Science, 1998.

• htttp://pontecorvo.jinr.ru• Film “Bruno Pontecorvo”, Science-Video, 2003

Born at 22.08.1913 in Pisa

Grandfather – Pellegrino Pontecorvo

Textile bisness

strada P.Pontecorvo in Pisa

Father: Massimo PontecorvoMother: Maria Maroni

• Guido - biologist, FRS, Prof. in University of Glasgow

• Giuliana - politics, Italy

• Giovanni David - agriculturist, England

• Anna - teacher, England

• Laura - nurse, Italy

• Paolo - radar research work, USA

• Gilberto - register and producer, Italy

The Fermi school• Entering Facolta di Ingegneria dell'Universita di

Pisa at 16 years• Facolta di Fisica e Matematica dell'Universita di

Roma at 18 years• Degree of laurea at 20 years.• "Influence of hydrogeneous substances on the

radioactivity produced by neutrons"

E.Fermi, E.Amaldi, B.Pontecorvo, F.Rasetti, E.Segre

October 22, 1934.• Patent on slow neutrons, October 26, 1934

The work with F.Joliot-Curie• Fellowship of Ministero

dell'Educazione Nazionale for studies with neutrons.

• February 1936, Paris, F.Joliot-Curie.... Working with Joliot it is impossible not to be his friend...He has clear mind, broad scientific erudition, deep understanding of the scientific problems, huge working abilities and assureness in himself...There are two distinctions of Joliot: powerful scientific fantasy and what italians calls "spregiudicatezza" - an ability to accept any, even seemingly "impossible" or "strange" fact.

• Curie-Carnegie prize for study of nuclear isomerism

• Institute of Radium, Paris

• Mussolini’s racist law of 1938

The communist• Joint Communist Party

• “Bruno became a Communist because he believed Communism would create a New Man – people that were better than they were before, and better than the people that exist today. And many Italian intellectuals believed in that. For example, I too was a Communist”

Gillo Pontecorvo, Interview from the film “Bruno Pontecorvo”.

• “He had a very passionate belief in the Soviet Union, perhaps a very childish and naive belief. I remember when the radio broadcasts the Kremlin chimes Bruno would come up to the radio especially to listen to those Kremlin chimes. Those were the sounds – the chimes – of his dreams”

Gillo Pontecorvo, Interview from the film “Bruno Pontecorvo”.

Paris, 1936-1940

• Hotel “Grand Hommes”

Married Marianna Nordblom.

Gil (30.07.38).

June 1940, escaped from Paris.

August 1940, departure from Portugal to USAwith Duccio and Giuliana Tabets

USA, 1940-1943

• Work on oil logging at Wells Survey, Inc. Tulsa Oklahoma

(with help of E.Segre)

• Invention of neutron oil-logging.

• All patents were properties of the Wells Servey, Inc

Chalk River (1943-1949)

• 1943 Join Anglo-Canadian Research Reactor Project. Montreal and Chalk River.

• First method of neutrino registration (Cl-Ar method),1946.(trying to perform that in a track).

• Unification of weak interactions,1947.• Muon decays into 3 particles. No e, 1948.• High multiplication proportional counters, 1949.• First limit on neutrino mass (m<500 eV) from

spectrum of 3H, 1949.

Harwell, 1949-1950

• February 1948, British citizenship.

• January 1949. Family set at Harwell.

• May 1949. Lecturing in Paris.

Looking for work:– Anglo-Iranian Oil Company– University chair in Pisa– University chair in Liverpool -- accepted

1 September 1950 – start of the new work

First Bruno’s

logbook in Dubna

First entry of the 1950 logbook.

Working at

Ustanovka “M”

• best world accelerator of that time (480 MeV)

• no war applications,

e ≠

• Proposal for 500 A proton cyclotron on 800 MeV, 1958. Rochester conference in Kiev, 1959.

• Are the electron and muon neutrinos identical?

“.... for people working on muons in the old times, the question about different types of neutrinos has always been present.“

B.P."The infancy and youth of neutrino physics"

• B.Pontecorvo, "Electron and muon neutrinos", 1959

“Models of new accelerators are being discussed now in whichthe intensity of the accelerated protons may be increased as much as bythree orders of magnitude”.• The neutrino beam from decays of stopped muons with E ~ 35 MeV.+ e+ + + e

+ p + + n

+ p e+ + n

• M.Schwartz, L.Lederman, J.Steinberger, 1959

• Tо measure high-energy neutrinos to study (p) for unitarity crisis in weak interactions• AGS exp N11, "Study of neutrino interactions, search for intermediate boson“• The neutrino beam from decays of (1GeV) – E 220 MeV

• "The net result is that in 1959 Pontecorvo proposes to address the right question but with hopeless technique… and Schwartz addresses a problem that doesn't solved until the 1982 discovery of the W but his proposal is the right experiment to solve e problem…."

L.Lederman, Neutrino'94 Conference

Neutrino oscillations

• S.M.Bilenky "Early years of neutrino oscillations", hep-ph/9908335, 1999.

• "Mesonium and antimesonium", 1957. (+e) ↔ (e+) "The possibility of K0 K0 transitions induced by weak interactions makes it necessary to consider neutral K mesons as a mixture of particles of different combined parity (K0

1 and K02). We

discuss here the problem as to whether there exist other "mixed" neutral particles (not necessarily "elementary" ones) which are not identical to the corresponding antiparticles and for which particle antiparticle transitions are not strictly forbidden."

• "If the theory of two component neutrino was not valid (which is hardly probably at present) and if the conservation law for neutrino charge took no place, neutrino antineutrino transitions in vacuum would be in principle possible”.

“Inverse - processes and non-conservationof lepton charge", 1957.

• ... it is assumed that a) the neutrino and antineutrino emitted in the processes p n + + + and n p + - + are not identical particles; b) the neutrino charge is not strictly conserved.

• ...It follows from a) and b) that neutrinos in vacuum can transform themselves into antineutrino and vice versa. This means that neutrino and antineutrino are particle mixtures, i.e. symmetrical and antisymmetrical combination of two truly neutral Majorana particles 1 and 2 having different combined parity.

• ... a beam of neutral leptons from a reactor which at first consists mainly of antineutrinos will change its composition and at certain distance R from the reactor will be composed of neutrino and antineutrino in equal quantities.

• ...effect of transformation of neutrino and antineutrino and vice versa may be unobservable in the laboratory because of large values of R, but will certainly occur, at least, on an astronomic scale.

MNS or P mixing?

• MNS: neutrino – part of nucleon

• First high-energy neutrino experiment at accelerator (V.Veksler, A.Tyapkin, B.Pontecorvo) 1961

• From 9 runs – 8 were OK

• If 10 will be OK – we start writing a paper

• No, we will increase the shielding!

All main ideas of the modern neutrino physics was suggested by Bruno Pontecorvo.

Val Telegdi

‘The role of the leader”, 1976

• great care for students and young physicists

• no “official” pupils

• “The leader in the scientific group is a typical scientist, slightly older and more experienced, but less able to perceive new things.”

• “The leader should not demand from his employees that they should be similar to him.”

• “There are people which like to spend day and night in the experimental hall (the most typical is Yu.D.Prokoshkin). That is nice feature but nobody proved that all people must behave like that and that is the only way for a successful scientist.”

• The leader should use different characters and different features of the members of the team. The strength of the group is just in complementarity of different features

• The leader should be ready to learn from young members of his team as much as they learn from him.

• Citation from Lenin:«Sometimes old generation don’t understand the youth, which should come to socialism (science – B.P.) in other way, in other form and in different environment as their fathers. Therefore we for full independence of the youth. Because without full independence the youngsters neither could be good socialists (scientists - B.P.), nor be ready to move socialism (science – B.P.) forward.We are for full independence of the youth, but also for full freedom of comrade criticism of their mistakes. We should not flattened to the youth.”

“Agreement between B.Pontecorvo and M.Balandin”, 1970

1. M.Balandin obliged from 1 November of 1970 NOT to come to work to the laboratory. He should stay home and prepare his PhD. As exception, he could come to the library.

4. The PhD must be practically ready by January 1971. Meaning of the word “practically” could be judged by B.Pontecorvo and G.Selivanov.

5. If these points will not be fulfilled the promises of B.Pontecorvo to M.Balandin will be invalid.

• Each member of the team obtained personal quartal plan.

• The weekly seminar is by Fridays.

The teacher

• Professor of Moscow State University 1961-1966

• Head of the chair on elementary particle physics

1966-1986

“Take note that when one saying that this experimentalist has clever hands, it means, mainly, that he has clever head. More than 70% of great experiments was not only done but also suggested by the experimentalists themselves.”

Student’s folklore

• Exams on the table

• Diploma student and cards

• Vertushka and COMPASS

• Rolling the coin

The writer

• Unfinished manuscript about E.Majorana

• “This man could solve the most difficult problems of Nature, but could not find the sense of its own life.”

“Don’t loose the precious time!”

Yunost, 1964

What the neutrino physics could do for kolkhoznik from

Ryazan?I don’t know how the

neutrino physics could helps to a kolkhoznik of Ryazan, but to some persons the study of neutrino physics really helps to earn some money.

Me, for instance.

To my mind the human being have no right not to study structure of matter.

Recently I was in Italy and deliver a lecture in Scuola Normale in Pisa. Greatest italian mathematics and physics, such as Fermi, Bernardini, Rubbia etc. have graduated from this School . The theme of my lecture was similar to the present one. But in Pisa I don’t stressed enough this duty of the human being for the fundamental knowledge.

“fatti non foste a viver come bruti

ma per seguir virtute e canoscenza “

Dante

Scepticism about abstract science is not unexpected. FERMI, SLOW NEUTRONS

• We don’t know exactly what practical outcome will be from investigation of the structure and properties of the elementary particles. But we are absolutely sure that these investigations will lead to the practical benefits. The prove of that is the whole history of physics.

• Developing science we are working in this way for the good of our children, for the good of next generations.

B.Pontecorvo