cosmic rays: discovery and early researchh24-files.s3.amazonaws.com/24759/122449-mvbcn.pdf ·...

Cosmic rays: Discovery and early research

Florence 29 November 2011 Per Carlson

Talk partly based on:

LayoutA mysterious invisible radiation investigated 1900 - 1910

Wulf and Gockel 1909-1911

Domenico Pacini, a partly forgotten scientist

August 7, 1912: Hess discovery and confirmation by Kohlhörster

World War I 1914 - 1918, Nationalism

Consensus 1926: radiation extraterrestrial

The nature of the radiation: Bothe, Kolhörster, Rossi, Millikan and others

The Nobel Prize to Hess 1936

Two decades of particle discoveries 1932-1953

Antimatter and air showers, two lines of today’s research

Conclusion

Memoires de l’Académie Royale 1785, p.612

Charles-Augustin de Coulomb

18th and 19th centuries

1785 Coulomb: Spontaneous discharge

1835 Faraday: Confirmes discharge

1879 Crookes: Discharge rate is reduced with reduced pressure. Ionized air the cause.

End of 19th century:

A steady stream of milestone discoveries

Thomson: The electron

Röntgen: X-rays

Becquerel: Spontaneous radioactivity

Curie’s: New radioactive elements

Radiation produces ionization

1900:

The scene was set for a more general research on electrical conductivity of air, to solve the puzzle of atmospheric ionization.

1900-1908

In action on penetrating radiation:

Elster and Geitel, Wilson, Rutherford, Cooke, McLennan, Burton, Mache, Strong, Eve

Improvements and experiments:

Electroscope improvementsMetal shieldsIn tunnels, on sea

After experimenting with a gold leaf electroscope, Wilson concludes 1901

”It is unlikely, therefore, that the ionization is due to radiation which has traversed our atmosphere; it seems, as Geitel concludes, a property of air itself”

Wilson, Elster and Geitel 1900-1901

Experiments on electroscopes gradually losing charge

It is assumed that the ionization is caused by the newly discovered X-rays or gamma-rays coming from outside the electroscope vessel

1900-1908


Elster and Geitel, Wilson, Rutherford, Cooke, McLennan, Burton, Mache, Strong, Eve


Electroscope improvementsMetal shieldsIn tunnels, on sea

General view 1908:

The earth and radioactivity is the source of the radiation











Conclusion

Th. Wulf Phys. Zeitschr. 11, 811 (1910)(Phys. Inst. Des Ignat.-Koll., Valkenburg, Holland)

Theodore Wulf (1868-1946), German scientist and a Jesuit priest, visits friends in Paris easter 1910. He brings his electroscope and climbs the Eiffel tower.....

Expected with an 80 m absorption length was a few percent of the radiation at ground. Results requires another source for the gamma-radiation or a significantly weaker absortion of gamma..OR?

http://french.lovetoknow.com/image/121015~Eiffel_tower_5.jpg

OR

Is the radiation coming from the tower structure?

Albert Gockel 1860 - 1927First balloon flight 1910

Results inconclusive

http://www.sps.ch/artikel/physik_anekdote

km

Ionization











Conclusion

Used by Pacini

Domenico Pacini 1878-1934

June 1911

With an electroscope 3 m deep in the sea at Livorno and Bracciano Pacini finds a significant 20% decrease in the radiation.

He concludes in the Nuovo Cimento article (translated from italian):

”..a sizable cause of ionization exists in the atmosphere, originating from penetrating radiation, independent of the direct action of radioactive substances in the soil”

Pacini made important contributions that were not fully appreciated

More about Pacini: several articles and talks by Alessandro De Angelis

Hess and Eugster published

Weltraumstrahlung und ihre biologische Wirkung in 1940.

The translated edition shown here was published by Fordham University Press in 1949 and incorporated research carried out in the interim.

Hess and Eugster writes about the contribution of Pacini:

"The first who expressed some doubts as to the correctness of this view was D. Pacini, who, in 1910, from measurements over sea and on shores at Livorno concluded that part of the observed ionization might be due to sources other than the known radioactive substances."

Pacini, who died in 1934, was never nominated for the Nobel Prize. Hess was first nominated in 1933 and received the prize in 1936.

In a very complete 1909 review Kurz concludes that the known amounts of radioactive substances in the soil, in water and in air could fully account for the observed ionizations.

Why ignored?











Conclusion

Hess

7 August 1912

7th flight

Diplomarbeit Georg FedermannInstitut für Radiumforschung und KernphysikWien, 2003

Hess 7th flight

7 August 1912Following Elbe in the Bohemian (Böhmen) countryside.

Data 7th flightDiplomarbeit Georg FedermannInstitut für Radiumforschung und KernphysikWien, 2003

Ionization as function of altitude

Hess 1912Kolhörster 1913-14

V.F. HessPhys. Zeit. 13(1912)1804

Reported at a meeting in Münster, September 1912

The results of the present observations seem to be most readily explained by the assumption that a radiation of very high penetrating power enters our atmosphere from above, and still produces in the lowest layers a part of the ionization observed in closed vessels.(Transl. A.M Hillas, Cosmic Rays, Pergamon 1972)

1909-1914


Pacini, Wulf, Gockel, Hess, Kohlhörster


Electroscope improvementsOn sea, in sea, on Eiffel tower, with balloons

Common view 1912-14:

There is a penetrating radiation coming from outside the earth

But:

Not everybody believed an external source for the radiation











Conclusion

A difficult time for Europe and for Science: World War I 1914-1918

Also on 28th June 1914: Kolhörster measured the ionization at 9300 m!

1914-1918 World War I

Scientific research almost stopped

More nationalism

Less communication

Source: E Crawford

Central Power Nobel CandidatesPercent











Conclusion

Millikan and Cameron 1926Experiments in two Californian lakes, Muir Lake (3600 m) and

Arrowhead (1500 m)

Millikan changed opinion 1926 and accepted the radiation as extraterrestrial ....”showing that the rays do definitely come from above”

Figure adapted from Hillas: Cosmic rays (1972)

The early 1920s

Few measurements in Europe, focus moved to the US.

Radiation was uniform, not depending on e.g. thunderstorms or on the time of the day. An extra-terrestrial nature of the radiation was still questioned.

Millikan (Nobel Prize 1923) at the 1924 APS: ”The whole of the penetrating radiation is of local origin”. Compton was of another opinion.

Millikan changed mind in 1926 and coined the name ”cosmic rays”. He suggested that the penetrating gamma-rays were ”birth cries of atoms” in our galaxy.

Focus went to properties of the cosmic rays: Radiation or particles? Source?

Phys. Zeit. 29(1928)705

1927-1930: Millikan vs. Austria/Germany











Conclusion

Clay 1927, 1928: Ionization increased with latitudeClay’s work disputed by Millikan

Bothe, Kolhörster 1929: Particles, confirmed by Rossi

Compton 1932: Detailed latitude survey showed that cosmic rays were charged particles. Millikan attacked Compton.

Millikan 1933: Admitted that there was a latitude effect

1933: Three independent experiments, Alvarez and Compton, Johnson and Rossi, showed a significant east-west effect, cosmic ray particles are positive

Schein 1941: Cosmic rays mostly protons

Uncovering the nature of the radiation

1932

What are the cosmic rays?

The Geiger-Müller tubeH. Geiger and W. Müller 1928

A break-through i cosmic ray research!

The Bothe – Kolhörster experiment 1929Starting point for Rossi

W. Bothe and W. Kolhörster Z. Physik 56(1929)751, Die Naturwiss. 17(1929)271

Compton collisions: the only known process of γ-radiation interactions.

If Compton e- caused the coincidences, a small absorber should stop them.

However 4.1 cm gold only reduced the rate by 24%.

The radiation is corpuscular!

Conclusion not accepted by Millikan

Coincidence resolution by photographic recording about 0.01 s. Lead very old, thus not very radioactive!

Rossi:

”For me, the paper by Bothe and Kolhörster opened a window upon a new, unknown territory, with unlimited opportunities for exploration”.

B. Rossi: ARCETRI, 1928-1932, in Early History of Cosmic Ray Studies, Ed. Y. Sekido and H. Elliot, (Dreidel Publ. Comp., Dordrecht 1985)

Bruno Rossi 1905-1993

Bruno Rossi 1905 – 19931928 - 1932: Florence

1932 – 1938: Padua

1938: Expelled from the university because of racial laws. Copenhagen, Manchester

1939 – 1943: With Compton in Chicago

1940 - 1943: Cornell

1943 – 1946: Los Alamos, Manhattan project

1946 – 1970: MIT, ”institute professor”

1974 - 1980: Offered a chair in any Italian university, chose Palermo

1993: Died at his home in Cambridge, MA

On the steps of the laboratory at Arcetri: Left to right: Rossi, Occhialini, Bernadini and Bocciarelli


Rossi Physics Today October 1981

45B. Rossi: ARCETRI, 1928-1932, in Early History of Cosmic Ray Studies, Ed. Y. Sekido and H. Elliot, (Dreidel Publ. Comp., Dordrecht 1985)

On Rossis right several counters. Batteries were used to provide the high voltage for the counters.


47

Rossi invented the coincidence circuit: Method of Registering Multiple Simultaneous Impulses of

Several Geiger Counters, Nature 125,636(1930)

B. Rossi: Phys. Rev. 36, 606(1930)

Rossi proposes the East-West experimentsduring a visit to Bothe’s Berlin laboratory, summer 1930

A “cosmic ray telescope” consisting of two coincidence counters mounted on pivots so measurements could be made in any direction desired.

EAST-WEST EXPERIMENT SETUP, Eritrea 1933

The East-West effect was established 1933Alvarez and Compton

Johnson

Rossi

Particles are positive butPositrons?

Protons?

Nuclei?

”The frequency of the coincidences recorded with the counters at a distancefrom one another, shown in the tables as “chance coincidences” appears tobe greater than would have been predicted on the basis of the resolvingpower of the coincidence circuit. Those observations made us questionwhether all of these coincidences were actually chance coincidences. Thishypothesis appears to be supported by the following observation . . . Sincethe interference of possible disturbances was ruled out by suitable tests, itseems that once in a while the recording equipment is struck by very extensive showers [degli sciami molto estesi di corpuscoli] of particles, whichcause coincidences between counters, even placed at large distances fromone another. Unfortunately, I did not have time to study this phenomenonmore closely.”

Rossi discovered air showers when estimating random coincidences!


...”At the invitation of Fermi, I gave an introductory speech on the problem of cosmic rays. The main thrust of this talk was to present what, to my mind, were irrefutable arguments against Millikan’s theory of the ”birth cry” of atoms. Such a brash behavior on the part of a mere youngster (I was then 26 years old) clearly did not please Millikan, who for a number of years thereafter, chose to ignore my work altogether.”

Rossi Physics Today October 1981

The Rome conference October 1931

Rome conference 1931

Bruno Rossi, Robert A. Millikan, and Arthur H. Compton at the Rome conference, October 11–18, 1931.


The Rome conference 1931 ‘‘marked the beginning of the historical debate about the nature of cosmic rays….”

B. Rossi Zeit. f. Physik 82(1933)151L. Bonolis Phys. Perspect. 13(2011)58

Two components in the cosmic rays: a soft and a hardUsing a triple coincidence, Rossi showed that about 50% of particles that traversed 10 cm lead also traversed 1 meter!

50 cm Pb

From Rossi’s notebook

”In the late fall of 1932, having won a national competition for a chair in experimental physics in the Italian Universities, I was called to fill a vacancy at the University of Padua. I left Arcetri with a heavy heart. I was still young, and I knew that there would be, in my life, other periods of interesting and rewarding work. I also knew, however, that none would have the very special flavor of my years in the Florentine hills.”


Bruno Rossi remebering 1932:





World War I, Nationalism


The Nobel Prize to Hess



Conclusion

1936: The Nobel Prize to Hess

The Royal Swedish Academy of Sciences had received a total of 22 Prize proposals from 31 nominators for 18 different Prize Candidates in Physics.

Hess was nominated by J. Clay, Amsterdam, for a non-shared prize and by A.H. Compton, Chicago, for a prize shared with J. Clay, Amsterdam. Compton also nominated C.D. Anderson for the discovery of the positron.

Hess had been nominated the first time in 1931 by Pohl, from Göttingen, and then in 1933 by Plotnikov, from Zagreb and in 1934 by Willstätter, from Munich.

We note that Pacini was never nominated.

Nominations for the 1936 Nobel Prize in Physics

Arthur H. Compton

Nobel Prize in Physics 1927"for his discovery of the effect named after him"

Phys. Rev. 43(1933)387

The latitude effect at different altitudes

The latitude effect is greater for softer radiation.

4360 m

2000 m

Sea levelLatitude

“The time has now arrived, it seems to me, when we can say that the so-called cosmic rays definitely have their origin at such remote distances from the Earth that they may properly be called cosmic, and that the use of the rays has by now led to results of such importance that they may be considered a discovery of the first magnitude. ...

It is, I believe, correct to say that Hess was the first to establish the increase of the ionisation observed in electroscopes with increasing altitude; and he was certainly the first to ascribe with confidence this increased ionisation to radiation coming from outside the Earth”.

Compton’s (Nobel Prize 1927) nomination 1936

“Before it was appropriate to award the Nobel Prize for the discovery of these rays, it was necessary to await more positiveevidence regarding their unique characteristics and importance in various fields of physics.This has now been accomplished. Studies of the magnetic latitude effect on cosmic rays have shown that they include electrical particles of much higher energy than are available from artificial sources, further that these rays come from a source which may be properly called cosmic. The usefulness of the rays has been demonstrated by the experiment which have revealed the existence of the positron”.

Compton’s nomination cont’d

FAQ’sWho can nominate?

FAQ’sWho can nominate?

PhysicsMembers of the AcademyNobel LaureatesNordic professorsChair holders in foreign universitiesSpecially invited

FAQ’sWho can nominate?Who selects the Nobel Prize Laureates?

The Royal Swedish Academy of Sciences for the Nobel Prize in Physics and Chemistry.

The Nobel Assembly at Karolinska Institutet for the Nobel Prize in Physiology or Medicine.

The Swedish Academy for the Nobel Prize in Literature.

A committee of five persons to be elected by the Norwegian Parliament (Storting) for the Nobel Peace Prize.

Who selects the Nobel Prize Laureates?

FAQ’sWho can nominate?Who selects the Nobel Prize Laureates?How many candidates are nominated?

FAQ’sWho can nominate?Who selects the Nobel Prize Laureates?How many candidates are nominated?Nominate for a posthumous Nobel Prize?

10 December 1936, Stockholm











Conclusion

1932: The positron discovered in a cloud chamber photo by C. Anderson

Mass determined from ionization and range

1 cm Pb plateDecay 0.5 cm below plate. Incident about 2 GeV/c.

A ”V0” particle

Armenteros et al. Nature 167, 501(1951)

π+ → µ+ + νµ

µ+ 0.6 mm

e+

Nuclear emulsions1940s

The first observation of the decay of a kaon into 3 pions, recorded in special photographic emulsion by Cecil Powell's team at Bristol University in 1948.

K+ → π+ + π+ + π-

K+

Particle Instrumentπ+ and π- Nuclear Emulsion

π0 Counters and Emulsion

Λ Cloud Chamber

K+and K- Nuclear Emulsion

K0 Cloud Chamber

Σ+ Nuclear Emulsion

Σ- Cloud Chamber

Σ0 Bubble chamber

Ξ- Cloud Chamber

Ξ0 Bubble Chamber

Anti Λ0 Nuclear Emulsion

Particle discoveries with emulsion and cloud chamber

The International Cosmic Ray Conference 1953 marks the birth of subatomic physics and a change of focus for cosmic ray physics.

Cronin: EPJ-H 2011











Conclusion

Pamela coll.O. Adriani et al. Nature 2 April 2009

Pierre Auger Observatory Coll. ICRC2011, F. Salmida et al. arXiv 1107.4809

The GZK cut-off confirmed

Conclusions

The discovery of cosmic rays came after detailed studies 1900-1914 using electroscopes on land at sea level, on sea, in sea and at high altitudes

Scientists in Europe and North America participated in the work characterized by lack of communication and by nationalism causedprimarily by World War I.

The nature of the radiation was established 1927-1941 in steps: first particles, then positive particles, then primarily protons

The physics of elementary particles started with discoveries of many new particles 1932-1953 using cosmic rays

Today cosmic ray physics is a well estabished lively field of research.

Florence 29 November 2011 Per Carlson

Thanks for your attention!

Thanks to

Alessandro de Angelis

Alan Watson

The Center for History of Science, Royal Swedish Academy of Sciences

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