Cosmic rays: Discovery and early research. Florence 29 November 2011 Per Carlson

Transcription

1 Cosmic rays: Discovery and early research Florence 29 November 2011 Per Carlson

2 Talk partly based on:

3 Layout A mysterious invisible radiation investigated Wulf and Gockel Domenico Pacini, a partly forgotten scientist August 7, 1912: Hess discovery and confirmation by Kohlhörster World War I , 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 Antimatter and air showers, two lines of today s research Conclusion

4 Memoires de l Académie Royale 1785, p.612 Charles-Augustin de Coulomb

5 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.

6 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

7 1900: The scene was set for a more general research on electrical conductivity of air, to solve the puzzle of atmospheric ionization.

8 In action on penetrating radiation: Elster and Geitel, Wilson, Rutherford, Cooke, McLennan, Burton, Mache, Strong, Eve Improvements and experiments: Electroscope improvements Metal shields In tunnels, on sea

9 Wilson, Elster and Geitel Experiments on electroscopes gradually losing charge 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 It is assumed that the ionization is caused by the newly discovered X-rays or gamma-rays coming from outside the electroscope vessel

10 In action on penetrating radiation: Elster and Geitel, Wilson, Rutherford, Cooke, McLennan, Burton, Mache, Strong, Eve Improvements and experiments: Electroscope improvements Metal shields In tunnels, on sea General view 1908: The earth and radioactivity is the source of the radiation

11 Layout A mysterious invisible radiation investigated Wulf and Gockel Domenico Pacini, a partly forgotten scientist August 7, 1912: Hess discovery and confirmation by Kohlhörster World War I , 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 Antimatter and air showers, two lines of today s research Conclusion

12 Theodore Wulf ( ), German scientist and a Jesuit priest, visits friends in Paris easter He brings his electroscope and climbs the Eiffel tower... Th. Wulf Phys. Zeitschr. 11, 811 (1910) (Phys. Inst. Des Ignat.-Koll., Valkenburg, Holland) 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?

13 OR Is the radiation coming from the tower structure?

14 Albert Gockel First balloon flight 1910 Results inconclusive km Ionization

15 Layout A mysterious invisible radiation investigated Wulf and Gockel Domenico Pacini, a partly forgotten scientist August 7, 1912: Hess discovery and confirmation by Kohlhörster World War I , 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 Antimatter and air showers, two lines of today s research Conclusion

16 Domenico Pacini Used by Pacini

17 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

18 Hess and Eugster published Weltraumstrahlung und ihre biologische Wirkung in The translated edition shown here was published by Fordham University Press in 1949 and incorporated research carried out in the interim.

19 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. 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 Why ignored?

20 Layout A mysterious invisible radiation investigated Wulf and Gockel Domenico Pacini, a partly forgotten scientist August 7, 1912: Hess discovery and confirmation by Kohlhörster World War I , 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 Antimatter and air showers, two lines of today s research Conclusion

21 Hess 7 August th flight

22 Hess 7th flight 7 August 1912 Following Elbe in the Bohemian (Böhmen) countryside. Diplomarbeit Georg Federmann Institut für Radiumforschung und Kernphysik Wien, 2003

23

24 Data 7th flight Diplomarbeit Georg Federmann Institut für Radiumforschung und Kernphysik Wien, 2003

25 Ionization as function of altitude Hess 1912 Kolhörster

26 V.F. Hess Phys. 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)

27 In action on penetrating radiation: Pacini, Wulf, Gockel, Hess, Kohlhörster Improvements and experiments: Electroscope improvements On sea, in sea, on Eiffel tower, with balloons Common view : There is a penetrating radiation coming from outside the earth But: Not everybody believed an external source for the radiation

28 Layout A mysterious invisible radiation investigated Wulf and Gockel Domenico Pacini, a partly forgotten scientist August 7, 1912: Hess discovery and confirmation by Kohlhörster World War I , 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 Antimatter and air showers, two lines of today s research Conclusion

29 A difficult time for Europe and for Science: World War I Also on 28th June 1914: Kolhörster measured the ionization at 9300 m!

30 World War I Scientific research almost stopped More nationalism Less communication

31 Percent Central Power Nobel Candidates Source: E Crawford

32 Layout A mysterious invisible radiation investigated Wulf and Gockel Domenico Pacini, a partly forgotten scientist August 7, 1912: Hess discovery and confirmation by Kohlhörster World War I , 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 Antimatter and air showers, two lines of today s research Conclusion

33 Millikan and Cameron 1926 Experiments 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)

34 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 extraterrestrial 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?

35 Phys. Zeit. 29(1928) : Millikan vs. Austria/Germany

36 Layout A mysterious invisible radiation investigated Wulf and Gockel Domenico Pacini, a partly forgotten scientist August 7, 1912: Hess discovery and confirmation by Kohlhörster World War I , 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 Antimatter and air showers, two lines of today s research Conclusion

37 Uncovering the nature of the radiation Clay 1927, 1928: Ionization increased with latitude Clay 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

38 1932 What are the cosmic rays?

39 The Geiger-Müller tube H. Geiger and W. Müller 1928 A break-through i cosmic ray research!

40 The Bothe Kolhörster experiment 1929 Starting point for Rossi 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! W. Bothe and W. Kolhörster Z. Physik 56(1929)751, Die Naturwiss. 17(1929)271

41 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, , in Early History of Cosmic Ray Studies, Ed. Y. Sekido and H. Elliot, (Dreidel Publ. Comp., Dordrecht 1985) Bruno Rossi

42 Bruno Rossi : Florence : Padua 1938: Expelled from the university because of racial laws. Copenhagen, Manchester : With Compton in Chicago : Cornell : Los Alamos, Manhattan project : MIT, institute professor : Offered a chair in any Italian university, chose Palermo 1993: Died at his home in Cambridge, MA

43 On the steps of the laboratory at Arcetri: Left to right: Rossi, Occhialini, Bernadini and Bocciarelli B. Rossi: ARCETRI, , in Early History of Cosmic Ray Studies, Ed. Y. Sekido and H. Elliot, (Dreidel Publ. Comp., Dordrecht 1985)

44 Rossi Physics Today October 1981

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

46 On Rossis right several counters. Batteries were used to provide the high voltage for the counters. B. Rossi: ARCETRI, , in Early History of Cosmic Ray Studies, Ed. Y. Sekido and H. Elliot, (Dreidel Publ. Comp., Dordrecht 1985)

47 Rossi invented the coincidence circuit: Method of Registering Multiple Simultaneous Impulses of Several Geiger Counters, Nature 125,636(1930) 47

48 Rossi proposes the East-West experiments during a visit to Bothe s Berlin laboratory, summer 1930 B. Rossi: Phys. Rev. 36, 606(1930)

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

50 EAST-WEST EXPERIMENT SETUP, Eritrea 1933

51 The East-West effect was established 1933 Alvarez and Compton Johnson Rossi Particles are positive but Positrons? Protons? Nuclei?

52 Rossi discovered air showers when estimating random coincidences! The frequency of the coincidences recorded with the counters at a distance from one another, shown in the tables as chance coincidences appears to be greater than would have been predicted on the basis of the resolving power of the coincidence circuit. Those observations made us question whether all of these coincidences were actually chance coincidences. This hypothesis appears to be supported by the following observation... Since the interference of possible disturbances was ruled out by suitable tests, it seems that once in a while the recording equipment is struck by very extensive showers [degli sciami molto estesi di corpuscoli] of particles, which cause coincidences between counters, even placed at large distances from one another. Unfortunately, I did not have time to study this phenomenon more closely. B. Rossi: ARCETRI, , in Early History of Cosmic Ray Studies, Ed. Y. Sekido and H. Elliot, (Dreidel Publ. Comp., Dordrecht 1985)

53 The Rome conference October 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

54 Rome conference 1931

55 Bruno Rossi, Robert A. Millikan, and Arthur H. Compton at the Rome conference, October 11 18, The Rome conference 1931 marked the beginning of the historical debate about the nature of cosmic rays. B. Rossi: ARCETRI, , in Early History of Cosmic Ray Studies, Ed. Y. Sekido and H. Elliot, (Dreidel Publ. Comp., Dordrecht 1985)

56 Two components in the cosmic rays: a soft and a hard Using a triple coincidence, Rossi showed that about 50% of particles that traversed 10 cm lead also traversed 1 meter! 50 cm Pb B. Rossi Zeit. f. Physik 82(1933)151 L. Bonolis Phys. Perspect. 13(2011)58 From Rossi s notebook

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

58 Layout A mysterious invisible radiation investigated Wulf and Gockel Domenico Pacini, a partly forgotten scientist August 7, 1912: Hess discovery and confirmation by Kohlhörster World War I, Nationalism The nature of the radiation: Bothe, Kolhörster, Rossi, Millikan and others The Nobel Prize to Hess Two decades of particle discoveries Antimatter and air showers, two lines of today s research Conclusion

59 1936: The Nobel Prize to Hess

60 Nominations for the 1936 Nobel Prize in Physics 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.

61 Arthur H. Compton Nobel Prize in Physics 1927 "for his discovery of the effect named after him"

62 The latitude effect at different altitudes 4360 m The latitude effect is greater for softer radiation. Latitude 2000 m Sea level Phys. Rev. 43(1933)387

63 Compton s (Nobel Prize 1927) nomination 1936 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.

64 Compton s nomination cont d Before it was appropriate to award the Nobel Prize for the discovery of these rays, it was necessary to await more positive evidence 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.

65 Who can nominate? FAQ s

66 FAQ s Who can nominate? Physics Members of the Academy Nobel Laureates Nordic professors Chair holders in foreign universities Specially invited

67 FAQ s Who can nominate? Who selects the Nobel Prize Laureates?

68 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.

69 FAQ s Who can nominate? Who selects the Nobel Prize Laureates? How many candidates are nominated?

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

71 10 December 1936, Stockholm

72 Layout A mysterious invisible radiation investigated Wulf and Gockel Domenico Pacini, a partly forgotten scientist August 7, 1912: Hess discovery and confirmation by Kohlhörster World War I , 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 Antimatter and air showers, two lines of today s research Conclusion

73 1932: The positron discovered in a cloud chamber photo by C. Anderson Mass determined from ionization and range

74 A V 0 particle 1 cm Pb plate Decay 0.5 cm below plate. Incident about 2 GeV/c. Armenteros et al. Nature 167, 501(1951)

75 Nuclear emulsions 1940s π + µ + + ν µ µ+ 0.6 mm e +

76 K + K + π + + π + + π - 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.

77

78 Particle discoveries with emulsion and cloud chamber Particle π + and π - π 0 Instrument Nuclear Emulsion Counters and Emulsion Λ K + and K - K 0 Cloud Chamber Nuclear Emulsion Cloud Chamber Σ + Σ - Σ 0 Ξ - Ξ 0 Nuclear Emulsion Cloud Chamber Bubble chamber Cloud Chamber Bubble Chamber Anti Λ 0 Nuclear Emulsion

79 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

80 Layout A mysterious invisible radiation investigated Wulf and Gockel Domenico Pacini, a partly forgotten scientist August 7, 1912: Hess discovery and confirmation by Kohlhörster World War I , 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 Antimatter and air showers, two lines of today s research Conclusion

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

82

83 The GZK cut-off confirmed Pierre Auger Observatory Coll. ICRC2011, F. Salmida et al. arxiv

84 Conclusions The discovery of cosmic rays came after detailed studies 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 caused primarily by World War I. The nature of the radiation was established in steps: first particles, then positive particles, then primarily protons The physics of elementary particles started with discoveries of many new particles using cosmic rays Today cosmic ray physics is a well estabished lively field of research.

85 Thanks for your attention! Thanks to Alessandro de Angelis Alan Watson The Center for History of Science, Royal Swedish Academy of Sciences Florence 29 November 2011 Per Carlson