Mould - 75tf Anniversary.indd

NOWOTWORY Journal of Oncology • 2010 • volume 60
Number 2 • 46e–49e
Historia medicinae
75th Anniversary of the artificial production
of radioactive elements
by Irène & Frédéric Joliot-Curie
Richard F. Mould
Following the discovery of X-rays in 1895, of radioactivity in 1896, of radium & polonium in 1898, of the positron in 1932
and the neutron also in 1932, the next most important discovery was that of artificial production of radioactive elements in
1934 and the 75th anniversary of this event is celebrated by this short article.
Key words: artificial radioactivity, Irène & Frédéric Joliot-Curie, Nobel Prize, Warsaw Radium Institute, nuclear fission,
Wilson cloud chamber
Introduction
24Mg
The year 2009 marks the 75th anniversary of the discovery
in 1934 of the artificial production of radioactive
elements by Irène & Frédéric Joliot-Curie [1]. The JoliotCuries were awarded the 1935 Nobel Prize for Chemistry,
which was the third Nobel awarded to members of the
Curie family. The 1903 Prize for Physics was awarded
to Henri Becquerel, Pierre & Marie Curie and the 1911
Prize for Chemistry awarded to Marie Curie.
The Joliot-Curies had missed out on the discovery of
the positron (discovered in 1932 by Carl Anderson) and
of the neutron (discovered in 1932 by James Chadwick)
by failing to completely understand the results of
critical experiments by Walter Bothe in 1930 [2] and by
themselves in 1931 [3, 4]. In the experiments described
in this 1931 paper it had been shown that the radiation
excited in beryllium possessed a penetrating power
distinctly greater than that of any gamma radiation yet
found from radioactive elements.
+ 4He → 27Si + 1n
Frédéric Joliot-Curie described in his Nobel Lecture
of 12 December 1935 the experiment with 27Al. “The
atom formed is very probably silicon, but being present
Discovery in 1934
However, in January 1934 the Joliot-Curies did not miss
out and made the discovery of artificial radioactivity
when bombarding boron with alpha particles from a
polonium source, (Figure 1). Radioactive nitrogen 13N
was produced with the emission of a neutron.
10B
+ 4He → 13N + 1n
13N
disintegrated with the emission of positrons to give
stable 13C. The Joliot-Curies then quickly repeated the
experiment with aluminium and with magnesium.
27Al
+ 4He → 30P + 1n
Figure 1. The Joliot-Curies in the Physics Laboratory of the Institut
du Radium, Paris, in 1934: the year of their discovery of artificial
radioactivity.
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Figure 2. The Joliot-Curies and the Warsaw Radium Institute’s Chief Physicist, Cezary Pawlowski,
in 1936.
in infinitesimal quantity, it is not possible to identify it
chemically. On the other hand, when the atom formed is
radioactive; it can be identified by applying radiochemical
methods. For example, in the case where aluminium
irradiated by alpha rays emits neutrons, the atom formed
being radioactive, it is possible to verify that it possesses
the chemical properties of phosphorus.
A thin piece of aluminium sheet, irradiated
beforehand by alpha rays is attacked and dissolved in
a solution of hydrochloric acid. The chemical reaction
produced nascent hydrogen which carries over the
radioactive element into a thin-walled tube where it is
collected over water. The separation clearly demonstrates
some element other than aluminium has been formed on
irradiation by hellions. It furnishes indisputable proof of
the transmutation achieved; also, traces of phosphorus
would be separated from the aluminium in the same
experiment.
Finally, activated aluminium is dissolved in a
mixture of acid and oxidant. To the solution is added a
small quantity of sodium phosphate and a zirconium salt
and it is found that zirconium phosphate as it precipitates
carries with it the radioactive element. For aluminium
these experiments are delicate, for they must be made
in about six minutes, the average life of the radioactive
atoms which are formed being less than five minutes.
Figure 3. The electromagnet: which is now exhibited in the Maria Sklodowska-Curie Museum
in Warsaw.
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Figure 4. Frédéric Joliot-Curie with a Wilson cloud chamber at the Collège de France, Paris.
Chemical tests of the same kind have shown us that the
radio-element formed in boron under the action of alpha
rays is an isotope of nitrogen”.
Nobel Prize award donation to
the Warsaw Radium Institute
The Joliot-Curies visiting the Physics Department of the
Warsaw Radium Institute in October 1936 (Figure 2)
after donating 12,000 Złoty from their Nobel Prize
to provide the Institute with a special electromagnet
(Figure 3) needed for a Wilson cloud chamber. Later,
in 1939 in the Nuclear Chemistry Laboratory of the
Collège de France, Paris, after the discovery in 1938 of
nuclear fission by Otto Hahn & Fritz Strassmann [5],
Frédéric Joliot-Curie was to be the first scientist to take
a photograph of nuclear fission using a Wilson cloud
chamber (Figures 4-5).
Biographical references for
Irène & Frédéric Joliot-Curie
There have been relatively few books devoted solely to
the lives and works of Irène Curie (1897-1956) and of
Frédéric Joliot (1900-1958) [6-13] when compared to the
large number devoted to Marie Curie. Other publications
Figure 5. The first photograph of the phenomenon of nuclear fission, January 1939 by Frédéric
Joliot-Curie.
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Acknowledgements
I am very grateful to the Musée Curie in Paris and the
Muzeum Marii Sklodowska-Curie in Warsaw for providing
me with photographs over a period of many years, including
Figures 1-7.
Richard F. Mould, MSc, PhD
4 Town End Meadow
Cartmel
Grange-over-Sands
Cumbria LA11 6QG
United Kingdom
Figure 6. Advertisement for Irène Curie’s electroscope.
also contain relevant material [14-16]. These [6-16] cover
their early lives, experiences during two world wars, their
scientific work and their political affiliations.
In conclusion, it is of interest to note, what are now
largely two forgotten scientific achievements by Irène.
She developed an electroscope in the later 1920s [17]
(Figures 6-7), and was the author of a 1946 textbook
Les Radioélements Naturels [18] which was used by her
students at the Sorbonne. The six section titles in this
book are given in Table I and as seen, the include the
topic of artificial radioactivity.
Table I. Sections in Les Radioéléments Naturels [18].
(1) Propriétés chiniques et préparation des radioéléments sauf le
protection et les dépôts
(2) Propriétés chiniques et préparation du protoactinium
(3) Propriétés chiniques et préparation des corps des dépôts actifs
(4) Radiochimie, électrochimie, indicateurs radioactifs
(5) Appareils de mesures, méthodes de dosage
(6) Propriétés chiniques et préparation des radioéléments artificiels
représentant des eléménts
References
1. Curie I, Joliot F. Artificial production of a new kind of radioactive
element. Nature 1934; 133: 201-2.
2. Bothe W, Becker H. Künstliche Erregung von Kern-γ-Strahlen. Zeitschrift
für Physik 1930; 66: 289-306.
3. Curie I. Sur le rayonnement gamma nucléaire excité dans le glucinium
et dans le lithium par les rayons alpha du polonium. Comptes rendus de
l’Académie des sciences 1931; 193: 1412-4.
4. Joliot F. Sur l’excitation des rayons gamma nucléaires de bore par
les particules alpha. Energie quantique du rayonnement gamma
du polonium. Comptes rendus de l’Académie des sciences 1931; 193:
1415-17.
5. Hahn O, Strassmann F. Ueber die Entstehung von Radiumisotopen aus
Uran durch Bestrahlen mit schnellen und verlangsamten Neutronen.
Naturwissenschaften 1938; 26: 755-6.
6. Joliot-Curie F. Textes Choisis. Paris: Editions Sociales, 1959.
7. Biquard P. Frédéric Joliot-Curie. Paris: Editons Eghers, 1961. Also
published as: Biquard P. Frédéric Joliot-Curie the Man & His Theories.
London: Souvenir Press, 1965.
8. Joliot-Curie F, Curie I. Oeuvres Scientifiques Complètes. Paris : P.U.F.,
1961.
9. Ziegler G (ed). Choix de Lettres de Marie Curie et Irène Joliot-Curie 19051934. Paris : Les Editeurs Français Réunis, Editions Messidor, 1974.
10. Goldsmith M. Frédéric Joliot-Curie. London: Lawrence & Wishart,
1976.
11. Pflaum R. Marie Curie & Her Daughter Irene. Minneapolis: Lerner,
1993.
12. Chouchan M. Irène Joliot-Curie ou la Science au Coeur. Paris: Hachette,
1998.
13. Pineault M. Frédéric Joliot-Curie. Paris: Editions Odile Jacob, 2000.
14. del Regato JA. Jean Frédéric Joliot. In: del Regato JA. Radiological
Physicists. New York: American Association of Physicists in Medicine,
1983, pp 97-115.
15. Radvanyi P. Les Curies Deux Couples Radioactifs. Pour La Science
November 2001-February 2002. Also published as: Radvanyi P. Die
Curies eine Dynastie von Nobelpreisträgern. Spektrum der Wissenschaft
Biographie 2003; issue 2.
16. Brian D. The Curies a Biography of the Most Controversial Family in
Science. Hoboken: John Wiley, 2005.
17. Curie I. Electroscope pour le mesure de la radioactivité des engrais. Ann
de la Sci Agronomique Fr et étrangè 1922.
18. Joliot-Curie I. Les Radioéléments Naturels. Proprietés, Chimiques,
Préparation, Dosage. Paris : Hermann et Cie, 1946.
Received: 15 June 2009
Accepted: 20 July 2009
Figure 7. Irène Curie at the Institut du Radium preparing a radioactive
source in 1920.