Disintegration of uranium by neutrons: a new type of nuclear reaction. Offprint from Nature, Vol. 143, No. 3615, 11 February 1939 [PMM 422b]. [Offered with:] Products of the fission of the uranium nucleus. Offprint from Nature, Vol. 143, No. 3620, 18 March 1939

First edition, extremely rare offprints, of the discovery of nuclear fission, a process which had been observed by Otto Hahn and Fritz Strassmann the previous year but for which they were unable to provide an explanation. "In the late 1930s, a series of experiments showed that bombarding uranium with neutrons produced several new radioactive elements, which were assumed to have atomic numbers near to that of uranium (Z = 92). This assumption followed naturally from the prevailing view of nuclear decay, which involved the emission, through tunnelling, of only small charged particles (α and β). How then did one explain the formation of an element which was, as far as could be determined, identical to barium (Z = 56), and thus much smaller than uranium?" (Nature Physics Portal)  "Experiments conducted in 1938 at Berlin by Hahn and Strassmann were reported to Lise Meitner, an Austrian scientist who had fled to Copenhagen to escape religious persecution. She and her nephew, O[tto] R[obert] Frisch, working in Niels Bohr's laboratory, found the true explanation of these phenomena. The interpolation of a neutron into the nucleus of a uranium atom caused it to divide into two parts and to release energy amounting to about 200,000,000 electron volts. This process bore such a close similarity to the division of a living cell that Frisch suggested the use of the term 'fission' to describe it" (PMM). In the second offered offprint, Meitner & Frisch report experiments that strengthen their conclusion by showing that the products of the bombardment of uranium with neutrons could not be transuranic elements, i.e., elements with atomic number greater than 92, as had earlier been suggested by Hahn & Strassmann. The two fission offprints are offered with two further offprints by Meitner, one of which is inscribed by her. No copies of the first two offprints on OCLC. ABPC/RBH list a single copy of the first offprint (Sotheby's, 16 November 2001, lot 126), and none of the second.

"In December 1938, over Christmas vacation, physicists Lise Meitner (1878-1968) and Otto Frisch (1904-79) made a startling discovery that would immediately revolutionize nuclear physics and lead to the atomic bomb. Trying to explain a puzzling finding made by nuclear chemist Otto Hahn (1879-1968) in Berlin, Meitner and Frisch realized that something previously thought impossible was actually happening: that a uranium nucleus had split in two.

"Lise Meitner was born in Vienna in 1878. She grew up in an intellectual family, and studied physics at the University of Vienna, receiving a doctorate in 1906. As a woman, the only position available to her at that time in Vienna was as a schoolteacher, so she went to Berlin in 1907 in search of research opportunities. Meitner was shy, but soon became a friend and collaborator of chemist Otto Hahn. In 1912 the Kaiser Wilhelm Institute for chemistry was established, and she obtained a position there. During World War I Meitner volunteered as an x-ray nurse in the Austrian army. Upon returning to Berlin she was made head of a physics section at the KWI, where she did research in nuclear physics.

"After the neutron was discovered 1932, scientists realized that it would make a good probe of the atomic nucleus. In 1934 Enrico Fermi (1901-54) bombarded uranium with neutrons, producing what he thought were the first elements heavier than uranium. Most scientists thought that hitting a large nucleus like uranium with a neutron could only induce small changes in the number of neutrons or protons. However, one chemist, Ida Noddack (1896-1978), pointed out that Fermi hadn't ruled out the possibility that in his reactions, the uranium might actually have broken up into lighter elements, though she didn't propose any theoretical basis for how that could happen. Her paper was largely ignored, and no one, not even Noddack herself, followed up on the idea.

"Following Fermi's work, Meitner and Hahn, along with chemist Fritz Strassmann (1902-80), also began bombarding uranium and other elements with neutrons and identifying the series of decay products. Hahn carried out the careful chemical analysis; Meitner, the physicist, explained the nuclear processes involved.

"Meitner, who had Jewish ancestry, worked at the KWI until July 1938, when she was forced to flee from the Nazis. Her research was her whole life, and she had tried to hang on to her position as long as possible, but when it became clear that she would be in danger, she left hastily, with just two small suitcases. She took a position in Stockholm at the Nobel Institute for Physics, but she had few resources for her research there, and felt unwelcome and isolated. She kept up her correspondence with Hahn, and continued to advise him about their joint research.

"In December 1938, Hahn and Strassmann, continuing their experiments bombarding uranium with neutrons, found what appeared to be isotopes of barium among the decay products. They couldn't explain it, since it was thought that a tiny neutron couldn't possibly cause the nucleus to crack in two to produce much lighter elements. Hahn sent a letter to Meitner describing the puzzling finding.

"Over the Christmas holiday, Meitner had a visit from her nephew, Otto Frisch, a physicist who worked in Copenhagen at Niels Bohr's institute. Meitner shared Hahn's letter with Frisch. They knew that Hahn was a good chemist and had not made a mistake, but the results didn't make sense. They went for a walk in the snow to talk about the matter, Frisch on skis, Meitner keeping up on foot. They stopped at a tree stump to do some calculations. Meitner suggested they view the nucleus like a liquid drop, following a model that had been proposed earlier by the Russian physicist George Gamow and then further promoted by Bohr. Frisch, who was better at visualizing things, drew diagrams showing how after being hit with a neutron, the uranium nucleus might, like a water drop, become elongated, then start to pinch in the middle, and finally split into two drops.

"After the split, the two drops would be driven apart by their mutual electric repulsion at high energy, about 200 MeV, Frisch and Meitner figured. Where would the energy come from? Meitner determined that the two daughter nuclei together would be less massive than the original uranium nucleus by about one-fifth the mass of a proton, which, when plugged into Einstein's famous formula, E=mc2, works out to 200 MeV. Everything fit.

"Frisch left Sweden after Christmas dinner. Having made the initial breakthrough, he and Meitner collaborated by long-distance telephone. Frisch talked briefly with Bohr, who then carried the news of the discovery of fission to America, where it met with immediate interest.

"Meitner and Frisch sent their paper to Nature in January. Frisch named the new nuclear process "fission" after learning that the term "binary fission" was used by biologists to describe cell division. Hahn and Strassmann published their finding separately, and did not acknowledge Meitner's role in the discovery" (American Physical Society, ).

"A few months later [i.e., after submitting the first offered paper], [Meitner & Frisch] jointly demonstrated experimentally that radioactive fission fragments could be collected on a water surface close to a uranium layer undergoing neutron irradiation. They further showed that the sulfide precipitated from the material so obtained had a decay curve of the same shape as the precipitate derived directly from the irradiated uranium. They concluded that no observable amounts of uranic elements were produced" (DSB, under Meitner).

"Scientists quickly recognized that if the fission reaction also emitted enough secondary neutrons, a chain reaction could potentially occur, releasing enormous amounts of energy. Many scientists joined the efforts to produce an atomic bomb, but Meitner wanted no part of that work, and was later greatly saddened by the fact that her discovery had led to such destructive weapons. She did continue her research on nuclear reactions, and contributed to the construction of Sweden's first nuclear reactor. Hahn won the Nobel Prize in chemistry in 1944, but Meitner was never recognized for her important role in the discovery of fission" (APS, ibid.).

Offered with the two offprints on nuclear fission are offprints of two papers from Meitner's later period in Stockholm, after she had left the Nobel Institute (in 1947) and had moved to the laboratory of the Royal Academy for Engineering Sciences, where an experimental nuclear reactor was being built.

Einige Bemerkungen zu den Einfangquerschnitten langsamer und schneller Neutronen bei schweren Elementen. Offprint from: Annalen der Physik, 6. Folge, Bd. 3 (1948), pp. 115-119. Self-wrappers.

"In the spring of 1947, plans were approved for an experimental nuclear reactor, Sweden's first, to be built deep into the granite underlying Drottning Kristinas Väg. Sigvard Eklund was the project director; together with Meitner, they attracted young physicists and engineers interested in basic nuclear research and reactor technology. Among other studies, Meitner measured neutron capture cross-sections for several heavy elements, for fast and slow neutrons. The results were of theoretical interest, as it appeared that certain spin selection rules might be responsible for some abnormally small slow-neutron capture cross sections in lead and bismuth; the investigation was also relevant to reactor function, as fission produces numerous new isotopes with a wide range of neutron absorption characteristics" (Sime, p. 359)

Einige Bermerkung [sic] zur Struktur der Atomkerne. Offprint from: Festskrift for Herbert Jacobsson (Traung, ed.). [Göteborg, Wezäta, 1948.], pp. ???? Original printed wrappers. Inscribed by Meitner 'Mit herrlichsten Grussen // L.' on front wrapper.

Jacobsson (1878-1948) married into a large Swedish shipping family. From 1925 he assumed part of the responsibility for running the business. Together with his wife, he made large donations for scientific purposes.

Norman 1487 (journal issue); PMM 422b (both for the first offered paper). Sime, Lise Meitner, 1996 (see Chapter 10).