Other Players
Early in 1935 the chief Italian journal of physics, Nuovo Cimento , pointed out that Lawrence was behind Fermi's group in the discovery of Na24 . The Research Corporation likewise came late in the effort to patent it. On October 26, 1934, Fermi's group obtained an Italian patent covering activation by the absorption of fast or slowed neutrons and the products of the process, including radiosodium, as well. This violation of the physicist's ethos originated not with Fermi but with his patron O.M. Corbino, who had close ties to what high-tech industry then existed in Italy. "Age gave him wisdom," Mrs. Fermi writes, "[and] the boys were used to following his advice."[132]
But they, too, had been anticipated by "the inventor of all things."[133] In March 1934, a month or so after learning about artificial radioactivity and before Fermi's group had demonstrated the efficacy of neutrons, Szilard applied for a British patent on the "transmutation of chemical elements." His "invention," which he never reduced to art, had three parts: generation of neutrons to provoke reactions; separation of radioisotopes produced by the
[130] Lawrence to DuBridge, 14 June 1939 (15/26A). Probably no cyclotron laboratory charged for its products before the war; J.A. Fleming to V. Bush, 6 Sep 1940 (MAT, 25/"biophys.").
[131] Texas Ind. Comm., Texas giants , 6–7; Brobeck, interview by Seidel, June 1985 (TBL); IEEE, "1978 Conference," IEEE trans., NS, 26 (1979), 1703–32; Highfill and Wieland, ibid., 2220–3.
[132] A.P., Nuovo cimento, 12 (1935), 123–4; Segrè, Fermi , 83–5; L. Fermi, Atoms , 101, quote; Russo, HSPS, 16:2 (1986), 286.
[133] McMillan to Mann, 3 Jan 1952 (12/31).
(n,g ) process; and utilization of the heat liberated in the transmutation. Szilard's eccentric genius is displayed to full advantage in his method of obtaining neutrons. He planned to use deuterons accelerated by a high-tension device to create neutrons in collisions with light nuclei like beryllium or deuterium (he had made good use of the indications then accumulating of the d-d reaction that had misled Lawrence); he also proposed getting his neutrons from light, via (g ,n), and sketched an apparatus for making and absorbing photoneutrons.
The productivity of the transmutation evidently depends upon the number of neutrons at work. Szilard observed that if there exists a nucleus that when struck by a neutron liberates another without capturing the first, a very rapid buildup of a free neutronic population might occur. Mixing these hypothetical neutron multipliers with the material to be transmuted would increase the efficiency of transmutation; and a large enough sample of the material capable of sustaining the chain reaction (n,2n) would make a fine explosive. For the rest, Szilard proposed to separate isotopes made by (n,g ), which are chemically identical to their parents, by exploiting a process he did take the trouble to test.[134] His scheme as of June 1934, including provision for extracting power, appears in figure 4.2.[135]
Szilard considered assigning his first British patent on isotope and energy production to the Research Corporation in return for a grant for three years to continue research on the subject.[136] Instead, he licensed it to a relative of Brasch's, a Havana importer named Isbert Adam, in return for $15,000 in research support. (Szilard thereby made more money from radioactivity than the Research Corporation, even after subtracting the $7,000 he subsequently repaid Adam to reacquire the patents in 1943.)[137] In March 1936, when Szilard obtained a second patent on chain
[134] British patent application no. 7840, 12 Mar 1934, preliminary drafts, and supplements, 4 Jul and 20 Sep 1934, in Szilard, CW, 1 , 605–28, resulting in British patent no. 440,023, granted 12 Dec 1935.
[135] From supplementary application, 28 June 1934, resulting in patent no. 630,726, of 30 Mar 1936; Szilard, CW, 1 , 650.
[136] Szilard to Fermi, 13 Mar 1936 (Sz P, 17/197), and to Cockcroft, 27 May 1936, in Weart and Szilard, Szilard , 47–8.
[137] Szilard licensed patent no. 440,023 to Adam, Dec 1936 (Sz P, 29/311).
Fig. 4.2
Szilard's cornucopia of radioelements. Deuterons from the source 1 make
fast neutrons from the beryllium target 28, which spread through a sphere
3 composed of all elements that might multiply neutrons and that might
develop energy on absorbing neutrons. The tubes 107, 110, 111 contain a
coolant that delivers the heat of the reaction to an engine not shown.
Szilard, CW, 1 , 650.
reactions, he had reason to believe that multiplication of neutrons was possible. In his applications of 1934, he had imagined three sorts of interactions: a neutron multiplication (n,2n), a neutron conversion (n,2n ), and a neutron reduction (2n ,n), where 2n is a hypothetical heavy neutron with twice the mass of an ordinary one. In his definitive specification of June 1934, the basis of his patent of 1936, Szilard made the success of the chain reaction depend upon the existence of heavy neutrons, and offered indium, which in his experiments suffered an (n,4n ) reaction, as an element of the conversion type.[138]
He mobilized fellow Hungarian refugees Eugene Wigner and Michael Polanyi to procure the material needed to initiate a chain reaction. He acquired a cylinder of beryllium, and access to a big radium bomb in a London hospital, to make photoneutrons. He convinced himself that indium could give out at least one double neutron via (n,2n) or (n,2n ).[139] A trip to the United States provided leisure to weigh the whale he had hooked; and in March 1935 Szilard filed for an American patent on a large-scale transmutation process, similar to the earlier schemes, but with uranium and water (to slow the neutrons) as the neutron multiplier. All this was before the discovery of fission.[140] The responsibility for the chain reaction grew too heavy for Szilard to carry and in order to keep it secret he offered to assign the patent detailing it (his second British patent on transmutation) to the War Office. The official who examined the gift could see no value in it. Szilard had better luck with the Admiralty, which accepted his assignment in March 1936.[141]
As Szilard explained his actions to Fermi and to his British colleagues, he had never considered the patents to be his private property. He proposed to Fermi that they share responsibility for
[138] Szilard, CW, 1 , 643–6 (28 June 1934); memos of 13 and 28 Jul 1934 (Sz P, 29/309, 17/197); Weart and Szilard, Szilard , 39–40.
[139] Szilard to Wigner, 7 Aug 1934; to Lange, 6 Nov 1934; to Brasch and Lange, 12 Dec 1934; to Lindemann, 3 June 1935; all in Sz P, 17/197. The important part of the letter to Lindemann is also in Weart and Szilard, Szilard , 41–2.
[140] Szilard to Singer, 16 June 1935 (Sz P, 17/197); U.S. patent application no. 10,500, filed 11 Mar 1935, in Szilard, CW, 1 , 654–90.
[141] J. Combes to War Office, 8 Oct 1935, and director of navy contracts to Szilard, 20 Mar 1936 (Sz P, 17/197); Szilard to C.S. Wright, Admiralty, 26 Feb 1936 (Sz P, 44/476), in Szilard, CW, 1 , 733–4.
controlling a fund secured by the promise of their patents. "It must be awkward for any scientist to have a personal interest from such patents," Szilard wrote, "while other scientists, who also could have taken out such patents, refrain from doing so." As for the research the fund might support, Szilard did not see the wisdom of the course of the Research Corporation and its Berkeley client; "I personally do not think very much of producing radioactive elements for medical purposes and I should not like to be responsible for inducing manufacturers to embark upon such an enterprise at present."[142] (In that he was not entirely free from duplicity, since he wrote by the same mail to his patron Adam that the first priority was a systematic search for long-lived elements suitable for medical purposes). Nor did Szilard think much of the cyclotron. As he wrote to encourage Adam: "The artificial production of radioactive isotopes in California that you mention depends on a principle different [from mine], which I think is not susceptible of development and will have scarcely any commercial importance."[143]
For development of his more promising scheme, Szilard thought that he could do with perhaps 1,000 pounds sterling a year and, if Fermi came in, 5,000 pounds for three years, less than a sixth of Lawrence's rate of consumption.[144] Still the sum was not easy to raise. The agent of the Italian group, G.M. Giannini, agreed that the combined patents would make a nice set and professed an interest in cooperation; Segrè liked the idea of capitalizing the patents for a research fund, and for the researchers, "which would also indirectly advance science." But nothing came of it. Szilard continued to consider himself a disinterested broker.[145] The Italians preferred to make money and hoped for a
[142] M. Goldhaber to Szilard, 18 Mar 1936, in Weart and Szilard, Szilard , 44: "Of course, your intentions were misunderstood to be financial or otherwise unscientific." The idea of a patent pool for public purposes appears in Szilard's memo to himself of 13 Jul 1934 (Sz P, 29/309).
[143] Szilard to Fermi, 13 Mar 1936, in Szilard, CW, 1 , 729–30; to Segrè, 1 Apr 1936, ibid., 732; to Adam, same date (Sz P, 29/310), and 14 Oct 1935 (Sz P, 44/476).
[144] Szilard to Singer, 9 and 16 June 1935 (Sz P, 12/197); to Fermi, 13 Mar 1936, in Szilard, CW, 1 , 729–30; to Segrè, 1 Apr 1936, ibid., 731–2.
[145] Giannini to Szilard, 8 Mar and 20 Apr 1936; Segrè to Szilard, 21 Mar 1936; Szilard to Giannini, 8 Aug 1936, all in Sz P, 44/476.
time to set up an industrial concern; they turned down an option on the patents offered by Metropolitan-Vickers on Allibone's recommendation and ended by selling their European rights for $3,000 to Philips of Eindhoven, which had set up a nuclear section partly as a result of a visit from Segrè.[146] They failed to interest any American corporation in their radioactive technique. Still, they obtained more than they dreamt of in the 1930s when, after much haggling, the U.S. government, which had exploited their technique during the war, paid them $400,000 as "just compensation."[147] As for Szilard, he felt obliged to explain his altruistic policies to the major British physicists, and, when Fermi's group went its own way, to license Adam.[148]
There is another round to the story. In 1938 Szilard removed his headquarters from England to New York City, where he rightly expected to find greater scope for his schemes. He now concentrated on improving the neutron source. From data on neutron yields provided in papers from Berkeley and Rome, Szilard calculated that the energy that could be stored in transmuted radioactive atoms might be one hundred times the energy of the bombardment required to make the neutrons to make the transformations. Economics had given its blessing; only a little ingenuity was required to make a nuclear-powered airplane. "Perhaps we ought to think of new methods for producing really strong neutron beams." Szilard had proposed to Brasch to scale up a hightension machine to slam electrons into metal walls at 10 MeV. The resulting x rays would sire neutrons in profusion from a beryllium target.[149]
[146] Bakker to Segrè, 21 Jul 1935 (letter in Segrè's possession). Siemens of Berlin also began to take an interest in radioelements in 1935, in October, when it established a laboratory under Gustav Hertz to investigate production possibilities. Osietzki, Technikges., 55 (1988), 32–3.
[147] Allibone, PRS, A282 (1964), 451, and in Hendry, Cambridge physics , 171–2; Segrè, Fermi , 84–5. The American patent covered activation by slow neutrons; the Italian group tried also to patent all neutron activation, which Lawrence thought "ridiculous." Lawrence to Poillon, 24 Sep 1940 (15/18).
[148] Szilard to Cockcroft and to Rutherford, 27 May 1936, in Weart and Szilard, Szilard , 45–8; to Cockcroft, 21 May 1936 (Sz P, 17/197).
[149] Szilard to Brasch, 3 and 10 Jul 1937 (Sz P, 29/307); cf. Szilard to Adam, 2 Oct 1935 (Sz P, 44/476), on Szilard's earlier efforts to mobilize Brasch.
For money Szilard appealed to Lewis Strauss, a Wall Street financier with an interest in radiation therapy for cancer, who thus entered on his controversial career in atomic energy. As a light inducement to cooperation, Szilard offered to give to any taxexempt nonprofit corporation Strauss might wish to set up for producing radioelements a nonexclusive license to exploit whatever of his rights he had not sold to Adam. Strauss tried to enlist Westinghouse, General Motors, and General Electric; but all that came of it was an introduction to another supplicant, "whose friendship for the following twenty years was one of the finest experiences of my [Strauss's] life." That was Lawrence, who this time got nothing from Strauss. The future friend had decided to support Brasch and Szilard, if only a suitable place for Brasch's experiments could be found. One was. Toward the end of 1938 the ever-acquisitive Millikan offered space at Caltech, on the understanding that it would cost him nothing.[150]
Brasch intended to reach for 15 MV, which Millikan thought "exceedingly interesting and thrilling," and also expensive, over $100,000. Strauss doled out his money in droplets; Brasch complained that he could not exist on "homeopathic doses" of dollars, and raised the estimate to $200,000; by 1940 the adventure had come to an end nowhere near its goal.[151] Meanwhile fission had been discovered, and the royal road to atomic energy. Szilard kept Strauss apprised of progress by telegram, although they were almost neighbors, and asked his benefactor to find him another. Szilard had in mind Alfred Loomis, a retired investment banker and a first-rate amateur physicist, who soon became one of Lawrence's main advisors and supporters.[152] Szilard wished Loomis to help underwrite the cost of experiments he planned to try at Columbia University, where he had a guest appointment, to determine how fission might be exploited for atomic energy. To complete the circle, the new émigré professor of physics at Columbia, Enrico Fermi, was then engaged in the same line of work. We shall return to their unequal competition.
[150] Szilard to Strauss, draft, n.d., and to Adam, 16 Nov 1938 (Sz P, 29/306); Strauss, Men and decisions , 163–5.
[151] Brasch to Szilard, 27 Jan 1939, and n.d. (Sz P, 29/306); Millikan, quoted by Strauss, Men and decisions , 168.
[152] Szilard to Strauss, 28 Feb 1939, and telegrams, Feb–Apr 1939 (Sz P, 17/198).