An Easy Clone
The first working cyclotron outside the United States came to life not in a great center of nuclear physics in Europe, but at the Institute for Physical and Chemical Research (Riken) in Tokyo. This precociousness was born of a conjunction of forces characteristically Japanese: a conviction on the part of government and industry that excellence in Western science was essential to Japan's place in the sun; an ability to assimilate foreign designs; and no vested interest in any machinery for splitting atoms. Just as the great substantive discoveries and instrumental improvements in experimental nuclear physics were being made in Europe and the United States, the Japanese, pulling themselves out of the Depression by military adventure and economic aggression, found the money and motive for multiplying particle accelerators in Tokyo. In 1932 Riken examined the leading Western alternatives and decided on a Van de Graaff; they next added a Cockcroft-Walton; and in 1935 they undertook to make a cyclotron.
They stayed close to their prototype. They procured a Poulsen arc magnet as a gift from the Japan Wireless Telegraph Company and gave it symmetric poles. They raised other capital costs from a foundation (the Mitsui) then recently established by industry and got their oscillator free from the Tokyo Electric Radio Com-
pany. They succeeded, where Lawrence had failed, in obtaining operating expenses from the utility that supplied their power, the Tokyo Electric Light Company. For technical guidance, Riken sent a man to Berkeley. Lawrence had warned that otherwise they would never make a cyclotron in a reasonable length of time. "It is rather ticklish in operation, and a certain amount of experience is necessary to get it to work properly." The emissary was Ryokichi Sagane, who, despite his name, was the son of Hantaro Nagaoka, the elder statesman of Japanese physics and an important voice in the allocation of research funds. Sagane arrived in Berkeley in the fall of 1935 and remained for over a year. He did his job if anything too well: following his instructions, his compatriots copied Berkeley mistakes as well as successes and Lawrence had to instruct them to fill up holes they had drilled in the tank plates in emulation of a measure once tried and immediately discarded at the Laboratory to improve the magnetic field. The machine, with 27-inch poles on the Poulsen magnet, wax seals and glass insulators in the chamber, and an oscillator arranged in the Berkeley manner, took just over a year to build. When it started up in April 1937, its builders again aped Lawrence and called in the press. The reporters celebrated Riken's "large and fantastic laboratory for the atomic nucleus" and ranked it second only to Berkeley's.
The main responsibility for the construction of the cyclotron rested on Tameichi Yasaki, who had the benefit of only a brief sojourn in the Laboratory. Not being proficient in the high art of shimming, he could not coax more than a few µA from the machine. With Sagane's trained touch, Tokyo gained a very respectable deuteron beam of 30 µA (later 47 µA) at 3 MeV. The cyclotron ran well, eventually for as long as thirty hours at a stretch, at least as reliably as Berkeley's 27-inch. Its anticipated
success caused the Japanese to adopt still another of Lawrence's practices. Long before they got the first beam from their 26-inch cyclotron, they had determined to make a bigger machine, indeed the biggest. With extraordinary confidence and deferential effrontery, they asked to copy the Crocker cyclotron while it was under construction. Lawrence met the request with his usual generosity and enlightened self-interest. He helped the Japanese order the necessary metal in the United States, where it was cheaper than in Japan, and had Brobeck and Cooksey help Sagane oversee the machining of the iron, the coiling of the copper, the procurement of the coil tanks, and so on. Why was he so forth-coming? No doubt the flattery implied by the copying, the tug of the exotic East, and appreciation that Riken had pioneered the cyclotron abroad inspired his actions; so, too, did the hope that two 60-inch machines could be built at less than twice the price of one. "I should be glad to help the Japanese in this way," he wrote Revere Copper and Brass, "because, in addition to helping out the scientific work in Japan, it should be possible for us to get somewhat better price quotations if we place double orders for the material and equipment." When it became clear that there was no economy of scale, Lawrence made a virtue of necessity. He wrote Columbia Steel: "My position is only that of one who desires to be of help in furthering important scientific work in this county and abroad."
The metal for the Japanese Crocker arrived in Tokyo in the spring of 1938. Its completion was delayed by an impulse to innovate and by a new sort of trouble with oscillators. Here the cyclotron made its first acquaintance with war. Riken required for its oscillator precisely the same sort of tubes that the Japanese Army used in its broadcasting stations in China; none could be bought in Japan and import restrictions inhibited procurement abroad. Cooksey suggested to Sagane that they make their own tubes, in accordance with blueprints he provided, and Lawrence offered to supply any further information required "about our design and
technique." In 1940, having decided that their innovations were not improvements, the Japanese applied to the Laboratory for all blueprints of the perfected 60-inch cyclotron. Here again they ran into war. The Laboratory, previously so cooperative, now would give nothing. Cooksey wrote in 1943: "When the Japs left this country [after a visit in 1940], they were making every effort to obtain from us the final details about our construction and methods. We have consistently refused them any information for approximately the last three years." Why details of the cyclotron became confidential before Pearl Harbor will be explained in due course.
The two Tokyo cyclotrons bracketed the prewar foreign implementation of Lawrence's prepotent invention. The installations that had achieved a beam by 1940 are listed, with some vital statistics, in table 7.1. As appears from the table, five cyclotrons were operating in Europe in 1939. The stories of four of them—we neglect Stockholm's, since it came on only briefly, literally on the eve of the war—instance the disparity between Lawrence's Laboratory and the physics institutes of the Old World.
Conversion rates will assist evaluation of the sums to be mentioned. Between 1934 and 1939, the Danish krone held steady at 22 cents; the French franc declined gently but gravely from 6 cents to 3 cents; the German Reichsmark held at 40 cents; the Italian lire fell from 8 cents to 5 cents; and the British pound, having hovered around $4.95 since 1934, dropped to $4.43 in 1939.
A Preference for High Tension
The major laboratories for nuclear physics in France and Britain had declined the opportunity to clone the 27-inch cyclotron from the obsolescent Poulsen-arc magnets decommissioned by the
French radio service in 1932. Their disinclination had both negative and positive causes. On the minus side, the cyclotron of 1932 ran unsteadily, could not accelerate electrons, and when operating delivered only a fraction of a µA to the target. It retained its reputation for unreliability after it had attained the ability to work an eight-hour day, perhaps because visitors who came when it was under repair advertised their disappointment. As late as the winter of 1935/36, the cyclotroneers themselves acknowledged that their machines did not function most of the time. At Princeton they expected to operate only two hundred hours a year. Making his usual virtue of necessity, Lawrence reassured Chadwick that he need not worry much about the power bill for his planned cyclotron since it would run so infrequently. We may recall Lawrence's inability to supply $2,000 worth of radiosodium to clients of the Macy Foundation in 1935.
By the winter of 1937/38 a well-made cyclotron could work steadily if not driven at its maximum capabilities. In the spring of 1938 the 37-inch ran at an average of eight hours a day, seven days a week, and Princeton's cyclotron went on for three months without serious mishap. Nonetheless the impression remained abroad that, as Lawrence wrote to an English physician trying to promote a medical cyclotron in Britain, "the cyclotron is still a very unreliable apparatus;" and occasionally he had to reassure American inquirers that "the cyclotron is no longer a capricious laboratory device. . . . [but] an efficient and thoroughly rugged and reliable apparatus." And yet, between the desire to improve performance and the need to repair and replace parts, cyclotroneers often had their machines apart. In July 1938, in a tour of all the cyclotron laboratories in the East, Livingston saw nothing to see. "Don't let this get out," he wrote Lawrence, "but I did not find a single cyclotron operating."
In addition to their unreliability, the early Berkeley machines were depreciated in Europe for their finicky and "empirical" character. The Europeans had the "general impression [Lawrence acknowledged] that the cyclotron is a very tricky and difficult apparatus to operate." As for empiricism, the missionary cyclotroneers freely admitted the charge, and even gloried in what elevated a possible science into an actual art. In describing the Cornell cyclotron, Livingston pointed to the size of the gap between pole faces, the height of the dee aperture, the position of the source filament, and the shimming of the magnet as parameters that could only be fixed by "experimental maneuvers;" at Princeton, Henderson and White admitted to the method of cut and try in setting the dimensions of their magnet, the position of their filament, and so on, and to their inability to justify many design details, "except to say that [they are] known to work." Nor did the mother church affect to know the principles of its practice. In describing the definitive version of the 27-inch cyclotron late in 1936, Lawrence and Cooksey recommended maximizing the beam by ad hoc adjustments to, among other things, the deflecting potential, the shimmed magnetic field, and the positions of the dees, deflecting plate, and source filament.
All this summed to trop d'empirismes , too much tinkering, according to Nahmias, who thus depreciated the cyclotron after a visit to Princeton. The criticism was almost out of date when Nahmias made it in the spring of 1937; cyclotrons then being built would operate with fewer empirismes as well as with greater regularity. Here one story is worth a thousand words. Cooksey and Kenneth Bainbridge of Harvard visited the Bartol cyclotron in April 1938. Its creator, Alexander Allen, threw the switches; a beam came immediately, without fiddling. Bainbridge, who had never seen a cyclotron work, cried in astonishment, "Why, he just turned it on!"
In comparison with cyclotrons, again according to Nahmias's survey of March 1937, Tuve's improved two-meter Van de Graaff generator, which operated with great reliability at 1,000 kV and even at 1,200 kV, "under good conditions, compounded of low humidity, good fortune, and infinite other ingredients," had the advantage of few empirical adjustments to achieve a strong, homogeneous beam. High-tension apparatus not only produced better beams for exact work, but it did so by scaling up devices familiar to physicists. The cyclotron could not make headway in Europe until it could demonstrate advantages so decisive that physicists there would undertake to master the alien field of radio technology. After a visit home to the Cavendish in 1934, Bernard Kinsey succinctly explained his countrymen's reluctance to make cyclotrons: "They are all scared stiff at the thought of setting up an oscillator." Lawrence himself pointed to the radio engineering as the most challenging part of his operation: "The difficulties encountered [in making a new cyclotron] are similar to those found when a new radio broadcasting station of design and power that's never been used before is first constructed." The high-frequency oscillator for Bohr's cyclotron was to have an energy and to present a difficulty larger than the shortwave transmitter of the Danish state radio. Why trouble with a finicky machine and unfamiliar technology when other sorts of accelerators seemed capable of doing the same or similar jobs?
Tuve's group had advertised their technique by veiled reference to the superiority of the point of view of the investigator in a high-tension laboratory to his counterpart in a (or rather in the ) cyclotron laboratory. Their call for detailed exploration of reactions initiated by homogeneous beams before subliming to high voltages met with widespread agreement outside Berkeley. A clear conscience and a pure beam did not exhaust the advantages
of high-tension over magnetic-resonance acceleration. As Tuve told Nahmias, a Van de Graaff version of high-tension accelerators could work at continuously variable voltages, could push electrons as well as positive ions, could make x rays, might achieve as much as 10 MeV, and would do it all at less expense than any other model. Hence, he said, Westinghouse was building a Van de Graaff with two concentric spheres, the larger 10 meters in diameter, large enough to enclose an ordinary laboratory space, and capable of maintaining a pressure of 10 atmospheres. If all went well, and, as we know, it did not, Westinghouse would get 10 MeV for $15,000.
Decisions taken at the Cavendish in 1935 and 1936, when the laboratory recognized the need to go to higher energies, indicate the considerations then at work against cyclotrons. In May 1935 its newly appointed building committee for a high-tension installation approved a report drawn up by Cockcroft and Oliphant, who stressed the "immediate importance to develop apparatus for accelerating charged particles by at least two million volts." They recommended "an extension of the [Cockcroft-Walton] method of producing high steady potentials which has been in successful operation for two [more accurately three] years." In reaching this conservative conclusion they had the assistance of Philips of Eindhoven, which they had visited the preceding January. The Philips laboratories were "an eyeopener" to Oliphant, so he wrote Rutherford, "and in the opinion of Cockcroft . . . far superior to any in America." Oliphant eyed a million-volt high-tension set and desired to build a similar one, at twice the voltage, at the Cavendish. In explaining their decision to Lawrence, Cockcroft pointed to the Cavendish's interest in x rays as well as positive ions and to the existence of "plenty of [American] laboratories who would be capable of using the cyclotron method."
Cockcroft and Oliphant calculated that their laboratory would require a building sixty feet long, forty feet high, and forty feet wide, with concrete walls a foot and a half thick and a mobile
crane to install and repair the large tubes, transformers, and generators. They estimated the cost of the building at 4,000 pounds and that of the apparatus at under 3,000 pounds, over twice the price of the cyclotron then nearing completion at Princeton. They underestimated by much more than a factor of two. "The approximate cost of 15,000 pounds [for the building] staggered me, as I imagine it will you," Oliphant wrote Rutherford. "I can see the new laboratory receding into the distance if we are not careful. . . . It is a thing we need urgently, and not in some distant future when all the cream has been scooped off by folks whose results we dare not trust too deeply." From which it appears that Oliphant had in mind to do physics and further battle with Berkeley with his machine.
By July 1935 Rutherford had accepted these objectives and promoted Oliphant and the building. The former he made assistant director of research in place of Chadwick, who left the Cavendish for a professorship at Liverpool. The latter he lobbied for so effectively before the council of the senate of Cambridge University that it recommended proceeding at once with university funds to be repaid by proceeds from an outside appeal for the 250,000 pounds the laboratory deemed necessary to meet all its research needs. Rutherford's reluctance to ask for money has been overestimated.
The great cost of the building, which was completed in 1937, and technical difficulties precluded going directly to 2 MeV. Again the Cavendish had an opportunity to consider a cyclotron and a more modest establishment. Again Oliphant went to Philips and again returned inspired. He decided to buy a copy of the 1.2 MV installation he saw at work. "After a stiff fight with some of
my colleagues and with Philips themselves over the price [just under 6,000 pounds] I have persuaded the Prof. [Rutherford] to invest in one of these sets." This trouble-free, ready-made instrument arrived in its impressive building ("a cinema outside, a cathedral within") after Christmas 1936 and worked as advertised. By then its promoters had forsaken it. Oliphant had been appointed professor in Birmingham the previous June, effective October 1937. Cockcroft had at last pronounced in favor of a cyclotron, and returned from a visit to Berkeley in 1937 intending to recommend selling Cambridge's high-tension equipment. That pleased Lawrence immensely. "The Cavendish Laboratory has expended large sums of money in installing high voltage equipment," he wrote in 1937, in a puff of Berkeley. "Although the Cavendish Laboratory pioneered with high voltage methods the distinguished scientists there have come to the conclusion that the cyclotron is superior, and are adopting it." The Philips accelerator, which had seemed essential to the Cavendish's place in nuclear physics, fell eventually under the management of a Swiss physical chemist, Egon Bretscher, who used it as a neutron source to make radioisotopes for chemists and biologists.
Several other British institutions followed Cambridge in preferring high tension to the cyclotron in the second generation of particle accelerators. At Bristol, for example, two members of the staff each tried to make a Van de Graaff generator, while a third, Cecil Powell, built a Cockcroft-Walton machine. In a few years, when they wished for a cyclotron, they judged that they could not acquire one on their own resources. At Oxford, the New Clarendon was designed for a Van de Graaff or a Cockcroft-Walton, although the professor, F.A. Lindemann, doubted that his university would put up the money for such expensive apparatus. As for
the cyclotron, "an instrument most popular abroad," it had the disadvantages, according to Lindemann, of not being cheap either and of not accelerating electrons. When in 1938 he decided that he wanted a cyclotron and proposed that the Ministry of Health pay for it, the ministry declined on the ground that physicists had not yet "decided on the scientific basis of the cyclotron." Lindemann rejected this opinion, which he supposed to derive from a prominent British physicist, as the nonsense it then was: "There is no possible doubt about the scientific basis of the cyclotron in Oxford and still less in California. . . . I have no doubt that if one liked to spend the money one could buy a ready-made cyclotron from America which would function quite satisfactorily." One did not like to spend the money, and Oxford got no cyclotron.
High-tension machines were also the preferred second-generation accelerators on the Continent. In Germany, where university physics had been all but destroyed by the implementation of Nazi racial laws, the leading centers of experimental nuclear physics sheltered in the institutes of the quasi-independent Kaiser-Wilhelm-Gesellschaft. In 1934 Walther Bothe, whose work had set up the discovery of the neutron, became head of the physics department of the Kaiser-Wilhelm-Institut für Medizinische Forschung in Heidelberg. He had considerable experience in high-voltage technique. With the help of Wolfgang Gentner, who had worked with Joliot and who was to become the first German cyclotroneer, he set up a Van de Graaff at 950 kV, which began to operate in 1937. Despite the name of their institute, Bothe and Geiger's work with high tension centered on basic physics, for example, photoinduced nuclear reactions, work that in Joliot's judgment was for a time the most productive "in radioactivity and nuclear physics." That made a curious reversal of the situation of cyclotron laboratories in physics departments in the United
States, which then were beginning to produce radioactive materials for biological work.
Also in 1937 the Kaiser-Wilhelm-Institut für Physik, a brand new institute built with a gift from the Rockefeller Foundation, officially opened its doors. Designed to emphasize nuclear physics, it had a tower fifteen meters in diameter and fifteen meters high to house a cascade generator of 2 MV. The Kaiser-Wilhelm-Gesellschaft's two high-tension installations were the only machines in Germany in 1937 capable of furnishing particle beams of a million volts or more. Not until 1938 did Bothe put forward a proposal to erect a small cyclotron, at a cost of 20,000 RM, which Gentner was to complete during the war.
In Copenhagen and Paris they planned cyclotrons along with the more familiar high-tension apparatus. In both cases the decisions were influenced, if not inspired, by the policies of the Rockefeller Foundation, which, as we know, in 1932 adopted Weaver's program excluding support for basic physics. Weaver did not wait for supplicants. In May 1933 he discussed opportunities with Niels Bohr, then shopping at the Rockefeller Foundation's headquarters in New York; Bohr's Institute for Theoretical Physics, which had been extended in the 1920s with some $45,000 of Rockefeller money, seemed poised for a push toward biology. Bohr himself had been lecturing in a vague philosophical way on the connection between his interpretation of quantum physics and the limits of biological research. More encouraging, no doubt, to Weaver was the possible collaboration of Georg von Hevesy, who was considering resigning from his institute for physical chemistry at the University of Freiburg (which, to complete the circle, had been built with the help of $25,000 from the Rockefeller Foundation). In the summer of 1933 Hevesy decided to leave Nazi Germany; in January 1934 the Rockefeller Foundation granted $6,000 to establish him in Bohr's institute for three years.
Hevesy was the world's expert in the use of naturally radioactive substances as tracers in chemical research. If he and Bohr could be teamed with August Krogh, professor of physiology at the University of Copenhagen, whose institute, yes, the Foundation had helped to build, the sort of group that Weaver wished to create would come into being and the Foundation would have the satisfaction of integrating and capitalizing its earlier investments. By the spring of 1934 Bohr had become actively interested in biology, "aided undoubtedly," according to W.E. Tisdale, the Rockefeller man who spoke with him, "by the ramifications involved in the purification of the German race." Bohr's plans, then still "rather vague and philosophical," firmed during the next six months, under the impact of the neutron activation work of Fermi's group: he would collaborate with Hevesy and Krogh, beginning with heavy-water physiology and continuing with artificial radioactive substances to be produced by a high-tension set. In the spring of 1935, the three put forward a proposal, which the Rockefeller Foundation immediately funded, for $54,000 over five years, of which $15,000 was payable on request for apparatus and the balance provided an annual grant for research expenses. With a pledge from the Danish Carlsberg Foundation to pick up Hevesy's salary when his Rockefeller stipend expired, the project had the guarantee of a good long life.
The $15,000 was to go for "the installation of an apparatus for the production of radio-active materials, patterned after the equipment of Lawrence at Berkeley." The rationale for the installation, according to Tisdale, advised by Hevesy, was to make possible preparation of radioisotopes not obtainable from high-tension apparatus operating at 1 MV. "Von Hevesy assures me that this project, involving as it does so much physics, is completely orien-
ted toward bio-physical problems and is in no wise an attempt on Bohr's part to obtain equipment to permit him in any wise to compete with the Rutherfords, the Lawrences, and others who are working in the field of pure [!] physics." Nonetheless, as Tisdale could not help but realize, a particle accelerator "would not be limited in its usefulness to the single purpose of preparing radioactive materials for the cooperative problem, but would also permit of studies in nuclear physics from the physics point of view." It was an awkward matter, this possible application to physical science of a machine built for biological research, but the eminence of Bohr, as Weaver had earlier remarked, would "probably protect us from anything that would reach real embarrassment" in so blatant a compromise of the Foundation's policy against supporting pure physics.
Although the cyclotron had been reviewed favorably in Denmark in 1934 as the machine of choice above a million volts, it was not the preference of the Copenhagen group. In November 1934 they considered the merits of Cockcroft-Walton, Van de Graaff, and Lawrence machines, and decided on a high-tension set designed for 2 MV. Having obtained 150,000 kroner for his primary objective from the Carlsberg Foundation, Bohr asked the Rockefeller Foundation for a cyclotron as a secondary piece of apparatus.
Hevesy did not wait for either machine. He procured a source for his experiments by raising enough Danish money to buy 600 grams of radium for Bohr's fiftieth birthday in October 1935. The cost of the gift, $21,000, exceeded the estimate for the cyclotron; but it could be used immediately, mixed with beryllium, to yield the neutrons to convert sulphur into radiophosphorus for Hevesy to feed to rats. The foundations of the hall to house the high-tension apparatus were going down as the radium came to hand.
The apparatus itself consumed much more than its budget—it swallowed the Carlsberg Foundation's 150,000 kroner and the Rockefeller Foundation's $15,000—and gave back much less. Unable to get beyond the region already well explored at Cambridge and elsewhere, it offered no incentive to applications to basic physics and so served its purpose, as an Italian physicist disdainfully reported, "of biological research." Early in 1937 Bohr returned to the Rockefeller Foundation for $12,500 to complete his cyclotron, for which he had also to raise additional support in Denmark. That came primarily from the Thrige Foundation of Odense, a charity run from the profits of a large electrical concern, which gave the magnet and generators.
In Paris Joliot did Bohr one or two better. The discovery of artificial radioactivity in 1934; the Nobel prize for chemistry in 1935; and, not least, the coming to power of the Popular Front, which appreciated science, in 1936, and which Irène Curie served for a time as undersecretary of state for scientific research; all this catapulted Joliot from chargé de recherches and consort of Marie Curie's daughter to a professorship at the Collège de France and the leadership of French nuclear physics. Early in 1935, before acquiring the prize or the professorship, Joliot had turned to the Rockefeller Foundation for help in converting his research to biophysics, since, according to Tisdale, "he had no hope of competing with the Rutherfords, the Lawrences, etc., who seem to have a great deal of capital behind them." As for himself, Joliot said, he had access to a small Van de Graaff at an engineering school outside Paris near Arcueil, where he wished to build two more accelerators, both high-tension machines, that is, transformers in series (to reach 2 MV) and an impulse generator (3 MV). All would be used to make isotopes for biological research; three were required so that at least one would always be working to meet the expected high demand. Not a word about cyclotrons.
Joliot had collected promises for the land and for operating expenses calculated at 120,000 francs; all he needed was the capital investment, some two million francs for erecting and equipping the laboratory, from the Rockefeller Foundation. "We know the great profit that science and humanity have drawn from the judicious help that the Rockefeller Foundation has given to similar undertakings."
The Foundation's initial response was not favorable. Weaver doubted that Joliot could compete successfully with the Cavendish, Berkeley, Caltech, and the Carnegie Institution, and he doubted that Joliot's conversion to biology was sincere. "I suppose that Joliot and his associates have been only human in their desire to give a biological slant to their proposal." But Joliot's professions convinced the men in the field. There was no alternative to making big complicated tools of physics to create biologically useful radioisotopes and no way to make up-to-date tools without research into their basis in physics. The magnitude of Joliot's proposal forced the Foundation to reconsider its policy of closing out support for physics per se. "The proposal as a whole is indicative of the limitations that are inherent in our saying that 'pure physics' has gone far enough—now let's give no more support to it but only to its applications. That attitude runs into a ditch every time." The Foundation eventually did decide to help Joliot, but not before he had helped himself.
By the end of 1935 Joliot had added the impulse generator at the laboratory of the Companie générale electrocéramique at Ivry to his arsenal. This device, rated at 3 MV, proved a very poor source of radioisotopes but a cornucopia of x rays, of which it gave the equivalent of the gamma radiation from more than a kilogram of radium. That impressed the Rockefeller Foundation. In 1937, after Rutherford had advised a major British center for cancer treatment to invest in 20 grams of radium for a single bomb, Tisdale informed the same center that Joliot could give in 19 seconds an irradiation of high-voltage x rays equivalent to six
hours' exposure to a gram of radium. Such apparent progress; lavish support from the French government, which put up well over two million francs to buy and furnish a "Laboratoire de synthèse atomique;" strong collaboration with French biologists; and "the ability and expertise which merited the award of the Nobel prize" brought Rockefeller support to Joliot's nuclear enterprises, some $20,684 for the study of life, disease, and death, in December 1937. Joliot stuck to his word: neither he nor his wife did any of their research in nuclear physics or chemistry during the 1930s with beams from Joliot's accelerators. Instead, they used their standard, old-fashioned source, polonium, which gave enough alpha particles to use either directly or, via beryllium, as a source of neutrons.
When the committee planning expansion of the Cavendish went to Paris during Easter 1937, it inventoried Joliot's equipment as follows: the impulse generator at Ivry; a small Van de Graaff at the Collège de France; two more Van de Graaffs brought from Arcueil for exhibit in Paris; and, again at the Collège, "in a room surrounded by paraffin and borax solutions," a cyclotron under construction. It was the stepchild of Joliot's family of accelerators. Arno Brasch visited the family in the spring of 1938. In his report, he made no mention of the cyclotron, which was not yet working, but lavished praise on the complex of high-tension generators, which had no equal anywhere in his experience.
The leaders of British nuclear physics began to warm to the cyclotron in 1935. No doubt the increasing strength of its currents and yields played a major part in their revaluation. So did a worry that they might be left behind. "Everyone in America is building cyclotrons!" So Fowler overestimated the situation, while making clear his understanding of the reason for the stampede: Lawrence was getting "something like a beam," namely a microamp of 11 MeV alpha particles. Chadwick saw the cyclotron as an engine for strengthening his position at Liverpool while indulging his aesthetic sense: the "magnetic resonance accelerator," he wrote its inventor, "ranks with the expansion [cloud] chamber as the most beautiful piece of apparatus I know. . . . I must have a cyclotron apparatus. When I look at your cloud chamber photographs and see the enormous number of recoil tracks I realize what I am missing." Cockcroft declared his desire to see a cyclotron built in Britain, but did not yet—in the summer of 1935—know how or whether to commit the Cavendish to it. "The medical applications would probably provide an excuse."
The Cavendish soon committed itself. The initiative came from an unlikely source, the Soviet Union, which, by detaining its citizen Peter Kapitza during his visit home in 1934 had upset Cambridge physics. Kapitza held a special professorship, financed by the Royal Society, to preside over a laboratory for high magnetic fields and low temperatures established within the Cavendish through the generosity of the industrial chemist Ludwig Mond. To coax Kapitza to cooperate, the Soviet government proposed to reproduce the Mond Laboratory in Moscow. In the late fall of 1935, Cambridge agreed to accept 30,000 pounds from the USSR for the Mond's magnetic equipment, for duplicates of the liquefaction plants, and for other apparatus; and by the end of the following year Kapitza had his stuff and the Cavendish its cash.
Rutherford decided not to replace the big generator for producing the very high magnetic fields that were Kapitza's specialty, but inclined to buy a large electromagnet, for—among other things—accelerating ions. Cockcroft consulted Lawrence on the dimensions of the putative all-purpose magnet. The reply—"the bigger the magnet the better"— did not cause the Cavendish to commission construction. Lingering doubts may have been resolved by notification by Lawrence of the fine initial performance of Cooksey's first vacuum chamber. "If you are undertaking the construction of [a cyclotron], whoever is directly in charge of the work will probably derive some comfort from [Cooksey's experience], because in many quarters it is not realized that it is possible to build an accelerator with a predictably satisfactory performance." This reassurance was dated February 3, 1936; on February 22, Rutherford wrote that he had decided to proceed with the magnet, but not to dedicate it to resonance acceleration. It would be available "for general purposes, and also probably for use as a cyclotron." Cockcroft provided details: they thought to have a magnet with pole pieces 100 cm in diameter, capable of 17.5 kG, the pole faces mounted vertically rather than horizontally as at Berkeley in order that the instrument be adaptable to cosmic-ray work.
Meanwhile Chadwick was busy raising money for a Liverpudlian cyclotron. He approached A.P.M. Fleming, director of research of Metropolitan-Vickers, who went to inspect Berkeley's 27-inch in November 1935 and agreed to create something similar for 5,000 pounds. That was just twice what Princeton expected to pay and over twice the 2,000 pounds that Chadwick had in hand. Lawrence sent the advice of experience: commission Metro-Vick with the 2,000 pounds and goad or embarrass Fleming into providing the rest gratis. Fleming was interested in cancer, as Lawrence had learned during Fleming's visit to Berkeley. He would therefore be interested in the recent discovery at Berkeley that a certain mouse tumor is more strongly affected by neutron
beams than by x rays. "If malignant tumors in general are correspondingly more sensitive to neutron radiation, neutrons will supersede x rays in the treatment of cancer. . . . You might tell Dr Fleming that in view of this important possibility, we are definitely planning to go forward with the treatment of human cancer with our cyclotron."
Fleming decided to be generous—eventually he gave Chadwick oscillator tubes and other essential parts—and he, Chadwick, and Cockcroft joined forces to design magnets for three cyclotrons. Fleming wanted a small one, for a 1 MV or 2 MV machine; the Cavendish, rich in rubles, wanted "a very large magnet indeed;" "for my part [Chadwick wrote] I must build for ten million volts." All wanted to put the poles vertical for magnetic work and cosmic-ray studies. Lawrence discouraged their uprightness. The vacuum chamber had to be removable and accessible, and mounted horizontally on wheels to roll out on tracks for servicing and repair. When Lawrence rejected vertical poles and implied that a cyclotron required a dedicated magnet, the Cavendish had just come into additional wealth that allowed it to multiply magnets outside the Mond laboratory. On May 1, 1936, the vice chancellor announced that the automobile manufacturer Lord Austin had given the 250,000 pounds sought for the Cavendish Laboratory. That put an end to Rutherford's penny-pinching. "It amazed me [Pollard, of Yale] to see the free way in which money is passed around. The Cavendish . . . seems to be wallowing in cash." Cockcroft got rid of his Morris car and collected plans for magnets with horizontal poles.
No doubt the main force that drove the creation of cyclotrons at Cambridge and Liverpool was the desire of the directors of
both laboratories to have the complete equipment for nuclear research. But that did not drive Metro-Vick, whose attitude was decisive for cyclotroneering in Britain. In September 1935 an official of Metro-Vick, George McKerrow, had asked Cockcroft whether they should try to acquire rights under Fermi's patents or whether they should work up their own process. Cockcroft answered with Berkeley's latest neutron yields. They excited McKerrow greatly: "The business is just on the edge of practical possibility." Since Philips intended to work Fermi's patents via neutrons from high-tension machines, Metro-Vick's best bet appeared to be cyclotron production. At the end of February, just after the Cavendish had decided on a cyclotron, McKerrow asked Cockcroft for drawings of Lawrence's machine. After more careful consideration, the industrial possibilities, already circumscribed by the Research Corporation's patent on the cyclotron and Fermi's patents on nuclear activation, must have seemed less promising. Oliphant was no doubt right in placing the blame for the delay and inefficiency of the first British cyclotrons on the growing indifference of Metro-Vick.
You cannot always get what you can pay for. Take the magnet, for example. Everyone at Berkeley knew the importance of having poles absolutely symmetrical and the gap between them big enough to admit shims, accommodate a proton chamber, and allow easy service. Lawrence suggested a gap of over 7 inches for magnets of pole pieces 36 inches (90 cm) in diameter, the size chosen at Liverpool, Cambridge, and Copenhagen; Joliot began with the hope of 100 cm, but the cost reduced him quickly to 80. The British adopted a wide gap (8 inches), as at Berkeley, despite the resultant sacrifice in magnetic intensity (a maximum of 18 kG); but the Continentals, reaching for 20 kG and not consulting Lawrence, narrowed the gap to 3.5 inches (9 cm) at Copenhagen
and Paris and landed in trouble.
All the magnets were built by large industrial contractors, in England by Brown-Firth of Sheffield and Metro-Vick; in Denmark by the Thrige works; in France—or rather in Switzerland, where Joliot had his magnet made by the only firm in Europe he thought capable of it—by Oerlikon of Zurich. In every case the construction of the mammoths—forty-six tons of steel and eight of copper for the robust British, thirty-five tons of steel and three tons of copper for the Danes, thirty tons for the delicate French—went slowly. In the spring of 1937 the Cavendish discovered that Metro-Vick was winding its magnet at the rate of one coil a week and would finish in eight months, well over a year after commissioning, if something were not done. And the Cavendish magnet had precedence over Liverpool's. After appeal to Metro-Vick, they expected delivery in August, then in October; but neither Cambridge nor Liverpool had its magnet for Christmas. As they realized their orders competed with commissions for armaments. This difficulty also stymied magnet making in Sweden, whose noble neutrality and Nobel industry earned it an enviable trade in arms. In Copenhagen they looked forward to having their donated magnet around Easter 1936, but it had not arrived by September; when it came it exceeded all expectations as to the magnitude of its field, but failed in homogeneity, which could not be corrected by shimming because of the narrow gap. That made a most awkward situation, since Thrige, which had built and donated the magnet, did not like to admit and rectify its
The precise Swiss precisely calculated their delay in advance: seven and a half months, counting from November 1, 1936. They finished the following May and tested in June; the magnet proved "eminently satisfactory," magnifique , "beyond expectation," "much better [according to Wolfgang Gentner, who saw it at Oerlikon] than the American ones." It could give 22 kG, though, to be sure, at a great expenditure of power, 130 kW. Then it occurred to Joliot that the 9-cm gap that came with the big field might not accommodate the dees. He asked Lawrence. The answer—that the large capacitance between the dees and the tank consequent on their proximity would certainly make many difficulties in the construction of the oscillator circuit—was not reassuring.
The narrowness of the gap exactly matched the place that Joliot planned to put his cyclotron, a sub-basement at the Collège de France beneath the foundations of the chemistry building, enlarged from a cellar for storage of dangerous materials, a place condemned by government architects for lack of heat and ventilation. Into this hole Joliot expected to fit all the auxiliary equipment for his cyclotron and to hook it up to the vacuum chamber crammed with little working space into the 9-cm gap between the pole pieces of his magnificent magnet. An American visiting in 1939 saw a machine "built in a strangely cramped way by a Swiss firm and . . . stowed away in a strangely narrow subterranean chamber where working conditions . . . are not only uncomfortable but positively dangerous." Another inspector of Joliot's cyclotron cave judged "the French attack on nuclear physics [to be] about as adequate as their preparations to repel Hitler."
The oscillator provided as fine an opportunity as the magnet for delay and frustration. Joliot entrusted his difficult radiofrequency system to Culmann et compagnie, specialists in a French specialty, electric furnaces, who offered in June 1936 to install a modification of Livingston's original design, adjustable down to a wavelength of 17 meters, for 45,000 francs without the tubes. The plan was scrapped a year later in favor of an ambitious design with several stages and regulators. The price rose faster than the power, reaching 359,282 francs by June 1938, some two years after the original contract; and that omitted 449,800 francs for equipment that Joliot, who had ordered economies on wiring, regulators, and safety devices, decided he did not need. But with all this the furnace maker never got his oscillators going properly and Joliot had eventually to ask the Rockefeller Foundation for salaries for two specialists in high-frequency construction to correct the installation. The other would-be cyclotron laboratories would not meet the price of commercially built oscillating systems (30,000 DKr from Philips, too much from Metro-Vick) and decided to make them. This decision did not result in disaster because each laboratory had acquired the most important instrument for the efficient construction of a cyclotron: a man trained in Berkeley.
Already in the winter of 1935/36 Lawrence was offering students as well as advice and blueprints to Chadwick and Cockcroft. He recommended Bernard Kinsey, who in three years at Berkeley as a Commonwealth Fellow had become "a thorough master of the art of high frequency oscillators," to the Cavendish. But it was Chadwick who acquired him and made him responsible
not only for the oscillators, which he completed in the summer of 1937, but for the entire installation of the Liverpool cyclotron. A visitor with Berkeley experience, James Cork, judged the oscillators to be "stupendous." Cambridge chose something less spectacular, a simplification of an oscillator circuit devised by the BBC. In the spring of 1937 Lawrence proposed to Chadwick and to Cockcroft that they find a stipend for Harold Walke, another Commonwealth Fellow nearing the end of his tenure, who wanted only "enough to barely live on . . . , to go on with research for a while." The Cavendish did not supply the pittance, since they were getting a Berkeley man for free, Donald Hurst, who had an 1851 Exhibition fellowship. With his help ("Hurst is a great acquisition"), Cambridge got the first faint evidence of a beam in August 1938. Unfortunately for Walke, Chadwick found him a place, which he took up in October 1937. Walke and Kinsey succeeded in getting the Liverpool machine going in 1939. Later in the year, while replacing the grid resistance of Kinsey's stupendous oscillator, Walke touched a 230-volt line, which was enough to kill him.
Early in 1937 Joliot realized that he needed Berkeley experience. He obtained a fellowship from the Rockefeller Foundation for Nahmias to go to the United States and arranged with Bohr to divide the services of one of Lawrence's students for a year, again with Rockefeller money. The grant for a travelling student was made, but Lawrence declined to supply one on these terms: Joliot and Bohr must each have a man for a year. As Tisdale reported Lawrence's argument, "the job of designing, installing, adjusting, and testing a cyclotron is considerably longer, more arduous, more tricky [!], and more difficult than other people expect." As Nahmias misreported it, all the cyclotroneers building outside Berkeley had had "experience of at least two years with the monster." The
Rockefeller Foundation doubled its grant accordingly. The Berkeley experts—Paxton (Paris) and Laslett (Copenhagen)—arrived at their stations in July and September 1937, respectively.
Laslett needed all his talents to bring about the reconstruction of the Copenhagen magnet and to design and help make the thousands of components deemed too expensive to buy. He built and wired the switchboard that controlled the measurement instruments and safety equipment. By October he had proved himself to be of great use; in the end he was "indispensable," and Bohr arranged to keep him on with a grant from the Rask-Oersted Foundation, which recirculated dollars from Denmark's sale of the Virgin Islands to the United States in 1917. That the Copenhagen machine could give a tentative beam in November 1938 (or, rather, a few flashes on a fluorescent screen, "which can hardly have been anything but positive ions"), and so became the second European cyclotron to operate, was "to a large extent due to his efforts."
Paxton shouldered a more formidable task. Joliot had left his magnet in Zurich while awaiting completion of its subterranean den. It was buried there in January 1938 with a vacuum chamber designed by Paxton and built by Oerlikon between its teeth. Swiss efficiency again threw British bumbling into relief: it took Metro-Vick over a year to finish Liverpool's vacuum tank and perhaps as long to do Cambridge's, although both were built almost exactly to plans furnished by Lawrence. (Cooksey had designed and built
his tank in a month or two.) But Joliot's high-frequency system would not work, or put enough voltage on the dees if it did; leaks and sparks still plagued the vacuum system and insulators when Paxton left Paris in September 1938 to help start up the Columbia cyclotron. By the end of January 1939, Nahmias, who had returned with such Berkeley experience as he had permitted himself to acquire, had cured some of these ills and sought a better vacuum, more dee voltage, and a beam. He was at last requited, on March 3, 1939. He immediately called Tisdale. "Nothing will do but that I must come over and see the phenomenon—which I did. Needless to say that there is great elation."
The New World and the Old
None of the European cyclotrons was in regular operation in 1938. The Cavendish had only "evidence" of a deuteron beam at the end of August (they had been expecting since March), but nothing on target; they switched to protons, coaxed forth 0.02 µA, and started shimming. Lawrence advised more voltage on the dees; hit the ions hard enough, he said, and "the beam will come through without any attention to shims at all." That worked: before Christmas Cockcroft had 12 µA of 5 MeV protons. But in trying to reach the design energy for deuterons, some 11 MeV, he ran into trouble from parasites, faulty insulators, and a badly machined chamber. At the end of May 1939, the deuteron beam amounted to only 3 µA at 9 MeV; the following month it had risen to 5 µA steadily on target and as much as 15 µA at peak performance.
That was enough to do experiments and almost to impress visitors. J.G. Spear, of the Strangeways Research Hospital, Cambridge: "The Cambridge cyclotron is now beginning to function and is running at about 5 micro-amps—sufficient to make biological experiments possible but not up to the Berkeley standard yet." Bohr judged Cockcroft's cyclotron to be as capable as his own. Lawrence applauded the onset of steady operation and the 15 µA "so early in the game." It had taken three years from the commissioning of the magnet, experts and blueprints from Berkeley, the largest British electrical manufacturer, and the resources of the Cavendish to accomplish the feat. That was the fastest English pace; they still sought a stable beam in Liverpool. "With your cyclotron working so nicely [Lawrence wrote Cockcroft], Chadwick and Kinsey should feel much better, for I am sure that with all their trouble they must have doubted that a cyclotron could be made to work satisfactorily [in Britain]." Both British cyclotrons operated satisfactorily and at substantial currents during the early war years, when they provided information for guiding speculations about the possibility of nuclear explosives.
A similar story can be told of the running in of the Copenhagen cyclotron. It, too, was designed to produce deuterons at over 10 MeV. In December 1938 its builders had about 1 µA of 4 MeV deuterons, with which they drove a beam of neutrons equivalent to the yield from a kilogram of radium mixed with beryllium. The Danish press, which believed Bohr could do anything, advertised that he had made a kilogram of radium. Frisch wanted to use this fine source for physics; Bohr insisted that the machine be adjusted to give bigger currents at higher energies, in order to make in quantity the radioisotopes for which the Rockefeller Foundation had paid. Instead, it broke down.
Repairs brought back the microamp of 4 MeV deuterons, "a real thrill, and a great relief," but the machine did not yet run well. The main difficulty was the same as Cambridge's, too little
voltage on the dees; not until the fall of 1939 was Bohr's cyclotron "brought to the stage of producing an efficient beam of high-speed particles." During November the Copenhagen group caught a glimpse of 9 MeV and a grant from the Thrige Foundation to develop the electrotechnical part of the cyclotron "to the utmost efficiency." They achieved a steady deuteron beam at 9.5 MeV in the spring of 1940. During 1939 and 1940, the cyclotron manufactured isotopes for Hevesy as planned. It ran until March 1941, when it was idled for improvements and to conserve electrical power.
Joliot was getting a fair yield of deuterons in June 1939, but the oscillating system still did not perform satisfactorily. He had the machine pulled apart for modifications, which, however, could not be completed before the mobilization of the laboratory. Joliot succeeded in recalling Nahmias from the French Army late in 1939 and in acquiring from the Rockefeller Foundation, then still in business in France, 60,000 francs for stipends for an expert and a helper in high-frequency electronics. The machine had not been returned to working order before the occupation of Paris. "I am thankful for that," Nahmias wrote from the temporary safety of Marseilles, where he had found a job in a cancer clinic, "because being in such a messy state it may look unworthy of a German lab."
The fall of France closed off the Rockefeller Foundation's subvention to Joliot on orders from the U.S. government and brought the German military into the sub-basement of the Collège de France. The first officers to contemplate the broken, unkempt cyclotron wished to confiscate it for its copper and other strategic materials. The proposal came to the attention of the head of research for German Army Ordnance (Herereswaffenamt), Eric Schumann, who had been alerted to the possibility of nuclear explosives by Paul Harteck. Schumann immediately flew to Paris
and saved Joliot's cyclotron. An agreement was then concluded according to which Joliot would continue his research and admit three Germans to work in his laboratory.
According to the field representative of the Rockefeller Foundation, Joliot thought the Germans were sincere in their expressed wish "to follow the edict that science was international, that scientific work should go on, and that, as Joliot represented a distinguished member of the scientific world, his laboratory should be approved of and supported by the Germans in every way possible." This highly implausible reading of the situation turned out to be realized. The Germans put Joliot's former collaborator Gentner, then in the service of the Heereswaffenamt, in charge of their presence in the laboratory. Gentner managed to discourage his superiors from removing the cyclotron—it would be too costly and dangerous to rip it from its cellar—and to protect it from entrepreneurs like Manfred von Ardenne, who was trying to interest Nazi agencies in building accelerators to assist in research on the exploitation of nuclear energy. With the help of Gentner and German experts in radio technology and of Oerlikon, which made up the steel and copper Joliot procured into new parts for the electromagnet, the Paris cyclotron was at last set to going reliably, with an output of alpha particles equal in number and energy to those from 100 kilograms of radium.
It is said that the cyclotron faltered when Bothe wanted to use it to study the fission of uranium. The French operating crew then sabotaged it in subtle ways that gave Bothe the impression that he had mishandled the controls. Gentner understood and overlooked the maneuver. He protected Joliot, whom he knew to be a leader of the Resistance, and helped French physicists elude the Gestapo. The German authorities did not approve of Gentner's style of supervision and in 1942 returned him to
Heidelberg, where he made the first cyclotron in Germany, give an indication of a beam in December 1943. This machine had been planned since 1937, together with one for the University of Leipzig, both of which were ordered from Siemens in 1939. Siemens worked on them and on a larger one for the Heereswaffenamt during the war, while Krupp tended to two others, for Manfred von Ardenne and for the Research Institute of the German Post Office. The very sizable expenditures in strategic material and trained mechanics this manufacture required were intended by the physicists and the manufacturers as investments for a postwar competition in useful radioisotopes. It was also, according to a consensus of industrialists and Nazi officials, "a matter of prestige for Germany, which must be pursued even during the war, although cyclotrons have no decisive military importance." These industrialists also invested in betatrons, "exclusively," according to Steenbeck, "for business purposes. If the Americans were working on it, we must hurry, so that after the war, no matter how it turns out, we can bring our apparatus into the market place as soon as possible, if necessary with the American firm we license."
Two cyclotrons were operational when the war ended: Bothe and Gentner's in Heidelberg, and the Post Office's in Miersdorf. Neither enhanced its builders' market value. The Russians stole the Miersdorf machine. As for Gentner, he had no need of out-of-date cyclotronics to enhance his merits. The French remembered his friendship and courage in the matter of Joliot's cyclotron and made him an officer of the Légion d'honneur.
It is scarcely an exaggeration to say that a week's sweating over a Berkeley cyclotron was worth six months' immersion in its blueprints. In just a few days in the spring of 1937 Cockcroft saw enough to "feel . . . that the uncertainties in my mind about
cyclotron operation have been completely removed." His visit followed immediately after one by Bohr, who found in the working machine reassurance for himself and his patron: "The decisive importance of the new grant for our work [he wrote the Rockefeller Foundation] has become still more clear to me during my stay in Berkeley, where I have been most impressed by the ingenuity with which Professor Lawrence and his group in the Radiation Laboratory ha[ve] developed his wonderful cyclotron into an ever more efficient but of course an ever more complicated apparatus." Also in the spring of 1937 Nahmias arrived from Paris and Sten von Friesen from Stockholm, presaging, so Lawrence fancied, a "world wide epidemic of cyclotron construction."
The epidemic continued in the winter of 1938/39 with Oliphant from Birmingham and Bothe and Gentner from Heidelberg. Their letters point not only to the value of the information they acquired but also to a quality present in an exaggerated degree in Berkeley and rapidly dwindling in Europe. Bothe: "I am especially impressed by the atmosphere of enthusiasm and comradeship ruling in your laboratory." And well he might be, since by then the institutes of the Kaiser-Wilhelm-Gesellschaft were riddled with Nazis. Among the "noteworthy" items he mentioned in his official report on his trip to the United States was "the model camaraderie among the 10 or 15 members of the cyclotron crews." Gentner had not expected the great hospitality and generosity he experienced in Berkeley, where no one seemed to mind that he represented (though he did not approve) a totalitarian state. He remained for seven weeks in the cyclotroneers' Mecca: "For here [as he explained his long sojourn to his sponsors] is the center of cyclotron construction, and all other installations are more or less close imitations of the fundamental work of Professor Lawrence."
As for Oliphant, he was swept of his feet: "Many things about the cyclotron are now clear, which formerly were hazy. . . . I return with a greater confidence and a greater belief in the cyclotron, in physics, and in mankind." Oliphant had plenty of money—some 60,000 pounds from Lord Nuffield, the magnate of Morris Motors, more than enough to outdo Austin's cyclotron at the Cavendish—and plenty of enthusiasm. Cambridge copied the 37-inch; Birmingham would exceed the 60-inch. Oliphant expected to be finished by Christmas 1939 and did manage to erect his magnet, "of phantastic dimensions," according to Frisch, who saw it in August. But Oliphant's new confidence in mankind was misplaced; war stopped construction, and Lord Nuffield's cyclotron was obsolete when it started up in 1950.
The culture shock experienced by some Europeans who spent time in American accelerator laboratories makes the same point in reverse. The lust after machinery, the squandering of time on mere technical improvements, offended them as uncivilized and unscientific. "Americans are mostly coarse types, very good workers but without many ideas in their heads. . . . Their number is impressive, it is true, but one should not worry too much about their technical facilities. It will be a long time before they get from them what they can." So wrote Walter Elsasser, a Göttingen Ph.D., who had worked in Germany and in France and was to make his career in the United States. He excepted Lauritsen from his indictment: "Everything in his laboratory is built with great simplicity and without the technical elegance that Americans love so much. . . . Lauritsen is a European by birth as well as in spirit." Likewise Emilio Segrè remarked on the want of subtlety of the machine makers at the Radiation Laboratory. Segrè trained all over Europe—in Rome with Fermi, in Hamburg with Stern, and in Amsterdam, where he continued his studies of spectroscopy in the laboratory of the old master, Pieter Zeeman. This itinerary provided a perspective quite different from Berkeley's: Fermi and
Stern had command of deep theory as well as of experimental technique, and Zeeman had made a career of accuracy in measurement. As Franz Kurie wrote of himself and his fellow cyclotroneers: "One feels quite the blundering caveman beside one's spectroscopic brothers."
We already know some of Nahmias's ideas about American techno-physics. Here is his summary: "I've observed here [Tuve's lab] and at Van de Graaff's a certain rush to realize projects immediately after we first discuss them. [Americans] work quickly and in groups, but [he reassured Joliot] you should see their alarm when one talks about future European installations." The coordination needed to realize the projects oppressed him so heavily that he decided not to do experimental work in Berkeley. "I occupy my time better in reading nuclear physics, biology, and electro-technology than in hypnotising myself in front of an electroscope with the nth new period [of radioactive decay]." When Lawrence suggested that Joliot ask the Rockefeller Foundation to extend Nahmias's stay to enable him to learn by helping to assemble the 37-inch, Joliot declined, thinking that his emissary had learned and suffered enough.
The fascination with hardware and the subordination of the individual to the group that characterized Berkeley by the late 1930s were to spread from accelerator laboratories to other parts of physics and from the United States to the rest of the world. Ryokichi Sagane may serve as a weather vane. After a year at Berkeley and a return there, he toured laboratories in the United States and then visited the Cavendish. "I was rather disappointed and also astonished," he wrote Lawrence. Although he judged that some pieces of native apparatus showed some ingenuity, it was clear to him that the British like the Japanese would have to derive their methods from the Americans. "So far as the experimental techniques are concerned, America has surpassed very far the England." The award to Lawrence of the Nobel prize in phy-
physics for 1939—an event of great importance for our history—was at once an emblem of this dominance and the certification of the cyclotron at the international level. The American style of physics established a beachhead in Europe before the war. Lawrence's machine was the landing craft.