Generating an electrical charge of a few thousand volts was practical. Confining ions in a magnetic field for about one hundred orbits was practical. In Lawrence’s expansive vision, Rutherford’s goal of 10 million electron volts was already within reach. All he needed to achieve it was an oscillating electrical charge of sufficient power, an electromagnet of sufficient size, and a source of ions to be propelled around what he was already picturing as a “proton merry-go-round.” As Lawrence told Shane that first night, he could see nothing wrong with it.
He was right about the concept, right about its importance, and right about one more thing: it was going to make him famous.
• • •
Yet transforming blackboard scribbles into a working device was not so simple a matter, as Szilard had understood. Lawrence did not yet command a laboratory staff—only three graduate students, each already working on projects he had approved. Nor were all his friends and colleagues as taken with the proton merry-go-round as his neighbors at the Berkeley Faculty Club on that first bleary-eyed evening. Merle Tuve, who was still struggling to produce high-energy particles with his obstreperous Tesla coil, saw little practical application for Lawrence’s curved variation on a linear accelerator. Everyone seemed to have a different reason why resonance could not work, and none a reason why it should. The ion particles would fall out of phase, they said, or would crash into the walls of the accelerating chamber, or would collide with stray air molecules in their way. Lawrence replied that by accelerating his particles in a vacuum tank and holding them on their path with a magnet, he could eliminate collisions, but this idea only introduced the technical question of how to maintain an airtight vacuum within a maelstrom of powerful electromagnetic forces. As the new term opened at Berkeley, Ernest kept the spiral accelerator on the shelf, as there were numerous other projects to keep him distracted. One of these, an X-ray tube he developed with an exceptionally single-minded grad student named David Sloan, seemed to promise electrons of a million volts—not suitable as a nuclear projectile but useful for a wide range of other experiments.
Then, after Christmas, a couple of jolts prompted him to take the accelerator off the shelf.
The first was a conversation with the distinguished German quantum physicist Otto Stern, a future Nobel laureate who was stopping at Berkeley during the holiday. Stern’s expertise was the action of magnetic fields on atoms and subatomic particles. When Ernest described his idea to him at a faculty dinner, he became uncommonly interested. For the first time, Lawrence heard a physicist with a solid grasp of subatomic behavior express support for his idea rather than smothering it in quibbles.
“Why don’t you get on with it?” Stern barked impatiently, or as John Lawrence, a witness to the encounter, recalled Stern’s words in his own fractured German: “Sie mussen Zurich gehen!” His meaning was clear: “Get back to the lab!”
A few days later, the second jolt arrived in the form of the January 1 issue of Physical Review. The journal carried a report by Merle Tuve claiming that his Tesla coil could drive alpha particles to energies as high as 10 million electron volts without “any serious difficulty.” At that energy, Tuve calculated, the particles delivered power equal to that of 2,600 grams of radium. The significance of Tuve’s claim was not lost on any physicist who recalled Marie Curie’s 1921 voyage to the United States for her single gram of radium, valued at $100,000. Ernest remained skeptical that Tuve’s coil could function as a practical accelerator, for the tendency of the high voltage to break down with an enormous spark placed a hard limit on how much sustained power it could impart to a particle beam. But Tuve’s announcement impelled him to show that he had a superior idea.
The opportunity to get on with it arrived when Lawrence’s graduate student Niels Edlefsen completed his doctoral work early in the new year. Edlefsen was a late bloomer, six years older than Ernest yet still only a teaching assistant. But he was devoted to Lawrence, who uniquely among the physics professors was not above showing up at LeConte Hall in the middle of the night to lend his students a hand, announcing his presence with the words “Mind if I work with you awhile?”
Lawrence now asked him for help. “I’ve got a crazy idea,” he told Edlefsen. “It’s so simple, I can’t understand why someone hasn’t tried it . . . Why don’t you line up what we need?” It was the first appearance of Lawrence’s method for building the world’s first great Big Science laboratory: the remorseless exploitation of cheap graduate-student labor, a resource he would soon have in surfeit.
By mid-January, Edlefsen was hard at work assembling Lawrence’s apparatus. Over the winter months and into the spring, he fashioned a series of protocyclotrons out of metal and glass containers, which were flattened, split laterally, fitted with filaments and electrical wires, and slathered over with thick gobs of sealing wax to hold a vacuum.
The first models, small enough to fit in the palm of the hand, betray little family resemblance to their ever more painstakingly engineered progeny, much less the miles-long behemoth humming beneath rural villages in Switzerland in the twenty-first century. Edlefsen’s devices resemble whisky flasks run over by a truck. At Ernest’s direction, Edlefsen would position these units between the four-inch poles of the physics lab’s electromagnet, pump them free of air and fill them with hydrogen gas, and then ionize the gas with a charged tungsten filament.
The results were equivocal. According to Edlefsen’s rudimentary ion detectors, something was going on inside the flask, but whether it was protons accelerating in resonance with an oscillating electric field was by no means clear. Whatever doubts Edlefsen harbored, however, were overmatched by Lawrence’s optimism. Ernest was willing to assume that he had achieved a proof of concept; verifiable results required only superior detection equipment. As he reported in one of his frequent, dutiful letters to his parents in South Dakota, “If the work should pan out the way I hope, it will be by all odds the most important thing I will have done.”
That summer, Edlefsen left Berkeley for a postdoctorate job at another university. Ernest, who had spent the vacation months in “laxity” playing tennis, wrote up a talk on the project for a meeting of the National Academy of Sciences in Berkeley on September 19, 1930, and a report for the journal Science to be published a few weeks later. These were carefully phrased to suggest, without saying so outright, that he and Edlefsen had achieved the resonance they had been seeking. The article avoided making any reference to actual readings, for they had none to report. But it bristled with Lawrence’s self-confidence and his manner of intuitively grasping possibilities well ahead of realities—in this case, the production of sustained resonant proton beams with a million volts of kinetic energy. “Preliminary experiments,” he wrote, “indicate that there are probably no serious difficulties in the way of obtaining protons having high enough speeds to be useful for studies of atomic nuclei.” By echoing Merle Tuve’s words, he had quite deliberately planted his flag next to that of his boyhood friend. But now the physics world expected him to make good on his boast. Fortunately, the next in a long line of talented collaborators was already on the scene.
• • •
Milton Stanley Livingston was a burly farm boy who had been raised in the foothills of California’s San Gabriel Mountains, where his father owned an orange grove. Stan had received his physics education at Dartmouth College, which was not known for its science programs; Livingston acknowledged that his master’s degree from Dartmouth was perhaps the equivalent of a bachelor’s degree at a more rigorous research institution. But he had learned enough to land a teaching fellowship at Berkeley. (“There was not nearly as much competition then,” he would recall.)
Unlike others making their way to Berkeley in the fall of 1930, Livingston had never heard Lawrence’s name; the first he knew that a Professor Lawrence even existed was when he registered for Lawrence’s undergraduate magnetism course during his first few weeks of breakneck studies designed to fill in the holes in his physics education. But he s
oon got swept up into Ernest’s orbit. Having polled the faculty for a suitable topic for his doctoral thesis, he was most intrigued by Lawrence’s suggestion that he study “the resonance of hydrogen ions with a radio frequency field in a magnetic field.” In short: the cyclotron effect. Leonard Loeb, notwithstanding his role in recruiting Lawrence to Berkeley, warned Livingston superciliously that working on Lawrence’s project would be a waste of time. “He didn’t think [the cyclotron] would work,” Livingston would recall. Livingston carried Loeb’s doubts back to Lawrence, who extinguished them with a typically powerful display of self-confidence. Livingston signed up.
It was a fortuitous partnership, for Livingston’s skills neatly complemented Lawrence’s. The latter contributed the vision and an inspired experimental blueprint; Livingston’s farm upbringing trained him to be comfortable with machines and adept at hands-on maintenance and the repair of complicated gear that could not be sent out for servicing. His role would be to transform Lawrence’s ideas and Edlefsen’s jerry-built apparatus into an accelerator that worked.
Livingston’s first task was to scrub the hyperbole from the claims that Lawrence and Edlefsen had made. Whatever Edlefsen had seen inside his little chamber, Livingston concluded, it was not resonance. There was no evidence that hydrogen ions had charged around Edlefsen’s “rather sketchy” apparatus at all, much less at any appreciable fraction of 1 million electron volts. Livingston figured instead that Edlefsen had merely created heavy ions from the atmospheric nitrogen and oxygen left inside the device by poor evacuation technique. These may have traced a curved path for a short distance, but those that reached the detector had probably done so after only a single acceleration. Most had probably expired in collisions with the walls of the fist-sized tank. The cyclotron principle was still waiting to be observed and experimentally confirmed. It was Livingston’s job “to do just that.”
He started from scratch, replacing Edlefsen’s lumps of metal and sealing wax with a vacuum chamber fashioned from brass in the shape of a flat cylinder four inches in diameter. One half of the chamber’s interior was occupied by a hollow semicircular electrode shaped like the letter D and known forever more as a “dee.” The other half was empty except for a copper strip serving as a target. Accelerated particles would strike this strip at the end of their spiral journeys, with their final energies to be measured by an electrometer wired to it. Subsequently a second dee would be nestled next to the first, strengthening the effect of the electrical charge that accelerated the particles every time they passed from one dee to the other—producing, that is, two accelerating kicks for every complete circuit by the particle. Livingston would describe this first formalized device as one in which “all the basic features of the modern cyclotron were present in utero.”
Indeed, he had overcome the practical obstacles to turning Lawrence’s fancy into a real-world accelerator. That was in September. But it would be December 1 before he witnessed anything resembling true resonant acceleration and could write in his workbook, with unabashed relief, “At last we seem to be getting the correct effect.” By Livingston’s calculations, he had accelerated ionized hydrogen molecules, H2, twenty times over the course of ten complete circuits. Shortly after Christmas, he managed to cadge on temporary loan from a laboratory colleague a magnet twice as powerful as his paltry four-inch model. It was a timely acquisition, for Ernest had succumbed to a rare spasm of self-doubt. “We are having a bit of trouble with our high speed protons,” he wrote to Swann. “We can make them spin around alright but we have not been able to determine how many times and therefore what speeds we have been able to produce.”
Livingston’s results with the bigger magnet dispelled the clouds. His measurements indicated that he had accelerated ions to 80,000 volts by spiraling them around the vacuum chamber forty-one times, thereby delivering eighty-two resonant jolts. “Lawrence was really excited,” Livingston recalled. “You see, we’d proven the point. He was off to the races.”
More precisely, Ernest was racing for money to build an even more powerful accelerator. Ernest’s habit of thinking ahead to the next step before the last one had been fully played out now materialized, spurred in part by the need to validate his optimistic forecasts of what the next step would bring. Even before Livingston’s results had been validated properly, Ernest was mapping out a campaign to acquire a more powerful electromagnet to drive protons beyond the million-volt threshold. The apparatus would cost $700, according to the estimate he submitted to the university’s board of research. The board duly passed it on to Robert G. Sproul, who had been inaugurated as the university’s president only three months earlier. It was his first bill for the cost of turning Berkeley into the nation’s pioneering institution of Big Science.
Sproul had become fully aware of Lawrence’s value to Berkeley that fall, when Northwestern University approached the physicist with the startling offer of a professorship at $6,500, more than half again the salary of a full professor at Berkeley—not to say a Berkeley associate professor aged twenty-nine. The prospect of losing Lawrence provoked panic on the science faculty. Observing that Lawrence was “the best experimental physicist among men his age in the country”—the loss of whom would present “a very serious handicap” to the university—a committee of senior science professors unanimously recommended that he be offered a full professorship and a raise to $5,000. Queried at long distance by Sproul, the loyal Swann declared that his protégé was destined to become one of the world’s ten leading physicists before the end of the decade. A more direct observation came from Gilbert Lewis, the eminent dean of the chemistry faculty, who informed Sproul that the question at hand was not whether to appoint the youngest professor in Berkeley history “but whether or not we are going to have a physics department.”
The debate over Lawrence’s future at Berkeley climaxed at an acrimonious faculty conclave pitting the hard sciences, represented by Birge and Lewis, against the humanities and social sciences departments. A promotion of such magnitude for a junior professor, leapfrogging faculty members with greater seniority and longer records of accomplishment, was unprecedented, the dissenters said; to show such favoritism to one department could only demoralize the others. The thirty-nine-year-old Sproul made a show of weighing the pros and cons, but his decision was preordained. “If there is one chance in ten that he’ll be one of the top physicists in the country, I’ll take that chance,” he declared in approving Lawrence’s promotion. As it happened, Lawrence would meet Swann’s ten-year timeline with room to spare, bringing home the Nobel Prize only eight years later.
In truth, Lawrence had not found Northwestern’s offer all that compelling. His goal was not to obtain a large raise for himself but to obtain explicit recognition of his lab’s importance to the university under its new administration. In this, he succeeded. The funding request for the new cyclotron was his first chance to exploit his new standing. He was not disappointed. Having made a special case of Ernest Lawrence in one of his first official acts as Berkeley’s president, Sproul was not about to skimp on his new star’s research budget. He signed off on the $700 requisition with virtually no discussion.
With an additional $500 cadged from the National Research Council, Lawrence ordered a custom magnet with nine-inch pole faces from the Federal Telegraph Company. He placed the responsibility for fashioning a suitable new vacuum chamber in Livingston’s hands, and then vanished from the laboratory to go “angling for funds and other support,” Livingston recalled. “I didn’t know what he was doing exactly, but I could see that he was spending a lot of energy searching for support to make the next step.”
When he surfaced, it was not always to ease the way forward. Reappearing one day in March, Lawrence announced, “Stan, you’ve got to stop now and write up your thesis.” With a start, Livingston realized that he had only two weeks to complete the work necessary to receive a doctorate that June. Much was at stake for both him and Lawrence: the doctorate was required before Livingston cou
ld be given an instructorship, which in turn was necessary if he were to stay at Berkeley into the fall term. And Lawrence considered that necessary, in its turn, because he needed Livingston to complete the construction of the new accelerator.
Livingston dropped everything to write a hasty thesis based on his work with the four-inch accelerator. Then he sat for an oral exam on radioactivity conducted by Birge and three other professors. It was evident from the very first question that his involvement with the accelerator had left him utterly unprepared for the inquisition. Birge “asked me the outright question had I ever studied Rutherford, Chadwick, and Ellis, the most famous book in the field? And I had to admit that I had not. I hadn’t had time.” Staggering from the examination room, Livingston sought out Lawrence to warn that he almost certainly would be refused his doctorate, due to his failure to demonstrate a grasp of basic nuclear physics. Lawrence absorbed the news with surprising equanimity, for reasons that soon became obvious. The committee awarded Livingston his doctorate without cavil. Plainly Lawrence had placed his thumb on the scale. “I imagine,” Livingston reflected years later, “that he was persuasive.”
Livingston promptly returned to his labors on the accelerator. He was ready with a freshly designed vacuum chamber, eleven inches in diameter, when the new magnet arrived on July 3. The chamber was fitted between the pole faces and immediately fired up. Two weeks later, Lawrence was spreading the news that the apparatus had accelerated protons up to 900,000 volts. Only a year after launching the effort, he was knocking on the million-volt door.
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