Lion Hunting
Loeb began stalking Lawrence in 1926. The game was then a National Research Fellow at Yale, where he had arrived in the intricate wake of his teacher W.F.G. Swann, whom Berkeley wooed in vain. Lawrence, a native of South Dakota and a graduate of its state university, had sought out Swann in 1922, on the recommendation of Merle Tuve, likewise from South Dakota, whom Lawrence had known from childhood. (It is singular that Tuve and Lawrence came from similar middle-class backgrounds of Scandinavian origin, had similar training in physics, and later went at atom smashing with instruments similar in cost and size.) Lawrence joined Swann and Tuve at the University of Minnesota to work on a master's degree. In 1923 Swann left Minnesota for the University of Chicago, where Lawrence followed, to begin work on the photoeffect in potassium vapor. He made good progress in designing equipment before Swann wandered to Yale. There Lawrence finished his dissertation and took up another investigation, which also posed delicate instrumental problems, for example, the creation of a monochromatic beam of slow electrons.[55] That project acquainted him with the magnetic analysis of particle streams, which may later have assisted his design of the cyclotron.
As a National Research Fellow at Yale, Lawrence extended his work on the photoeffect to other alkali vapors and used his monochromatic electrons to demonstrate that the excitation function for ionization of an alkali vapor—the dependence of the probability of ionization on the energy of the ionizing agent—was the same for electrons as for x rays. This demonstration attracted Loeb, head-hunting at the American Physical Society's meeting of May 1926. He spoke with the demonstrator, and wrote his chairman: "I felt out one of the most brilliant experimental young men in the East—a lad whose name is on everyone's lips on account of his recent papers on Ionizing Potentials. . . . He is personally one of the
most charming men I have met. . . . When asked whether he would consider an Assistant Prof. at Berkeley following the termination of his fellowship, he was quite enthusiastic." Birge too praised Lawrence's "really splendid experimental work" on the excitation functions.[56]
Two projects were never enough for Lawrence. A fellow midwesterner, Jesse Beams, who had settled at the University of Virginia, had tried to measure the interval between the absorption of a quantum and the ejection of a photoelectron. While failing, he had devised a very fast electric switch incorporating two Kerr cells. (A Kerr cell is a parallel-plate condenser with a gaseous or liquid dielectric.) Beams and Lawrence teamed up to try to study the speed of the onset of birefringence and to incorporate Beams's idea into a practical device for creating very short bursts of light.[57] Lawrence was to stick to the Kerr effect, as he did to photoionization, until the cyclotron turned his attention to bigger things; and he was to stay in productive contact with Beams while the idea of the cyclotron developed.
Berkeley made its first offer to the young electro-optician in the spring of 1927; Yale did the same; Lawrence stayed East (plate 1.4). His rejection of Berkeley would have discouraged men of weaker will than Birge and Loeb: "I like Yale, the personnel, the laboratory and the facilities for research perhaps even as much as I like the friends I have acquired in New Haven." Loeb and Birge persisted. They extolled Berkeley's "democratic spirit," research ethic, and, what the NRC campaigned for and every ambitious academic desired, light teaching load. Lawrence allowed that if Yale made him work too hard, he might go West: "I am more interested in finding some more of Mother Nature's secrets than telling to someone else things I already know about her." The announcement by his flighty mentor, Swann, of a new nest, the Bartol Foundation in Philadelphia, "a hard blow to Yale and to me," increased Lawrence's mobility.[58]
Loeb now hinted that Berkeley might offer an associate professorship with unusually few teaching responsibilities. Yale countered by improving Lawrence's laboratory and reducing his courses.[59] Friends of California were commissioned to enlighten Lawrence. They reported that he believed that at Berkeley only full professors could supervise graduate students (a regime to which he could not submit) and that he had no conception of the treasures of Le Conte Hall. Loeb and Birge set him right in February 1928, when Berkeley formally offered Lawrence an associate professorship. They itemized the research staff, budget, and facilities, pointed to auxiliaries in the Chemistry Department, praised the liberality of the Physics Department in assigning graduate students to junior faculty, and fired off their biggest gun: "The teaching schedules are as light as at any place in the country, with the exception of Harvard."[60] There remained only salary. The very experienced Swann advised Lawrence to ignore the few hundred dollars difference between Berkeley's offer and Yale's, which the lower cost of living in California would cancel, and to concentrate on the research opportunities. Birge reassured the captured lion that promotion came rapidly to vigorous young research men. It was as if the University had been preparing itself ever since the war for the reception of Ernest Lawrence: "Younger men are now being appointed and advanced on an entirely different plane from that of the older men. . . . I doubt if any man has ever been offered the permanent position of associate professor at this University with as short a period of teaching and research experience as in your case. . . . The conduct of this University now is really in the hands of the exact scientists."[61]
Lawrence arrived in Berkeley in the summer of 1928. By September he was writing with such fervor about his new surroundings that Beams rated him "a 'Native Son' of California already."
The enthusiast took up residence at the Faculty Club, where Gilbert Lewis brokered influence and crossed disciplines nightly at the dinner table.[62] Lewis became a strong supporter of Lawrence's and, after the invention of the cyclotron, a transient, but most influential, collaborator. The antecedents of the grand invention are not to be sought, however, in the research work that Lawrence did between dinners with Lewis. He continued his study of the photoeffect in alkali vapors.[63] What counted more for his future were his sojurns at General Electric's research laboratories in Schenectady during the summers of 1929 and 1930.
In arranging for his visit of 1929, Lawrence wrote A.W. Hull, an expert on x rays and vacuum tubes who would be his host, that he wanted to study the photoeffect and the Kerr cell. Nothing new there. But Hull was then working with Beams on a lightning arrestor and on the development of sparks under high voltages, and Lawrence was drawn into the investigation.[64] Here he faced for the first time the practical difficulty of holding a potential of more than half a million volts. If we credit Beams's unlikely recollection, this experience inspired a line of thought remarkably, indeed astonishingly, close to the reasoning behind Lawrence's great invention. "There's just no use trying to build this [voltage] up," Lawrence argued. "You may get a few million volts. That's limited. What we've got to do is to devise some method of accelerating through a small voltage, repeating it over and over. Multiple acceleration."[65]
In the event, Lawrence did not labor with Beams or Kerr cells or photoeffects. He wandered about GE's well-equipped laboratories, familiarized himself with Hull's state-of-the-art vacuum tubes, with high-voltage equipment, and with so much of the firm's applied research that he was offered (but declined) a consultancy. Lawrence brought this lore back to Berkeley, along with two other items of importance: a glass blower, E.H. Guyon, a specialist in x-ray and vacuum tubes; and a genius at electronics,
Hull's assistant David Sloan, whom Lawrence persuaded to improve his B.S. in physics from Washington State College with graduate work at the University of California. Sloan came in 1930, on a Coffin Fellowship (established in 1922 in memory of GE's first president, Charles A. Coffin) from GE.[66] He remained throughout the 1930s, kept from his degree by lack of interest in his studies and injury to his back. The early successes of Lawrence's Radiation Laboratory owed much to David Sloan, who would not have come to Berkeley but for Lawrence's sojurns at GE.