Chapter Six—
In the New World: Refugee at Berkeley (1938–1943):
Smell of Cyclotron Oil

Tu lascerai ogni cosa diletta
più caramente; e questo è quello strale
che l'arco dello essilio pria saetta.
. . . . . . . . . . . . . . . .
per lui fia trasmutata molta gente,
cambiando condizion ricchi e mendici

(Thou shalt leave all that thou hast loved most dear;
This is the arrow, shooting from the bow
Of banishment, which thou hast first to fear.
. . . . . . . . . . . . . . . . . . . . . . .
Through him shall many taste an altered lot,
The beggar and the rich exchanging place.)
Dante, Paradiso 17.55–57, 89–90 (trans. Laurence Binyon)

I landed in New York on July 13, 1938, expecting to return to Italy in the autumn for the beginning of the school year. Instead, nine years were to elapse before I revisited Italy. By that time, having lost my Italian job, I had built a second career, participated in great historic events, won a superior university position, and become a U.S. citizen and a Californian. Fate had been kind to me, although I had had my share of "blood, sweat and tears." I am grateful that I was spared both morbid homesickness and the terrible disasters that befell our parents and many of my friends. In my early American years I was lucky to

have in science an absorbing occupation that both gave me pleasure and helped me rebuild my life.

On my arrival at New York, I visited my Columbia University friends and then, after a few days, left for Berkeley. I wanted to execute my work program as fast as possible. Leo Szilard, the Hungarian physicist I had met a few years earlier in England, came to see me off at Grand Central Station on my departure for San Francisco. He inquired about my plans, which I detailed to him. When I told him I expected to return to Palermo in October, he said that would be impossible because of what Mussolini might be expected to do; Italy might adopt Hitler's racist politics, and in any case, Hitler might start a world war soon. With these cheerful thoughts, I started on the first leg of my trip, from New York to Chicago.

At Chicago I bought a newspaper and read a short but chilling news item on the new charter of anti-Semitism in Italy, the Manifesto della razza (race manifesto), which obviously Mussolini had encouraged, even if it bore only the signatures of his minions.^[1] I ruminated for the rest of the trip on its contents and implications. I decided not to mention the subject to strangers in Berkeley, however, until I knew more.

I was thus catapulted from my apparently secure job in Palermo into a precarious new situation. It is true that I was not unknown as a scientist, but my prestige was not sufficient to place me in the category of those for whom it was easy to find a job. Furthermore, I had arrived a few years later than contemporaries like Bethe, Bloch, and Teller, and the job market was more saturated. Strangely, the first shock did not affect me very much emotionally. The blow was not unexpected, and all in all I was too busy trying to rebuild my life to brood aimlessly. The result was that I did not feel the sudden rending from my previous life as an irreparable wound, as happened to many émigrés.

On my arrival in Berkeley, I immediately tried to look up my friend Lorenzo Emo, but he was away for a few days. The owner of the house where he lived had another room for rent and I took it. In that house

I found a little book of Admiral Nelson's letters to Emma, Lady Hamilton, his lover. In them Nelson often complained about seasickness and signed with his Neapolitan ducal title, Bronté. Thus, in our friendly intercourse, I nicknamed Lorenzo "Bronté" or "Brontuzzo."

Lorenzo was of the greatest help to me in my early days at Berkeley. First, he explained to me the university minuet that one danced at Berkeley, as one does in all universities; then he guided me a little among the various personalities I met. Above all, he was a trusted friend with whom I could share my worries about what was happening in Europe. Between us we could talk with open hearts, sure of mutual understanding. In those weeks our acquaintance grew into a solid, intimate friendship that lasted for life.

Lorenzo, a handsome man, a man of the world, a count, and of independent means, was most popular among physicists and their wives, both at the university and at the Radiation Laboratory. Although he looked to be a farfallone amoroso (amorous butterfly), he was an astute observer of people and shrewdly appraised them. The first people I met through him were Don Cooksey (Lawrence's alter ego), Francis Jenkins and his wife Henriette, and Robert Brode and his wife Bernice.^[2] In addition, Lorenzo introduced me to Dr. Giacomo Ancona, a physician from Florence living in San Francisco, who we discovered had examined me in 1926 when he was a young assistant to the professor of medicine at the University of Florence, Frugoni. I also struck up a close, lifelong friendship with Ancona.

I looked around the lab and saw at once that, while the cyclotron was a wonder, the methods used to measure radioactivity left much to be desired. I then tried to secure an ionization chamber of the type I had used in Rome and Palermo, and finding that Franco Rasetti, on a short visit in 1935, had left parts of such an instrument in Berkeley, I completed it. I was used to coupling the ionization chamber to an electrostatic electrometer, but when I asked Lawrence to buy such an instrument, he denied my request. He said that it was old-fashioned stuff, and that I should build a DC amplifier with an FP 54 tube. I had no choice and started working. Fortunately, Lee DuBridge, the future president of Caltech, then a professor at Rochester University, was

vacationing in Berkeley. He was an expert on DC amplifiers and kindly offered his help, rapidly assembling the rest of the instrument. The resultant simple apparatus was used later for many investigations. It is now a museum piece at the Smithsonian Institution in Washington, D.C.

The more familiar I became with the Rad Lab, the more surprised I was; it operated very differently from any other laboratory I had been in. There were many students, but they seemed to me to be left to themselves, without scientific guidance. I was simple-minded or imprudent enough to mention this to Lawrence, and I even offered to help in guiding students. He answered me rather coolly that the Rad Lab and America were not a German university with a big boss dominating the students; that here students were free and learned by themselves, and similar tales.

The truth was that Lawrence's interest centered on the cyclotron and on building the Rad Lab's diverse activities; his knowledge of and interest in nuclear physics were limited. Students, in practice, served as cheap labor for the building and tending of the cyclotron and any move that might divert them from this task was frowned upon. It was difficult for me to understand the scientific policy of the Rad Lab. The cyclotron was a unique device, with seemingly infinite potential, but the main concern of those who controlled it was apparently to make the machine bigger and put it to work in areas outside of physics; there was little thought given to making proper use of what was on hand for nuclear studies.^[3]

In hindsight I now believe Lawrence's attitude was more far-sighted than I then deemed. The concentration of effort was necessary in order to develop the machine, and Lawrence tried to do what he knew best. His early efforts in the nuclear field had not been a success and may have left him with unpleasant memories. The cyclotron in 1938 was still a relatively simple machine and could be developed primarily by empirical procedures, without a deep understanding and an elaborate theory of its functioning. To some extent, the methods used initially at the Rad Lab resembled the approach to technical development of an Edison or a Marconi; Lawrence fitted the same slot: brawn prevailed

over brain. Financial support was what limited the development of the machine, and Lawrence spent most of his time raising money from foundations, from the university, and from anywhere else he could get it.

In the Rad Lab there were men of greatly differing ability, but all were young. L. W. Alvarez and Ed McMillan were obviously first-class scientists.^[4] Emo had described the first to me as a little fascist leader, fawning to the Duce, but mean to his equals or inferiors. McMillan, according to Emo, was very clever, but lazy. They were the only ones who also had University of California appointments. Of the others, R. L. Thornton, M.D. Kamen, and R. R. Wilson were more than able. Thornton, in addition, was a true gentleman, brought up English-style, who combined technical prowess with superior human qualities. Kamen worked as a physicist and a chemist to earn a living but his heart was in music, and if he could have afforded to do so, he would have become a professional musician.^[5] Wilson had his roots in the Wild West, but made a serious effort to civilize himself. At Berkeley, he and McMillan were the first to make a serious experimental study of the fine points of the workings of the cyclotron and to try to understand them theoretically. Outside of Berkeley, Hans Bethe, Morris Rose, and L. H. Thomas had applied sophisticated theory to accelerators, but had less contact with the realities of the problems.

At a somewhat lower level, there were Paul Aebersold, David Kalbfell, Robert Cornog, Philip Abelson, and many other graduate students or young postdoctoral fellows. They had sufficient ability, but, I believe, would have profited from more guidance. In addition, there was a whole group of medical doctors using radiation as a clinical and research tool. They were privileged because money came to a large extent from foundations nourishing optimistic hopes of medical applications, especially cancer cures.

Don Cooksey had a unique position. He came from a rich, cultivated family and had met the young Lawrence at Yale, where Cooksey and his brother Carleton were both members of the physics staff. Cooksey had limited scientific ambitions, but an immense love for and confidence in Lawrence. He devoted his considerable technical ability, his refined

manners, his generosity and human understanding, to helping Lawrence in every way. Lawrence reciprocated by making Cooksey his most intimate confidant and advisor.

Soon after my arrival in Berkeley, I met Glenn Seaborg at the Faculty Club. He had obtained his doctorate the previous year and was a research assistant to G. N. Lewis, a famous chemist and one of the most important members of the Berkeley Faculty. Seaborg was keenly interested in anything happening around him and kept his ears and eyes open. Almost immediately he offered me his cooperation, which I gladly accepted. I found that he knew analytical chemistry according to the system propounded by A. A. Noyes and W. C. Bray,^[6] rather than the more classical schemes I was familiar with. It seemed to me he knew everybody in the Chemistry Department and could find anything we needed. At the time Seaborg had a heavy load helping Lewis in his organic chemistry research, as well as in anything else that Lewis's fertile mind came up with. On the side he worked on nuclear problems for several hours every day and compiled data for an important review article he was preparing, as well as for a table of isotopes.^[7]

Seaborg could do all this because he had iron discipline, a lively and highly systematic mind, immense persistence, exceptional endurance for work, and a sincere, open-minded interest in science. He was a superb organizer, but was not too strong in physics or instrumentation. At the beginning of our collaboration, I probably remembered my much earlier experience with Bakker at Zeeman's laboratory in Holland, when I, a newcomer, and he, the local boy, greatly helped each other and became steadfast friends. Little did I recognize Seaborg's unbridled ambition and his unshakable determination to succeed and to be preeminent.

As a general guideline for myself, I decided to fulfill my obligations as a citizen of the Cyclotron Republic but, at the same time, to try to preserve my individuality and to avoid being absorbed completely by the Rad Lab. I also wanted to use the immense opportunities offered by the cyclotron as much as possible, which I considered a contribution to the Lab. I soon found students willing to work with me. The first was Chien-Shiung Wu, who joined me when she realized that, in so

doing, she would be able to learn something. She was very handsome, and very elegant in her Chinese dresses. When she walked on campus, she was often followed by a swarm of admirers, like a queen. She was a fiend for work, almost obsessed by physics, highly talented, and very shrewd, as well as witty. Many years later she became world-famous for the experimental demonstration of the non-conservation of parity. I admired her and liked her, and we remained friends for life.

Alex Langsdorf, Jr., a postdoctoral fellow, also started working with me. Disappointed with Lawrence, he had begun building a continuously operating cloud chamber, but this project ran into difficulties, and Alex joined me. He was the son of a well-known professor of electrical engineering at Washington University in St. Louis; while we worked, he diligently instructed me in things American, and we became steady friends.

A few days after my arrival, I started my first investigation, with Seaborg, a search for short-lived technetium isotopes. This was the natural continuation of my work at Palermo, the reason for which I had come to Berkeley in the first place. One of the new radioactivities, obtained by deuteron bombardment of molybdenum, immediately presented an unexpected and interesting nuclear phenomenon; it was a case of nuclear isomerism—that is, of a nucleus possessing long-lived excited states. We did not dream then that this isomer would in time become a mainstay of nuclear medicine as a powerful diagnostic tool. Today it is used by thousands of practitioners, and its applications are the basis of a multimillion dollar industry.

However, what interested us at the time was the phenomenon of nuclear isomerism. In 1936 C. F. von Weizsäcker had proposed a theoretical explanation of isomeric states, attributing to them a high angular momentum that forbids transitions to lower, small angular momentum states. It followed from this, according to theory, that there should be plenty of internal conversion electrons. Seaborg and I looked for them and found them, reporting our results in a letter to the Physical Review on September 14, 1938. A few days later, however, on the advice of J. Robert Oppenheimer, who for reasons unknown had told him (but not us) that we were mistaken, Lawrence demanded that we wire the

editor of the journal to stop publication of our letter. I protested within the limits permitted by my position, and the letter was resubmitted to the Physical Review on October 14, 1938, after Bruno Pontecorvo had reported getting results on rhodium similar to ours.^[8]

This was one of my first contacts with Oppenheimer, then professor of theoretical physics at Berkeley, later famous for his part in building the atomic bomb, for his political activity, and for his unjust victimization.^[9] At the time, he was considered a demigod by himself and others at Berkeley, and as such he spake in learned and obscure fashions. Besides, he knew quantum mechanics well, and in this he was unique at Berkeley. He taught it in none too easy a fashion, which showed off his prowess and attracted a number of gifted students. His course later formed the basis of Leonard Schiff's well-known treatise on quantum mechanics.^[10] Oppenheimer's loyal disciples hung on his words and put on corresponding airs. Just as we in Rome had acquired Fermi's intonation, in Berkeley Oppenheimer's students walked as if they had flat feet, an infirmity of their master's.

Oppenheimer and most of his acolytes followed the political line of the Communist Party of the United States, which was highly uncritical and simple-minded. Although most of these young people were not members of the Party, some were members of auxiliary organizations and later fell victim to cruel persecutions. Oppenheimer and his court did esoteric things; they read very highbrow books, cooked and ate unusual food, and during the summer went to a mountain ranch in New Mexico leased by Oppenheimer, beautifully located near Santa Fe. Their physics was valid, but often they attacked problems prematurely, or problems beyond their capabilities, resulting in indifferent success. The best of Oppenheimer is perhaps his astrophysical work on neutron stars, which many years after his death proved truly prophetic. His research on cosmic rays and atomic and nuclear problems embodied many good and even prescient ideas, but was often inconclusive. Oppenheimer's beneficial influence on the development of theoretical physics in the United States was considerable, and several of his pupils have achieved major results, as well as deserved fame.

Oppenheimer and his group did not inspire in me the awe that they

perhaps expected. I had the impression that their celebrated general culture was not superior to that expected in a boy who had attended a good European high school. I was already acquainted with most of their cultural discoveries, and I found Oppenheimer's ostentation slightly ridiculous. In physics I was used to Fermi, who had a quite different solidity, coupled with a simplicity that contrasted with Oppenheimer's erudite complexities. Probably I did not sufficiently conceal my lack of supine admiration for Oppenheimer, and I found him unfriendly, even if covertly, for a good part of my career, except when he wanted me to join his team at Los Alamos.

At Berkeley, in 1938, I had the impression that Oppenheimer regarded me as a great Fascist. I was a Fascist Party member, as every Italian state employee was required to be by law, but it did not take much acumen to figure out that I could not be a Fascist at heart. I could not, however, conceal my skepticism when I heard him repeat, with the faith of the true believer, the nonsense originating from Stalin's Cominform.

Talking politics with American colleagues, I found an incomprehension of things European that was appalling to me. My partners in conversation had many different opinions, but most seemed convinced that what happened in Europe did not concern the United States, and that if the Americans minded their own business, they could avoid entanglements in European quarrels. It was, fundamentally, the isolationist thesis; they did not grasp Hitler's nature and his plans of world domination. These plans were the products of a deranged mind, but the disease had spread to a whole nation as powerful as Germany, and it was not something to trifle with. There was also a good measure of optimistic skepticism about Hitler's true intentions, which in effect proved much worse than the most pessimistic forecasts.

Others, although not many, followed the Communist Party line, like Oppenheimer, and deemed that the European quarrels were caused by capitalist imperialists, and that Holy Communism would avoid them. Which side of the bad capitalists won was irrelevant. If they weakened themselves sufficiently in their internecine strife, Mother Russia would later establish the millennium. This senseless view suddenly changed

when Hitler and Stalin signed their nonaggression pact. Hitler suddenly became palatable!

My guts rebelled when I heard such talk. I strove to persuade isolationists that things were not as they hoped and believed. For the Communist true believers, there was nothing to be done, because their "ideas" were more religious feelings than political reasoning. Fortunately, President Roosevelt saw farther and more clearly than the majority of Americans. Anyone who was in the United States in the years immediately preceding World War II knows the difficulties Roosevelt faced in opening the eyes of the Congress and of the American people on the subject of Hitler.

I followed the news from Italy with increasing alarm, but I could relieve my feelings and unburden myself only with Emo. The Fascist Manifesto della razza had been followed by legal measures that left no doubt about the final purpose of the campaign. I recognized more and more the foresightedness and wisdom of having preserved a certain amount of money abroad. By the end of July, I had decided to forget Palermo and to summon my wife and son to California.

In the meantime, to escape the summer heat, Elfriede had taken Claudio to Frassenè, a resort in the Alps, where she was shortly joined by her parents from Germany. The publication of the Manifesto della razza followed a few days later. Elfriede was less alarmed than I, because Italian newspapers published a version of the facts that played down the probable consequences. When I wrote asking her to pack up and come to America, however, she agreed immediately.

In the following months, Elfriede had to face a heavy burden, first alone in Italy, and then in America. To start with, in Italy, she was confronted with sticky bureaucratic problems that required infinite patience, while the sultry summer weather and the effort of taking care of a one-year-old child further sapped her strength. She had good help, but the proceedings were morally debilitating and physically exhausting. All this emerges from her letters of the time.

In the meantime, the Czechoslovakian crisis was progressing and seemed likely to precipitate a world war. I thus urged Elfriede to speed

up her departure, cabling her: "Vieni immediatamente con tuo comodo" (Come immediately, at your leisure), counting on her realizing that the first two words were the key ones.

Finally, Elfriede had to return to Sicily, lock up our apartment, and board a ship. She arrived in Palermo dead tired and sick with digestive troubles. There she was met at the dock by my student Ginetta Barresi, whom she had told she was coming. Ginetta was accompanied by her father, a colonel in the army, and by two other gentlemen. They asked without further ado what Elfriede needed. She explained the state of her passport—that it had the necessary Italian validation, but no U.S. visa—and said she wanted to close up our apartment and depart as soon as possible. The answer was immediate and to the point. "The next ship leaves on  . . ." and they gave the date. "You get some rest now, and we'll take care of EVERYTHING ." I do not know whether Elfriede went to our apartment or to the Barresis' villa at Mondello; in any case, they brought her food and, three or four days later, in time for embarkation, her visa, the ticket, and everything she needed. As far as closing the apartment and forwarding its contents were concerned, Ginetta asked for instructions and in due course took care of everything to perfection. Moreover, Ginetta visited my parents whenever she was in Rome and sent us news of them. "I am pleased my compatriots are showing themselves to be decent people. Having gotten to know Ginetta and her like better, however, I shall become a Sicilian by choice," I wrote to my parents on August 3, 1939, responding to a letter of theirs in which they took comfort in the signs of friendship and esteem they were receiving in Tivoli. From Ginetta we had proofs of friendship in "heroic degree," as the Church says of virtue.

In 1938 and 1939 my parents continued to live more or less as they usually did, at least on the material side. They traveled a good deal, vacationing at Forte dei Marmi or some other familiar resort when Rome was too hot, and spending long periods at Tivoli. In almost all their letters, they mention old friends, above all Signora Rasetti and Amaldi, Bernardini, and other physicists who went to visit them and tried to cheer them up. In these letters, my father's great moral strength,

clarity of mind, and farsightedness are also apparent. He never loses sight of the essential point. In rereading my parents' letters half a century later, I am impressed.

It was an anxious time. I was afraid that hostilities might break out while Elfriede and Claudio were on an Italian ship, and that they might be detained at Gibraltar for the duration of the war. Furthermore, in view of the circumstances, I had cabled certain instructions concerning my funds, and I received an answer in a commercial code that was incomprehensible without the key. I confided this to Emo, who, half jokingly, half because he did not know what to say, indulged in the blackest hypotheses on the mysterious meaning of the words of the cable I had received. "Homgo Homil," it began, and Emo said that this obviously meant "All is lost!"; for many years these words remained our private joke. Finally, I found a European apprentice at a bank in Berkeley who recognized the code and translated it for me. It was nothing important, but at the time, Emo and I were so upset by the events that we lived on milk shakes only; we could not eat because any solid food disagreed with us.

At the worst of the Czechoslovakian crisis, Elfriede, in blissful ignorance of everything, was at Gibraltar on an Italian liner, but the situation cleared up, at least temporarily, and she was able to proceed to New York. There she caught a train, and since it was her birthday, October 2, I sent her a telegram, using one of those long and pompous standard texts delivered on a special birthday form, all for twenty-five cents. "The darkest clouds have a silver lining," it declared among other things. On receiving the telegram en route in a style so unnatural for me, and unaware of Western Union's bargain services, Elfriede thought I had lost my mind. Finally, in early October, we were reunited, to our great mutual joy.

During the summer I had also started to become acquainted with some of the attractive features of life in the United States under the guidance of Brode, Jenkins, and their wives. As one of the first lessons, the husbands and their friend S. K. Allison, a physicist from the University of Chicago,^[11] took me for a long hike in Yosemite National Park. We visited the high mountains near Vogelsang Pass, from where,

in a couple of days, we descended into the Valley, walking along the Merced River. Jenkins had brought along an extra rod and he showed me how to fish for trout. Within an hour I was hooked on the sport, which delighted me for many years. My three physicist companions sometimes marveled at my ignorance of things American, and I still remember Jenkins's laugh when I told him that to inform myself about America, I had read Defoe's Moll Flanders . From it, however, I had learned that Quakers like himself were good, kind people. He and his wife liked to tease us when we could not understand New Yorker cartoons they showed us. On the other hand, he was very surprised when I pointed out to him that if there were counties, one expected to find also counts. He had never thought of the connection between the two.

Jenkins, Brode, and Allison, all three of them children of professors, were much more cultivated than Lawrence and some of our other colleagues, and they were also better-natured and more easygoing. The Jenkinses remained our best and closest American friends until their sad, early deaths. We often visited them informally in the evening, and their tales, example, and help with the problems of daily life contributed substantially both to our morale and to our adaptation to American customs.

Don Cooksey was another dear friend who valiantly helped us to adapt to America. He owned a ranch in Trinity County in northern California, not far from Forest Glen. One reached it after a walk of about forty-five minutes in a pine wood along the South Fork of the Trinity River. The ranch's log cabins were in a clearing near a small placer-mining operation. The cabins had been built around 1906 by a couple who had cared for Don, who was orphaned at an early age. These people had willed the cabin to their charge. The gold-mining claim had never been important in itself but helped in securing a deed from the Forest Service. A man who lived permanently at the camp with a couple of horses helped Don with the upkeep of the place. At the camp, one lived very simply, spending a good part of the time on or near the river. There was complete freedom: one could do nothing, read one of the interesting books stored in the cabin, swim, fish, float on an inner tube, walk around, or even, if one really wanted to, pan

for gold. The trout fishing was good, and in the water one could see huge salmon that came to spawn in the river. The company was congenial: it consisted of the owners, and, in turn, Thornton, Kamen, McMillan, and several others connected with the Rad Lab. Whenever Cooksey's observant eye saw somebody in need of a restorative vacation, he invited him to his camp. There we were treated with exquisite courtesy, which we tried to reciprocate by helping with the necessary chores. Photographs show the kind of life we enjoyed. Such vacations made deep impressions and left all those who had the good fortune to share them with pleasant memories.

Before Elfriede's arrival, Henriette Jenkins and I went looking for a furnished house to rent. We found one at 2532a Piedmont Ave. in Berkeley for forty-five dollars a month, and as soon as she saw it, Henriette urged me to take it. I signed the rental agreement at once. The house was a wooden cottage in a yard behind some larger homes. It had a kitchen, living room, a couple of bedrooms, and a small porch. The whole was in indifferent shape and old, but in a convenient location and sufficient for us, at least temporarily. There was enough furniture so that we could manage until our own arrived from Palermo. When it arrived, with some effort we fitted it in. The landlady was a widow who tried to be helpful and accommodating. With a little good will, we could even take in a guest; and in fact Felix Bloch came to stay with us when he was working at the cyclotron with Alvarez. He slept on the porch in his sleeping bag, and Claudio used to wake him up in the morning, calling in Italian: "Bloch! Lavora!" (Bloch! Work!). Amaldi too spent some time with us and happened to be with us when World War II started.

With an eighteen-month-old baby to take care of, Elfriede also had to learn what food to buy, and where; where to find clothes; how to get medical help if necessary; and how to cope with a thousand details of daily life that were different in the United States. Above all, in Italy we had had a maid and a nanny; here everything fell on Elfriede's shoulders. She soon learned how to cook excellently, something she had never done before. No wonder she acquired the nickname "Tuechtigona" (an italianized augmentative of the German tüchtig, able and

hard-working), which she fully deserved on all counts. How strenuous and demanding all this was emerges from our correspondence with my parents, where one often finds hints of tiredness.

In the beginning we did not have a car, but university, Rad Lab, and shopping centers were all within a fifteen-minute walk from home, so we did not need one. I did the shopping and I knew that my carrying strength sufficed up to five dollars worth of groceries. In May 1939, we bought our first American car, and a few days later Elfriede got her driving license, increasing our mobility.

From the moment of our arrival, we had had an immediate and important problem: obtaining an immigration visa. My tourist visa was for six months, so it lapsed in January 1939. In order to change one's visa, it was necessary to go to a U.S. consul outside the United States, and the most convenient place seemed to be Mexicali in Mexico. Immigration restrictions were steadily increasing as Hitler exacerbated his persecutions and more people tried to flee Europe; there was no time to waste. I remembered Rasetti's instruction in the subtle and marvelous points of Section 4(d) of the immigration law then in force, but when I tried to obtain some help from a service in San Francisco that was supposed to help immigrants, I concluded that it was better to do everything myself (one of Fermi's fundamental rules).

I asked the good Dean Pegram of Columbia University for a letter of recommendation to the consul, and he wrote a masterpiece. I asked for help in Berkeley too, but with little success. The university officials I contacted were polite but seemed exceedingly scared by the idea of incurring (nonexistent) responsibilities and limited themselves to the minimum they could not deny. However, armed with Pegram's recommendation and with my knowledge of the law that fitted my case perfectly, I took a bus and in two days arrived at Mexicali. Elfriede and Claudio were already in Berkeley with a tourist visa, but they could not possibly come with me at the time, and I thought it better to make two trips to Mexicali rather than wait until we could all go together.

On November 16, 1938, I obtained the visa that solved my immigration problems, and in February 1939, we returned to Mexicali to exchange Elfriede and Claudio's tourist visa for an immigration one too. We

hoped we would not have to produce Claudio, but the consul insisted on his presence. As soon as Claudio entered his office, however, he started crying and yelling loudly, and the consul, at a loss for what to do, said, "Take him away immediately," which we did. Thus, with two trips to Mexicali, we settled our immigrant status. Later I read in a newspaper that the consul at Mexicali had been convicted of selling visas!

On November 29, 1938, we celebrated our first American Thanksgiving, with Emo and Bloch as our guests. I thought that we had every reason for celebrating, and that we pretty well resembled the early colonists who had originated the custom. Fermi used to say, whenever somebody bragged about his Pilgrim ancestry, or when he heard about the Daughters of the American Revolution, that he and other newly arrived refugees were the true, new pilgrims, who understood and appreciated some American ideals better than the American-born. About the same time, I received the news of the departure of my Rimini cousins from Italy for Montevideo, in Uruguay.

On February 2, 1939, we celebrated my father's eightieth birthday. We had written to him in time.

On May 10, 1939, my brother Angelo arrived in New York with his wife and two children. At first he tried to work at Columbia University in his field, economic history, and initially he had some success at this. Subsequently, however, he quarreled with everybody and gave up teaching, devoting himself entirely to painting. He exhibited in New York and had a certain critical success, but no financial reward, and did not persist in trying to sell his work. Although I invited him repeatedly to visit us in California, he never budged from the East Coast.

Angelo lived on family money, administered by me, according to my father's policies. I was cautious in the use of this money. I thought it should first be at my parents' disposal if they wanted to emigrate, and this took precedence over everything else. Second, one had to consider emergencies that might occur at any moment. I thought my family and I should live on my earnings alone as long as we could do so without great sacrifices and without endangering our future.

As soon as Angelo arrived at New York, he started pestering me

with demands that ran counter to my instructions and policy. I gave him a monthly allowance of $150; it was not much, but it should have sufficed under the circumstances; in emergencies, he could ask for more. Angelo greatly upset me by threatening to complain to our father. Fortunately, a trusted friend of the family was out of Italy for a business trip, and through him I was able to communicate with Papà, who let me know that he approved of my conduct. Later, when I started earning a little more at Los Alamos, I sent some money of my own to Angelo, whose son needed an operation. In thanks I received a letter from Angelo saying that he considered my gift restitution of funds I had wrongly appropriated.

In 1938 after I had worked at the Rad Lab for a few weeks, Lawrence asked me if I could extend my stay beyond the month of October, the date I had given him for my return to Palermo. The offer was a godsend, but I sensed that precipitous acceptance was not to my advantage. I thanked Lawrence profusely and asked for some time to answer. Lawrence then went to Alaska on vacation, and I began to fear that he might change his mind, and that by trying to be too smart, I had destroyed my chance. Fortunately, on his return Lawrence renewed the offer of a salary of $300 a month for six months. My title was to be "research associate," a nondescript qualification that could apply to persons at very different levels. It had, however, one definite connotation: it implied a temporary job and did not commit the university or the Rad Lab beyond the term of the contract. At Christmas we were invited to Lawrence's home for dinner; oddly enough, he took the opportunity of telling me on this occasion that the lab was short of money, and that if necessary he would ask me to return part of my salary.

In 1939, $300 a month was a good salary, and it got me out of the woods for some time, but after six months, in July 1939, Lawrence, who by then must have realized my situation, asked me if I could return to Palermo. I answered by telling him the truth, and he immediately interjected: "But then why should I pay you $300 per month? From now on I will give you $116." I was stunned, and even now, so many

years afterward, I marvel at Lawrence's impulsiveness; he did not think for a second of the impression he conveyed. With a minimum of reflection and diplomacy, he could have saved his $184 a month without cutting a horrible figure in my eyes. However, although I have not forgotten his conduct, I now see it in a different light than I did then.

I did not know what the salaries of other members of the Rad Lab were at the time. It was I who, with $300 a month, was the exception, and salaries around $116 were not rare. If I had known this and how Lawrence behaved with Americans who were unemployed because of the depression, I might have viewed the episode somewhat differently. I was somewhat older and better established as a scientist than some excellent Americans were, but they too got meager salaries, although they had academic positions and guaranteed careers.

In any case, with a wife and a child, a salary of $116 was scant, but it was not totally impossible to live on it. With $200 a month I could make ends meet, sparingly, but without deprivation, and I could bring my salary to that level by using my private funds, the existence of which was known only to Elfriede and to my friend Emo, whose discretion was absolute.

Elfriede and I constantly thought of our faraway parents. We wrote at length and regularly, at least once a week. Neither transatlantic airmail nor usable telephone connections with Italy existed, but the mails were better organized then, and a letter did not take much longer to reach Italy than it does today. My mother and Elfriede wrote at greater length than my father and I did, but he added at least a few lines, sometimes insignificant, sometimes important, to every letter. Each side tried to reassure the other, so the letters sounded a little more optimistic than they should have, and definitely more optimistic than those I exchanged with my cousins in Uruguay. When I complained, as I sometimes did, about the precariousness of my position, my father insisted that there was only one way of improving it: do good physics. If I succeeded in this, recognition would not fail to come, and career problems would take care of themselves. The times demanded prudence in writing; my parents interspersed praises of the Duce and other phrases intended

for the eyes of a possible Fascist censor in their letters, although I doubt they would have fooled him.

The letters mirror Italian Jewish life in those tragic years, as one by one the young people emigrated and the older generation were left increasingly alone. At the same time, to their credit, many good old friends appeared, seeking to comfort my parents with frequent visits: Rasetti and his mother; Amaldi; Ginetta Barresi; the Salvati family and others in Tivoli, among them both important citizens and humble people; Ada Rimini and other relatives; my cousin Renzo Ravenna, the mayor of Ferrara, who came to visit his aunt and uncle and his close friend Italo Balbo, in Rome for a meeting of the Fascist Gran Consiglio. The letters report a great variety of other news: marriages, births, deaths, the recipe for some cakes I liked, urgings to Elfriede not to overdo things and to get the rest she needed, encouragement to use family money, indirect news of Elfriede's parents, as well as of Bindo and Riccardo, and so on. There is even a report on an exchange of letters with E. O. Lawrence in which they congratulated him on his Nobel Prize and received a friendly answer. On July 6, 1940, my father writes: "I am eager to know your arrangements with Lawrence, but in any case I am happy if scientific concepts absolutely prevail, an opinion shared by M" (this sentence means that I should, if necessary, use family funds to support myself). On April 9, 1941, he comments on the friendliness of a Carabinieri officer who had come to withdraw my Fascist Party card. Other news: the U.S. consul, who had rented our Palermo apartment, is leaving. On May 7, 1941, my mother "is memorizing our letters" and father "is working to prevent idleness from wearing out his spirit."

Correspondence with Germany and with Elfriede's parents was much more difficult and dangerous, and thus is much less informative.

All regular communications stopped in December 1941, with the entry of the United States into the war.

At Berkeley I had realized that there was only one salvation: to do good physics. With that weapon I might perhaps save myself; without

it, I would be thrown out without mercy. This simple estimate of the situation was supported by my father's advice and inspiration and by prudent, but well informed and extremely welcome, encouragement from Fermi. Fortunately, I did not lack ideas, and the Rad Lab, for all its defects, offered unique opportunities for experimentation.

Half a century later, I see that my personality did not allow me any other way of survival; someone else might have made an easier life for himself than I did by being less touchy, less proud, more able to dissimulate, better at public relations, and simultaneously less timid and and less critical. I have by now attained some slight knowledge of myself, and I know how unpleasant I can be. However, if I am a curmudgeon, I have paid for it.

The 60-inch cyclotron was under construction; the magnet was there, but not much else yet. The sight of such a big, powerful magnet suggested to me the possibility of improving on my previous studies of the quadratic Zeeman effect. Jenkins was a spectroscopist, and we collaborated in this work.^[12] Such research continues today because with bigger magnetic fields and much better spectroscopic resources, physicists keep finding new interesting details. The subject is now part of the study of what today are called Rydberg atoms.

In January 1939, having clearly understood the relation between nuclear isomerism and conversion electrons, it occurred to me that it might be possible to separate nuclear isomers with a method similar to that devised by Szilard and T. A. Chalmers for isolating products of the (n,g ) reaction. I communicated my idea to Seaborg and told him that I needed a chemist who could synthesize a suitable organic molecule containing Br⁸⁰ . Seaborg found me Ralph Halford, who knew how to prepare a suitable organic bromine compound. We imprudently spoke of our project at the Faculty Club in the presence of Willard Libby, later famous for his carbon dating (I have been told that the suggestion came from Fermi in a Chicago seminar). At the time Libby was Seaborg's great rival and an assistant professor, while Seaborg was slightly his junior. Without telling anybody, Libby went to his lab and applied my method to tellurium isomers. He then wrote a letter describing the result to the Physical Review and was about to send it, when Seaborg

got wind of the fact. A row developed, and I asked Libby to wait twenty-four hours before sending his letter, so as to allow us to finish our work, which was half done. Under strong pressure, Libby acquiesced, and the two letters to the Physical Review thus appeared side by side.^[13]

It was an unusual experience for me. I do not think that Libby would have gotten away with such behavior in Europe at the time, certainly not in Rome. Criteria of intellectual property were more elastic in America; on the other hand, at least at the Rad Lab, there was great generosity in the exchange of instruments. It is difficult to pass judgment. Subsequently several Berkeley radiochemists, including Joseph Kennedy and Seaborg, eagerly pursued this method for separating radioactive isomers.

At the end of 1938, there were great hopes in Berkeley that Lawrence would win the Nobel Prize. I thought that if it did not go to Otto Stern or somebody older, it would go to Fermi. (The year before in Palermo, to my great surprise, I had received a nomination form, and I had nominated him.) I did not, of course, know that Bohr had confidentially told Fermi that he would be chosen that year if he wanted to be, or that Fermi was preparing to emigrate. When the official news that the physics prize for 1938 had been awarded to Fermi arrived, I was delighted and wrote to congratulate him, adding: "The only sadness is the thought of the various people of the old guard who would have rejoiced to be near you now that the reward of so much work, so many hours of labor, as well as c.i.f. (con intuito formidabile , 'with formidable intuition,' a joking acronym we used for statements by Fermi that were true, but that he could not prove), is here, and they are prevented by an inscrutable destiny." Lawrence acted with good grace, but he was clearly disappointed. He asked me whether I thought he would get the prize next year. I said I did, and this indeed came to pass. By chance, on November 14, 1939, the day of the announcement of Lawrence's prize, he was having dinner at our house, and we opened a bottle of champagne, as reported in a letter home.

At the beginning of 1939, the news of the discovery of fission by Otto Hahn and Fritz Strassmann reached Berkeley. The experiments were immediately repeated, but not by me. I did not like to rush into

a competition, and although I had been among the first to work on uranium, I continued my investigations on other subjects. On my arrival in 1938 I had renewed my conversations of 1936 with Philip Abelson, who clearly indicated that he considered uranium his property, not troubling to hide his feelings about foreign interlopers. I therefore left uranium to him until the discovery of fission. Abelson then recognized that he had seen X-ray lines belonging to the tellurium K-series, but had misinterpreted them, a rather crude error, by which he missed making a great discovery. However, uranium also fooled Fermi, the Joliot-Curies, Hahn and Meitner, and other eminent scientists, all of whom made gross errors, and my own mistakes on the subject stand out. If Abelson had reason to be angry with himself, some time later I did too.

After the discovery of fission, Joliot-Curie and McMillan independently devised a clever physical method for separating the fission products from the product of the (n,b ) reaction occurring in uranium. As a result of bombardment of a thin uranium layer, the fission fragments emerge from the layer and can be collected on a suitable adjacent foil, while the products of the (n,b ) reaction stay in the uranium foil. It was thus possible to confirm Hahn and Meitner's finding of a 23-minute activity due to U²³⁹ . In addition the uranium layer showed an activity, with about a 2-day period, and I started studying it chemically. I suspected it was a beta-decay product of the 23-minute activity and hence an isotope of element 93 (neptunium) of mass 239, but I did not expect that element 93 might be chemically similar to a rare earth. Everybody up to then believed that element 93 would be similar to rhenium, and this was one of the errors that had produced great confusion in the interpretation of all the results of uranium bombardment. I established chemically that the activity I was studying behaved similarly to a rare earth and then convinced myself that a fission fragment constituted by a heavy rare earth might stay in the uranium layer. I discussed this with Felix Bloch, who concurred, but the responsibility for the error is totally mine. On second thoughts, I should have realized that my interpretation was, to say the least, suspect.

I tried to make a stronger sample and to see whether the 2-day activity

could be interpreted as the radioactive daughter of the 23-minute activity. In this I had bad luck. The ionization chamber I used had a window too thick for the beta rays of Np²³⁹ , which are unusually weak. Furthermore, I went to the movies at a critical time when I should have been in the lab measuring the activity, although this fact was not of paramount importance.

In conclusion, I erred and did not recognize the genetic relation between the two activities. The resulting paper is fundamentally wrong, but it contains an important truth: the similarity between element 93 and the rare earths.^[14] This similarity had even been considered in the literature, but the relevant papers had escaped me, and not only me. Shortly afterward, the problem of the 2-day activity was cracked by McMillan and Abelson, who discovered neptunium. After their discovery, in a letter home, dated June 4, 1940, I observed:

I do not know whether I have ever written to you of my misadventure with element 93. After so much work, discoveries and undiscoveries, last spring I had it in my hands for several weeks and did not recognize it. On the contrary I have even published a short note affirming that the substance they have now proved to be element 93 was a rare earth. Altogether it is an ugly blunder, combined with my having lost, in a most stupid way, the opportunity for a rather interesting discovery. Now there is nothing else I can do about it. Let us hope that the thing will not be proclaimed to all comers by my friends.

In other studies on fission products with Alex Langsdorf and Chien-Shiung Wu, we inter alia found Xe¹³⁵ , which is a tremendous neutron absorber. This last fact was discovered only later, when xenon poisoned the first nuclear reactors.^[15]

In spite of my scientific activity, Lawrence must have come to the conclusion that I was too expensive. I contributed to the exploitation of his machine, but not sufficiently to its development or operation. Hence I could not aspire to a permanent position at Berkeley. Lawrence told me all this very forthrightly in December 1939 and demanded that I use at least half of my time in the service of the Rad Lab, probably intending the cyclotron. I may have believed that I was already using all my time for the benefit of the lab. He also urged me to find a job

elsewhere and suggested I try an oil-prospecting company in Tulsa, Oklahoma. "In industry they are no great shakes and you will pass for a good physicist," he added. So saying, he wrote me an excellent recommendation. Lawrence's intentions may have been good, but his diplomacy was not. Remembering also the salary cut I had suffered, I reluctantly started thinking of leaving Berkeley.

I remembered, however, how my dear friend George Placzek consoled himself for having passed from the state of a wealthy gentleman to his present penury: "See! I am at Cornell University. I have an excellent salary: $1,000 a month, but expenses kill me!" He then listed imaginary expenses: $150 a month for having escaped the Nazis; $150 for living in a good climate; $100 for the use of the library and for having access to seminars and to worthy colleagues, and so forth. "I am left with only $120 per month, but it could be worse," Placzek concluded.^[16]

By attending meetings, writing letters, passing the word around, and so on, I strove to find a more stable place than the one I held at Berkeley. Some of the answers were friendly, but some were chilling, like that of S. K. Allison, who pointed out to me that not even his student Skaggs (a completely unknown character) had found a job. The idea that I came after Skaggs in the mind of so knowledgeable a friend and gentleman as Allison scared me. Among the encouraging and friendly letters I received, I remember one from James Franck, the great experimental physicist of Göttingen, who had been dismissed by the Nazis and was then working at Chicago. Since Franck was a major figure in physics and was also known for his good heart (besides his courage), I expect he received many appeals for help. I wrote him and he answered with a solicitous and encouraging letter dated September 1, 1939. Finding insufficient what he had dictated to his secretary in English, he added by hand in German, "In your case I am truly optimistic, because people do not let slip a man of your ability." The encouragement of such a person helped me. Later Franck visited us in Berkeley and I met him many times in subsequent years, the last time at a meeting of Nobel laureates in Lindau, Germany, in 1962.

I also tried to mobilize Fermi's help, but I had the impression he

was unwilling to bestir himself on my behalf. I now believe his unconcern was more apparent than real, because he preferred to appear indifferent rather than to say that he could not do much. More important, I believe that seeing me doing good work at Berkeley, he reasoned, like my father, that my position in Berkeley was undoubtedly scientifically most advantageous, and that it would be an error to exchange it for a permanent job in a minor university.

Few machines were to be as productive of important discoveries in nuclear physics as the 60-inch cyclotron, which started working at the beginning of 1940. I immediately suggested that since it could accelerate alpha particles enough for them to penetrate potential barriers of heavy elements, one could form isotopes of the missing element 85 by bombarding bismuth with alpha particles. Robert Cornog has described what followed:

One Monday night at a meeting of the Radiation Laboratory group, Emilio Segrè described his plans to make element 85 by bombarding bismuth with alpha-particles accelerated in the 60-inch cyclotron. After the meeting, as Dale Corson and I walked together across campus, we talked of Segrè's proposed experiment. Unaware that Corson was already preparing to do some alpha-particle bombardments with the 60-inch cyclotron, I said: "You know, Dale, I have a lump of bismuth." "And I have a linear amplifier," Dale countered.

The next morning, bright and early, Corson and I bombarded bismuth with alpha-particles from the 60-inch cyclotron. We saw gobs of giant pulses when we placed the bismuth in front of our linear amplifier. I was elated but felt guilty as sin to have poached what I felt was Segrè's experiment, so I went directly to see Segrè. "Emilio, would you mind much if I had a try at that bismuth experiment you described last night?" I asked. After a short pause Segrè replied: "No. There are other experiments that I can do." Now came the sticky part. "It's worse than that, Emilio. Dale Corson and I have already bombarded bismuth. We got giant pulses on his linear amplifier." Segrè paused somewhat longer. "I have only one request. Let me do the chemistry."

It was a day or two after these events that Luie [Alvarez] was especially articulate and direct. He suggested that I work either on discovering element 85 or on discovering the stability of hydrogen-3 and helium-3, but not on both! So Corson, MacKenzie and Segrè discovered element 85 and Alvarez and Cornog discovered hydrogen and helium of

mass 3. All these events notwithstanding, Segrè continued to let me use his electrometer, an instrument which now resides in the Smithsonian collection.^[17]

Today, as we proposed, element 85, the last of the halogens, is called astatine. As in the case of the other halogens, the name refers to one of its outstanding properties: its instability. Astatine chemistry is complicated, and as all its isotopes are short-lived, it can be studied only on the tracer scale. Chien-Shiung Wu and I also tried to form the last cisuranic missing element, of atomic number 61, by suitable bombardment of rare earths, but at the time the chemical separation of rare earths presented difficult problems, subsequently overcome by elution on resins. We certainly produced isotopes of element 61, but we could not prove it to our satisfaction, and the element was later discovered by Glendenin and Marinsky.

From January 30 to February 20, 1940, Fermi came to Berkeley as Hitchcock Lecturer. I was delighted to see him (it was the first time we had met since leaving Italy), and we resumed our habit of taking long walks together, talking mostly physics. Fermi explained to me his latest studies on the stopping power for ionizing particles and on its relativistic rise. We tried to verify some of his predictions experimentally using the electrons of P³² , but the results were inconclusive. On the other hand, with the new 60-inch cyclotron we fissioned uranium with alpha particles, reporting our findings in the last paper we coauthored (although certainly not the last we discussed in the planning stage or to interpret results).^[18] At that time Fermi did not mention his studies of the chain reaction to me. As I have emphasized, he was always reserved, and in this case he had weighty reasons for being more than merely cautious.

As was to be expected, Fermi often spoke to Lawrence, but when he started talking physics, Lawrence usually changed the subject, possibly because it was uncomfortable for him. Fermi doubted Lawrence knew or understood much physics, and thought he was rather full of himself. "It's a real problem when people must play the great man but are not up to it," he said. Fermi also attended Oppenheimer's seminars; coming out of one of them once, he said: "Emilio, I must be getting

senile. I went to a learned theoretical seminar and could not understand anything except the last words, which were 'And this is Fermi's theory of beta decay.'"

Some of the conversations I had with Fermi concerned beta decay and its ramifications, and it occurred to me that it might be possible to alter the decay constant of a K-electron capturer by chemical means. Since the decay constant is proportional to the electronic density at the nucleus, by subtracting electrons from an atom, it should be possible to alter that density. I estimated the effect and found out that it would be small but probably observable. The best substance to try was Be7, because of its atomic and nuclear characteristics. On second thoughts, I also concluded that the same mechanism should alter the internal conversion and, as a consequence, the decay periods of my old friends the nuclear isomers. Generally the technique opened up a small chapter of nuclear physics, on altering nuclear processes by chemical means. This had been tried by simple-minded methods by the founders of nuclear physics, but since they lacked the necessary insight, their results had always been negative.

In pursuit of this idea, Chien-Shiung Wu and I tried preparing radioactive BeO and asked the Brush Beryllium Co. to convert some of it to metal. However, after a while more urgent work forced us to drop the project for the duration of the war. I did not publish anything on the subject then, because I disliked publishing ideas of experiments without having performed them. It was most fortunate that we suspended the work, because we did not know of the toxicity of beryllium and would unwittingly have incurred deadly dangers. After the war I completed the investigation with C. E. Wiegand, who was then my student.^[19]

In 1940 Lawrence was planning a 184-inch cyclotron to reach the then-enormous energy of 100 MeV. Lawrence expected to overcome relativistic difficulties by putting a million volts on the dees and reaching the final energy in only fifty revolutions. It was a typical brute force method, which might have pleased Admiral Farragut of "Damn the torpedoes—full speed ahead!" fame, but I do not know if it would have succeeded. Lawrence was convinced that with enthusiasm, hard work,

and persistence one could overcome every obstacle, or that somebody would find a way out by a new invention, as indeed occasionally happened, particularly in this case. However, ingenuity may circumvent nature's laws, but not violate them.

I realized that if I were to survive at the Rad Lab, I had better contribute to the great 184-inch cyclotron project, so when asked, I eagerly started helping William Brobeck, the exceptionally able engineer who headed the project. Brobeck was a rich young man, the son of a prominent San Francisco lawyer, and in love with his profession. He had a profoundly salutary influence on the Rad Lab because he introduced sound engineering practice in place of the physicists' roughand-ready way of doing things. Machines were planned with reasonable safety margins, and good engineering techniques replaced improvisation. Due attention was paid to gaskets, welding, stress distribution, and choice of materials. Brobeck introduced all sorts of important preventive maintenance routines. In short, he injected the art of engineering into accelerator development. As a consequence the functioning of the machines greatly improved, the wasting of time owing to breakdowns markedly diminished, and overall efficiency increased substantially. Brobeck was highly respected by the ablest physicists, who understood that his demands were well-founded and abundantly repaid the work and expense of complying with them. From 1937 until 1956, when he left the Rad Lab, Brobeck was involved in all its projects.

In 1940 Brobeck was planning the 184-inch cyclotron magnet, and I helped him in the building and testing of a model of it. In the beginning, it seems, Brobeck had a certain diffidence about working with a foreign physicist, unfamiliar with American engineering units and methods. However, we very rapidly found ourselves to be congenial and greatly enjoying the collaboration. Each learned from the other. I was pleasantly surprised in finding that Brobeck had advertised my work to Lawrence, who was impressed, since the praise came from an unexpected source. A letter home of May 22, 1940, says I was working full-time on the magnet.

At this time I ran into another serious poisoning risk, besides that of beryllium. I used to fill my ionization chamber with methyl bromide

to enhance its sensitivity to gamma rays. The commercial gas came in a small canister, which I used every so often to refill the ionization chamber. Fortunately, for no conscious reason, I always performed the operation in the open air, on a balcony. When the cylinder was empty, I called the salesman to get a new one. "How did it go?" he asked. "Have you killed all the rats?" I was surprised by the question, and he told me that he knew of only one use for the gas: as a fumigant for rats. I shuddered. There was no indication of toxicity on the cylinders, and I had not known that the gas was poisonous. Possibly my having handled it in open air saved my life.

As mentioned, soon after Fermi's visit, Lawrence recommended I apply for a job with an oil-exploration firm in Tulsa. I went, to explore the possibilities. By then it was spring, and I decided to go, not only to Tulsa, but also to Washington, D.C., for the annual meeting of the American Physical Society, and to some other place to advertise my existence. In Washington, I saw Rasetti, Rabi, Lee DuBridge, and others; in New York I visited my brother Angelo.

In May 1940, I spent a week in Tulsa, where I met two young men about my age: Serge Scherbatskoy, a Russian aristocrat whose father had been a czarist general, and his partner, a Jew from Russian Poland named Neufeld (who I fancied might have escaped some pogrom commanded by Scherbatskoy's father). They were trying to prospect for oil by radioactive methods; first they had used gamma-ray diffusion on rocks surrounding a drilling hole. Now they wanted to extend their method to include the use of neutrons, which they hoped might help identify hydrogenous material.

They offered me a good salary to join them as their physicist. I looked around carefully and concluded that the only reliable method for interpreting the logs they would get was to build an artificial well in the lab and to observe the behavior of neutrons under conditions similar to what they might find in nature. A calculation without experimental verification was possible, but unreliable. We discussed these technical problems and other details, but after a few days, I decided it was not a job for me.

My stay in Tulsa coincided with the end of the phony war period,

and while I was there I heard that Germany had invaded Belgium and Holland, starting an active offensive war in the west. I remember I was having breakfast when the radio gave the news. I almost choked.

From 1930 to 1946, for over sixteen long years, my youth was dominated by the specter either of war or of political disaster. So much worrying must perforce have influenced my character and made me something of a pessimist. I have never been able to live simply from day to day, and the anticipation of events, which unfortunately often came to pass, and from which I did not know how to, or could not, defend myself, has caused me much suffering. Conflicts born out of such frustrations have embittered me greatly and for a long time.

When I turned down the Tulsa job, Scherbatskoy asked me about Bruno Pontecorvo, who then was in Paris with Joliot-Curie, and I warmly recommended him. The oil-exploration firm, Wells Surveys, then decided to offer him a job and cabled him. Thus Pontecorvo, escaping on a bicycle from Paris, about to fall to the Nazis, and in imminent peril of his life, suddenly found himself with an assured job in America. A true miracle!

My trip on the whole had not been successful. I returned to Berkeley because there I could do good physics and I had not found anything better elsewhere. My situation, however, became increasingly precarious until it took an unexpected turn for the better.

In the summer of 1940, we were visited at Berkeley by the head of the physics department at Purdue University, Karl Lark-Horovitz.^[20] He was of Austrian origin, of a touchy and sullen character that made him many enemies, but at heart a very decent man and a good physicist. At Purdue he had created an excellent physics department and ruled it autocratically, but with good results. He recognized quality in science and helped whoever he thought merited it. When I became acquainted with him, I felt I could openly tell him my personal problems. He invited me to go to Purdue for a limited period. He could not secure a permanent job for me, but thought that even a temporary appointment would greatly improve my position at Berkeley. Thus in the fall of 1940, Elfriede, Claudio, and I took the train for West Lafayette, Indiana. At Purdue, we settled in at Union Hall, which was strongly heated and

extremely dry, so much that in walking on its insulating carpets, one got highly electrified, and I could amuse Claudio by pulling sparks from his nose. I had also prepared some experiments I could easily and rapidly carry out, and I did my best to elicit appreciation for my lectures. LarkHorovitz's plan worked to a fault. Things went well, and I was pleased.

At Berkeley, when they perceived that I was really leaving, Lawrence and the head of the physics department, Raymond T. Birge,^[21] found the money to pay me and wired me with the offer of a lecturership. It was not a tenured position, but it was great progress. I had, more or less, returned to the position with which I had started in 1938, before they knew I could not return to Italy. I asked for a contract with the University of California, not with the Rad Lab, of which I had had enough. I knew that Birge kept his word, whereas Lawrence's intentions and capabilities could change at any time. In any case I would have access to the cyclotron, and I hoped that relations with Lawrence would improve, because having good work done by me in the Rad Lab at no expense to himself, he would be happy and sweet, as indeed happened. Thanks to Lark-Horovitz, I had $300 a month and a much improved position.

My new boss, R. T. Birge, was a very fussy man, a true hair-splitter, and this had served him well, allowing him to ferret out many scientific errors of long standing and greatly to improve our knowledge of universal constants. To better understand his peculiarities, one has to read his history of the physics department at Berkeley.^[22] It reveals his many good qualities, which, all in all, more than made up for his weaknesses. These flaws, on the other hand, are easily recognized reading between the lines. In some respects, he was a narrow-minded man, with prejudices against foreigners, especially Chinese, women, and anyone who spoke with an accent. His perfectionism sometimes caused him to lose sight of what was important and run after minute details. Once I was invited for dinner at his home, with Fermi, Harold Urey, and other important people, all in black tie and the wives in long dresses. A magnificent roast turkey arrived at the table, and Birge, at the head of the table, carved it with perfect art, but it took him almost an hour, and we all felt we had to wait until the end of the carving operation

before we started to eat, so that the turkey on our plates was by then almost cold.

Birge had a lively sense of humor, which I appreciated, and did not mince words, saying forthrightly what he thought, or, rather, often thinking aloud. His comment to a teacher at a summer school was typical. This professor arrived and found that he had been assigned a small classroom that was possibly insufficient. He complained to Birge, who answered, "Let me see; last year Fermi taught this same course, and we had to change classrooms twice, because they were always too small, but for you this one will be sufficient."

As a department head, Birge had some good, clear ideas; for instance, he early realized the great future in store for the Rad Lab, fostered it, and always kept in mind that it was to the reciprocal advantage of the department and of the Rad Lab to cooperate and to avoid fights. Furthermore, in the early years of his career as head of the department, he made excellent appointments, which greatly contributed to Berkeley's later success. He remained head of the department for over twenty years (1933–55), although at the end he lost contact with active research. Nevertheless, for a period after the war, he still managed to exert a beneficial influence with the advice of younger faculty members.

In any case, in 1940, I found myself much better off dealing with Birge than with Lawrence. For this reason I strove to be employed by the university rather than by the Rad Lab. Furthermore, I liked teaching and I much preferred the cultural aspects of physics to the engineering ones, although I operated in both and recognized their interdependence. All told, I was a born professor and felt more at home at the university than in the Rad Lab, and I established good relations with Birge, who, I believe, had a good opinion of me, despite my imperfect English pronunciation.

So much for Birge; I return to my story. From Purdue University, before reverting to Berkeley, I went to visit Fermi at his home in Leonia, New Jersey. At Berkeley in January 1940, he had hardly mentioned nuclear energy release. At Leonia things were different, and we went into it in depth. In very cold weather, we hiked along the

Hudson River, which was dotted with small icebergs. On the bare trees, to my surprise, I saw hanging many used prophylactics; the winter absence of leaves made this strange vegetation conspicuous. Our thoughts, however, were elsewhere. It was expected that U²³⁸ by neutron capture and beta decay would form 94²³⁹ , of which no one knew anything. One could, however, speculate by analogy to U²³⁵ , that this even-odd nucleus might undergo slow neutron fission. If this was the case, 94²³⁹ could perhaps replace U²³⁵ as a nuclear fuel or explosive. It all depended on unpredictable cross sections, decay periods, and the number of neutrons emitted per fission. The prospect was obviously of great importance, but one needed information on this hypothetical isotope.

In a favorable case one might expect an entirely new source of a material fissionable by slow neutrons, independent of the separation of uranium isotopes. Further vistas were immense, including reactors producing the new isotope and its use as a nuclear explosive. On the other hand if the nuclear properties of the new isotope should turn out to be unfavorable, that whole approach would come to nothing. The only way of answering these momentous questions was by direct experiment. One had to make enough of the new substance to measure the desired unknowns. This was possible with the help of the cyclotron. We made several calculations and estimates and found that, with some luck, the plan was feasible. It was imperative to try. Similar ideas also occurred to others, among them Alvarez, L. A. Turner, and Egon Bretscher, but I was unaware of this, and I believe Fermi was too.^[23]

To accumulate sufficient material, one needed a substantial cyclotron bombardment, and since this would commit the machine for some time, we required Lawrence's approval. By chance he was then in New York, and on December 14th, 1940, Fermi, Lawrence, Pegram, and I discussed the matter in Pegram's office at Columbia University. Lawrence immediately gave his assent, and a few days later, I returned to Berkeley and started the work. From the very beginning of 1941, I realized that I could not carry out the work as fast as needed alone, and I asked Seaborg to help.

On January 10, 1941, I wrote to Fermi: "Here I found Lawrence who

had received from Washington (over Abelson's signature!) a letter concerning our experiment and the suggestion to entrust it to Seaborg. We all agreed that it is not a one-man job, and thus Seaborg and I will carry it on, except that (with Lawrence's concurrence) we will bring in somebody else to help if necessary." Those brought in were J. W. Kennedy, a recent Ph.D., with whom we had previously worked on isomerism, and A. C. Wahl, a graduate student.

Kennedy was a Texan of Irish ancestry, lively, intelligent, very shrewd, and utterly honest. He was a year or two junior to Seaborg, who had introduced him to radiochemistry and collaborated with him on several investigations of radioactive isotopes. Slowly I found out that it was easier to deal with him than with Seaborg. Kennedy's openness inspired confidence, whereas I came to feel that Seaborg had secret personal plans. Kennedy and I noted the unparalleled documentation he was accumulating, way beyond what was needed for current work, with a mixture of admiration and puzzlement.^[24]

Seaborg also made every effort to acquire and maintain strict control over our group's communications with the outside world. In this he was helped by the difficulties I had as an alien, by my uncertain position, and above all by my meager ability in public relations, as well as by Kennedy's junior status. As time went by, Kennedy and I, alarmed by what we saw, ended by associating very closely in self-defense.

At the time, Arthur Wahl was a rather innocent student, out of rural Iowa, and ignorant of the world. At least at the beginning, he was strongly influenced by Seaborg. He was a thoroughly good and honorable fellow, but too inexpert and ingenuous to understand the game he was being drawn into. Later he opened his eyes, associated strictly with Kennedy, and came to Los Alamos with him. After the war, Wahl, together with other Berkeley chemists who had originally been students or collaborators of Seaborg's but were averse to further ties with him, went to Washington University in St. Louis, Missouri, which had appointed Kennedy as head of a revitalized chemistry department.

The history given by several of the published documents pertinent to that period is not always complete, and there are occasional disagreements.^[25] The authors wrote under the demands of secrecy regu-

lations, patent requirements, and the wish to protect their own personal scientific claims to the utmost. Thus there are occasional disagreements. The possibility of Nobel Prizes being awarded did not simplify matters.

I give here some chronological points: in June 1940 McMillan bombarded uranium with deuterons and by chemical methods he and Abelson had previously devised, separated from it a beta activity due to neptunium and let it decay. After the beta activity had decayed, he found that the residue emitted alpha particles, possibly due to element 94.

In December of 1940, after McMillan had left Berkeley to go to radar work, Seaborg, Kennedy, and Wahl, with McMillan's agreement, started work on deuteron-bombarded uranium. In their bombardment, they obtained a mixture of several isotopes of 93, and this multiplicity of isotopes complicated further work. The beta activities of element 93 decayed, leaving alpha active residues, most likely due to element 94. Some preliminary chemical trials showed that the alpha activity could be chemically separated from most elements. I believe that this was all that was known at the beginning of our common work.

The primary purpose of the investigation by Kennedy, Seaborg, and myself was to measure the fission cross section of Pu²³⁹ . In order to obtain an isotopically pure sample of this substance, it was best to bombard uranium with slow neutrons. Those gave results that were easier to interpret and also gave larger amounts of Pu²³⁹ than those obtainable by deuteron bombardments.^[26]

At the beginning of our work, we simply chemically separated neptunium from bombarded uranium, using a rare earth carrier, and let it decay. The samples thus obtained, however, were too thick for accurate investigations of alpha and fission processes.

In the meantime, Kennedy, Seaborg, and Wahl continued developing the chemistry of plutonium and its separation from neptunium, but they did not tell me their reagents, having received orders to be prudent with an alien. It took until the end of February 1941 before Wahl found a clean way of oxidizing 94 to various valence states. By then Kennedy, Seaborg, and I already had samples of Pu²³⁹ , co-precipitated with cerium fluoride, in relatively thick layers.

Around March 1, 1941, we performed a big neutron bombardment of uranium to prepare a substantial sample of pu²³⁹ . It was a dangerous operation considering the large amount and the explosiveness of the ether we used, as well as the radioactivity of the bombarded uranium and its fission products. Everything went well, however, and we survived to tell the tale. A first thick sample was ready by April for first rough measurements. In May the sample was thinned by Wahl, using the separation methods he had developed, to a total weight of about 200 micrograms (almost totally rare earth carrier), and we got accurate results.

We all worked on all phases of the investigations, but Wahl performed the bulk of the microchemical operations (I performed some chemical separations without knowing the reagents I was given!). Kennedy, Seaborg, and I performed the bulk of the physical measurements. In the following months, Wahl further developed the chemistry of neptunium and plutonium and laid the foundation for much of the later work,

We inferred the mass of 94 we had in our sample from the measured beta activity and the half-life of its mother substance, 93. From the mass of 94 and its alpha activity, we calculated its decay period. For the slow neutron fission cross section, direct comparison with a known uranium sample in the same neutron flux gave the best results. From all this substantial work, we gathered, by May 1941, that the slow neutron fission cross section of 94²³⁹ was about equal to that of U²³⁵ , and its decay period about twenty-five thousand years. Later measurements confirmed all these data. About May 25, 1941, Seaborg, Kennedy, Lawrence, and I signed a letter to Dr. Lyman J. Briggs, chairman of the government's Advisory Committee on Uranium, reporting these results.

We had thus gathered information of capital practical importance, demonstrating the feasibility of using 94²³⁹ as a nuclear fuel or explosive, and we had opened up a new way of tapping nuclear energy, avoiding the need for isotope separation. We fully realized the importance of our results, and Kennedy, Seaborg, Wahl, and I wrote a letter to the Physical Review reporting them. In compliance with the policy of vol-

untary secrecy then prevailing for results of possible military importance, however, we requested that publication be withheld until better times, and the report eventually appeared only in 1946.^[27]

In spite of Lawrence's concurrence, at the beginning of our experiments it had been difficult even to obtain the necessary uranium. I had to write to Fermi at Columbia University asking for it. In a letter of January 11, 1941, I wrote him. "For the uranium work, Cooksey, who holds the purse strings, is not very lavish. It would be most useful if you could send us 5 kg of pure uranyl nitrate. Please let me know if there is any way of getting some money to buy the ether and several vessels for the first extraction after the bombardment. Such difficulties may slow us down." The government had no part in this phase of our work. It woke up after the facts, in June 1941, and asked us to file a secret patent application. We complied, to our advantage, as we shall see in due course.

I do not know to what extent Lawrence initially realized the importance of our findings, although he had helped, indirectly, in obtaining them. I tried to discuss them with him, but I doubt he appreciated the weight of their implications. He told me to talk to his friend Alfred Loomis, a multimillionaire banker and amateur physicist of great intelligence who was visiting the Rad Lab.^[28] I hesitated because of security, but Lawrence reassured me by saying that Loomis was cleared for every technical secret concerning defense, and that furthermore he was a cousin and close friend of Secretary of War Henry Stimson's. Loomis understood everything I told him promptly and completely. I believe he helped to open Lawrence's eyes, although it is possible that Lawrence had fully grasped what I told him, and simply wanted Loomis to hear the news directly from the horse's mouth.

It was in this period that Kennedy and I, surprised and confused by some of the occurrences during our work, opened up to each other. We talked at length while walking around the physics building innumerable times.

Lawrence wanted a clean and correct situation and did not care much about personalities. His position is shown in a letter dated May 31, 1946, to Harold Urey, in which he wrote: "Sometime ! should like to talk

to you about this whole business [of transuranics], as I think that the work of Abelson, McMillan, Seaborg, Segrè, Wahl and Kennedy should be recognized some day in Nobel awards; perhaps the Nobel Prize in Physics to McMillan and Abelson and another one in Chemistry to Seaborg and associates. At any rate sometime I should like to get your ideas and opinions along this line." There were also other forces at play, including G. N. Lewis, the famous Berkeley chemico-physicist, a commanding authority in the chemistry department, and above all Professor W. M. Latimer, who was well known for his xenophobia and anti-Semitism. They communicated with Seaborg only, and naturally they were inclined to accept whatever they heard from him.

Seaborg used his uncommon organizing talents to foster the plutonium study. He enlisted in his operation all the chemistry graduate students he could contact, hiring young chemists left and right and planning large-scale investigations. In short, he was busy building an empire. If I compare this operation to that of other emperors I have known: Lawrence and Fermi (absit iniuria verbo), I immediately perceive a great difference. Lawrence was the chief of a great enterprise he had created from scratch, and he identified himself with the Rad Lab and its successes. He was devoid of jealousy and generous in attributing credit. Although no more than a mediocre scientist himself, he perhaps mildly looked down on his fellow scientists and their squabbles, which he disliked. He justly felt that their successes, if obtained in the Rad Lab, would always extend to him too.

Fermi, a very great scientist, was primarily interested in physics and did not especially like administrative work. He was perfectly honest, open, and scientifically generous, as befits one who had so much to give. He was emperor because subjects and equals in rank recognized him as such, and as such trusted and liked him. Seaborg, a great organizer, and a man of exceptional stamina and capacity for work, but not an exceptional scientist, had unbridled personal ambitions and was determined to get ahead by any means. The simplest was to hire a great number of young collaborators who could not overshadow him, and to take a small part of the credit for their work. Many of these students later had distinguished careers of their own (a very incomplete list of

them might include Jack Gofman, Fred Leitz, Ray Stoughton, Morris and Isidor Perlman, Gerhart Friedländer, René J. Prestwood, S.G. English, and Stanley G. Thompson). Taking 10 percent of the work and reputation from each of fifty young men, he could become deservedly famous. The method had been previously used on a large scale by illustrious organic chemists, and similar methods now prevail in large physics collaborations.

What was unusual in Seaborg was the long-term planning he diligently applied to everything. In 1941 he would say: in 1946 I shall be a dean; in 1948, chancellor of the University of California; in 1955, senator for California, and so on, and he never lost sight of his aims. In 1938 he always dressed in a blue suit, with a tie, differently from his colleagues, because he thought that these clothes would help him become a full professor, a small first step in the grand design. Ultimately, he devoted much effort to public service as chairman of the Atomic Energy Commission and many other organizations, receiving more than fifty honorary degrees and collecting pictures of himself with a number of presidents of the United States and other such figures.

Seaborg's designs were fostered by his marriage to Helen Griggs, Lawrence's secretary, an attractive young woman, superior in her profession. She may have helped him by giving him access to documents she controlled. Some disappeared from Lawrence's files when Seaborg and his wife transferred to Chicago in 1942. Some were particularly important to Kennedy and me because they contained data on the plutonium work. Kennedy, alarmed, guessed where they might be and asked Lawrence to enquire from his former secretary whether she had taken them to Chicago in error. The documents were promptly returned, with apologies for the mistake. In the process, however, the original documents had suffered some alterations. In the letter on the discovery of 94²³⁹ , some of the names under the document had been cut out. When I complained to Gregory Breit, the secretary of the Advisory Committee on Uranium, he answered in a letter dated October 26, 1942:

I have your letter of October 17th. It is indeed true that your letter to Dr. Briggs written jointly with Seaborg, Kennedy and Lawrence is in the

official files of the Reference Committee on Nuclear Physics and Isotopes and that it has been circulated as Report A-33. The report is registered for publication in the Physical Review .

In circulating the contents as a report, it has been thought advisable to omit your and Kennedy's names. This was purely a formality concerning the report and not the authorship of the paper in the Physical Review . At the time the matter of clearance was a difficulty and the letter was transmitted to the NDRC in fulfillment of financial obligations as a report from the official investigators at Berkeley. I should like to assure you, however, that so far as the Physical Review is concerned the authorship of the communication has not been changed. It is in fact largely for this reason that the original letter has been transferred to the files of the Reference Committee.

The authorship of this communication is kept secret for the duration of the emergency so as not to disseminate information regarding who is concerned with important work in the section.

This curious letter hardly explains the matter.

At the beginning of 1941, I found it advantageous to buy a house rather than to continue renting. I was able to use family money for the purpose, and for about $8,000 I bought a house at 1617 Spruce Street in Berkeley, about fifteen minutes' walk from the campus. It was a great improvement on our previous house and had a garden with apricot and apple trees, in which we were able to grow excellent vegetables and flowers (although my heart was not in gardening). Our immediate neighbors Were Dean Mulford of the School of Forestry and his wife, who were a good deal older than we were. Mrs. Mulford once told us that the FBI had gone to them asking about us; she resented the intrusion, but had given them a glowing report.

On Sunday, December 7, 1941, I was working in the garden when I heard over the radio of the bombing of Pearl Harbor. We were surprised by the fact in itself and by the unpreparedness of the United States. We realized at once that the losses were serious, but a few days later we heard President Roosevelt detailing the construction programs by which he intended to repair the blow. I remember I thought they were like Mussolini's humbug, and that it would never be possible to build so many ships, airplanes, tanks, and so on, in the time allotted by the

president. I was wrong, and actually the goals were surpassed. Even after living three years in the United States, I underestimated its industrial potential and what it could accomplish once mobilized.

The reaction to the attack was strong and even hysterical, as in the deportation of Axis citizens. The Italian declaration of war on the United States, which followed at once, interrupted direct communications with my parents. Our letter #129 was returned to sender with a stamp indicating the suspension of service. It was a great sorrow to us, but little compared with the tragedies that were engulfing the world.

The Pearl Harbor attack immediately unified a country that seemed still divided, full of isolationists and of friends of peace at any cost. The effect on the Rad Lab was equally radical. Lawrence woke up to the possibility of nuclear weapons and devoted himself and the Lab to the separation of uranium isotopes, which he decided to do by means of colossal mass spectrographs. Typically, he chose the most direct and "brute force" method and pursued it with indomitable energy. He used the magnet of the 37-inch cyclotron for a model mass spectrograph and started studying it. The 60-inch cyclotron was left intact because it was needed for other programs, especially studies on transuranics, but the magnet of the 184-inch cyclotron, which was under construction, was converted to mass spectrography too.

In all this frenzied activity, one obtained currents depositing uranium ions into suitable receptacles. The hope was that isotopes would be separated according to plan, but initially there was no isotopic analysis of the product. I believed it was imperative to set up an adequate analytical method to know what was happening. I found a solution to this problem by weighing a sample, measuring its alpha activity, and measuring its fission cross section for slow neutrons. Crudely speaking, the mass gives the amount of U²³⁸ , the alpha activity that of U²³⁴ , and the fission cross section that of U²³⁵ . I thus organized an analytical lab, with Lawrence's enthusiastic encouragement and support. Kennedy and several graduate students, who were immediately hired by the Rad Lab, joined in this enterprise.^[29] Unemployment among physicists was by now on the wane.

One day I was trying to build a power supply for an electronic

apparatus on my own. A student started looking at me, and after a while, with a half-disgusted expression, asked whether he could help me. I was happy to accept, and within half an hour he provided me with a much better power supply than I could ever have made. The student was Clyde Wiegand, and this started a collaboration and friendship that lasted for the rest of our careers.

With the entry of the United States into the war, the migration of physicists to war work, which had started long before Pearl Harbor, greatly increased. Alvarez, McMillan, Jenkins, Brode, and others joined war projects under way elsewhere and left Berkeley. At the same time the university was swamped by students undergoing military training who needed accelerated physics instruction. In this emergency, Birge asked me to teach some "peace" physics courses to the few regular students who were left. I eagerly accepted the assignment because I liked teaching and because I thought it might help me to win a permanent position. The salary too was slightly higher than what I had been receiving up to then. Thus I found myself teaching various branches of physics at an upper division or graduate level: physical optics, quantum mechanics, spectroscopy, thermodynamics, atomic physics. I knew the subjects adequately from experience, and I did reasonably well, acquiring much credit.

In one of the optics courses there was a student who amused himself in finding flaws in the lectures. His objections, always polite, were often well taken and showed a critical and alert mind. I appreciated the young man, who obviously was interested in the course and used his head, and I made friends with him. He was Owen Chamberlain, the son of an eminent radiologist. I must likewise have impressed him favorably, because he became my graduate student and remained my associate for many years.

The outbreak of war between the United States and Italy made me an "enemy alien," and soon the government decreed that enemy aliens must leave the Pacific Coast—first the Japanese, then the Germans, and lastly the Italians. If they did not go voluntarily, they were to be rounded up in relocation camps. In the meantime, they must register, obey a curfew, and surrender their radios and arms. The government started

executing these orders by deporting the Japanese. The action proved unnecessary, cruel, and of dubious motive, since it turned out that there were interests that profited by buying up the property of the internees at ruinous prices. Fortunately, after the experience with the Japanese, the government regained its senses and left the Germans and the Italians alone. I was, however, justly alarmed. I found myself in the ridiculous situation of being privy to information so secret and important that the government kept it even from its own high military authorities and from the Congress, but I could not take a walk after sundown or go to the movies in the evening. Of course, under different regimes such contradictions might have been cured by fatal methods. . . .

I spoke to Lawrence about this situation and asked for his help. He answered me that he could do nothing; that laws were laws and must be obeyed, and dropped the subject; however many years later I saw correspondence showing that he had tried hard to protect me. I do not know why he did not tell me then.

In the meantime, I consulted with Elfriede on what to do. I took an atlas, Lo Surdo's wedding present, studied it a little, and then said: "If the government is serious about deporting us, we shall go here to await the end of the war"—and I put my finger on Santa Fe, New Mexico. "It is an isolated place, far from the coast, it has a good climate, and life should be cheap there." Within two years we were indeed there, but the reason—the creation of the Los Alamos Laboratory—was then totally unforeseeable. While the country was mobilizing, strange episodes occurred at the university. One day a gentleman arrived at the Faculty Club and asked to be introduced to several physicists and chemists. It seemed he wanted to know what was going on in some laboratories, and he struck up a conversation with me. He then followed me to my lab, always talking. With utmost politeness, I offered him a chair, oriented in such a way that he could not see anything of interest. He then asked me many questions about uranium, and I became even more suspicious. I answered him, always courteously, but being careful not to give any information not available in common books, and usually telling him the book where he could find greater details. I then came to speak about the deportation orders then in force, and since he had

told me he was a government lawyer working for the Immigration Department, I advocated my case, of course without hinting at the nature of my current work. After he left, I reflected on the whole performance. The more I considered it, the more suspicious it looked to me. I concluded that the man was either a spy or an agent of counterintelligence. I therefore went to Cooksey and told him of the strange visit, urging him to report it to the FBI. In my opinion, if the man was a spy, they would catch him; if he was in counterintelligence, we would come out looking alert and diligent. In any case, there was nothing to lose. Unfortunately, Cooksey did not follow my suggestion.

About two weeks later, the same gentleman reappeared, this time in the uniform of a lieutenant colonel, and summoned the Rad Lab's scientific personnel. He told us that he had come earlier on an inspection tour in disguise to see how we kept security. On the whole he had been pleased, but he had a criticism: somebody should have reported him, because his behavior should have looked suspicious. At this, Cooksey, like the true gentleman he was, rose and said: "It is my fault, because Segrè suggested it to me." The colonel's name was John Lansdale, Jr.; he had later important assignments and testified in the Oppenheimer case.

My encounter with Colonel Lansdale had a sequel years later, when I was at Los Alamos. Riccardo Rimini was then in Uruguay, where he was practicing medicine, and I sent him a reprint of an article I had written on new chemical elements.^[30] When we moved to Los Alamos, we were allowed to give our new address—Post Office Box 1663, Santa Fe, NM—to all our correspondents, and I had sent it to him. One day, at Los Alamos, I received a letter from Riccardo, saying, approximately: "I have received your reprint, which I found most interesting. I am pleased that you will be continuing your old type of work. Do not fail to keep me informed of any progress." A few days later Colonel Lansdale appeared in my office and asked: "Have you received a letter from Uruguay, saying such and such?" He obviously had a translation of the letter that had been intercepted by a censor. "Yes," I answered. "Doesn't it look strange to you?" he said. "Yes, but I can explain it to you; here is a copy of the reprint." I also told him the identity of the

sender of the letter, told him that Riccardo was an Italian refugee and a known anti-Fascist, which it would be easy for him to check through the U.S. consulate in Montevideo. I learned later that Lansdale had first spoken to Oppenheimer, who told him that he could not enlighten him, and that he had better ask me himself. The matter ended there as far as I know.

In February 1942, I received a letter from Fermi hinting at the possibility of my going to Chicago to direct the plutonium work there. I think there may have been difficulties because of my "enemy alien" status, but Fermi was in the same condition and the difficulties had been overcome. However, the two cases were somewhat different: Fermi was indispensable in the full sense of the word, and I was not. It seems, however, that Seaborg had his own ambitions. A. H. Compton, chief of all the Chicago operations, had sent Norman Hilberry, his trusted agent, to Berkeley to recruit me. He arrived at 7 A.M. on March 22, 1942, and to his surprise found Seaborg waiting for him at the station. Hilberry talked with Seaborg, Kennedy, Wahl, and other chemists, but did not see me, and I did not even know he was in town. Hilberry ended by recruiting Seaborg, after having talked to Kennedy and Wahl, who told him that they would not go to Chicago if Seaborg was to be in charge there. With some surprise, I learned all this from Hilberry in 1967 on the twenty-fifth anniversary of the Chicago chain reaction.

Seaborg's departure cleared the air at Berkeley; with Kennedy the work proceeded without tension. On the other hand we found ourselves shifted to problems of less scientific interest, because many of those scientifically interesting and practically important for the making of the atomic bomb had migrated to Chicago, where Seaborg formed a powerful organization that tended to monopolize transuranic elements. It lasted several years and produced valid scientific results as well as strong feelings among his colleagues.

At Berkeley we started systematic studies on spontaneous fission of heavy nuclei, which was also of practical importance. It was expected, but it was difficult to see because it was very rare in the nuclei then known. To observe such rare events, we had to take precautions against spurious signals, considering even fairly unlikely causes. Hence we

needed a particularly isolated and quiet laboratory. We first set up shop in a semi-abandoned shack belonging to the university; later in a building on a small alley in Berkeley. The work did not give important results until many months later, when we had moved to Los Alamos. Kennedy, and some chemists, Morris Perlman, Gerhart Friedländer, and Milton Kahn among them, participated in this work. Wiegand strived to perfect the electronics. On the occasion we radically improved the ionization chambers by learning how to collect electrons and not positive ions. This trick substantially increased the resolving power of the chambers.

At about that time, John Manley, a physicist I knew from my visits at Columbia University, became the secretary of a group studying the building of an atomic bomb. Gregory Breit had previously been the head of the group, but although a first-class theoretical physicist, with many accomplishments to his credit, he had weaknesses, such as an obsession with security, that seriously interfered with his performance, and he was replaced with Oppenheimer.

During the summer of 1942, a theoretical group under Oppenheimer's direction met in Berkeley to try to design a nuclear bomb. Hans Bethe, Robert Serber, Edward Teller, E. J. Konopinski, and two younger physicists, Stanley Fraenkel and Eldred Nelson, worked on this project. As they proceeded in their calculations, they needed more and more experimental data that had not been measured, and we tried to help them out as much as possible. To proceed with a concrete plan for a bomb, it was necessary to know, among other things, the fission cross section of uranium, as well as many other cross sections, as a function of neutron energy. At the time such data were few and unreliable. It was hard to obtain monoenergetic neutrons of known energy between a fraction of an eV and a couple of MeV. Some specific energies could be reached using photoneutrons. Chamberlain, Wiegand, some other students, and I used photoneutrons generated by gamma rays of Na²⁴ on beryllium or deuterium. During these experiments we had a nasty accident when Chamberlain dropped a strongly radioactive solution of radiosodium. He was seriously irradiated and his blood showed sufficient alterations to require a vacation.

In the meantime, as has been described in several books,^[31] the government had assumed control of the atomic bomb project through a series of often changed supervisory committees. The military took a leading role in September 1942, with the creation of the Manhattan District, headed by Brigadier General L. R. Groves. In November 1942 the need for a special lab devoted to bomb construction became irresistible. Oppenheimer was designated as its director, and he and others chose the Los Alamos site.

Oppenheimer asked me to join the new lab, to be created shortly. He became unusually friendly and invited me and Elfriede to dinner at his home high in the Berkeley Hills, a house built in an austere Spanish style, named Eagle Nest. I found him reading Petrarch's sonnets in Italian, and he fed us chicken livers and wild rice, which were excellent; we had never before savored wild rice. Concerning Petrarch's sonnets, I am afraid I did not hide my suspicion that he did not understand them. I remembered the story of a Count C. in Tivoli, who was illiterate, but always went to Mass with his breviary. "Sir, why do you read upside down?" he was asked by a lawyer. To which the count answered: "When one knows how to read, it does not make much difference which way one holds the book." I believe that during the course of the evening I told this story to Oppenheimer. Subsequent to this invitation, I received a small lemon tree from Oppenheimer as a gift. I planted it in our garden, and it was always called Oppenheimer's lemon, but unfortunately, after the war, it died.

I had no choice about going to Los Alamos. War work was a duty to the United States that I felt strongly about, and once one was asked, it was impossible to refuse.^[32] In fact, whenever somebody employed in industry or at a university was asked to come to Los Alamos, a telephone call with a few appropriate words and hints sufficed to enlist the candidate, and he arrived on the spot within days. In my specific case I felt doubly obligated to help a country that had received me in particularly trying circumstances. In addition to this, the hope of being able to contribute to Hitler's undoing and to a victorious conclusion of the war appealed to me greatly.

Having agreed to go to Los Alamos, I had to think about personnel

and instruments. For the latter, we would take with us some equipment from Berkeley, but we would build on the spot most of what we needed, according to the problems encountered. For the personnel, I thought of creating a group of physicists strictly connected to the chemists. Kennedy had been asked to head the chemistry division of the lab, and I was sure that we would have a smooth collaboration. It was not known who would be the leader of the physics division. Manley was a plausible candidate, most agreeable to me. For my own group I had my old students and under prevailing conditions, it was easy to enlist them. Chamberlain, Wiegand, George Farwell, and G. A. Linenberger formed the basic nucleus. The chemists Milton Kahn and John Miskel joined us at once. Kahn's wife became the secretary of our group.

On November 9, 1942, our first daughter was born. We called her Amelia Gertrude Allegra; the first two names honored her two grandmothers, the last was a wish for her life. I do not remember how we communicated the news to my parents, but we managed somehow, and my mother registered the name in a small genealogical tree she had compiled.