The Making of the Atomic Bomb

lanthanum. It apparently did not occur to them that what was crystallizing out of solution might be another activity with a similar half-life, leaving a 3.5-hour lanthanum activity behind. They still could not believe — nor could anyone else — that uranium bombardment might produce an element thirty-five steps away down the periodic table. A Canadian radiochemist then visiting Dahlem records their German critic's response: “You can readily imagine Hahn's astonishment… His reaction was that it just could not be, and that Curie and Savitch were very muddled up.”

Despite his threat to Joliot in May, Hahn had not yet repeated the Curie-Savitch work. Now he passed the Comptes Rendus along to Fritz Strassmann. Strassmann studied the French paper and speculated that the muddle might have a physical cause — two similar radioactivities mixed together in the same solution. He told Hahn. Hahn laughed; the conclusion seemed improbable. On second thought, it was worth examining. As the Czechoslovakian crisis broke across Europe the two men bombarded uranium in peaceful Dahlem. They used a lanthanum carrier to precipitate rare-earth elements such as actinium (if any), a barium carrier to precipitate alkaline-earth elements such as radium (if any). (Carrier chemicals made it possible to separate from the parent solution the few thousand atoms of daughter substances produced by neutron bombardment. A chemically similar daughter substance, traceable by its unique half-life, would lodge in the spaces of the carrier's crystals as those regular solids formed from solution by chemical precipitation and would thus be carried away. Which carrier accomplished the carrying gave a clue to the part of the periodic table to which the unknown daughter substance belonged. Then it became a matter of further separating the daughter substance from the carrier by fractional crystallization, following it as before by tracing its characteristic radioactivity.)

After a hard week's work Hahn and Strassmann succeeded in identifying no fewer than sixteen different activities. Their barium separations gave them their most startling results: three previously unknown isotopes which they believed to be radium. They reported their findings in November in Naturwissenschaften. The creation of radium, element 88, from uranium, they pointed out, “must be due to the emission of two successive alpha particles.”

If the physicists had found it hard to swallow that slow-neutron bombardment might produce thorium (90) or actinium (89), they found it even harder to swallow that it might produce radium. Lise Meitner wrote in warning from Stockholm suggesting pointedly that the two chemists check and recheck their results. Bohr invited Hahn to Copenhagen to lecture on the strange findings and tried to concoct a sufficiently crazy explanation:

Bohr was skeptical and asked me if it was not highly improbable… I had to reply that there was no other explanation, for our artificial radium could be separated only with weighable quantities of barium as carrier- substance. So apart from the radium only barium was present, and it was out of the question that it was anything but radium. Bohr suggested that these new radium isotopes of ours might perhaps in the end turn out to be strange transuranic elements.

Of the sixteen activities they had identified in neutron-bombarded uranium Hahn and Strassmann therefore now turned their full attention to the three controversial activities carried out of solution by barium.

Laura Fermi woke to the telephone early on the morning of November 10. A call would be placed from Stockholm, the operator advised her. Professor Fermi could expect it that evening at six.

Instantly awake to his wife's message, Fermi estimated the probability at 90 percent that the call would announce his Nobel Prize. As always he had planned conservatively, not counting on the award. The Fermis had prepared to leave for the United States from Italy shortly after the first of the year. Ostensibly Fermi was to lecture at Columbia for seven months and then return. For stays of longer than six months the United States required immigrant rather than tourist visas, and because Fermi was an academic he and his family could be granted such visas outside the Italian quota list. The ruse of a lecture series was devised to evade a drastic penalty: citizens leaving Italy permanently could take only the equivalent of fifty dollars with them out of the country. But the plan required circumspection. The Fermis could not sell their household goods or entirely empty their savings account without risking discovery. So the money from the Nobel Prize would be a godsend.

In the meantime they invested surreptitiously in what Fermi called “the refugee's trousseau.” Laura's new coat was beaver and they distracted themselves on the day of the Stockholm call shopping for expensive watches. Diamonds, which had to be registered, they chose not to risk.

Near six o'clock the phone rang. It was Ginestra Amaldi wondering if they had heard. Everyone had gathered at the Amaldis to wait for the call, she reported. The Fermis turned on the six o'clock news. Laura long remembered the news:

Hard, emphatic, pitiless, the commentator's voice read the second set of racial laws. The laws issued that day limited the activities and the civil status of the Jews. Their children were excluded from public schools. Jewish teachers were dismissed. Jewish lawyers, physicians, and other professionals could practice for Jewish clients only. Many Jewish firms were dissolved. “Aryan” servants were not allowed to work for Jews or to live in their homes. Jews were to be deprived of full citizenship rights, and their passports would be withdrawn.

The passports of Jews had already been marked. Fermi had contrived to keep his wife's passport clear.

They probably heard the news from Germany as well: of a vast pogrom the previous night — Kristallnacht, the night of glass. A seventeen-year-old Polish Jewish student had attempted to assassinate Ernst vom Rath, third secretary in the Germany Embassy in Paris, on November 7, in reprisal for Polish mistreatment of the student's parents. Vom Rath died on November 9 and the assassination served as an excuse for general anti-Semitic riot. Mobs torched synagogues, destroyed businesses and stores, dragged Jewish families from their homes and beat them in the streets. At least one hundred people died. A volume of plate glass was shattered that night across the Third Reich equal to half the annual production of its original Belgian sources. The SS arrested some thirty thousand Jewish men — “especially rich ones,” its order had specified — and packed them into the concentration camps at Buchenwald, Dachau and Sachsenhausen, from which they could be ransomed only at the price of immediate pauperized emigration.

Fermi took the Stockholm call. The Nobel Prize, undivided, would be awarded for “your discovery of new radioactive substances belonging to the entire race of elements and for the discovery you made in the course of this work of the selective power of slow neutrons.” In security the Fermis could leave the madness behind.

Lise Meitner had written Otto Hahn of her worries a few days before the Fermis arrived. “Most of the time I feel like a wind-up doll running on automatic,” she told her old friend, “smiling along happily and empty of real life. From that you can judge for yourself how productive my efforts are at work. And still in the end I'm thankful for it because it forces me to keep my thoughts together, which isn't always easy.” She was sorry Harm's rheumatism had returned and was afraid he wasn't taking care of himself; she asked after Planck and von Laue by their private Hahn-Meitner nicknames, Max Sr. and Max Jr.; she greeted Hahn's wife, Edith, and wondered what Christmas plans he had for his son. His uranium work was “really very interesting.” She hoped he would write again soon.

She was living in a small hotel room — there was hardly space to unpack — and having trouble sleeping. People told her she was too thin. Worse, conditions at the Physical Institute were not what she had expected them to be. A Swedish friend, Eva von Bahr-Bergius, a physicist she knew from Berlin who had been a lecturer at the University of Uppsala, had helped with arrangements and was gradually breaking the bad news. Manne Siegbahn had not wanted to take Meitner on. He had no money for her, he had complained; he could give her a place to work but no more. Von Bahr-Bergius had pursued the Nobel Foundation grant. But it provided nothing for equipment or assistance. Meitner blamed herself: “Of course it's my fault; I should have prepared much better and much earlier for my leaving, should at least have had drawings made of the most important apparatus [she would need].”

She was a strong woman, but she was miserable and alone. Hahn responded with sympathy. At midmonth she thanked him for that “dear letter,” then changed moods and charged him with indifference: “Concerning myself I sometimes suspect you don't understand my way of thinking… Right now I really don't know if anyone cares about my affairs at all or if they will ever be taken care of.”

Hahn was pursuing Meitner's affairs as well as his own. With her moody letter at hand he stormed down to the revenue office, which was responsible for inventorying her furniture and other property before allowing its release, and laid on what he called “a little seizure of my ‘ecstasy,’” after which “the matter went somewhat better.” That news he wrote to Meitner on Monday evening, December 19, from the KWI. Only then did he report why he had not yet left the laboratory: