CHAPTER TWO

ROME

“CLEAR THE WAY; LOOK OUT,” shouted Enrico Fermi as he exited his laboratory clutching an irradiated sample of aluminum, and sprinted to a Geiger counter in a lab down the hall. It was winter 1934. Fermi, a physics professor at the University of Rome, was attempting some modern-day alchemy, bombarding samples of aluminum and other non-radioactive atoms with neutrons, trying to turn them radioactive.

The radiation would last just a short while, often less than a minute. To make certain that errant neutrons didn’t contaminate the results, he placed the neutron source and the Geiger counter that measured the intensity of the radiation at opposite ends of the building. Thus, the 33-year-old Fermi and his post-graduate students racing down the hall like crazed schoolboys became a familiar sight all during that winter, spring and fall. 9 Fermi prided himself on his fleetness of foot and his ability to out-run, out-hike and out-swim his young associates. 10

These were exciting times for Fermi and his “boys,” as they were called. Scientific understanding of radiation and atomic structure had advanced dramatically over the past decades, and the recent discovery of neutrons promised to open the atom’s nucleus to still greater exploration.

The inspiration for Fermi’s experiment came from two French scientists who had bombarded atoms with positively charged particles. Their choice of ammunition, however, had one drawback. Atomic nuclei have a positively charged outer barrier that repels positively charged particles. Their experiments could only induce radiation in lighter atoms, those with weaker barriers. 11 Fermi reasoned that neutrons, which have no electric charge, could penetrate even the strongest defenses.

In preparation for their experiment, Fermi’s associates visited Mr. Troccoli, owner of Rome’s largest chemical supply store. There, they purchased samples of aluminum, carbon, platinum, gold and other elements, some 60 in all. 12 Back in the lab, they began the tedious process of irradiating each sample. One by one, they wrapped them around a glass tube containing a source that spewed out thousands of neutrons a second and then placed the whole in a lead-lined box. 13 If all went according to theory, some of the unguided neutron missiles would penetrate atoms within the sample and be absorbed into their nuclei. The nuclei would become unstable, begin to decay and emit radiation.

By the fall of ’34 Fermi and his “boys” had induced radiation in 40 different atoms, far exceeding the successes of the French scientists. Thanks to Fermi and his neutron missiles, the nucleus, a tiny speck of mass floating in the atom’s vast inner space, was now open for exploration.

For their final test Fermi and colleagues targeted uranium. Uranium was naturally radioactive, so no one was certain how it would react, if at all. To find out, they followed the bombardment with a chemical analysis. But instead of producing clarity, the tests left the Italian explorers scratching their heads.

Scientists classify atoms according to the number of protons and neutrons in their nuclei. An atom with one proton is hydrogen; two protons, helium; 29 protons, copper; 92 protons, uranium. After analyzing the test results, Fermi was surprised to find that nuclei that had once contained 92 protons now contained 93. The bombarded atoms had undergone a chemical makeover. No longer uranium, they had been transformed into a heavier “transuranic” atom. If the results were accurate (Fermi wanted to do more testing to make sure), he was the first scientist ever to manufacture a brand new atom, an atom unlike any other on planet earth.

Treading cautiously, Fermi and his associates co-authored a paper reporting that the evidence “ suggests the possibility” that a new element had been created. 14 A short while later, without consulting Fermi, his boss, the director of the Physics Institute at the University of Rome, announced unequivocally that Fermi had manufactured a new atom. The world’s press took notice. The New York Times trumpeted Fermi’s achievement with the headline “Italian Produces 93rd Element by Bombarding Uranium.” 15

FERMI HAD PIONEERED THE USE of neutrons as vehicles for nuclear exploration. Some speculated they might lead to the wellspring of atomic energy. But, as quickly as the speculation surfaced, it was shot down. The Nobel laureate Ernest Rutherford called the idea “moonshine”.

Albert Einstein concurred, saying that using neutron bombardment to harness atomic energy would be like “shooting in the dark at scarce birds.” Despite the naysayers, it was clear that something strange and exciting was going on within the nuclei of bombarded atoms. And the surprises kept coming.

In October 1934, Fermi was on his way back from a lecture tour in South America, when his colleagues telegrammed him that something was wrong. The intensity of the artificial radioactivity seemed to vary from experiment to experiment. Fermi had just delivered an important lecture describing their experiments. He was not pleased, and he let his young associates know it.

While Fermi was away, they had bombarded aluminum in the lead-lined box and then tried to verify the results by repeating the experiment. To their dismay the two experiments produced different results. The divergent findings meant that their months of work were now in question. Determined to find out what was going on, they designed a new test. In one experiment, they placed an aluminum sample and neutron source in a corner of the box; in a second experiment, they placed it in the center. To their surprise, they got different results. Similarly, an experiment conducted on a wooden table turned out differently than the same experiment laid out on a marble table. 16

One day, still searching for an explanation, Fermi’s associates set up an experiment to test what would happen if a piece of lead were inserted between the neutron source and a piece of silver. They were out of the lab, proctoring student exams, when Fermi wandered in and decided to go ahead with the experiment. On a whim, he removed the lead and substituted a piece of paraffin wax instead.

After conducting his experiment, Fermi grabbed the silver sample and sprinted down the hall to the Geiger counter as he had done dozens of times before. But this time the results were unlike any he had seen. The radioactivity level soared. The intensity reached a level more than a hundred times greater than in any previous experiment. When his colleagues arrived, they repeated the experiment. And, according to Enrico’s wife Laura, pandemonium broke out. “The halls of the physics building resounded with loud exclamations: ‘Fantastic! Incredible! Black magic!’” 17

Fermi theorized that the neutrons had collided with the hydrogen atoms in the paraffin. The ricocheting back and forth had slowed them down and reduced their energy before they reached the silver target. The marble and wooden table tops in the previous experiments and the walls of the lead-lined box had apparently had a similar weakening effect. But, why slow neutrons induced greater radioactivity than fast ones was still a mystery.

That night, as Fermi and his students gathered at the home of a colleague to write a report on their findings, no one imagined that an act of sheer whimsy, creating those slowpoke neutrons, would unlock “nature’s greatest secret.” 18

EARLY ON THE MORNING OF November 10, 1938, the telephone bell rang in the Fermi’s spacious Rome apartment. Laura Fermi rushed into the hall to answer it. “I wish to inform you,” the caller said, “that this evening at six Professor Fermi will be called on the telephone from Stockholm.” 19

Fermi had been tipped off a month earlier, while attending a conference in Copenhagen, to expect the call. Excited, Laura asked her husband to take the day off. Out on the Roman streets, Laura and Enrico went on a buying spree. They bought expensive watches. She bought a beaver-skin coat. Unlike diamond purchases, which were recorded and might draw official scrutiny, watches and beaver coats did not leave a paper trail. Equally important, they could be resold and turned back into cash when needed.

Following an afternoon of shopping, they returned to their apartment. The telephone rang. It was a friend, calling to see if they had heard yet. At six o’clock, still waiting, they turned on the radio. The news was not good. Italy’s dictator, Benito Mussolini, had just announced new restrictions on the rights of Italian Jews. Enrico was Catholic and their children were raised Catholic, but Laura was Jewish. Jews made up only a tiny fraction of the population and Italians, for the most part, were not anti-Semitic. Yet months earlier, Mussolini, following in the footsteps of Adolf Hitler, had launched a campaign against Italy’s Jews. 20 Now, it seemed, every day brought more bad news. This time, the commentator announced laws excluding Jewish children from public schools, dismissing Jewish teachers and restricting Jewish professionals to working for Jewish clients only. To make matters worse, authorities announced that the passports of Italian Jews would soon be confiscated.

Laura and Enrico had lived a comfortable professorial life up to now: a nice apartment in Rome; summers at a cabin in the Alps; interesting travel with lecture tours in South America and the United States. Now, looking ahead, they saw only hardship and despair. They had planned to abandon their home and leave Italy early in the new year, but it now seemed time was running out.

Shortly after six o’clock, the telephone bell rang again. It was the secretary of the Swedish Academy of Sciences in Stockholm. Enrico took the phone and the woman on the other end read him the citation on his Nobel Prize: “For his identification of new radioactive elements produced by neutron bombardment and his discovery . . . of nuclear reactions effected by slow neutrons.” 21

When the news of Fermi’s Nobel Prize got out, friends rushed to his apartment to join in the celebration. But Laura was torn. Mussolini’s latest pronouncement had left her shaken. “I did not know whether to be happy or sad, whether to heed the telephone or the radio.” Enrico, his usual confident self, assured her everything would work out. The timing of the Nobel Prize was a godsend. 22

As the Fermis planned their escape from Italy, fanatical anti-Semitism in Germany erupted into widespread violence. On the night of November 9, 1938 and into the following morning, Nazi mobs all across Germany burned and vandalized Jewish synagogues, homes and businesses. They killed 100 Jews, arrested 30,000 more and sent them to concentration camps. The paroxysm of violence came to be known as the “night of broken glass,” in German Kristallnacht . German anti-Semitism had inspired localized violence before, but Kristallnacht was the first government-orchestrated nationwide outbreak.

A month later, Enrico, Laura, their young son and daughter and their nursemaid traveled to Stockholm where Fermi accepted his prize and a large monetary award. The Fermi’s did not return home. Instead, they used the prize money to book passage on an ocean liner bound for New York City. Anticipating their escape, Enrico had accepted a job offer at Columbia University.

Laura, Giulio, Nella and Enrico Fermi

(AIP Emilio Segrè Visual Archives, Wheeler Collection)