Luis Alvarez needed a haircut. Taking a mid-morning walk across the hilly rise of the Berkeley campus, the 27-year-old physicist, blond locks tousled in the breeze, admired the view out across the San Francisco Bay. In the distance he could see the new federal prison on Alcatraz; past that, the recently constructed suspension bridge across the Golden Gate, the longest and tallest bridge in the world. Reaching the barber, he settled into the chair and pulled up the morning’s San Francisco Chronicle with immense satisfaction. It was Tuesday, 31 January 1939.
Alvarez stared at the page in shock. The Chronicle had picked up Hahn and Meitner’s discovery of nuclear fission from a wire service. Stopping the barber mid-cut, Alvarez snatched the page, leaped from the chair and sprinted back to the Radiation Laboratory. This was at the heart of the campus, a small, ugly wooden hut sandwiched between the grand, Beaux-Arts colonnades of LeConte Hall and the rising needle of the campus clock tower, modelled after the Campanile of San Marco in Venice. Inside, the Rad Lab was a chaotic mess, full of cages of mice for biomedical experiments, blackboards chalked with equations and giant magnets for the ‘proton merry-go-round’ that was the Berkeley particle accelerator. It was probably the most advanced laboratory in the world.
Skidding through the door, Alvarez hurried to his assistant, Phil Abelson, to tell him the news. ‘I have something terribly important to tell you,’ Alvarez relayed. ‘I think you should lie down on the table.’ Abelson was game and, grinning, climbed up on the workbench, spreading himself out among the chemical reagents and machine tools. Fission! Atoms can split apart! Abelson went numb; he’d been experimenting with uranium, had noticed similar results to Hahn’s and was probably moments away from making the discovery himself.
Alvarez didn’t stop, rushing around to tell everyone, not caring that he had accidentally invented the mullet. He started herding anyone nearby, including future Manhattan Project leader Robert Oppenheimer, to show them the fission energy ‘kicks’ coming off the lab’s own machines. For years, the ‘atom smashers’ had been picking up strange radioactive noise, but it was always dismissed as a quirk of the machine. The Berkeley team had all missed the discovery of the century – and it had been staring them right in the face.
By nightfall, news of the breakthrough had reached the journal club, where a 26-year-old researcher called Glenn Seaborg heard the tale. ‘I walked the streets of Berkeley for hours,’ Seaborg later recalled in his autobiography, Adventures in the Atomic Age. ‘My mood alternated between exhilaration at the exciting discovery and consternation that I’d been studying the field for years and had completely overlooked the possibility.’
Seaborg was a chemist who had been adopted by the physics set. Immensely tall and lean, with a wide grin and pocked cheeks, the young man hailed from Ishpeming, an icy backwater in the wilds of north Michigan, not far from the Canadian border. His family as far back as his great-grandfather were machinists from Sweden and were hardy stock used to rolling up their sleeves. When his grandfather had passed through Ellis Island in 1867, an immigration official had Anglicised ‘Sjöberg’ to ‘Seaborg’ with a wave of his pen. There was no way the official could realise that his invented surname would, 130 years later, be inked indelibly into human history.
Seaborg had grown up speaking Swedish at home, scraping out a life in a town whose ‘unpaved streets were tinged red from iron ore’. It was a hard upbringing; Ishpeming’s only claim to fame was hosting the first away game for the newly formed Green Bay Packers American football team (the Michigan men had sent three of the Packers off with broken bones in the first three plays). When he was 11, the family had moved to Los Angeles, where the young Seaborg’s world had suddenly expanded into technicolour. In Ishpeming he’d never heard a radio or seen a building more than a few storeys tall; in the City of Angels he’d found his world filled with lights, cars and oil riches. Inspired by the glitz and glamour of Hollywoodland at his doorstep, the young Glen had added an extra n to his name – it just looked cool – and had gone to find his fortune in science.
Science isn’t made for fortune hunters. Seaborg had struggled, paying his way through the University of California, Los Angeles first by working at factories and as a lab assistant, then by borrowing money from high school friends. Eventually, he had ended up at Berkeley. In 1937, in one of those quirky moments of luck that change history, he’d been strolling about campus when one of the Radiation Laboratory team had asked him to help with the tricky task of separating out different elements in a solution – he was literally the first chemist they could find. After that, he had been as much a part of the lab as any of them, covering the chemistry while the physicists created new radioactive isotopes of tin, cobalt, iron and Emilio Segrè’s element 43 (later called technetium). Many of these isotopes, such as technetium-99m and cobalt-60, were to become the cornerstone of modern radioactive medicine; today they are still used in millions of cancer treatments and diagnostic tests around the world.
The secret to the Berkeley Radiation Laboratory’s success was its revolutionary approach. The opposite of the Via Panisperna Boys’ homespun charm, the Americans were all about ‘Big Science’: big teams using big equipment from sponsors with big pockets. It was the brainchild of Ernest Lawrence, the grandson of Norwegian immigrants from South Dakota, who had broken through the stuffy, elitist physics department at Yale before moving west to make his name. Under his guiding hand as director, the Rad Lab had become a template for modern research. Rather than each scientist working on their own experiments, laboriously blowing their own glass tubes, making their own circuits and testing their own reactions, Lawrence expected everyone to work together. Berkeley was an epicentre of large-scale partnerships, teams working in shifts and each member focusing on their own area of expertise.
Figure 2 The Berkeley 60-inch cyclotron, a particle accelerator designed by Ernest Lawrence.
Throughout the 1930s, Lawrence had pioneered the construction of compact particle accelerators called cyclotrons, the most powerful research machines in the world. It was the spare parts from one of these behemoths that Segrè had cheekily borrowed to discover technetium. Unbeknown to their operators, the machines had already produced another element too.
Its discovery came hot on the heels of Alvarez’s barbershop dash. Edwin McMillan was a California native who had made it as far as Princeton before being lured back to his home state by Lawrence. Still in his early thirties, Ed was one of the cyclotron’s best operators and possessed a keen experimentalist mind that wouldn’t rest until it had answers.
With fission, the material doesn’t stay in one place: like a miniature nuclear bomb, the atom blows itself apart, scattering itself in all directions.1 Following the revelation that fission occurred, McMillan decided to run some experiments to see just how far things pinged away. Heading to the nearest atom smasher, he started pummelling a sample of uranium trioxide. Soon, he got a very strange reading. Something had been left near his original target material. It wasn’t uranium, and it hadn’t flown off far enough to be a fission product. Weirder still, the unknown radioactive lump had a half-life of 2.3 days, which didn’t match anything previously recorded. Was it the real element 93?
McMillan was flummoxed, so he asked Segrè – comfortably settled in California – to investigate. The Italian was a bad choice for a lab partner. Following the columns down the periodic table, element 93 was supposed to behave like the elements in group 7. Instead, it behaved like a group called the rare earth metals, or lanthanides – a line of elements beginning at lanthanum that all acted similarly to each other. These elements were so odd they had been considered apart from the rest of the periodic table, isolated on a naughty step just below the main chart (to this day, they are almost always displayed apart from the main table). Failing to learn from the slapdash approach to chemical confirmation during his days under Fermi, the Italian decided it wasn’t anything important and told McMillan to forget about it. He even went as far as to publish a paper: ‘An Unsuccessful Search for Transuranic Elements’.
McMillan wasn’t so sure. If his discovery was a fission product, why hadn’t it been scattered off like everything else? If it was an unknown isotope of uranium, why didn’t it behave like one? The result gnawed at the back of his mind. Over the winter, he tested his mystery sample with hydrofluoric acid and a reducing agent. The result – using chemistry so simple a student could do it – ruled out any of the rare earths. As he worked, life continued. The Second World War broke out in Europe; Gone with the Wind and The Wizard of Oz were released; the campus swung to the beats of Glenn Miller and Billie Holiday. In May 1940 Abelson returned to Berkeley on holiday (he’d since graduated and moved to Washington, DC), and McMillan asked for a second opinion. In two days, Abelson had performed the full chemical work-up Segrè hadn’t.
The results were conclusive. Edwin McMillan and Phil Abelson had discovered the real element 93. The duo published their findings in the Physical Review. The Second World War meant there was no fanfare; the great minds of Britain, France and Germany were at war. The only research into fission seemed to be coming out of Russia, where a pair of young physicists had proved that elements can spontaneously fission in nature. Instead of the physics world eagerly discussing their discovery, they received an official protest from James Chadwick and the British, currently under siege as they prepared for the Battle of Britain: Would you mind awfully just shutting up about things the Nazis might find useful? Abelson headed back east; McMillan kept working.
The person following McMillan’s progress the closest was Seaborg. Both men lived only a few rooms apart, and the chemist pursued the element maker around campus asking questions: in the lunch hall, in the corridor, even into the shower room. Seaborg was hooked, in love with the idea of a new element, desperate to know every detail. McMillan happily took Seaborg into his confidence about his latest scientific escapade. Using a cyclotron, he was bombarding uranium with deuterons (an isotope of hydrogen, with one proton and one neutron) to try and make an even shorter-lived isotope of element 93. His hope was that this more unstable version would undergo beta decay, turning into element 94. Things seemed to be going well. Then one day, McMillan was gone.
Seaborg soon found out why. The US was preparing to join the war, and Lawrence had been asked to give up his best scientists to the military. Along with Alvarez, McMillan had been sent to Boston to work on developing radar detection. Not willing to surrender his new passion, Seaborg wrote to McMillan asking if he could take over the project. Seaborg later recalled in his autobiography: ‘Ed wrote back immediately to say he had no idea when he would return to Berkeley and expected a long absence, so he would be happy for us to continue.’
The chemist wasn’t going to pass up his opportunity.
* * *
A neutron walks into a bar and orders a drink. ‘How much?’ the particle asks. The barman shakes his head. ‘For you, no charge.’
The oldest joke in atomic physics is proudly emblazoned on the menu at the Berkeley chemistry department’s coffee stand. I’m sat just outside, fighting off the jetlag and wind chill with caffeine and carbs. I thought California was supposed to be sunny? There’s a nip in the air this morning and I’m beginning to regret not bringing a thick sweater; part of me wants to give in, dart into one of the town’s countless clothing and thrift stores and get a hooded top – probably a goofy one with ‘I heart San Francisco’ all over it. For now, hot coffee will do.
Berkeley is a small town that morphs seamlessly into bustling Oakland, a relaxed suburb filled with counterculture shops, cheap eats and bars proudly pledging allegiance to its Golden Bears sports programme. The University of California campus dominates the whole area, its manicured lawns and imposing halls resting on a rise that slowly steepens, building to a climax at Grizzly Peak. Originally named after an Irish bishop who didn’t believe in the material world, Berkeley has always been home to the raucous and the radical – Ginsberg to Green Day – its left leanings evident on every lamppost or window plastered with slogans such as ‘Occupy’ and ‘Resist’. In the 1960s the Bay Area was the epicentre of the ‘flower power’ movement and anti-Vietnam protests; today it wears its campaigns for LGBT rights and an end to pseudoscience with righteous pride.
This is one of the world’s great science hubs. Starting with Lawrence’s Rad Lab, Berkeley has been on a roll of Nobel Prizes and ground-breaking science for 80 years. Just strolling through campus, you could bump into George Smoot, one of the world’s leading experts on the Big Bang, or Jennifer Doudna, the biochemist whose CRISPR discovery could allow us to rewrite our genes. The whole complex has a collegiate air, a sense that something very smart is going to happen, mixed with breezy cool and a hint of mischief. Quite what Bishop Berkeley would have made of it is anyone’s guess.
LeConte Hall and the Campanile still stand, though the old Rad Lab has since been torn down. Apparently, someone finally realised that conducting radioactive experiments in the centre of one of the world’s busiest campuses was a bad idea. Today its descendant, Berkeley Lab (officially Lawrence Berkeley National Laboratory), sits atop the sharp rise behind the university grounds, accessible either by a stiff hike or a convenient shuttle bus.
I’m not here for the lab today; that’s a mission for another time. I’m here to break into Gilman Hall. Gilman is another of the beautiful, grey-stone buildings on the campus where Lawrence’s men cut their teeth. In 1940, Seaborg had recruited two collaborators, Joseph Kennedy and Arthur Wahl, to continue McMillan’s hunt. Aware that their discoveries could be used for an atomic bomb, the team had sworn to work in secrecy. To complete the chemical separations required to explore new elements, the team needed space away from prying eyes. The third floor of Gilman was the best they could come up with.
Sneaking in through the large oak doors that guard the hall’s main entrance, it’s easy enough to slip onto the staircase – wonderful, heavy concrete stairs with sturdy metal banisters and wood lacquered to a sheen – and climb up to the top floor. Here are attic rooms, still in use by the chemistry department as offices. In Seaborg’s day they served as miniature lab spaces with industrial sinks and workbenches, with bottles of reagents, hand-blown glass beakers and retorts fighting for space against Bunsen burners, jars of powders and char-blacked draining boards. Cramped and cosy (particularly for the tall Seaborg), it’s the opposite of the vast underground lair Hollywood has associated with scientific breakthroughs. Down a whitewashed corridor, exposed pipes humming overhead, next to an emergency shower for chemical mishaps, you’ll find a hardy door. On the wall are two plaques that hint at what came to pass in the locked chamber. Room 307. The place where Glenn Seaborg isolated plutonium.
In mid-December, following McMillan’s plan, the trio created the new isotope of element 93. It was a vigorous beta radiation emitter, meaning it was likely turning into yet another element. But they had also made something that fizzed with alpha particles instead. Could 93 have beta decayed and given birth to an atomic daughter?
Work continued through a long, wet winter. Room 307 soon stank with reagents and reactions, forcing the team to open the windows and work out on the balcony. Here, in full view of the world, three men in their twenties played with perhaps the most secret substance ever to have existed. Much of the work was carried out at night, the conspirators making desperate runs with their radioactive samples between the Rad Lab machines and the Gilman lair. All that was missing was the final confirmation that element 94 was real.
The breakthrough came as a cliché. Every scientist knows that, sometimes, the best results come when everyone else has left and you’re trapped alone in the lab. On the night of 21 February 1941,2 a wild storm battered and bruised the San Francisco Bay. Wahl was still in the attic space, the whole room rattling with the wind and rain, lightning flashes occasionally illuminating the downpour outside. A little past midnight, his eyes growing heavy, Wahl finished his last chemical test. Chemists are obsessed with oxidation numbers – how many electrons lost or gained by an atom when it forms a compound. The group had just proved that the radioactive daughter particle had a higher oxidation number than any known element it could have been. It had to be element 94.
Standing in the hall, the place resonating with history, I can’t help but imagine Wahl laughing maniacally as the balcony doors burst open and the thunder pealed behind him. It’s probably the only time in scientific history mad scientist chic would have been appropriate.
* * *
To make a nuclear bomb, you need a chain reaction – one atom going off won’t release enough energy to make a big enough bang. This requires a ‘fissile’ isotope – one that, if hit by a neutron, will send neutrons flying out in turn, like a pool ball hitting the stack. These neutrons will hit other atoms, causing them to explode, which will send more neutrons out, causing yet more explosions, sending yet more neutrons out, etc. If you have enough fissile material – the critical mass – you get a sustained nuclear chain reaction. One atom undergoing fission could flick a speck of dust; 6kg (13lb) of atoms undergoing fission almost simultaneously could level a city.
As far back as late 1939, at the request of Albert Einstein,3 President Roosevelt had already put together an advisory committee to consider the feasibility of an atomic weapon. There was one obvious choice of fissile material to make the bomb: the naturally occurring uranium-235. Most natural uranium is U-238, but this was easy to mine, and could then be enriched by a process called gaseous diffusion to remove some of the unwanted isotopes and increase the concentration of U-235.
The second possibility was Seaborg’s suspected element 94. By the summer of 1941, Seaborg’s team had completed the final hurdles surrounding their creations. Even before Wahl’s final tests, the group became aware that at least one isotope of their creation might be fissile. Here, a familiar face joined the party. After dismissing McMillan’s discovery, Emilio Segrè had been working with a different group and discovered yet another element, the missing 85, later named astatine. Lawrence asked Segrè to partner up with Seaborg to see if element 94 could make a bomb.
Seaborg wasn’t happy. Segrè was a lousy chemist, and as an Italian he was classed as an ‘enemy alien’ and was not allowed to know the details of what was going on. The situation was crazy; Seaborg would gather chemicals and tell Segrè what to do, but could not tell him what substances he was dealing with or why he was using them. But Segrè had contacts Seaborg could only dream about. When the team needed a larger amount of uranium to bombard, Segrè made a call to Enrico Fermi, who had settled on the East Coast. Soon, 5kg (11lb) of uranium arrived at Berkeley with his former mentor’s compliments. With it, the unlikely duo worked out that you’d need to bombard 1.2kg (2.6lb) of uranium in a cyclotron to get 1 microgram (or μg – a millionth of a gram) of element 93, which degraded quickly to 94.
Now with enough element 94 to play with, Seaborg and Segrè soon determined that one of its isotopes was fissile. The team estimated that its fission rate was 1.7 times that of uranium. Element 94 was not just an option for a nuclear bomb. It was the best option.
Lawrence was a member of the advisory committee and sent Seaborg across the US to explain what he had found to Arthur Compton, the committee member tasked with writing the report on whether a bomb was feasible. Compton listened, but decided against telling the president about Seaborg’s new element. On 6 December 1941 the advisory committee met and decided they would proceed with making a nuclear bomb using uranium-235.
After the meeting Compton went to lunch with two of the committee members and brought up the topic of element 94 as an alternative to uranium. He had been talking with Lawrence and other scientists who had convinced him that the Berkeley discovery was worth investigating further. ‘Seaborg tells me,’ he informed his companions, ‘that within six months from the time [94] is formed, he can have it available for use in the bomb.’
One of the diners was James Conant, the president of Harvard University. The New Englander practically sneered at the suggestion. ‘Glenn Seaborg is a very competent young chemist,’ Conant remarked, ‘but he isn’t that good.’ Still, the group agreed it was useful to have an alternative option for a bomb just in case the US found itself at war.
Twenty-four hours later the Japanese attacked Pearl Harbor.
Notes
1 Things don’t stay in one place with alpha or beta decay, either; part of the big challenge in nuclear physics is nothing ends up where you want or expect it to go.
2 The plaque outside 307 insists that the discovery was the night of 23 February. Seaborg always claimed it was during the storm, and that’s good enough for me.
3 The letter was actually written by Leo Szilard, but was signed and sent by Einstein – and if Albert Einstein tells you something is a good idea, you should probably listen.