Superheavy

by Kit Chapman

  Then, on 9 January 1961, he would reach the highest echelon science has to offer. That morning, he received a phone call from a man with a thick Boston accent. The stranger, introducing himself as Jack, asked whether Seaborg would come and work for him. After a quick family ballot (with Helen and all of the six children voting to stay in California), Seaborg decided to exercise his parental veto and accept President-Elect John F. Kennedy’s invitation.

  Glenn Theodore Seaborg, the Ispheming boy who had come from nothing, became chair of the Atomic Energy Commission and responsible for the US nuclear arsenal. He also continued to champion his actinide elements. In 1957 Seaborg had written to the Atomic Energy Commission urging it to create a program that could provide ‘substantial weighable quantities, say milligrams, of berkelium, californium and einsteinium’. As chair, he was able to see his vision built: REDC and HFIR at Oak Ridge. The move ensured heavy element exploration would continue for at least the next 100 years.

  In Washington, DC, at the heart of JFK’s Camelot, Seaborg played on a stage well beyond anything he had ever encountered; only a year into his term he found himself at the heart of the Cuban Missile Crisis. In 1963 he was present as part of the negotiating team for the Limited Test Ban Treaty, which ended nuclear weapon tests above ground. During this time, he met both Khrushchev and his successor Leonid Brezhnev. When Kennedy was assassinated, Seaborg became a close adviser to the next president, Lyndon Johnson. The two men formed such a tight-knit bond that Seaborg was often invited into the Oval Office just to hang out. Under Seaborg’s influence, Johnson signed the Nuclear Non-Proliferation Treaty, a worldwide agreement to curb the spread of nuclear weapons for good. Seaborg, the man who had created the element that powered the first atomic bomb, had taken giant strides to stifle the use of his most terrible creation.

  Yet all of that was to come. In 1955 the Berkeley boys were more interested in celebrating their latest triumph. Gathering at Larry Blake’s restaurant, they joked, laughed and took photos of themselves next to a papier-mâché effigy of the absent Thompson. Eagerly, they looked forward to discovering their next element.

  But the next heavy element breakthrough wasn’t destined to happen at Berkeley. It came in Sweden – and started an argument that raged for 40 years.

  Notes

  1 This always reminds me of San Francisco’s most famous Volkswagen Beetle, Herbie, although cinema’s car with a mind of its own wouldn’t make its debut until The Love Bug, some 13 years later.

  2 The other problem, if you’re feeling really geeky, is that Stark’s target was made of palladium. The cross section of Stark’s reaction would have been woeful.

  3 Despite being broadcast in prime time, the KQED film didn’t get much of an audience from the Bay Area kids: it was on at the same time as The Lone Ranger. The re-enactment took place during the day, while the genuine experiments took place at night to ensure there was no traffic blocking the route between labs.

  PART TWO

  Transfermium Wars

  CHAPTER EIGHT

  Nobelievium

  Stockholm is a city built on an archipelago, a scattering of islets, islands and peninsulas that create a picture-postcard city of stunning harbour vistas and century-old secrets. At its heart is the old city, Gamla Stan, a crowded maze of backstreets, steep climbs and alleys just waiting to be explored. Today, the Swedish flags flutter above the Royal Palace, the sun causing the Stockholm waters to shimmer with allure. Smells of fresh cinnamon buns and chai lattes – fika, Swedish high tea – drift from hipster bistros and cafes. To the north, on the fringes of the city, is Stockholm University. Here, huddled away in a small corner of the campus, is the old Nobel Institute for Physics. It’s a pretty unremarkable building: Brett Thornton, a geochemist at the university, told me he worked barely 100m (330ft) away for years before he realised its significance. The only clue to its importance is on a painted plaque above the door: a white C set in a blue square. Below, the words Wallenbergsstiftelsens Cyklotron Laboratorium glisten in sun-flashed metal. It was here in 1957 that a team of Americans, Brits and Swedes announced that they had made element 102.

  Anders Källberg meets me at the entrance. An older man in a cheery blue waterproof jacket, he sets his bike against the wall and looks up at the big C. He doesn’t work here any more. Nobody does. In two weeks the building will be decommissioned, its experimental halls turned into a space for art exhibitions. Källberg is the last physicist standing, here to make sure the place is safe for its new role. ‘Everything is blown out,’ he says apologetically. ‘I’ve just been down to do some substance measurements in the cyclotron hall. Actually, it was kind of annoying. I detected some remnants, traces of europium-152, in drill-hole powder.’ Every element has a different maximum limit considered safe. Europium’s, to Källberg’s dismay, is very low. ‘The amount [of radioactivity] was above the limit that would allow the public to go inside, but it’s only one hundredth the natural radioactivity of uranium in concrete walls! Fortunately, the government ended up making an exception.’

  We head inside the abandoned halls like grave robbers breaking into a tomb, taking an industrial elevator down to the accelerator hall. Well below ground, Källberg leads on into a large, empty room. It feels like an abandoned warehouse, a vast space waiting to be cleaned up and filled. Portable floodlights haunt the desolate lair with strange shadows. Dust has settled over the cracked laminate tiles on the floor, and the whitewashed walls are full of drill holes where Källberg has taken samples. In the far corner, scorch marks signify where the cyclotron once stood. It’s an eerie place. The only sound is our footfalls, our voices and our breathing. Källberg turns and points up to the old loading cranes that hang from the ceiling, telling stories about hanging out of the shaft to press buttons and lower in equipment. Those cargoes are all gone. Only ghosts remain.

  Although Källberg wasn’t present in the 1950s, he knows the story of what happened all too well. As with Fermi’s Via Panisperna Boys 20 years earlier, it was a small team of scientists going up against the biggest laboratory in the world. The Swedish didn’t have Berkeley’s vast pockets, or Seaborg’s two decades of element-hunting experience. Their equipment was made by hand on a shoestring budget, their targets and beams borrowed from other labs. Yet somehow, they astonished the world – and the world struck back.

  * * *

  By the time of the Swedish experiment, element makers had moved beyond neutron capture. Accelerator science had improved to the point that ions of light elements, all the way up to neon (element 10), could be fired at targets with sufficient energy and intensity to achieve a fusion reaction. But firing even these small nuclei brought new challenges. As before, element makers had to shoot the beam with enough energy to overcome the Coulomb barrier – that positive repulsive force – which was protecting both nuclei. This meant that the energy required to get past the repulsion and form a compound nucleus was well beyond the fission barrier. Any new nucleus was supposed to just break apart instantly.

  But a nucleus has another trick up its sleeve that can reduce its energy and prevent fission. Rather than undergo alpha or beta decay, it can push out ‘evaporation residue’ made of neutrons and photons, much like a sinking ship casting off ballast. This creates a near-instantaneous race between evaporation and fission: either the atom will cast off enough neutrons and photons to lose some 35 to 40MeVs or it will explode. Fission almost always happens first. But in the rare cases when evaporation wins, you get a new element.

  As mentioned earlier, the Swedish thought they had created a new element in 1954 by bombarding uranium with oxygen ions for several hours to make the supposedly undiscovered element 100. That time, they had been pipped to their discovery by the Ivy Mike hydrogen bomb. Yet if the Swedish were disheartened, it didn’t stop them from pressing on. ‘We focused on trying to produce element 102,’ the official lab history records. ‘We received English plutonium for the study of nuclear reactions with oxygen ions, and Swiss neon-22 for uranium ir
radiation.’ While they were certain both combinations made element 102, the low cross section defeated them: there wasn’t enough material produced to prove they had succeeded with their low-budget, home-brew equipment.

  Instead, they banded together with a team from Argonne in the US and the UK’s Atomic Energy Research Establishment at Harwell. The collaboration’s process was designed to take advantage of each lab’s particular set of skills. Argonne supplied samples of curium-244 to the British; the British then painted these targets onto a thin aluminium foil and shipped them to Stockholm. Swedish engineers working under Manne Siegbahn would then bombard the foil with carbon-13 (carbon with one extra neutron). The Swedish cyclotron was similar in design to Berkeley’s; the only real difference was that they used a plastic catcher’s net instead of gold foil. This was a cheap and easy alternative: after an experiment, the Swedes would just take their catcher and set it on fire, melting away the plastic and leaving only the newly forged element behind.

  In 1957, after bombarding 6 different targets for 30 minutes, the team claimed victory. Three of the targets showed signs of alpha decay. It was the first signs of element 102. But the chemical experiment to check their readings failed. The team faced a tricky dilemma: should they announce their discovery to the world, or keep working?

  The Swedish admitted their evidence was not very strong. Part of that was down to the equipment available: precise detectors required funds the Swedish researchers just didn’t have. ‘The results of our irradiation were controversial,’ the lab history continues, ‘mainly due to the very low yield of the nuclear reactions, the broad energy spectrum for the alpha decay that was registered and the scarcely available equipment for measurement. It would have been completed if financial resources had been available.’

  ‘These data are shaky,’ Källberg agrees. ‘The alpha energy spectrum [used to detect 102] was measured with a home-built 16-channel analyser. It was early in the days of nuclear physics, you couldn’t just buy your equipment. The alpha spectrum was pretty crude. But, actually, I think they did a good job.’

  In July 1957 the team decided to publish their results. With it came their suggestion for a name: ‘Nobelium, symbol No, in recognition of Alfred Nobel’s support of scientific research and after the institution where the work was done.’ The choice caught the public’s imagination far more than any of Berkeley’s post-war discoveries. Nobel. Nobelium. Nobel Prize. It was an easy sell. Soon the name was everywhere.

  Seaborg and Ghiorso were together at Berkeley when the news from Sweden came in. Neither of them believed it; the data were incomplete and uncertain. Immediately, the Americans set out to copy the Swedish experiments to check. Soon Ghiorso was convinced that Stockholm was ‘completely wrong’. Nobelium, he and Seaborg joked in private, was nobelievium.

  Researchers from both the US and USSR soon pressured the Swedish team to withdraw their claim. Checking their data, the Swedish researchers stood firm; while they admitted that Berkeley ‘appeared to cast some doubts on [their] results’, they refused to back down. ‘We suggest that judgment on the discovery of element 102 should be reserved.’

  * * *

  Standing in the remains of the Nobel Institute, it’s easy to feel the spectres of history. Instead of plaudits, the Swedish found themselves in a battle over whether they had accomplished anything at all. When, a decade later, the Berkeley team managed to replicate the Swedish findings, they didn’t mention the experiment’s significance.

  Today, the Nobel Institute’s work is all but forgotten; its claimed discovery of nobelium will probably remain unproven forever. Yet Källberg’s memories aren’t bitter or resentful of what came to pass. Instead, he touches the wall gently, placing an open palm on the brickwork as he remembers the people who worked here. ‘It was a happy place,’ he says quietly.

  ‘Do you think they did it?’ I ask.

  My companion falls silent as he considers the answer. ‘I think the general feeling, when I was here, was that we really produced 102 but it wasn’t accepted … I get the feeling that Berkeley didn’t want anyone else in the field. “The Swedes, small guys doing things with almost hobby equipment? They can’t do it before us!”’

  For almost 20 years, Berkeley had been the leading name in element discovery, racking up 10 elements. In that time, the rest of the world had discovered three combined. It was small wonder its team felt that they, alone, had the expertise to expand the periodic table.

  They were soon proved wrong.

  The Russians were coming – and they had element hunters of their own.

  CHAPTER NINE

  From Russia with Flerov

  In April 1942 a 29-year-old lieutenant in the Soviet Union’s volunteer air force stumbled on the greatest secret in the world.

  Georgy Nikolayevich Flerov was fighting for his homeland at the time. In 1941 the Germans had invaded the USSR and pushed deep into the Soviet heartland. Almost a year later, the front line stretched across the country, from Leningrad (today Saint Petersburg) in the north to the Crimean peninsula in the south. Flerov was a junior engineering officer stationed in Voronezh, a short distance from the front line, who worked to repair bombers. As far as the state was concerned, he was a nobody – just one of the millions drawn from across Russia to fight in the Great Patriotic War.

  Flerov’s origins were humble. He was born in Rostov-on-Don to an impoverished family who couldn’t afford to provide him with an education. Throughout his teens, he was a labourer, engine greaser and electrician. In 1931, aged 18, he made his way to Leningrad to work at the massive zavod Krasny Putilovets, a munitions and tractor factory whose strikes had swept the tsar from power 14 years earlier. Two years later, he was sent by the state to attend university – the Soviet Union needed sharp minds – and fell in with Igor Kurchatov, the Russian answer to Ernest Lawrence. Under Kurchatov’s tutelage, Flerov blossomed into a promising nuclear physicist. In 1940, while investigating the different isotopes of uranium, he and another researcher discovered that fission can occur spontaneously in nature – that elements could become unstable and split apart on their own. It was an impressive discovery ... but the Axis invasion robbed him of any opportunity to follow it up.

  Flerov was convinced he was of more use to his country as a physicist than as a mechanic, and had vowed to keep his scientific career on track. When off duty, his preferred way to relax was to head to the local university library and catch up on the latest research journals. And it was during one of these breaks that he noticed something was missing. Two years earlier, he had written a paper on spontaneous fission. Nobody had responded to it. In fact, nobody seemed to have published a word about atomic research at all. Flerov couldn’t imagine that the British, Americans and Germans, with their amazing machines and vast resources, had abandoned the ‘uranium problem’ wholesale. That could mean only one thing: everybody else was working on an atomic bomb.

  The Russians didn’t have a nuclear weapons project. Instead, the state had prioritised metallurgy and heavy industry, and had dispatched its best chemists and physicists to work in industrial plants. Flerov had never been convinced this was the right course of action. In 1941 he had visited the Russian Academy of Sciences, outlining exactly how a bomb could be made, and had also written repeatedly to Kurchatov, begging the ‘prodigal son’ of nuclear science to unleash the power of the atom. Convinced the Americans were doing just that, Flerov knew he had to act. If the other physicists wouldn’t listen, perhaps The Boss would.

  Flerov wrote to Stalin.

  Dear Iosif Vissarionovich,

  Ten months have elapsed since the beginning of the war, and all the time I have felt like a man trying to break through a stone wall with his head […] Perhaps being at the front, I have lost all perspective of what science should deal with at present […] [but] I think we are making a big mistake. The greatest follies are made with the best intentions. All of us want to do all we can to rout the Nazis, but there is no need for such hurry-scurry, no need
to deal with problems that only come under the term ‘pressing’ military objectives […] This is my last letter, whereupon I lay down arms and wait till the problem has been solved in Germany, Britain or the USA. The results will be so overriding it won’t be necessary to determine who is to blame for the fact that this work has been neglected in our country, the Soviet Union.

  Flerov ended with a demand. A seminar with the best Russian scientists and ‘an hour and a half for the report, in your presence’ to plead for the creation of a Soviet atomic bomb. It was an astonishing gamble – Stalin wasn’t known for taking pen pals and had a habit of ‘disappearing’ malcontents – but the lieutenant had been pushed too far. All he could do was wait for his reply: a commendation or a bullet.

  The message reached Stalin’s office in the Kremlin. Its arrival coincided with a bundle of intelligence from Lavrentiy Beria, the head of the secret police, also making the case for an atom bomb. Stalin paced his office, puffing away on his cherry-root pipe as he discussed the idea with his scientific consultant, Sergei Kaftanov. Kaftanov agreed it was ‘necessary to act’. Next, Stalin called in his four greatest physicists and abused them. Why was some upstart lieutenant able to see something they had all missed? This ‘Lieutenant Flerov’, just a name on a piece of paper, had guts. Stalin liked guts. The USSR needed guts. The physicists were to start work on an atomic bomb immediately.