Superheavy

by Kit Chapman

  Groves’ donation wasn’t entirely altruistic: Uncle Sam wanted Berkeley. In November 1946 the Atomic Energy Commission took over the lab. Today it’s owned by the Department of Energy. Everything the lab does has to serve the taxpayer. As with Oak Ridge, it is one of the jewels in the US government’s research crown, with an annual budget of $800 million and 4,000 staff. It’s the home of smart windows that respond to changes in sunlight, the antiproton and the measurements of how fast the universe expands.

  The climb is 30m (100ft) up from Blackberry Canyon to the offices at the top of the rise; a little to the south, the university students know the area as ‘Tightwad Hill’ – overlooking the university stadium, it’s the perfect spot to watch Golden Bears games for free. Fortunately, I don’t have to go anywhere near that far. Making the climb, passing the checkpoint, I pant and wheeze my way to the first building on Cyclotron Road. This is the home to Berkeley’s current element workhorse, the slightly more modest 88-inch cyclotron. Here, in an office filled with far too many computer screens, journal papers in piles and general scientific detritus, I’m met by my laid-back guide to Berkeley’s secrets. Jacklyn Gates is my kind of scientist: she reclines back in a black hoodie, her sleeves rolled up to reveal an intricate network of tattoos on her arms, the baggy top paired with jeans and comfortable cowboy boots. Gates is tired; she’s just come off a week pulling all-nighters, working with the small team at Berkeley to ready their machine for a new set of experiments. Once the thriving epicentre of element discovery, Berkeley’s heavy element team is the smallest it’s been since Ernest Lawrence created it.

  Gates self-identifies as Berkeley through and through. She stumbled into nuclear science by applying for a position at Argonne, just outside Chicago – the perfect place for a young researcher to start their career. She hadn’t read the application quite right: the position was for Argonne-West, an offshoot located in the big emptiness of eastern Idaho. Hooked on the science but less enamoured with the location, she moved to Berkeley as a grad student.

  I mention how a vertiginous slope is an odd place for a lab.

  ‘Yeah, they originally started down on campus,’ she says. ‘Then they decided maybe doing all these things that cause radiation isn’t a good idea in the middle of a university. “Let’s move it near campus but not where you can irradiate students ...” It’s a steep hill, but the lab owned a bunch of property on it so Lawrence, when he was building one of his cyclotrons, started up here.’

  That was a long time ago. ‘The 88-inch cyclotron came after Lawrence,’ Gates continues. ‘It started running in 1962. There’s also a small medical cyclotron. It can produce oxygens, carbons, fluorines ...’ Today, Berkeley’s cyclotron isn’t set up for element discovery – although the team is one of the forerunners in the world for confirming the experiments of others. ‘Discovering a new element is not easy,’ Gates says – the understatement of the century. ‘We’ve improved our techniques [since Seaborg], but we’re still not perfect. These days you need a separator. We’ve got one, but it’s not ideal for determining new elements. For what we use it for it’s great. It’s got high efficiency, good suppression of background, but you have to know where the products are going to come from: if you’re 5 per cent out where you’re setting your magnets, you won’t see anything. These superheavies, the elements we’re discovering today, are 6 per cent off where the projections are.’

  That, Gates explains, is the real problem with element discovery – not hoping for fusion but spotting it when it does occur. ‘It reduces our efficiency for detection from 60–70 per cent to 10–12 per cent. We had that problem confirming the [element] 112 experiment. We thought we knew where it would be, and we were wrong. We didn’t see anything for a month of beam time. And that costs $50,000 a day. So, we spent $1.5 million because our magnets were 6 per cent off, and there was no way to know that.’

  The expense and difficulty mean modern-day Berkeley sets its priorities elsewhere. The team simply doesn’t have the money to go fishing for elements. ‘The state of science funding in the US has been pretty sad for the past couple of decades,’ Gates says. ‘We used to put a lot of effort into basic science, things that won’t get you a return on investment now but will lead to major discoveries in 30 or 40 years. We don’t see that as a priority [today]. And you have to ask: is making a new element more important than climate change, or renewable energy? It’s not an easy argument to make. I mean, I’m a heavy element person, and I’d pick renewable energy.’

  Gates makes an important point. Although this is the story of the big stuff – the major discoveries – it’s a tiny fraction of what any heavy element team does. They’re not there solely for the glory of discovering a new element, as cool as that may be; every isotope unlocks a little more of the universe or creates options for saving lives through medical isotopes or cleaner energy. Only a tiny fraction of Gates’s energies are dedicated to making elements. The rest of her work is fundamental science. Berkeley’s heavy element team is small, but it’s focused.

  Gates wrinkles her nose. ‘You want to get something to eat?’ We head back down the hill, through the brisk air, toward the nearest bar that does sticky finger foods. I ask if we have to climb back again. ‘Seaborg would have walked,’ Gates teases. ‘He had the lab build a set of stairs up the hill for him. They called them the Seaborg Steps. He walked them every morning for exercise, up and down, up and down. For years, every researcher knew that if they wanted his help, they could find him at the stairs. They just had to be willing to walk with him.’

  I shiver a little on the way to the bar. ‘You can always tell a tourist in San Francisco,’ Gates comments, tugging her hoodie sleeves down, safe under the security of her warm layers. ‘They think California is going to be sunny. They end up having to buy a sweater. You always see people in “I heart San Francisco” tops because they didn’t bring anything …’

  I keep my head down and mouth shut as we walk down Cyclotron Road.

  * * *

  While Berkeley Lab must justify everything it does today, the 1940s were a paradise for the physics of the unknown. A word from Lawrence or Seaborg and a project became reality. Nobody knew what the new elements could do, but they knew the awesome power of plutonium. Money was no object, and space and time were freely given. Perhaps the greatest example came a decade later, with the construction of the bevatron: a particle accelerator so vast it was the size of a modern cycling velodrome. Its name was a portmanteau of its purpose: the ‘billions of electron volts synchrotron’.2 Lawrence’s Big Science had become bigger than he ever could have imagined.

  But despite this ready source of funds, things weren’t easy for the new heavy element group. For three years, the team worked building their new lab in Berkeley’s Building 5, a small, cramped and crude shack near Lawrence’s dome. They had a lot of problems to solve – not least the lack of equipment. ‘The cupboard was bare,’ Thompson would later recall during a symposium in January 1975. As he worked, Thompson finished his PhD, laying claim to arguably the greatest PhD dissertation in history: his doctorate was awarded for exploring americium and curium. But no one – Seaborg, Thompson, Ghiorso or Lawrence – was prepared to rest on their laurels. There were more elements to come.

  The set-up to hunt for the next elements in sequence, 97 and 98, was relatively simple. Helium ions – alpha particles by any other name – could be fired at americium and curium, creating new atoms two places along the periodic table. But the targets posed a problem. The world’s supply of americium could fit into the eye of a needle, and nobody had isolated curium at all. There wasn’t anything to shoot at.

  For four years, Thompson and a host of other chemists worked on how to get more. ‘We worked on closed cycles and calculated masses, energies and half-lives,’ he recalled. ‘We used systematics, alpha half-life energy relationships for isotopes of different elements, and even developed some crude electron-capture schematics.’

  In short: it was hard. Ghiorso summed up
the team’s efforts during the 1975 symposium: ‘They would work very, very, very hard with a tremendous number of separations, very difficult procedures, and end up with a small sample. Then they would hand it over to me and say “Here, we’re tired, you find out what’s in it.”’3

  The answer was americium and curium, both in large enough amounts to make targets. On 19 December 1949 the team had a hit: a target containing a mere 7mg of americium was struck with helium ions and produced element 97. As Seaborg watched Thompson work, his heart rate began to rise, pounding against his chest in furious anger. The university doctor was summoned and soon became convinced Seaborg was having a heart attack. The chemist was rushed to hospital, where he was kept under observation for several days. It soon emerged nothing was wrong: he was just too excited about his latest discovery.

  Rather than wait for chemical confirmation, the creators named their new element immediately: ‘berkelium’. It had been such an arse to create that Thompson and Ghiorso wanted its symbol to be ‘Bm’. Seaborg overruled them and chose Bk.

  The team were on a roll. On 9 February 1950 an even smaller target, 8mg of curium, produced just 5,000 atoms of element 98. The amount was invisible to the human eye, but the team were so good even this was well within their ability to handle. ‘There were no false lunges at element 98,’ Seaborg recalled. ‘The predictions of both its radioactive and chemical properties were made with uncanny accuracy and led us to our prey without a single misstep.’

  Joining the trio of discoverers was Kenneth Street, a former US marine and one of the staff who had helped Thompson during his long years of chemical toil. The four men decided the new element was going to be called ‘californium’.

  When the papers officially announcing the elements emerged back-to-back in the Physical Review, reaction was muted. A few people objected to the spelling of berkelium, wanting to lose the second e; to this day, how it’s pronounced (berk-el-i-ium or berk-lium) varies around the world. Seaborg excitedly phoned the mayor of Berkeley to tell him a new element was named after his town, only to have the official hang up on him in utter disinterest. Two scientists from the Soviet Union contested the discoveries, insisting that they had predicted the properties of element 97 two years earlier based on the periodic table (wisely, the international community decided that predicting an element isn’t the same as actually creating it). The New Yorker even mocked the discoveries, pointing out that, given they had created elements 95 to 98, the team could have written universitium, ofium, californium, berkelium across the bottom of the periodic table.

  Reaction to the new elements was a little more positive in Sweden. The Royal Swedish Academy of Sciences decided to give Edwin McMillan and Glenn Seaborg the Nobel Prize.

  * * *

  The Nobels are considered the pinnacle of scientific attainment. Originally, they were supposed to be awarded to whoever made the greatest contribution to science in the previous year. Today, the awards are more commonly recognition for work in a ground-breaking field – a scientific lifetime achievement award. For the science prizes, the committees take their time, waiting to see how discoveries will pan out and whether they continue to deliver a ‘richness of consequences’ for humanity. No more cancer-causing parasitic worms or lobotomies.

  The award process is carefully regimented. First, around 3,000 people are invited to make their nominations – secret ballots, the records of which are then sealed for 50 years. Usually, this results in around 300 potential prize winners – it’s virtually unheard of for someone to win the first time they are nominated. Next, a committee goes through the possibilities, consulting even further with experts and former laureates. They investigate their potential winners in complete secrecy, digging deep to make sure the nominated person really did the work and didn’t just copy it from their subordinates (if that sounds outrageous, such skeletons have been uncovered in the past). Finally, each year between one and three people are awarded the prize for a single body of work; sometimes the prize is split evenly, sometimes one person gets half and the other two get a quarter. It really boils down to who did what.

  I’ve spoken to Nobel Prize winners about what comes next. Most do not expect it; when they receive the phone call from Stockholm, typically half an hour before the prize is announced to the world, they almost always assume it’s a practical joke. The committee chair keeps someone the person knows on standby, ready to come on the line and tell them it’s real. Once informed, the Nobel winner is in a strange, surreal limbo. They aren’t allowed to tell anyone, so most just try and get on with work, or perhaps phone their family and hint they should watch the news. Sometimes, during the lull, they get phone calls from previous Nobel laureates. ‘Congratulations,’ the speaker usually says, ‘this is the last 20 minutes of peace and quiet you’ll get for the rest of your life.’

  When the call came in November 1951, Seaborg had been forewarned. A guest lecturer had accidentally told Helen she would soon visit Sweden, and Glenn had heard speculation on the radio as he drove to work whether he would win the prize. Even so, as he took the call Seaborg was overjoyed. With the prize came instant fame, a large gold medal and a windfall of $16,000 ($158,000 today). It was enough for him to completely remodel the family home.

  Seaborg delighted in returning to the country his ancestors had left behind. Arriving with McMillan, Lawrence and their wives, he found himself caught up in a world where he had to crown pageant princesses, sign autographs for delirious children and watch as flags were flown in his honour. At the Nobel banquet, he was required to answer the toast given by King Gustaf VI Adolf. Rising, Seaborg dusted off the Swedish he had spoken at home as a child in Ishpeming. He had been practising for weeks. ‘Ers Majestät, Era Kungliga Högheter, mina damer och herrar …’

  There was a shocked gasp among the audience, as if he had just sworn at the king. Seaborg couldn’t understand what he’d done – he’d chosen his words with care. It was only in the morning, when he read the papers, that he found his answer. Seaborg’s Swedish had been flawless, but it had never occurred to him that his impoverished, machinist parents might have had thick working-class accents.

  Seaborg and McMillan did not win their Nobel for discovering elements beyond uranium (the prize is never rescinded, and Enrico Fermi had already claimed that honour). Instead, they won for ‘their discoveries in the chemistry of the transuranium elements’. It was a compromise that worked for them both. Congratulations flooded in from around the world, along with a fair lump of sour grapes. ‘I suppose if you can’t find new elements,’ quipped the British physicist Lord Cherwell, ‘you just have to make them.’4

  Nuclear power, and the elements that had come with it, captured the imagination of the world. Dreamers imagined cars and homes powered by quantities of uranium the size of a sugar cube. Plans emerged to make Antarctica habitable, prevent earthquakes, free up natural gas supplies and even change weather patterns. Ideas were even touted for nuclear bombs contained in hand grenades – until someone pointed out that throwing such a device would be suicide. More realistic uses became apparent too: weapons, energy and cancer treatments. In his later book Man and Atom, Seaborg listed 60 radionuclide sources used in medicine in 1966, treating a combined total of 33,743 patients in the US. Today, nuclear medicine is a standard part of every major hospital in the world.

  The synthesised elements became household names. Plutonium had given the world the atomic bomb. In time, the elements further along the table would find uses too. Americium, it turned out, released a steady stream of alpha particles, easily blocked by anything in the air. Today, my home smoke detector – and others like it around the world – contains 0.9mg of americium-241. It’s more expensive, gram for gram, than gold, and probably the only radioisotope you can buy in your local supermarket.5 Curium, meanwhile, is used to produce alpha particles for X-ray spectrometers in space probes, including the rovers currently roaming the surface of Mars. Berkelium and californium did not have any apparent uses, but as a demonstrat
ion of the superiority of American science they were unrivalled.

  The search for elements had started as scientific curiosity. It then morphed into a wartime imperative and, as the 1950s began, changed once more into a matter of national prestige. It was a sensation that would only grow as the rival ideologies of capitalism and communism began to split the world. Already, tensions were mounting. At Berkeley, faculty members were ordered to take a loyalty oath: just one symptom of the paranoid searches taking hold across the US for anyone considered ‘un-American’. In Europe, the breakdown between the West and the Soviet Union had split Germany in two. In Asia, the Korean War between the communist North and republican South, both sides backed by superpowers, had ground to a stalemate.

  The Cold War had begun. And the edge of the periodic table was about to turn into a battlefield.

  Notes

  1 If this doesn’t sound like much, try slashing your life expectancy by three months and see how you like it.

  2 A synchrotron is a particle accelerator shaped like a ring, rather than a spiral like a cyclotron. The most famous example is the Large Hadron Collider at CERN. These are amazing machines, but too powerful to create elements.

  3 Thompson’s work ethic was staggering. At one point, he and another researcher, Burris Cunningham, worked 36 hours straight in the lab. Stepping outside, they realised Thompson had misplaced his coat. The exhausted duo spent an age searching around until one of them noticed Cunningham had accidentally put it on over his own.