by Kit Chapman
Then the SHIP team decided to try cold fusion. In the time since Oganessian’s discovery, cold fusion had seemed dead in the water. Flerov had no interest in it and insisted the Dubna team went back to their previous scientific programme. Likewise, Berkeley remained unconvinced and still focused on Al Ghiorso’s mantra: 1 alpha is worth 1,000 spontaneous fissions. Neither decision is as ridiculous as it may seem in hindsight – Oganessian’s tests had largely been a proof of concept. Any reliable discovery would require a particle accelerator that was capable of firing beams of ions far heavier than anything the Americans or Russians could accomplish and a detector more advanced than anything else in the world.
Fortunately, that’s exactly what GSI had.
Oganessian remembers the Germans attempting to lure him to GSI, offering him a chance to run his beloved cold fusion and even bring his entire team over. He refused and remained in Dubna, though he couldn’t resist sneaking in cold fusion experiments whenever he could.
Heinz Gäggeler, on the other hand, decided to take the Germans up on their offer. He had seen cold fusion in action under Oganessian and knew the Germans were the only team capable of pulling it off. ‘It wasn’t like they were stealing [the idea of] cold fusion,’ Gäggeler stresses. ‘If you want to produce elements with cold fusion, you need excellent beams and excellent detectors. At that time, the technology in the Soviet Union was lower than in the West. GSI had SHIP, but even so they still had a hard time. Three years without success … although, these days, nobody talks about that part.’
The three years came and went. They were not wasted. The team were learning, working out how to measure some of the rarest events in the world, which in turn created the rarest elements in the world.
Then in one week, from 12 to 17 February 1981, Münzenberg’s team bombarded titanium into a bismuth target. Sure enough, the two nuclei collided, used that kick to sneak through the Coulomb barrier, then discarded a single neutron to reduce the chance of fission. The reaction produced the still-disputed element 105, before alpha-decaying into element 103.
Cold fusion worked.
A week later, on the morning of 24 February, the team tried a chromium beam (two protons heavier) into the target. At 10.48 a.m. they produced something. It followed the chain they had previously detected perfectly: first alpha-decaying into element 105, then into element 103. Nine hours later, they succeeded again; and again; and again. In four days, they had multiple perfect, pristine alpha decay chains, some even going down as far as californium before breaking apart. The atom’s mass was confirmed by its time of flight and its energy as it landed on the detector. ‘Within one week, we measured six decay chains,’ Hofmann recalls. ‘After this, Seaborg and the Berkeley people became interested. Flerov from Dubna too. They came to Darmstadt to visit our experiment.’
Seaborg arrived in September, Flerov in December. The two made an impression on Hofmann. Seaborg was ‘a great man, tall and serious’ … Flerov was ‘also a great man but younger, not so tall and not nearly so serious.’ Both giants of the superheavy world were impressed by the GSI team. Cold fusion didn’t produce a lot of atoms (by 1988 only 38 atoms had been created) or isotopes with very long half-lives. It didn’t matter. For the first time since 1955, everyone agreed that an element had been discovered and who had discovered it first. The Germans had created element 107.
GSI had gone from a clearing in the woods to the leading heavy element lab in the world in six years. Ghiorso flew to Germany with curium, hoping to make element 116. The experiment was a failure. So too was an attempt at Berkeley, with the GSI team flying out to join the Americans. Münzenberg loved Ghiorso, but the two tinkerers disagreed on the best way to proceed. Ghiorso wanted to leapfrog the unstable elements and head straight for the island of stability. The Germans, meanwhile, pointed out that this would have been impossible to prove. An alpha decay chain, for example, would have to pass through five unknown elements – each with unknown half-lives or chances of fission – before it joined up with known decay chains. Even if they succeeded, it would take years, perhaps decades, to prove the claim.
Instead, Münzenberg opted for another cold fusion experiment, this time looking for element 109. The reason for ignoring 108 was simple: even-numbered elements were more prone to fission. By leapfrogging, the team had a far better chance of creating one of the beautiful alpha decay chains that showed everyone exactly what had been made.
The new beam was made from iron-58 – a rare, expensive isotope that only makes up around 0.28 per cent of iron in nature. In August 1982 the team started the experiment. After five days they had the first sign of 109. After another 10 days, they had another. The team had been lucky – the hit came barely two minutes after they noticed they had run out of disk space and changed computer files. Two hits weren’t enough to prove the discovery conclusively, but GSI were on a roll.
‘In 1984,’ Hofmann recalls, ‘we studied iron plus lead (element 26 into element 82) and observed three decay chains, which decayed into the chain we’d previously studied. It was clear it was 108.’ This wasn’t expected: everyone suspected the isotopes would fission away rather than go through alpha decay. ‘It was a sensation,’ Armbruster and Münzenberg would later write in the European Physical Journal H, ‘which became even bigger in the following experiment when we produced the [...] isotope 264 of element 108.’
As new experiments demystified the complex mechanics of nuclear forces and discovered yet more isotopes and decay chains, the GSI results were confirmed. By 1989, when Münzenberg was promoted to director and Hofmann took over the team, the Germans had irrefutable claims to elements 107 to 109.
The Germans were in the driving seat – and everyone else was scrambling to catch up.
Notes
1 The Hanford site, where Thompson worked, is now known as ‘the most toxic place in America’, contaminated with leaking nuclear waste that costs billions to clean up. In 2018 a bill was signed into state law approving compensation for Hanford workers for a range of conditions, including several types of cancer.
CHAPTER FOURTEEN
Changing the Rules
In 1980 Glenn Seaborg accomplished the alchemist’s dream of turning a heavy metal into gold. The Berkeley accelerator was loaded with bismuth foil (lead’s neighbour on the periodic table – bismuth only has one stable isotope, so it’s easier to separate), which was soon pelted with carbon and neon ions. The beams chipped off protons and neutrons, leaving scattered fragments of gold dust. Seaborg had become the modern King Midas. It was a stunt: the experiment cost a day of beam time (worth about $120,000) to make quantities so minute they could only be detected through their radioactive decay. ‘It would cost more than one quadrillion dollars per ounce to produce gold by this experiment,’ Seaborg reported to the Associated Press. Even so, he had shown once and for all that science had surpassed alchemy.
In 1984, just as GSI was discovering element 108, another miracle happened: Darleane Hoffman broke her 40-year-old vow and agreed to become a teacher. Stepping away from Los Alamos, she took up the position of tenured professor at Berkeley, and with it the leadership of the heavy element group. Ghiorso happily folded under her wing, bringing his endless enthusiasm (sometimes, a little too much enthusiasm) to whatever their latest project happened to be. The three US superstars – Hoffman, Ghiorso and Seaborg – were all in one place, bringing a combined 125 years of heavy element experience to the table.
But the climate in the US for element hunting soon changed. On 2 April 1986 a late-night safety test at the Chernobyl power plant, near the town of Pripyat on the northern frontier of Ukraine, went horribly wrong. At 1.23 a.m. the plant’s number-four reactor exploded, shooting its parts through the roof of the building and starting fires across the complex. Almost 7t of radioactive matter scattered into the atmosphere.
The Chernobyl accident shifted US public opinion of nuclear power. Already, a less serious accident at the Three Mile Island Nuclear Generating Station in Pennsylv
ania on 28 March 1979 had made the public wary; Chernobyl tilted warped perceptions into outright fear. Nuclear opposition cited the ‘China syndrome’: that if a core went into meltdown, it wouldn’t stop tunnelling its way through the Earth until it reached China.1 The climate that had emerged in the 1940s and 1950s, a world excited at the prospect of new, clean and boundless energy, was over. Nuclear power was a pariah.
For Seaborg, the scepticism was a blow that almost unravelled his lifetime’s work. ‘I can’t claim to be blameless,’ he wrote in his autobiography. ‘My early boosterism of nuclear power may have contributed to later problems […] plants were prematurely escalated in size to proportions that strained the technology and magnified the potential consequences of an accident, no matter how unlikely.’
As political will faded and budgets shrank, the entire science of radiochemistry came under threat. It was a problem only compounded by the veil of Cold War secrecy. Sometimes, information couldn’t be published because of national security. On other occasions, the culture of mistrust and caution meant details that could and should have been shared were kept under wraps. There was also a lack of new blood in the labs. As the older element hunters refused to retire, the pipeline of younger researchers was blocked, limiting opportunities for recruitment. A few brilliant candidates found placements; many others looked elsewhere for their careers.
Funding cuts were even more devastating. Berkeley couldn’t call on the deep pockets of the government any more. The team asked for a rare nickel isotope for their beam to hunt for element 110; they were told the money wasn’t available. They asked for a separator as good as the German SHIP, but funds went elsewhere. Eventually they had to build the machine themselves from spare parts – its emergency valve, designed by Ghiorso’s son Bill, was made from the spring of a rat trap. Ghiorso, never one to pass up a good name, called it the Small Angle Separator System (SASSY).
Despite its make-do innovations, SASSY had no new elements to separate. Super-HILAC was hooked up to the bevatron, the giant velodrome-sized accelerator that dominated the hill, for use as an injector. The new combined monster – originally Ghiorso’s brainchild – meant other groups whose projects had more immediate applications sucked up every ounce of funding and beam time. On the rare occasions Super-HILAC was available, misfortune would inevitably strike. On one Friday, with the GSI team visiting, the entire lab was suddenly plunged into darkness. The local power company had an agreement with Berkeley Lab to cut the lab’s power if they were using too much juice – and Ghiorso’s machine had just pushed past the limits. The Americans and Germans scrambled about in the dark, talking over each other in complete confusion. It was such chaos that everyone forgot to turn off the helium flow to the separator. In an almost exact repeat of the 1959 HILAC explosion, the helium pressure rose and punched through the entrance window, breaking the curium target.
Fortunately, instead of showering the lab, the curium just contaminated SASSY. ‘Poor Ghiorso,’ Sigurd Hofmann later wrote in On Beyond Uranium, ‘he now had to spend the weekend cleaning up the mess. The rest of us felt guilty but left him to it; without special permission we were not allowed to help.’
* * *
If things were tough for the Americans, in Dubna Flerov’s group were feeling the effects of the Soviet Union crumbling around them. As the Cold War funds dried up and the Eastern Bloc began to crack, the JINR scientists started to see their funds wither, dwindle and die away. If they wanted to continue their work, they would have to do something drastic.
In 1989 Flerov was attending one of the regular superheavy conferences that saw the scientific community come together. Until that point, any Russian collaboration with Americans had been through private universities or formal visits (even if they occasionally broke down into Johnny Rivers jive sessions). Flerov decided that this would end. He spoke with Ken Hulet, the head of the delegation from Livermore, and suggested they join forces.
The two men chatted at length. Dubna had a cyclotron. Livermore had targets to use and expertise in detectors and equipment. Unspoken, but equally important, Livermore also had a level of scientific credibility; while the Russians were brilliant scientists, the battles with Berkeley had cast a shadow over their accomplishments. If Livermore came on board, Berkeley couldn’t question the validity of their experiments any more.
Hulet and Flerov, chemist and physicist, ended their chat with a handshake. It was unprecedented. The Americans and Russians had bridged the Cold War divide. Dubna and Livermore – a Soviet lab and a US nuclear weapons facility – were partners.2
A few months after Flerov’s pact with Hulet, the Berlin Wall fell. Early the next year, the first Livermore researchers, Ken Moody and Ron Lougheed, arrived in Dubna. There were the usual Cold War hassles – only one long-distance phone call permitted, KGB wiretaps in the hotel and minders around town – but once the team passed into the lab, there was only science.
Georgy Flerov had witnessed the history of nuclear physics writ large in technology, warfare and diplomacy. Finally, as the shadows of a silent war between superpowers fell away, he had masterminded the coming together of the US and USSR as a team. It was probably his greatest accomplishment. He would never see its results. In November 1990 he died suddenly in Moscow, aged 77. In Dubna all work stopped for three days as the team reacted to the loss. Moody and Lougheed were still in the USSR at the time, and attended the numerous memorials and services held in Flerov’s honour. The collaboration had lost its leader, but the work would continue.
Flerov also missed the concluding phase of the transfermium wars. In 1986, at the request of the Germans, the governing bodies of chemistry and physics, IUPAC and IUPAP, assembled a working group to settle the debate surrounding the superheavy elements. Known as the Transfermium Working Group (TWG), its members had to define when an element counted as being made, and who had got there first. It was like playing the first-ever game of football, only for the referee to explain the rules and work out who scored first after the match had ended.
Science was changing its rules. Yes. It can do that.
* * *
For the past 120 years everything in the world has slowly been getting slightly lighter. It’s because a lump of metal in a Parisian suburb wasn’t doing its job properly.
For millennia, there had been no need for everyone to have exact weights – nothing in the world required that level of precision. But by the end of the Victorian era, this was beginning to cause problems. Measurements were becoming so exact that it became essential to have a set standard for mass.3 In 1889 scientists agreed to define a kilogram as the mass of Le Grand K, a cylinder of platinum-iridium alloy at the International Bureau of Weights and Measures in Sèvres. The mass of Le Grand K would always equal exactly 1kg (2.2lb): no more, no less. Once every 40 years, the weight was taken from the vault and used to verify the mass of 67 copies stored around the world. From there, the mass of everything, from your bathroom scales to your grocery shopping, was set accordingly.
Le Grand K is stored at constant humidity and temperature next to six accompanying kilogram weights in a triple-locked vault. Security is so tight that one of the necessary keys to access it is usually kept abroad. Until recently, the reason for this pantomime lockdown was simple: if Le Grand K changed (for example, if someone cut a bit off), then the definition of what counts as a kilogram would suddenly shift. It may sound like the madcap ploy of a James Bond villain, but you can’t have someone monkeying around with the weight of the world.
Fiendish plots aside, the real problem is that Le Grand K has been gaining mass for decades. Even in its carefully controlled vault, tiny air pollutants – invisible specks of dust – can settle on the platinum, making the lump slightly heavier. This meant the definition of the kilogram became heavier, so everything else in the world officially became lighter.
This couldn’t go on, so in 2010 the International Bureau of Weights and Measures decided to change the rules. Rather than define a kilogram based on Le G
rand K, the bureau agreed to base the weight of a kilogram on the Planck constant – a fixed number central to modern quantum physics.4 Bizarrely, that also links the kilogram to the definition of the metre and the second – but at least it means we don’t need to worry about the mass of the world shifting if something happened to Le Grand K. By the time you read this, the switchover has probably happened (it was scheduled to take place on 20 May 2019).
These changes to things we think of as basic rules of the universe – when was the last time you doubted if the kilogram was real? – aren’t just idle tinkering. As science evolves, we always need better definitions. For the Victorians, Le Grand K was enough; today we’re at such a level of precision that it just won’t do.
By the late 1980s the same thing had happened with element discovery. For Antoine Lavoisier in the eighteenth century, an element was something that couldn’t be simplified; for Ernest Rutherford, it had been defined by having a unique number of protons in its nucleus. But nuclear science teams were already playing around with quasi-fission, making elements that almost came together before breaking apart. Did that count as a new element? And what proof did you need that anything had happened at all?
In the meantime, everyone else had a headache when trying to talk to each other about elements. If someone said ‘rutherfordium’, for example, did they mean the Russian name for element 103, or the American name for element 104? The situation had become so fraught that IUPAC even introduced ‘placeholder’ names for the elements based on their atomic number. Element 104 became ‘unnilquadium’ (one-zero-four-ium); 112 was ‘ununbium’ (one-one-two-ium). ‘In this Cold War, one of your strongest weapons in the public relations battle was the name you proposed for “your” element,’ explained Norman Holden, the man who invented the system, in the magazine Chemistry International. ‘You would never give up your strongest weapon and accept a neutral name. This would indicate that you didn’t believe strongly in your scientific case for the right to discovery.’