Page 4 of 8
But as the '60s began to wind down, the prestige associated with discovering heavy elements began to wane in America, and a research team in West Germany began to overtake the lab. The Germans built an enormous particle accelerator and pioneered a technique known as "cold fusion," which in the '80s would lead to a series of breakthrough discoveries. At the same time, the Department of Energy was showing less enthusiasm for Seaborg's original line of inquiry, and the lab began to diversify its scope of research, until today the work that was once the centerpiece of LBNL's mission is a lonely stepchild. The more advances Seaborg, Ghiorso, and Hoffman made in nuclear science, the less there was to learn, and the less interested the lab's directors were in pursuing them.
"Nuclear science was much more mysterious than it is today, we really hadn't figured anything out about it," says Pier Oddone, the deputy director for research at LBNL. "Today, the laboratory's centerpieces are much different: It's the work that we do with X-rays, and a huge program with biology and material sciences, trying to understand at the atomic level how materials are put together. Investigating protein structure, for example, is much, much bigger than looking at heavy elements. In a $400 million lab, I'd say there's maybe a million dollars worth of work in that line today."
Ghiorso believes that the lab lost a critical opportunity to stay at the cutting edge of heavy element research in the late '60s when the perverse national priorities of the era wiped out the budget of the LBNL heavy element team. "I'll tell you what the key thing was here: the Vietnam War," he says. "We were designing a machine here called the Omnitron, and it was going to be the first complicated accelerator in the world. It would still be the best machine in the world today, and if we had built it, we would have gone all the way. But we estimated that the Omnitron would have cost $30 million at the time. During the Vietnam War, we would shoot $30 million [in ordnance] every shift, three times a day, every day. And there was nothing we [at LBNL] could do about it. If I'm gonna blame anyone, I'm gonna blame Johnson's and Nixon's war."
Of course, it didn't help that conventional wisdom within the nuclear science establishment of the '60s predicted a natural end to heavy element research. In 1964, Swiatecki first published his "islands of stability" theories, but most researchers suspected that we had reached the limit of new elements waiting to be discovered. In 1976, Ghiorso himself told the New York Times that he didn't believe in the existence of superheavy elements, even as he was overseeing the laboratory team that was trying to find them.
To understand Ghiorso's skepticism, you have to understand the internal nature of an atomic nucleus, which is perhaps best described as suffering from multiple personality disorder. The nucleus of every atom is composed of neutrons, which provide mass but carry a neutral charge, and protons, which carry a positive charge. It is the protons that are the key factor in determining the element's distinctiveness and its atomic number; a carbon atom, for example, is defined by the fact that it has six protons in its nucleus. But protons don't actually want to be in nuclei. According to the theory of electric repulsion, particles with like charges repel one another, and while the electrons in the atomic orbital shells are separated from each other by comparatively vast distances, protons are crammed together in nuclei, even as they fight to get away from one another.
What keeps protons from splitting a nucleus apart is a phenomenon known as strong nuclear force. Each proton and neutron (which are collectively known as nucleons) are composed of smaller particles known as quarks. The forces that hold the quarks together in a nucleon create a residual force that causes nucleons to attract one another. When a batch of neutrons and protons are crammed close together, strong nuclear force overrides electric repulsion and keeps the structure of a nucleus intact. But strong nuclear force has a very short range, while the range of electric repulsion is much longer.
This is why Seaborg and Ghiorso had to use particle accelerators to discover, or build, heavy elements. Seaborg's team would take a light element like helium and use radio waves to infuse it with energy. That energy would be expressed kinetically, i.e., the element wanted to move very fast. They then steered it down a path and collided it into a target, typically a thin strip of a heavy element like plutonium. The protons in plutonium and helium don't want to get anywhere near each other, but Seaborg and Ghiorso infused the helium with so much energy that it overrode the mutual repulsion and got just close enough to the plutonium nucleus to come within range of the strong nuclear force. At that moment, the two nuclei would latch onto one another and fuse.
Seven Days - April 28, 11:36 AM
Seven Days - April 26, 6:48 PM
Seven Days - April 26, 12:16 PM
Seven Days - April 24, 7:24 AM
Seven Days - April 21, 2:12 PM