Even as wide-eyed researchers learn to use Argonne National Laboratory’s giant new X-ray machine, the lab’s leaders explore building another machine to make X-rays 100 times more powerful.
As exciting as the discoveries promised by Argonne’s Advanced Photon Source, a giant X-ray laser would be even more awesome in its ability to shed new light on nature’s secrets, say Argonne officials. Failing to plan for the next generation X-ray technology now would be irresponsible, they say.
But for dozens of scientists from companies and universities around the country who are just settling in as partners in using the APS, today’s technology blows away the science they could do with their old equipment.
For example, when Roger Leach studies catalysts using older equipment in his own company’s lab, “it’s like doing an autopsy” because the isolated chemicals he views are far removed from their normal venue–the lively interactions that churn out products from synthetic fabric to pesticides.
These days Leach is pleased to watch chemical reactions roaring away pretty much as they do in factory vats. He can see up close how molecules move as they change from one substance into another.
This is no small matter for Leach, who works for Du Pont Co., the giant chemical firm based in Wilmington, Del.
“In many ways using a catalyst is like magic,” said Leach, who heads Du Pont’s research team at Argonne. “We put in some metal and help the reaction go, but we don’t really understand why.”
By improving their understanding of chemical reactions, Leach and his colleagues hope they can improve upon existing commercial processes. This could mean making more product with less raw material, running processes faster or increasing purity of end products.
Argonne’s APS cost about $500 million to build, and the scientists using it are spending another $500 million for equipment to use the X-ray beams. The beams are produced by a huge machine, called a synchrotron, that creates bursts of positively charged electrons, which can be made to give off X-ray energy.
Leach said that Du Pont has used synchrotron X-rays to do research for 15 years and it jumped at the chance to come to Argonne’s state-of-the-art machine.
But while Du Pont’s chemists are familiar with doing X-ray science, the brilliance of the APS beam is also attracting researchers previously unfamiliar with the technology to do things never before possible.
Steve Pratt, an Argonne chemist, for instance, now makes detailed images of tiny globs of fungi that attach themselves to plant roots. His ability to X-ray delicate plant roots as if they were someone’s broken wrist is providing new insights into how fungi enable plants to absorb some heavy metals safely.
The bright X-ray beams at Argonne can pick out trace elements that exist in concentrations of only a few in a billion parts of their host material.
“The fungi improve a plant’s ability to extract nutrients from soil,” said Pratt, “but we’re only now seeing how this works.”
The same X-ray imaging techniques are being used by another Argonne scientist, Wenbing Yun, to analyze the structure of tiny laser-emitting semiconductors for Lucent Technologies. The goal is improving that structure to make them work longer and more reliably.
Mark Rivers, a University of Chicago geologist, is using the X-rays to watch what happens to molecules of iron that are compressed by forces equivalent to those deep inside the Earth. He and colleagues hope to learn more about the planet’s core through these studies.
From materials science to pharmaceuticals, researchers using the APS say they are pleased at the new precision with which they can now peer at the physical world.
But as pleased as he is with the new machine’s operation, David Moncton, the APS director, said he isn’t satisfied to sit back and watch as the research benefits of the new machine roll out over the next several years.
Instead Moncton is working with scientists at other national laboratories to plan the next generation X-ray machine, one that would be 50 orders of magnitude brighter and 100 times more powerful than the APS.
Building such a machine, a genuine X-ray laser, is a daunting task. It was at the center of former President Reagan’s Star Wars initiative–a laser to zap missiles from space.
But the X-ray laser envisioned by Moncton and others wouldn’t be a weapons-grade missile-zapper or a budget-busting multibillion dollar Pentagon mega-project.
“This would cost on the order of $1 billion to build,” Moncton said.
That is only about double the cost of the basic APS synchrotron, but even though an X-ray laser’s value to science would certainly be huge, its construction is far from a cinch.
For one thing, Moncton said, new physics will have to be explored to determine if the laser as contemplated is possible to build. When the APS was first conceived nearly 15 years ago, scientists knew the basic physics behind their plan would work if they could only produce the technology to bring it off.
A major hurdle will be to see if taking today’s synchrotron technology to a new level can produce X-ray laser beams.
Synchrotrons are large machines that accelerate subatomic particles such as electrons to near the speed of light. As bunches of electrons turn corners, they give off X-ray energy. By using magnets to wiggle the electrons as they zip along, physicists have found they can make the X-rays extremely bright.
It seems likely that if the electrons can be wiggled long enough and hard enough they would arrange themselves in phases and produce X-rays of identical length, which would be an X-ray laser.
To test this idea, Moncton and his colleagues plan to build an extended magnetic wiggle line and use existing equipment to fire bunches of electrons down the line.
On the scale planned, the experiment wouldn’t produce an X-ray laser, but if it produced an ultra-violet laser, that would be a good indication that it is feasible to make an X-ray laser by advancing synchrotron technology.
Recent results from Brookhaven National Laboratory in Upton, N.Y., which has a less powerful synchrotron than Argonne, suggest that microwiggler magnets can produce the hoped for brighter X-rays.
