Little Things in Small Places

Little Things in Small Places
The Columns - Little Things in Small Places - Summer 2007

Even if you have no idea what a “Large Hadron Collider” is, you can guess that it won’t fit in your broom closet. 

Headlines around the globe have hailed a 17-mile underground ring that goes from France into Switzerland and back again, the $8 billion it took to construct this Hubble Space telescope of the subatomic, and the millions of collisions per second that are to reveal secrets of the universe. More recently, there’ve been accounts of a small design flaw (something about three not being equal to two, it turns out) delaying the whole project at least a year.

Denison physics professors Dan gibson and wes walter are not competitive fellows by nature, and they would take no pleasure in the discomfiture of their colleagues. But they do point out that high energy particle physics, the kind that needs supercolliders and megabudgets to research, has won two Nobel Prizes in the last ten years. gibson and walter’s branch of physics—atomic, molecular, and optical (AMO)—has won three.

Much of the kind of research that breaks new ground in AMO can be done in spaces smaller than a 17-mile buried concrete torus. In fact, an expanded storage area in the basement of Olin Science Hall will do. 

Down the hall from the planetarium (Nobel prizes for astrophysics and cosmology in the last decade: two), behind some warning signs about wearing eye protection “or you’ll shoot your eye out, kid,” is Denison’s own research device. “Negative Ion Accelerator Mass Spectrometer” sounds like it could cover acres, but gibson and walter, together with many student researchers, have built this ten-foot-long assemblage, with a ninety-degree angle in the middle, out of a mix of precision tooled stainless steel fittings and some heavy duty aluminum foil (from the local grocery store), which “concentrates heat and reduces humidity in the ultra high vacuum,” walter reports. “Nothing else works better.”

“The right angle bend is where we sort the ions,” says walter, his eyes lighting up as he points to collection boxes and readouts branching off the turn, “then they enter the mass spec where we get more readings along here.” given that he and gibson built most of what makes this gadget work, their pride is evident and justified. the initial components of the system were funded by a 1998 National Science Foundation grant awarded jointly to gibson, walter, and two of their colleagues, Kim Coplin ’83 and Mike Mickelson. Gibson and Walter, who started researching negative ions together shortly after they both arrived in 1996, have since landed three more NSF grants that enabled them to design and build the new and improved apparatus, which was fully operational by July 2005. throughout the process, they have enlisted the help of about 20 students to build the equipment and run experiments.

“Atomic physicists are gadget builders,” gibson explains. “the creativity is in how we design our approach to our research. grants are given based on what is judged interesting, but also on whether your plan is going to be cost-effective and successful.” He points to what would be a hanging extension cord in any other workshop (which is what this space looks like, with a negative ion accelerator where the radial arm saw ought to be). But here, it’s another example of the genius behind their carefully-devised long-term strategy. “this is part of our fiber optic network which runs through the ceilings to other labs on this floor, so students and faculty can all use the laser for a variety of applications.”

Lasers? Walter explains that “this is both a mass spectrometer and a laser spectrometer,” pointing out eight pumps that create an ultra-high vacuum, a trillion times below atmospheric pressure, which allows the equipment to carefully sort and analyze negative ions. two lasers are required for the process. the first, a solid-state laser, fires four-nanosecond bursts of light through a man-made ruby, making it millions of times brighter than a standard lightbulb. this then powers the second laser, through which they can control the light colors they use to study various ions. (the problem they’re facing now, however, is that high-energy lasers go through parts fairly quickly, and some of those parts are increasingly hard to find. So they’ll soon have to seek the few hundred thousand dollars needed to purchase a new laser.)

What the physicists are looking for is “specific, fundamental information about atoms. we still don’t know everything about the atom itself,” says Gibson. Apparently, while the physics world ran off after quarks and muons and strings—the sub-atomic particles that are so often the focus of PBS specials—they left behind an incomplete understanding of the atom.

“Knowing more about the structure of the atom and how the various forces hold the electron shells together can give us useful information that ranges from time-keeping (atomic clocks) for very precise applications to nanotechnology,” Walter explains. “The thing we’re most interested in is how electrons talk to each other, which will help us determine how to design better molecules.” Work with emission patterns of electrons, or visualizing the outline of individual atoms and the structure of molecules, can have significant applications, such as creating new substances like Kevlar, designing new pharmaceuticals, and tracing the development and health of wetlands using the trace element Selenium. 

It’s the kind of research that can even dislodge prevailing theory, as Walter helped to do during his post-doctoral work at SRI International, where he and a few colleagues helped prove that calcium can in fact form a stable negative ion. As a result, many textbooks had to be rewritten. 

Gibson and Walter, along with several of their student researchers—who this summer include Corey Janczak ’07, Ali Snedden ’08, Richard Field ’09, and Jacob Shapiro ’10—are now trying to unlock the atomic secrets of lanthanide, or “rare earth” elements (the second row from the bottom of the periodic table). Their strategy is to learn all they can about cerium, which will in turn reveal properties of the rest of the lanthanides. They’re pleased with their progress to date, as is the physics academy, judging from the favorable reception of their work earlier this year at the American Physical Society–Division of Atomic, Molecular, and Optical Physics Conference in Calgary, Canada.

“The thing we’re most interested in is how electrons talk to each other, which will help us determine how to design better molecules,” says Wes Walter. 










As proud as they are of their homebrew in the basement, they are even more pleased with the opportunities it has created off-campus. Over the last several years, four Denison students together with Gibson and Walter have earned access to a major research device at the Lawrence Berkeley National Laboratory, a project of the U.S. Department of Energy and the University of California. There, in a facility overlooking the San Francisco Bay, working among current and future Nobel-honored scientists, they conduct the research that they designed in Olin on an Advanced Light Source (ALS), which produces X-ray light one billion times more intense than the sun. 

Getting time on the ALS is like getting time on the Hubble Space Telescope or the Fermilab Collider—high demand, limited availability, and a rigorous screening process mean not everyone gets to run their experiment on the equipment. The fact that Denison students have used the ALS means that their work in the Olin basement is giving them a good foundation in the competitive world of current physics research, even before they look at grad school. Could the gadget help someone win a Nobel? That’s a stretch, perhaps, but looking at the record, they may have as good a chance as they would with something that encircled Granville.

Published August 2007