From Georgia with innovation: A profile of Jefferson Lab staff scientist Youri Sharabian
Innovation comes naturally to the Jefferson Lab staff scientist. A native of the former Soviet state of Georgia, Sharabian, whose father and two brothers were engineers, grew up in the capital city of Tbilisi
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What looks like half a zebra-striped rugby ball sits solidly on a rectangular steel plate, on top of a chest-high file cabinet in Youri Sharabian's office. As the Jefferson Lab staff scientist pulls the contraption down from its resting place, holding the plate on either side and then handing it to a visitor, it's clear that the steel is by far the heaviest component. The white rugby-ball-like material, joined with thin strips of black epoxy, is actually lightweight Styrofoam, Sharabian explains. The Styrofoam is about three-fourths of an inch thick and weighs about one and a half ounces.
But this prototype chamber cell's size and appearance are deceiving. In initial tests, as air was withdrawn from its interior to create the purest possible vacuum, the handmade cell withstood an equivalent force of 1,300 pounds from atmospheric pressure bearing in from every direction. Meantime, inside, less than one-millionth of a normal atmosphere remained.
"It worked! Which surprised even me," Sharabian recalls. "It worked perfectly for one hour, and then I heard a crack. It was the foam shrinking while the epoxy joint remained the same. But even one hour meant that we could scale up [this design]."
Afterwards, using the same basic approach, Sharabian fashioned a second scattering chamber, which held nearly perfect vacuum for months without deteriorating. Now in Hall B, the full-scale scattering chambers, made from an ultra-light but strong plastic foam known as Polymethacrylimide (PMI) foam, are operating on a routine basis (the Hall B detector, known as CLAS, for CEBAF Large Acceptance Spectrometer, measures scattered beam and particles produced during interactions between the beam and a target material).
Construction is fast: a few days versus a month. Although not as resistant to radiation damage as those built from metal, the cells can be easily swapped out and replacements quickly added. Because the cells are spherical and far less dense than their conventional counterparts and also hold a vacuum, they will provide nearly 100 percent geometrical "acceptance;" that is, accurate measurements of particle interactions. Inadvertent collisions that interfere with sought-after experimental results will thus be greatly reduced or eliminated altogether.
"Designing new things, testing new things makes me happy," Sharabian says. "It's a very satisfying feeling when you come up with something and the result is good. Here I don't feel any limits. That feeling has always made me very excited."
Innovation comes naturally to the native of the former Soviet state of Georgia. Sharabian, whose father and two brothers were engineers, grew up in the capital city of Tbilisi. By the time he was in 7th grade, Sharabian had built a small workshop in his family's basement, outfitting it with an array of tools. Among his creations was a cylinder-and-piston engine that ran on compressed air, which he would later use as a home-aquarium pump.
When Sharabian's father, who worked in a Tbilisi-area plant making large-motor parts, came home with a new design for small engine springs that kept components separated from electrical contact, but complained of the difficulties in making the springs quickly, Sharabian was intrigued. Working in his basement workshop, the younger Sharabian subsequently fashioned a specialized apparatus that included a small motor and gearbox capable of winding wire accurately and rapidly. Some 400 springs could thus be made per hour, more than 13 times the 30-per-hour-rate then possible at the plant. Sharabian's father was so impressed with the son's ingenuity that the innovation was adopted with minor modifications directly onto the factory floor.
But it was the United States that really caught Sharabian's fancy. His eldest brother would bring home books and magazines on American culture. So it was that Sharabian became fascinated both by American architecture -- skyscrapers and bridges in particular -- and by a unique form of musical expression.
"I loved American jazz. That made me interested in American culture," he comments. "I knew about the United States well before I came here. What I knew was what I read and heard, maybe one percent [of reality]. What I experienced when I came here -- the other 99 percent -- was even better than I had imagined."
With a master's degree in experimental nuclear physics from Tbilisi State University in 1971, Sharabian set out for Yerevan Physics Institute in Armenia, where he obtained a Ph.D. in experimental and elementary particle physics in 1981. His leavetaking was not an easy one, a "very difficult time," Sharabian recollects, even though he eventually found a "very exciting and satisfying life" in Armenia. Even so, he says his arrival in the United States in the early 1990s and his decade-long stay at JLab have been equally rewarding: "People in the United States are very, very friendly. They're ready to help." If he had it to do all over, Sharabian says he would take the same career path.
Sharabian is now finishing up the evaluation of a new type of calorimeter he's designed. The first prototype being built is one in which 5,500 optical fibers are glued to a receiving plate and the gaps between them filled with flour-like tungsten powder. Because calorimeters measure the energy and position of emitted particles, more fibers of smaller diameter with the gaps between them filled translate into higher performance. In addition, the new calorimeter's configuration should provide an effective means of creating three-dimensional images of the resultant electromagnetic showers. Given the calorimeter's compact architecture, Sharabian estimates his design will increase individual calorimeter efficiency by at least 25-30 percent.
"These are exciting times at Jefferson Lab," Sharabian says. "I'm happy here. I'm not planning to stop anytime soon. As long as I'm needed, I'd like to stay."