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  • Cornell Dedicates 'G-Line' Facility
Jun 2004
ITHACA, N.Y., June 15 -- A facility producing some of the world's most intense x-ray beams for research, education and training was dedicated at Cornell University today. Built by Cornell and housing equipment purchased through National Science Foundation (NSF) grants, G-Line is dedicated to research and education in technology, biology and materials science.

"This will generate the opportunity for learning to design new beam lines and the next generation of x-ray optics," said Joel Brock, G-line director and professor of applied and engineering physics.

G-line is a division of the Cornell High Energy Synchrotron Source (CHESS), a national user facility funded by the NSF. Because of its federal support, CHESS is open to all researchers on a competitive basis and currently supports roughly a thousand user visits a year. Only about a quarter to a third of the users are from Cornell. By comparison, G-line has 80 percent of its time dedicated to Cornell users, with the remainder open to other researchers in recognition of the NSF support for the facility. Annual operating costs will be paid by 10 of the university's research groups.

The 3 000-square-foot facility, including a 140-foot-long tunnel connecting it to CHESS, is built into the side of a hill. Cornell provided $3 million for the civil construction. The NSF awarded $2.5 million over three years for equipment, which it followed up with three other awards, the largest for $445,000. Much of the equipment was designed and assembled on site by CHESS staff and Cornell graduate students, including the mirror box with its rhodium-coated, silicon mirror, one meter long, for focusing the x-ray beam as it comes off the storage ring. The beam is then split into two, in two vacuum boxes, each containing a synthetic multilayer monochromator crystal. The beams are then focused onto the samples by separate final mirrors. Even the building's heavy concrete walls embedded with iron fragments for radiation shielding were developed at Cornell.

Brock said, "G-line took the tricks learned everywhere else and used novel optics for novel beam lines."

The x-rays are provided by the Cornell Electron Storage Ring (CESR). The half-mile circumference ring stores counter-rotating particle beams that have been accelerated to nearly the speed of light in a parallel inner ring, the synchrotron. Physicists at Cornell's Wilson Lab study the subatomic particles created in the collisions of the beams, and CHESS uses the x-rays created as a byproduct of the beams.

The x-rays escape through beryllium windows located at specific locations in the storage ring and are fed into experimental stations, or hutches, for use by CHESS researchers. For G-line, a new opening was cut into the ring and two x-ray beams were directed into three new hutches. G-line's three hutches will be used almost entirely by graduate students for experiments that will lead to their doctorates, whereas the nine hutches at CHESS have a revolving number of users.

The research in the three new hutches will include the growth of semiconductor films and measuring the time dependence of the size and shape of proteins and nucleic acids as they fold. Many of the research programs use the x-ray beams for investigating new materials, supported by the NSF-funded Cornell Center for Materials Research.

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x-ray optics
The study of the physics of x-rays, where the x-rays exhibit properties similar to those of lightwaves. Also called Roentgen optics.
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