Everyday Science, em 09/02/2011
Synchrotron light
An electron accelerator ring of 146meters in diameter, is the newest project of the National Synchrotron Light Laboratory (LNLS), Campinas (SP). With a frequency range of light rays wider, the new machine can work in more applications than the UVX, the ring current.
The importance of this type of equipment to Brazil was the theme of the talk of the physical Antonio Jose Roque da Silva, director of the LNLS, during the 62nd Annual Meeting of the Society for the Advancement of Science (SBPC), which ends on Friday, Natal.
Budgeted at $ 200 million, Sirius, as it was called, is a synchrotron light source of the third generation, with applications in diverse areas of knowledge, as nanobiologia, pharmaceuticals, energy, microelectronics, food, materials and paleontology.
Electron accelerators
Synchrotrons are electron accelerators that produce different frequency bands of light, each one useful for one type of application and may involve studies of structures at the atomic, molecular, microscopic or macroscopic.
The UVX currently operates with an energy of 1.37 GeV (gigaelétron volts), which can generate electromagnetic radiation that go to the range of soft X-rays.
Sirius, in turn, will work with 3 GeV, which, besides generating more light intensity, will also expand its range of power to the hard X-rays, allowing the study of more dense structures.
“Can we see the interior of a fossilized dinosaur egg, for example, we can not do today,” said Roque da Silva. The professor also at the Institute of Physics, University of São Paulo (IF-USP) said that paleontology and archeology are areas that still use the services of very little current ring of light.
Electrons zigzag
The first generation of synchrotron rings appeared in 1940 as a result of the first particle accelerators. The machines geared to cause collisions between atomic and subatomic particles had an undesirable effect: energy lost because of synchrotron radiation emitted along the path.
This radiation began to be tapped for experiments for analysis of molecular structures. Workstations were upgraded in sections of particle accelerators that emit such radiation.
It was a matter of time until they came on the scene rings specific to synchrotron light emission, with no intention of making particles collide. Was born the second generation of rings, which is part of the UVX, LNLS, which has been operating since 1997 and was the first of its kind in the Southern Hemisphere and is still the only one in Latin America.
The third generation of rings makes use of magnets called insertion device. Installed in straight sections of the ring, these magnets make electrons move in a zigzag pattern, which provides new radiation.
With only four straight and 30 meters in diameter, the UVX has physical limitations to receive insertion devices, while Sirius will have 18 straight sections and a diameter of 146 meters, he explained Roque da Silva.
“The new degree of technology to study the matter in line with the synchrotron, is the free-electron laser, which is a much more expensive technology and has a much smaller range of applications,” he said.
Dipole permanent magnet
The director of the LNLS also highlighted the expertise that the country has achieved in synchrotron technology to build your own ring light. About 85% of the work and the technology employed in the national assembly are UVX, which generated a rare knowledge in the world. “If we had not built the first ring, we could not design this second,” he said.
LNLS workshops are already building prototype parts for use in Sirius, including an unprecedented worldwide, the dipole with permanent magnets. On the device, electrons are accelerated around the ring magnets driven by electricity.
The laboratory staff has proposed the replacement of permanent magnets, electromagnets, which would represent a significant energy savings. The difficulty of working with bricks of magnetic metal, among other factors, has inhibited its use in rings. Therefore, Sirius will be the first ring of the world to operate only with permanent magnets.
The new machine will also have one of the brightest torches in the world and one of the lowest among the largest emittance synchrotron machines designed and operating. The emittance sets the brightness of the source and the lower the value the better the quality of light. “When completed, Sirius will be among the three best machines of its kind in the world,” he said.
Technology synchrotron
With about 2,000 regular users, who perform 460 research proposals, LNLS is a laboratory open to scientists from Brazil and abroad interested in using synchrotron technology in their work. The new ring will not only expand the number of users as well as disciplines benefited.
Another niche is LNLS users of the industrial sector. “In Japan, there are 180 companies that regularly use the rings in there, which shows the importance of this technology for technological innovation,” said Roque da Silva.
He said countries like Taiwan, South Korea, Denmark and Sweden are building their own synchrotron accelerators, with the objective of meeting, beyond the academy, the country’s industrial park. In France, one of the largest users is cosmetology. “The nanocosmetics has been booming and the industry uses the French synchrotron technology,” he said.
In an effort to increase the number of users, LNLS has recently initiated a program to use remote. Through a high speed network researchers can accomplish, his laboratory experiments in the ring in Campinas. A test model was successfully performed this year when the equipment was operated from the Rio de Janeiro.
