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The race for the best light

Sirius will compete with a fourth-generation facility inaugurated in 2016 in Sweden and another planned to begin operating in 2020 in France

The European Synchrotron Radiation Facility in France, which will be upgraded in 2019


There is a rush to complete Sirius, Brazil’s new synchrotron light source, which will be one of the most advanced sources in the world. The goal is to keep delays oncompletion of its construction and assembly to a minimum. It is currently a modest six months behind schedule, which is acceptable in a project of this magnitude and technical complexity. It’s competition is just in sight. The facilities are designed to create a similar or even higher brightness than that of the Brazilian synchrotron, which will certainly attract the attention of academic researchers and companies interested in conducting experiments that require increasingly greater spatial and temporal resolutions.

This is why last May, while physicists and engineers from the National Synchrotron Light Laboratory (LNLS) completed the installation and performed the initial testing of the linear accelerator, workers and civil engineers were working on Sirius around the clock, from Monday through Saturday. They are working to finish the building by August so that other parts of the accelerator and the experimental stations can be assembled as soon as possible. Even if the facilities are ready in the near future, the new light source will not work without the connection between the high-voltage electrical grid and the substation that will feed Sirius and the rest of the campus at the National Center for Research in Energy and Materials (CNPEM), and this link has yet to be provided by Campinas-region utility CPFL Energia. Sirius and the campus together will consume the energy of a city of 40,000 inhabitants. “We need to hurry if we want to have the brightest light source in the world for even a short time,” says physicist Antônio José Roque da Silva, director of the LNLS and manager of Sirius’s construction.

Today, there are almost 50 synchrotron light sources operating in just over 20 countries. Almost half of them are concentrated in three countries: Japan has nine (many smaller sources), the United States has seven, and Germany has six. Just over 20 are third-generation sources, one generation earlier than the most modern equipment, which is now reaching the limit of what can be built. As a fourth-generation facility, Sirius will have two direct competitors: one light source that is already in operation in Sweden and another going into operation soon in France. There are also another 13 fourth-generation light sources being designed.

Located 500 kilometers south of Stockholm in Lund, Sweden, a city of 120,000 people, the MAX IV light source is the first in the world to be regarded as fourth generation. These devices are given this classification due to their innovative distribution of magnets around the electron storage ring, first proposed in 1993 by German physicist Dieter Einfeld and Slovenian physicist Mark Plesko in an article in the journal Proceedings of SPIE. This new magnetic lattice design was first adopted in MAX IV and allows smaller storage rings to be used to obtain more concentrated, brighter synchrotron light beams.

Perry Nordeng MAX IV in Sweden, the world’s 1st fourth-generation synchrotron light sourcePerry Nordeng

Built with components designed and manufactured in Sweden and other countries, MAX IV was inaugurated in June 2016 at a ceremony attended by the King of Sweden, Carl XVI Gustaf. The synchrotron consists of two storage rings: one containing electrons with 1.5 giga-electron volts (GeV), which feed two experimental stations currently in the commissioning phase, and a second with 3 GeV electrons, which provide synchrotron light for five stations, of which three are active and two are in testing. “Since the start of operations, we’ve already had 318 users,” says Brazilian-Swedish physicist Pedro Fernandes Tavares, MAX IV’s director of accelerators. According to Tavares, the higher-energy ring should provide sufficient synchrotron light this year for the experimental stations connected to it to operate for approximately 4,000 hours, the equivalent of 167 days.

If everything goes as planned, Sirius and MAX IV will soon face a strong competitor: the extrabright source (EBS) of the European Synchrotron Radiation Facility (ESRF), located in Grenoble, a city of 160,000 people in the southeast of France, at the foot of the Alps. The EBS will be an enhanced version of their current synchrotron light source, which was the world’s premier third-generation light source to go into operation, in the 1990s. The ESRF is operated by a consortium of 22 countries and, for the last three years, its technicians and engineers have been preparing for an upgrade, which will cost €150 million.

The current facility will be shut down in December of this year. Over the following 18 months, its storage ring will be dismantled and replaced by a new version with a circumference of 844 meters, which will provide electrons circling at 6 GeV of energy—double that of both Sirius and MAX IV. According to the ESRF communications office, the project is on schedule. It is expected that the new synchrotron, which will emit a brightness 100 times more intense than the current machine, will be reopened to users in 2020 and will provide beamlines to 44 experimental stations.

In the opinion of physicist Aldo Craievich, a retired professor from the University of São Paulo (USP) and one of the leaders in the construction of the first Brazilian synchrotron light source, the UVX, Sirius will compete on equal terms with MAX IV and the ESRF-EBS and attract international collaborators. “I am convinced that even researchers from the more developed countries of the Northern Hemisphere will come, because a good number of advanced experiments can only be done here,” he states. “It will be a strong stimulus for international cooperation, which should exceed what the UVX did.” The current Brazilian light source, which is to be shut down at the end of 2019, has an average of 1,200 users per year, with approximately twenty percent coming from other Latin American countries.