Synchrotron light sources are giant particle accelerators that produce intense radiation that can be millions of times brighter than the light that reaches the Earth from the sun. Synchrotron radiation is electromagnetic radiation that is emitted when charged particles, moving near the speed of light, have their direction changed by bending magnets. This radiation is tunable and can be concentrated on a small area, making it a highly useful probe. This synchrotron radiation is, in many cases, required when employing advanced characterization techniques. Some of these techniques, such as those to obtain the crystal structure of a material, can be done at university laboratories, but are less efficient, poorer quality, and more time consuming. Research groups from multiple Energy Frontier Research Centers use synchrotron facilities to aid their work in understanding the properties of materials.
Two synchrotron facilities in the United States are getting infrastructure upgrades to accommodate the demands of new spectroscopy techniques, as well as to make themselves more competitive user facilities within the international community. Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory in California and Advanced Photon Source (APS) at Argonne National Laboratory in Illinois, will be undergoing large scale facility upgrades. Both are in early stages of the process, with ALS-U in the design phase. APS-U is now under construction, with the new ring expected to begin commissioning in 2023.
The existing APS and ALS storage rings and their magnets within will be replaced with a new multibend achromat lattice design. This new design uses smaller and more tightly packed bending magnets that function much like a lens. The result will be dramatically more intense synchrotron radiation compared to the existing system.
The upgraded APS facility (APS-U) will have a 100 to 1,000 times increase in brightness of its already super-bright X-rays. Higher brightness means more intense light can be used by users, potentially making experiments faster. The APS upgrade will achieve higher brightness and coherent flux for high energy or hard X-rays.Coherent flux determines the time required to accomplish an experiment with given spatial conditions, while also providing more resolution. Depending on the technique used, APS-U will allow scientists to map the position, identity, and dynamics of the key atoms in a material. One example includes enabling users to study material synthesis in real time. Another is enabling studies in extreme environments— high pressure and high temperature for example —where hard X-rays penetrating radiation is required.
ALS will see a similar brightness increase after its upgrade. The motivation behind the ALS upgrade (ALS-U) is to increase the brightness and coherent X-rays for lower energy or soft X-rays (102-103 eV). The current ALS can provide some nano-scale resolution in 2-D, but the new ALS-U will offer nanometer resolution with soft X-ray electronic mapping and enable the study of nano-scale systems in 3-D. In addition, ALS-U will make it possible to observe chemical processes in real time.
While each synchrotron is in at a different stage in the upgrade process, they will both experience a ‘dark time’ in their future, where there will be no light being produced. The upgrade installation ‘dark time’ and following commissioning period for either facility can take as long as a year. Frequent synchrotron users must plan for the dark times, as they will inevitably cause a disruption in their research. For instance, we can expect to see a large increase in the amount of research proposal requests for other synchrotron facilities, such as the National Synchrotron Light Source II at Brookhaven National Lab in Upton, New York. Nevertheless, once the upgrades are complete, both facilities will provide complementary science capabilities for the next decades.
