ALS at Lawrence Berkeley National Laboratory and the APS at Argonne National Laboratory) and two second-generation facilities (the NSLS at Brookhaven National Laboratory and the SSRL in Palo Alto, California). The NSF supports one first-generation facility (CHESS), which is parasitic on the high-energy physics program at Cornell University, and one second-generation facility, the SRC at the University of Wisconsin. In addition, the state of Louisiana supports the Center for Advanced Microstructure and Design (CAMD) at Louisiana State University, a second-generation facility not originally operated as a national user facility but now being developed into one. DOC supports the small synchrotron at the NIST campus in Gaithersburg, Maryland, a second-generation source that is used primarily by the NIST staff for calibrations. Because the last two are not now user facilities, they were not included in this study.
No additional U.S. synchrotron sources are planned to be constructed in the near future, although research is continuing on a fourth-generation concept that will likely be based on a free-electron laser (BESAC, 1999). Planned investments focus on upgrading current sources (e.g., SSRL) and developing new beamlines and experimental instrumentation at existing facilities.
There are currently around 35 synchrotron user facilities in operation in 13 other countries. These include two third-generation sources comparable to APS in France and Japan and four third-generation sources comparable to ALS in Italy, South Korea, Sweden, and Taiwan. As of 1997, 11 light sources were under construction outside the United States, including third-generation sources in Germany, Japan, and Switzerland; another 15 were in various stages of design, including a third-generation source in Canada that has been approved for funding and two in China and France that are expected to be funded.1 The most advanced U.S. synchrotron facilities are regarded as state of the art and compare favorably with those in any other country.
Scientific trends in synchrotron applications have been analyzed extensively in several recent reviews (BESAC, 1997; Structural Biology Synchrotron Users Organization, 1997; OSTP, 1999); only emerging areas are highlighted here. The most notable current trend, one driving many of the demands on synchrotron facilities, is the explosion in use of synchrotron radiation in crystallographic analyses of biological macromolecules. This trend will continue.
Each property of synchrotron radiation—brilliance, tunability, time structure, and coherence—can be exploited for research. The hard x-ray beams emerging from the undulators at third-generation synchrotron sources are the most intense ever produced. This brilliance, when coupled with the analytical tech-
See Appendix D of BESAC (1997).