after extended discussions. It may be noted that the U.S. Department of Energy commissioned a similar report, the Eisenberger-Knotek report on "The Need for New Synchrotron-Radiation Facilities," in 1983, which reached similar conclusions and led to the construction of two new "third-generation" SR facilities: the Advanced Light Source (ALS) in Berkeley, California, and the Advanced Photon Source (APS) at the Argonne National Laboratory in Illinois.

In June of 1987, STA convened an ad hoc committee to discuss the necessity for the new-generation SR source and to examine the requirements for the new facility. The committee was chaired by Haruo Kuroda (recently retired from the University of Tokyo, and now at the Tokyo University of Science). The Kuroda committee established that a high-energy storage ring capable of providing highly brilliant synchrotron radiation (SR) in the x-ray spectral region was a high priority. Such a facility would promote a research and development (R&D) program in the fundamental disciplines such as physics, chemistry, biology, and materials science in the 1990s, according to the Kuroda committee. The importance of the high-brilliance light source that covers vacuum ultraviolet (VUV) and soft x-ray (SXR) domains was also noted. The energy of the storage ring was tentatively set to be 6 GeV. The Kuroda committee stressed that research and development should be carried out in a nationwide collaboration to overcome the technical difficulties associated with low-emittance, high-brightness storage rings.

RIKEN (the Institute of Physical and Chemical Research, an STA laboratory) started the design study and R&D work on the low-emittance storage ring in 1986. In the fall of 1987, JAERI (the Japan Atomic Energy Research Institute, another STA organization) joined with RIKEN in the

design work. Preliminary results of the design effort as well as the R&D for the 6-GeV design were issued as the first draft of the Conceptual Design Report (first edition) in May 1988.

In October 1988, JAERI and RIKEN established a joint design team to support the construction of the facility. At this stage, the design energy of the storage ring was raised to 8 GeV, and the two ring was raised to 8 GeV, and the two institutes organized an Advisory Committee for the 8-GeV SR Facility Project, chaired by Kazutake Kohra. Subcommittees on Accelerators (Kazuo Huke) and on Applications (Taizo Sasaki) were formed. In the Subcommittee on Accelerators, the necessity of straight sections longer than the regular 6.5-meter straight sections was strongly urged. The Advisory Committee submitted two interim reports in August 1989 and in February 1990 concerning the basic configuration of concerning the basic configuration of the facility, its use, etc. In Figure 1, the organization of the Spring-8 project team is shown. In the summer of 1989, the nickname and logomark of the facility were determined by public suggestions to be "Spring-8" (Super Photon ring8 GeV).

Harima Science Garden City in Hyogo Prefecture was selected as the construction site for Spring-8 in June 1989. This new city has been under development since 1986 as a part of the "Nishi-Harima Technopolis." The site has 141 hectares (348 acres) and is located about 100 km to the west of Osaka. The Faculty of Science, Himeji Institute of Technology, opened in April 1991. The grand site preparation was started in March 1990 by the Hyogo Prefectural Government, who made the site available to SPring-8 in April 1992. Construction of a part of the storage ring building is underway at this time.

The major purpose for building the large "third-generation" SR sources such as ESRF (European SR Facility), APS, and Spring-8 is to provide research

scientists with x-ray sources of far higher brightness than any existing today. Conventionally, SR x rays are taken from the "bending magnets" which determine the quasi-circular orbit of the stored electrons (or positrons) in the storage ring. These magnets are of relatively low magnetic field and provide a quasi-continuous spectrum of electromagnetic radiation (ER) from infrared to x rays. The SR x-ray source brightness typically is four orders of magnitude greater than laboratory x-ray sources. That was the thrill of the 1970s for x-ray scientists.

Of the storage rings utilized for SR sources in the 1970s, most were built for high-energy physics. In these designs, care was taken to provide the narrowest possible beam only in the interaction regions where the high-energy experiments were carried out. The SR beam lines utilized other parts of the orbit as source points, however, where designers had minimized costs.

Second-generation SR sources such as the Photon Factory in Japan and the National Synchrotron Light Source in the United States, were designed for dedicated SR sources, and significant improvements in beam quality were included. The SR x-ray source brightness was increased by another one to two orders of magnitude by introducing high-field "wigglers" into the electron orbit. The wiggler provides several bends of the electron beam within the source region, thereby multiplying the source brightness. Use of higher magnetic fields in the wigglers also shifts the spectrum toward harder x rays without requiring a higher electron beam energy.

Third-generation storage rings use "low-emittance" designs in which the transverse distributions of electron position and momentum are minimized all the way around the orbit, and long straight sections are included for insertion of wigglers and undulators.

In the high-precision orbits of thirdgeneration facilities, it is possible to insert long, short-period, high-field undulators. Undulators cause the electrons (or positrons) to undulate many times as they pass through the source region, albeit with very low amplitude. The resulting undulator radiation (UR) has a distinct, quasi-resonant, spiked spectrum; increased coherence; and greatly increased peak intensity.

The third-generation high-energy storage ring with long, high-field undulator x-ray sources is now the highest brightness source of soft and hard x rays by another one to four orders of magnitude over the wiggler sources. That makes the undulator x-ray source 9 to 11 orders of magnitude brighter than the once-powerful, rotating-anode, laboratory x-ray sources. Needless to say, new scientific progress is easily visualized with the astounding x-ray brightness to become available with the commissioning of third-generation facilities. Also needless to say, there are sure to be technological problems in the design of beam lines and experimental apparatus for use with such highly brilliant beams.

The aim of the SPring-8 project is to promote the basic research and development of advanced technology by using high-brilliance UR in the x-ray domain. The facility will be opened equally to research groups of universities, national laboratories, and industries.

The storage ring energy was determined by the requirement for a fundamental UR x-ray photon energy up to the K-absorption edge of element number 40 (Zr, K-alpha energy = 18 keV). Preliminary suggested undulator designs with a 3-cm period, 4-meter length in the Spring-8 beam show the fundamental peak about 13 keV for K=1.0. Harmonic UR will allow research with UR x-ray photon energy up to 40 keV or higher.

President, Japan Synchrotron-Radiation Research Institute, founder of the Photon Factory and Chairman of the Spring-8 Project Advisory Committee, followed with a brief history of the Photon Factory and Spring-8. Kohra also emphasized the international cooperation that has developed within the synchrotron-radiation community world wide. Although the organizing committee invited the directors of both ESRF in Grenoble, France, and APS in Argonne, Illinois, Kohra relayed the regrets of Ruprecht Haensel of ESRF. Thus progress on the first of the three new giants of the SR world was not presented at this symposium.

David Moncton reported, however, that ESRF has recently achieved its first circulating current in its 6-GeV storage ring, and commissioning by late 1993 or early 1994 seems probable. Commissioning of the APS is scheduled for the fall of 1996, and Moncton foresees no major obstacles to achieving that schedule. At this time, the APS construction project is on schedule and under budget, Moncton reported with obvious pleasure. Total construction cost for the APS is estimated to be $465M, but adding research and development costs, early operating costs, etc. brings the total cost to approximately $800M between 1988 and 1996.

Moncton was asked several questions concerning project management. How, for instance, would employment of construction personnel be handled at the completion of the project? How many staff members will be employed in beam line development? How will project scientists obtain beam time for their own experiments? How will the workload of staff scientists be balanced between support of user scientists and personal research? What will be the first experiment conducted on APS and how is that decided?

The current status of Spring-8 was reviewed by Hiromichi Kamitsubo. He described the technical progress thoroughly. Great care is being given to minimizing thermal fluctuation and mechanical vibration. The Harima Science Garden City site is considerably more stable geologically than the site of the Photon Factory, where realignment following earthquakes has been ment following earthquakes has been required frequently. Spring-8 will be built on bedrock, surrounding the top of a small mountain. At the Photon of a small mountain. At the Photon Factory, 40-meter-deep support pilings were used, which footed on an ancient stream bed, not on bedrock.

Following Kamitsubo's discussion of progress, Moncton asked why of progress, Moncton asked why Spring-8 will not open until 1998. The reply was that if funding were permissive, Spring-8 could be finished 1 year early. Reporters in the audience picked up the possibility and reported it in the next day's newspaper as a fact. However, the approved funding profile is considered unchangeable. Sasaki stated that the Spring-8 management team has no expectation that an early opening will be possible, although rescheduling of various elements within the construction may be possible as long as the overall funding profile is not affected.

Research Presentations

Following the theme started by Akio Yoshimori, most of the research papers concerned the general problem of understanding the atomic and electronic structure of various types of surfaces or interfaces. Many presenters utilized one of the several complex surfaces of silicon, such as the Si(111) 7x7, or one of the Si(100) surfaces as examples of the power of synchrotron-radiation x-ray experiments to determine surface strucexperiments to determine surface structures. Both clean and "contaminated" surfaces were discussed as important

surfaces to understand, especially in process situations such as cleaning, epitaxial growth, metalization, passivation, or etching.

Ben Ocko of Brookhaven National Laboratory discussed the possibility for understanding of the electrochemical interfaces using angle-dependent x-ray diffraction (XRD) and x-ray reflectivity for separating the surface layer from the underlying bulk. Interface layers contribute only 10% of the bulk XRD signal, so that high-intensity SR x rays are needed to obtain good interface data. X-ray reflectivity taken near a core-level x-ray absorption edge of a known interface contaminant is very sensitive to interfacial layers.

Ocko showed correlations of XRD and x-ray absorption with cyclic voltametry in iodine layers on Au(111). Bias dependence of these electrochemical interfaces has been shown to influence the surface atomic construction, but the theory is understood only in a general way from the general theory of Heine.

Paul Fuoss, AT&T Bell Labs, illustrated beautifully the power of x-ray studies of epitaxial growth mechanisms. In a collaboration with Kisker of IBM and Brennan of the Stanford Synchrotron Radiation Laboratory (SSRL), all three of the essential ingredients of the organometallic vapor-phase epitaxy process were studied in the same chamber: x-ray spectroscopy of the organometallic vapor and its fragmentation, grazing-incidence XRD, and x-ray scattering of the growing surface and substrate. For example, a growth surface cut only 0.5° off the (100) Bragg plane shows a splitting of the truncation rods in x-ray scattering. Observing these quantities in a time-resolved way requires very high intensity x rays, Fuoss declared.