Up Close: Advanced Light Source at Lawrence Berkeley Laboratory
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schedule, the ALS could begin providing XUV photons to its first users in late 1992. To maximize the probability that the ALS will, in fact, be available to users soon after the end of the construction project, a phased commissioning of its various Subsystems (linear accelerator and booster Synchrotron to inject electrons into the storage ring, the storage ring, and the insertion devices that generate the brightest radiation) is planned. In this way, the ALS project staff will not be overburdened by having to bring the entire facility on line at once.
Arthur L. Robinson
Spectral Brightness and Range Synchrotron radiation is generated by a relativistic electron beam racing around an approximately circular storage ring. One measure of the quality of the radiation is the spectral brightness, a composite figure of merit that incorporates the intensity of the light, the narrowness of its spectral distribution, and the ease with which it can be focused to a small spot. The so-called diffractionlimited or coherent light from a laser is the brightest ordinarily available. Over a substantial part of the spectral ränge of the ALS, which extends from roughly 1 to 10,000 eV, the Synchrotron radiation will be partially coherent. For this reason, the ALS light is said to be laserlike, especially at photon energies below about 1 keV. Two special and interrelated features of the ALS make this laser-like light possible. The first is the heavy reliance on periodic magnet structures called undulators that will be placed in the straight sections of the electron storage ring. It is the Synchrotron radiation generated when the electrons pass through the undulators that will have the highest
This article is part of a series focusing on the research capabilities and goals of interdisciplinary laboratories pursuing materials research in universities, industry and government.
A marriage of the new and the old is under way at the Lawrence Berkeley Laboratory (LBL), Berkeley, California. The new is the Advanced Light Source (ALS), a facility for generating laserlike, partially coherent beams of x-ray and ultraviolet (collectively, the XUV) Synchrotron radiation of unprecedented spectral brightness. (See Figure 1.) The old is the domed hall that has sheltered the historic 184-inch cyclotron, a nuclear accelerator built 46 years ago by the laboratory's founder E.O. Lawrence. The ALS is to reside in an enlarged Version of the old hall, a familiär landmark in the Berkeley-San Francisco area whose architectural features are to be preserved. Another sign of the marriage is an increased emphasis on materials research. Though by no means forsaking its nuclear science origins, LBL has seen its budget for materials research grow steadily in recent years, especially with the establishment of the Center for Advanced Materials and the construction of two new laboratories to house its activities. [See the April 1988 MRS BULLETIN, p. 54, for an Up Close article on LBL's National Center for Electron Microscopy.] With its focus on the use of electromagnet
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