Major accelerators are not built so much as rebuilt, better every time. The Advanced Light Source — a synchrotron-light source at Berkeley Lab — exemplifies this principle.
When commissioned in 1993, the ALS was among the bellwethers of the third generation of synchrotron light sources: optimized for small beam size and emittance and for numerous “insertion devices,” magnetic arrays that “wiggle” or “undulate” the electron beam and thus cause it to produce light.
Twenty-plus years later, the ALS looks much the same on the outside, and is similar in overall function and configuration: a source of light in, primarily, the vacuum-ultraviolet and soft-X-ray spectrum, based on an electron storage ring. In detail, however, it has evolved greatly, undergoing several large upgrades and dozens of small enhancements, with the result of providing higher-quality beams to its users. These improvements are led by ATAP, through our dedicated program in accelerator physics for the ALS. (The ALS was designed and built in the Accelerator and Fusion Research Division, predecessor of ATAP. The ALS became an LBNL Division in its own right in 1998, after which we continued leading their continuous efforts to understand and improve the machine, in addition to providing its operators.) Upon request our other programs and centers contribute to these efforts, and of course the Engineering Division and the ALS Division itself are integrally involved. More >