Trade.Information

New machine for the production of hard x-rays.

The Linac Coherent Light Source (LCLS) will be the world's first x-ray free electron laser when it becomes operational in 2009. LCLS is currently in the detailed project engineering and design phase, with a construction start planned in FY2005. Pulses of x-ray laser light from LCLS will be many orders of magnitude brighter and several orders of magnitude shorter than what can be produced by any other x-ray source available now or in the near future. These characteristics will enable frontier new science (click box below to explore LCLS science) in areas that include discovering and probing new states of matter, understanding and following chemical reactions and biological processes in real time, imaging chemical and structural properties of materials on the nanoscale, and imaging non-crystalline biological materials at atomic resolution. The LCLS project is funded by the U.S. DOE and is a collaboration of six national laboratories and universities.
Last Thursday, after years of work, LCLS physicists and engineers for the first time fired up the newly installed electron injector system, successfully creating and accelerating a pulse of electrons.

Last May, the LCLS collaboration cut the ribbon to the injector facility at Sector 20, and since then workers have been busy installing various components of the system. A custom-built drive laser initiates the process by sending a short burst of UV light to the RF gun located in the injector vault 30 feet below ground. The RF gun turns the laser light into electron pulses, which then accelerate through the injector pipes and into the linac. An animation of this process is available online.

This marks the official start of commissioning for the LCLS. To commemorate this achievement, this week SLAC will host a Friday afternoon Ice Cream Social on the main lawn in front of the A&E Building, starting at 2:00 p.m. Join your friends and colleagues to celebrate and relax with music and free ice cream.

A brief description of This project:
Almost all of the experiments at today's x-ray sources primarily give a "static" picture of materials averaged over relatively long time scales. Basic physical principles tell us that small building blocks of matter like nano-sized man-made structures, molecules, and atoms are able to rapidly change in time, the smaller the faster. In computers, for example, nano-sized bits are written and read today in several billionths of a second. Atomic motions are even faster -- by a factor of about 10,000 (a timescale of less than a trillionth of a second). LCLS will emit pulses that are this fast, a factor of 1000 or more shorter than pulses from existing x-ray sources. In addition, a single pulse will contain enough x-rays to record a single shot picture. It will be possible to record time-resolved images of chemical reactions, even to the point of following the change in the chemical bond as the reaction proceeds. This will give scientists a glimpse on a time scale never before possible, and open untold opportunities for understanding catalysis, chemical processes, and molecular assembly.

Stated differently, LCLS will be able to photograph atomic motion, much as a "strobe" flash is used to photograph the motion of a bullet in flight. This latest advance in stop-action imaging at Stanford has roots going back more than 100 years. Around 1872, Eadweard Muybridge started making stop-motion photographs of people, animals, and trains in motion on Leyland Stanford's farm. He is famous for showing that all four horse's feet leave the ground during a gallop. To be able to click a shutter fast enough to show each stride a horse makes when galloping required tremendous engineering ingenuity. LCLS will provide x-rays of such shortness and precision that stroboscopic experiments can be done with materials on the nanoscale, and even with individual molecules and atoms. In a more technical sense, this will provide the means to directly observe how the fundamental properties of materials change as their constituent atoms move, and how the clouds of electrons that glue atoms together shift and flow in response.

The tremendous brightness of the LCLS x-ray pulse will also be invaluable for imaging the atomic structures of small static objects. Individual single molecules or small clusters of molecules may be able to be imaged. When perfected, this new approach would enable biologists to study the structures of macromolecules that cannot be coaxed into forming the periodic arrays known as crystals (the basis for almost all work today in this area around the world). In fact, many biological macromolecules, including a very important class that occur imbedded in membranes, are very resistant to crystallization and hence their structures are not very accessible with today's methods. Such membrane-bound proteins are very important targets for many of the drugs that are important in treating disease today, and wider access to their structures could bring great benefits to human health.

The extremely high power of the LCLS x-ray pulse can also be used to both create in a controlled fashion and study new states of matter called warm dense plasmas. Such plasmas are thought to be associated with the interiors of planets, cool dense stars, and in plasma reactions initiated from solids. Today's sources are inadequate to study the very important properties of such materials.

LCLS construction and operation will build upon and utilize DOE's extensive knowledge, strengths and experience as the steward of the world's greatest collection of shared, multidisciplinary scientific user facilities. It will also leverage upon core competencies in accelerator science and technology at the collaborating institutions. No other facility on earth will be able to match the scientific power of LCLS as a new x-ray tool for discovery.

In pictures:
The 1st Photo Electrons from the LCLS RF Gun today


Source:
Stanford Linear Accelerator Center, Menlo Park, CA
Operated by Stanford University for the U.S. Dept. of Energy

Release link: http://www-ssrl.slac.stanford.edu/lcls/