April 2, 2004  


Director’s Corner

By Jonathan Dorfan

The Laboratory is abuzz with activity. Like the blossoming of spring these past few weeks, SLAC’s science program is in a period of tremendous evolution and productivity. The range of activities is broad, including: construction projects like the Gamma Ray Large Area Telescope (GLAST) and the Linac Coherent Light Source (LCLS), the development of exciting new theoretical ideas in particle physics, major R&D programs like the Next Linear Collider (NLC) and the Enriched Xenon Observatory (EXO), the development of new directions and instruments for particle astrophysics, and new approaches to meet the enormous challenges we face in computing, to name but a few. In addition to these exciting developments for our future, we are of course vigorously operating our accelerator facilities for the roughly 3,000 users world-wide who do their research at SLAC. In this month’s column I would like to update you on the operating facilities.

(Photo by Diana Rogers)

SPEAR3 is doing science! The first synchrotron light was brought into beam line 9 on March 8, and users are now back at work, signaling a new era of synchrotron radiation experimentation at SLAC. SPEAR3 will operate at 100 mA during this first year, while beam-line components are upgraded in preparation for full 500-mA operation next year. This has been an exemplary project that has set standards of competence that will be hard to match. SPEAR3 was built on time, commissioned on time, has performed beautifully from the start and of course, was on budget. We promised that SPEAR3 would be ready for users in March and here they are! Everyone who contributed to this Laboratory-wide project should feel justifiably proud of their achievement.

The B Factory, too, is bursting with new developments and achievements. A new mode of operation started on March 11, called the ‘dual trickle injection’ mode, which injects new bunches of particles continuously into both the electron and positron rings. Previously, BABAR datataking had to be suspended about once every 40 minutes while the storage ring currents were topped up to their maximum operating point. Trickle feed means that BABAR can take data virtually uninterrupted with both beams at full operating current, leading to a significantly larger number of events logged per day. New performance standards were set at the B Factory in March with record PEP-II peak luminosity, record data collected, both in one shift and in one day. PEP-II is the only accelerator in the world using this new technique of ‘dual trickle injection’, maintaining SLAC’s tradition of accelerator innovations. Don’t miss the article on the front page of this TIP that explains this development in more detail. Congratulations to the fabulous PEP-II team that made this breakthrough happen, and also to the BABAR folks who adjusted their detector data-acquisition to conform to this very challenging mode of operation.

The primary electron beam, besides being used for injection into PEP-II, is also currently the backbone of the Final Focus Test Facility (FFTB), whose running hours are shared between the high energy physics program and the synchrotron light program. FFTB is capable of delivering the shortest pulses in the world, either a) in the form of the electrons directly or b) after conversion in an undulator magnet, in the form of x-rays. In recent months the running time has been shared between the x-ray experiment SPPS and the E-164 collaboration which is doing advanced accelerator R&D.

The E-157, E-162 and E-164 collaborations (SLAC, UCLA and USC) have been studying the use of plasmas for future high-energy accelerators. Plasmas have the potential to provide acceleration rates much greater than those obtained using conventional technology. Data from E-162 experiments have already shown peak acceleration on the order of 200 MeV per meter, which is very exciting when compared to our linac’s average of 17 MeV per meter. The E-164 and E-164X experiments finished their latest FFTB run during which they were working toward attaining ultrahigh peak acceleration of up to 10 GeV per meter. At a recent meeting in Washington, DC, they showed preliminary results of accelerations in excess of 1 GeV per meter.

SPPS, a nine institution, three-nation collaboration, is breaking new ground in the use of ultra-fast pulses to study a wide range of otherwise inaccessible material properties. Given that this ultra-short pulse of synchrotron radiation is novel, much of what they are doing involves the development of new detection strategies. SPPS has already detected the arrival time and width of the electron beam in the FFTB with subpicosecond (a millionth of a millionth of a second) resolution and will work on developing similar techniques for the x-ray beam. They have also focused the x-ray beam to a spot more than 100 times smaller than a human hair. The combination of these developments will be exploited in the coming year to study how materials behave when exposed to peak x-ray power, approaching what is expected from the LCLS.

It is the Laboratory staff’s professionalism, dedication and their strong identification for the success of our mission that has enabled the current growth and change in so many sectors of the laboratory.



The Stanford Linear Accelerator Center is managed by Stanford University for the US Department of Energy

Last update Friday April 02, 2004 by Emily Ball