October 22, 2012
The Linac Coherent Light Source X-ray laser facility restarted experiments this month after a scheduled two-month break for maintenance, upgrades and research and development.
The work extended the energy range of X-ray laser pulses and tested a technique for conducting simultaneous experiments, rather than running them one at a time as the LCLS does now.
Nineteen teams of scientists who submitted proposals to use the LCLS are scheduled to carry out experiments through the end of the year, with studies ranging from analyzing important molecular systems involved in photosynthesis to blasting samples of crystalline nickel with a high-power laser. For the next run that begins January 2013, researchers submitted a record 154 proposals, of which about 40 were selected and will be scheduled.
LCLS re-launched operations Oct. 3 and 4 with some continuing work to make its Matters in Extreme Conditions (MEC) instrument fully operational; on Tuesday, a Department of Energy committee conducted a review, known as Critical Decision 4, to gauge the instrument's progress toward completion. MEC is expected to receive formal approval for its full completion within about five months, and review committee members noted the project's success in meeting milestones in a closeout report.
The first MEC user experiments were conducted in May, and user experiments at MEC resumed Oct. 18. User experiments at other LCLS instruments restarted Oct. 5.
During the break, SLAC researchers continued to work on upgrading LCLS's self-seeding capabilities, which produce more uniform X-ray pulses that can improve results in some experiments. Scientists have already begun using the seeded beam.
Self-seeding is now available on the four LCLS instruments that deliver high-energy or "hard" X-ray pulses, and research and development has begun to achieve soft X-ray self-seeding at the other two instruments.
Uwe Bergmann, LCLS deputy director, said scientists also worked to extend the energy range available for self-seeding experiments and for LCLS experiments as a whole. There is now safety and administrative approval for this extended range at one of the soft X-ray instruments, which dips to energies below the so-called "carbon K-edge," important for studies in materials science and other fields.
Other research during the break focused on a beam-sharing technique that could divert portions of the X-ray energy for one experiment while allowing another downstream experiment to proceed simultaneously.
Since its launch in 2009, scientists have submitted more than 700 proposals for research at the LCLS, said LCLS Director Joachim Stöhr during a presentation at a users' meeting earlier this month. Only about one in four proposals can be accepted, with the average proposal involving 15 scientists, he said.
Planned construction of the LCLS-II, an expansion of LCLS, will include extensive tunneling work parallel to the existing laser facility.
There are plans to operate LCLS through the end-of-year holiday period in fiscal years 2014-2016 – which is typically a downtime – to help compensate for a shutdown due to LCLS-II construction beginning in April 2014.