by Cindy Lee
A two-month scheduled shutdown of the ALS is nearly complete. The intermission in user operations allowed significant progress on two new beamlines under construction, QERLIN and Gemini, and also saw the completion of a long-term project to upgrade the storage ring’s radio frequency (rf) system. Several smaller upgrades and maintenance tasks were also performed. The facility should return to user operations as scheduled on February 28.
A major project during the shutdown was installing the 20-ton granite platform for the QERLIN (Q- and Energy-ResoLved INelastic scattering) beamline, which will stabilize the sensitive equipment and help shield it from vibrations and temperature changes. The spectrometer assembly, including the detector, will sweep like a hovercraft across the platform on a bed of compressed air as it measures a range of scattering angles from 30 to 150 degrees with a spectral resolution as high as 1:20,000. Located in Sector 6, the instrument will be used for x-ray absorption spectroscopy (XAS), x-ray emission spectroscopy (XES), and resonant inelastic x-ray scattering (RIXS), and is being developed with support from the Gordon and Betty Moore Foundation. The beamline’s “front end”—the equipment inside the shield wall, including the first optic—was also installed. (See a previous update on the beamline’s construction for more information.)
Time-lapse video showing progress on the QERLIN beamline installation during the recent shutdown. (Credit: C. Lee/Berkeley Lab)
The in-vacuum insertion device for Gemini, a state-of-the-art protein and small-molecule crystallography beamline under construction in Sector 2 thanks to support from the Howard Hughes Medical Institute, was installed in the storage ring and successfully integrated into the ring’s vacuum. Crews also completed the installation of the beamline’s front end. The beamline will be a higher-flux source of x-rays than other ALS crystallography beamlines and is on track to begin commissioning this spring.
Leda, the 10-ton insertion device that will generate x-rays for the Gemini beamline, was installed in the storage ring during the most recent shutdown. (Credit: C. Ralston/Berkeley Lab)An upgrade of the storage ring rf system was also completed during this shutdown and is now beginning commissioning. The long-term project included installing a second klystron—a microwave amplifier that maintains the energy of the electrons in the storage ring—as well as a wave guide “switch matrix” that allows rf to be redirected in a matter of hours rather than days in the event of a klystron failure. In addition to providing a more robust back-up system, the improvements allow for more rf energy, which is needed to run insertion devices at smaller gaps.
In addition to other small upgrades and maintenance, new vacuum chamber spools were installed in two sextupole/corrector magnets in Sector 7. These will serve as prototypes for enabling a higher rate of orbit corrections of the electron beam and a more stable beam overall.
The next long-term ALS shutdown is scheduled for July.