by Ina Reichel
During the Winter 2021 shutdown, which included work for the linear accelerator (linac), booster ring, and HVAC system, the Advanced Light Source was a hive of activity, though social distancing requirements during the pandemic meant that the activity looked a bit different from years past. The shutdown was originally planned to wrap up at the end of March. It has been extended slightly because replacement of two rf modulators for the linac took longer than expected. These are the projects our team checked off:
- Radiation safety system wireway and low-conductivity water (LCW) piping were relocated: this makes room for the new air conditioning system as well as the accumulator ring for ALS-U
- Storage ring alignment: the Survey and Alignment team routinely checks that all the components of the storage ring are positioned correctly
- New spools in sextupole magnets: the magnets were taken apart to replace aluminum spools with stainless steel fast corrector vacuum chamber spools
- Sector 4 stairs removed: the staircase that led into the pit has been removed to make room for the new air conditioning system
- Booster bend power supply repaired: the power supply for a booster ring bend magnet that was causing trouble at the end of 2020 has now been repaired
As always, our staff took care to complete the shutdown maintenance and upgrade projects as safely and efficiently as possible. Social distancing requirements introduced more complexity, and it was more challenging than usual to recover from any schedule delays because it was not possible to have multiple work groups at one work site. The freeze that gripped most of the nation in February also delayed delivery of crucial parts and components. Because shutdown projects were already planned for the shortest duration possible, these repairs could not be postponed to later shutdowns. Once our team began removing the old components (as old as the ALS) they had to install and commission their replacements before we could go back into operation.
The linac is powered by two rf accelerating sections, each having one modulator, which allow the electrons to reach a high enough beam energy to inject into the booster ring. Both modulators were replaced during this shutdown. We started commissioning on March 26 and plan to return to user operations after commissioning concludes. As a preview for the summer shutdown, our team expects to replace the liquid nitrogen tank.
Thanks to everyone for their safe and diligent work getting all this done. Also a thank you to ALS-U staff who pitched in to help.