by Ina Reichel
The main driver for the recent shutdown (January to early March) was preparing the storage-ring wall for the installation of the ALS-U accumulator ring, an additional accelerator that will reduce the size and spread of the electron beam and accumulate multiple batches or “injections” of electron bunches from the booster ring before transferring bunches to the storage ring. The accumulator ring will be installed near the top of the shield wall on the inside of the storage-ring tunnel, which required that the HVAC system currently occupying that part of the shield wall be moved lower.
The work during this shutdown included: finishing the upgrade (and relocation) of the HVAC system, adding a cooling water distribution system for the accumulator ring magnets, relocation of gates and crash off boxes (crash boxes serve as emergency off switches as well as “this sector is clear” switches when searching the ring) necessary as their old positions were in conflict with the new HVAC system, installation of support structures for the accumulator ring, cable trays, new lighting, and drilling for the accumulator ring rf system.
In addition the booster-to-storage-ring (BTS) transfer line was reconfigured. This transfer line connects the ALS booster ring to the ALS storage ring. In this shutdown a small portion of the BTS was reconfigured to make space for the future booster-to-accumulator-ring (BTA) transfer line. This preparation required the rotation of a quadrupole doublet (a pair of quadrupoles with opposite polarity), some support stand modification, and the reconfiguration of a wireway. About 40 devices had to be disconnected and reconnected in order to get this scope accomplished. As a final step, the BTS was recommissioned by the ALS operations team.
Other, non-ALS-U-related tasks accomplished during the shutdown included upgrades to the rf system, preparation for a future relocation of the booster bend magnet power supply, and upgrades to Beamlines 7.3.1 and 9.3.2.
The exit port of Beamline 8.2 was also scanned. This procedure helps determine where the beampipe for the beamline can be relocated during the ALS-U dark time given the new storage ring location and configuration. The team also rebuilt the shielding box to current standards. In addition, the M1 mirrors in Beamlines 12.2.2 and 12.3.1 were replaced, improving the flux by approximately a factor of two because of the better-quality mirrors.