Consistently providing users with about 99% of the scheduled x-ray beam time at the APS is an outstanding achievement, especially when one considers that a multitude of highly complex technical systems must perform their tasks at a nearly faultless level in order to maintain this high level of availability.

Much of the credit for keeping those systems in optimum x-ray delivery mode goes to the skilled members of many APS technical groups in both the APS Engineering Support Division (AES) and the Accelerator Systems Division. One of those groups is the Mechanical Operations & Maintenance (MOM) Group in AES, which is responsible for the operation and maintenance of the systems most essential for highly reliable accelerator system operations, the accelerator mechanical/water/vacuum systems.

 MOM takes care of the APS vacuum systems, the process water systems, mechanical subsystems, and conventional magnets. The group has an experienced staff of 27 engineers and technicians with an average of more than 22 years of service at the APS, many of whom helped to build this facility. This experience serves to maintain the high level of accelerator performance.

Accelerator, front end, and beamline water and vacuum systems are monitored daily to ensure that over 750 controllers and associated ion pumps and gauges are operating to maintain ultra-high vacuum levels. Over 1000 flowmeters and temperature and pressure sensors are interlocked to protect equipment and personnel. Daily monitoring of the performance of these systems provides information on the devices and their risk of failure. Vacuum and water engineers and technicians are on-call 24/7, 365 days to ensure that failures are readily addressed and that all of these systems are operating as required.

The three shutdown maintenance periods per calendar year and machine studies periods provide the opportunity to not only perform routine maintenance on these systems, but also support the testing and installation of new or upgraded devices in the accelerator, front ends, and beamlines. Regularly scheduled weekly shutdown and planning meetings are held over the six-week period leading up to each shutdown. At these meetings, representatives from each APS division, technical groups, users, and facilities discuss the importance and readiness of their projects and spell out resource needs from the support groups. All this information helps to plan and schedule the use of MOM engineers and technician to effectively support these requests and to accomplish routine maintenance. 

Process water systems utilizing more than 150 pumps circulate more than 20,000 gallons per minute of deionized water to cool and condition thousands of accelerator and beamline components, affecting machine reliability, beamline operations, and radio-frequency tuning and bake out for vacuum. The maintenance of deionized water chemistry requirements with dissolved oxygen levels of less than 10 parts per billion, resistivity of 10 Megohm-centimeter, and temperature controls as stringent as +/-0.01° F ensuring beam availability and stability.

To support the development and maintenance of vacuum systems, MOM runs a vacuum facility in building 382 at Argonne. The shop is equipped with a cleaning system, clean rooms, bake-out ovens, and two automated welding machines, all of which provide the capabilities to assemble, weld, and vacuum-certify chambers. The MOM Group has prepared vacuum chambers for the APS and for other facilities such as NSLS-II, SLAC, and DESY.

In addition to accelerator systems, the MOM Group operates and maintains the vacuum and pneumatic systems that support the front ends and beamlines. While the primary responsibilities of the group are for the accelerator technical systems, as schedules and resources permit the group also provides services to the APS user community, Divisions, and the broader national and international accelerator community.

— Leonard Morrison, [email protected]

The Advanced Photon Source is a U.S. Department of Energy Office of Science User Facility operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Argonne National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.