Researchers at SLAC work tirelessly to illuminate the mysteries of our universe, but it takes the hard work of the SLAC Vacuum Group to keep things crystal clear. Proper functioning of the linear accelerator and PEP-II requires pressures a billion times lower than atmospheric pressure and a spotlessly clean vacuum vessel. With over 20 miles of vacuum chambers, there is a constant need for maintenance and improvement. Thanks to the hard work of Vacuum Group technicians, physicists and supervisors, particle beams can speed their way unhindered to new discoveries in high energy physics.

The vacuum group is an integral part of SLAC. (Photo by Kelley Ramsey)

Creating optimal pressures along the linac and PEP-II requires an intimate knowledge of the entire system. Physicists in the Vacuum Group are constantly looking for new technologies to improve and customize vacuum conditions, a search that has contributed to the outstanding beam luminosity achieved by PEP-II. "We make sure the vacuum system does not limit the beam lifetime," says Daniel Wright (AMS), who has been working with vacuums at SLAC for the past 26 years. From turbo-molecular pumps that mechanically draw out air specialized ion pumps that charge and bind unwanted molecules, the Vacuum Group has a device to eliminate pretty much anything that comes their way.

Introducing new parts into the vacuum system to upgrade or service the system is, however, a precarious job. Any molecule present in the vessel can interact with the beam and ruin it. "A single fingerprint becomes a huge contamination," comments Dave Bostic (MFD), Operations Engineer. All vacuum parts must go through a rigorous cleaning process. After initial chemical cleaning, parts are assembled in clean rooms and then ‘baked out’ under high temperature and low pressure to burn off any trace contaminants and speed the release of absorbed air molecules.

Immaculately cleaned parts are then installed by field technicians, who must climb down to the belly of the accelerator and expose the delicate vacuum system to a host of contaminants. Portable clean rooms, or air showers, keep the dust and grime out of the vessel while technicians install parts. "The weight of all of our cleanliness effort is on the technicians shoulders at that point. They do an amazing job," says Bostic.

In addition to the daily operations, many technicians and supervisors have spent a sleepless night or two down in the linac or PEP-II, searching for leaks or part failures and fixing them fast. Experiments at SLAC run 24 hours a day and a serious problem with the vacuum system means major losses of data and money. "We’ve had people down there for three days, round the clock. It gets hard just to find someone for the next shift," says Matt Hayes (MFD), Vacuum Group supervisor.

Despite the long hours and close spaces, the Vacuum Group’s commitment to innovation, quality and efficiency has consistently provided excellent vacuum conditions for particle physics research at SLAC. Their work is challenging and rewarding. "This is a fun place to be," says Hayes. Must be something in the air.