"We plan to start up beam this week," said Eric Prebys, who is in charge of the Booster. "We have a couple of checkouts to do and we have to see whether the vacuum will be good enough. We need to let the pumps run long enough."

The shutdown goal for the Booster is to increase the number of protons that the machine can accelerate per cycle. The Booster provides beam to the MiniBooNE neutrino experiment as well as the Main Injector, which distributes beam to the Tevatron collider, the antiproton source, and--beginning in December--to the MINOS neutrino experiment. A larger number of protons allows all experiments to take more data, increasing the potential for discovery.

During the shutdown, technicians installed an additional RF cavity in the Booster, bringing the total number to 19. The new cavity has a larger opening that will reduce beam loss, preventing the cavity from getting too hot. "The aperture is five inches compared to two-and-a-quarter in the old ones," said Rene Padilla, manager of the cavity project. "The cavity is installed and has been power tested. All we need to do is finish some equipment outside the tunnel, which can be done when the machine is running."

The new cavity is one of two units built with the help of six universities--Caltech, Columbia University, Indiana University, Princeton, Tufts University and the University of Texas at Austin, which are involved in the MINOS and MiniBooNE experiments. University machine shops helped to fabricate cavity components. "It was an effective collaboration," Padilla said. "We managed to build two large-aperture cavities for little money."