The Bevatron Cryopump

A cryogenic vacuum pump, designed to lower the base pressure from 2 × 10-6 Torr to 3 × 10-7 Torr was installed in the Bevatron in February 1972. The ~ 11,000 ft3 vacuum volume contains > 100,000 ft2 of outgassing surface and is pumped with twenty-four 32-in. oil diffusion pumps. Nine cryopanels (90 ft total) were distributed around the 360-ft circumference, increasing pump capacity by 400,000 l/s for condensibles at 80°K and 140,000 l/s at 20°K. Benefits include faster pumpdowns, improved beam stability, and higher intensities.