Air flow into the LBL Bevatron

The Lawrence Berkeley Laboratory is currently installing an improved liner in its Bevatron. The new liner will be capable of producing a vacuum of 2 x 10-8 N/M2 (1.5 x 10-10 Torr) and a temperature on the order of 12K. There has been concern for quite some time about possible damage to the liner in the event of a beam line window breaking allowing atmospheric air to rush into the vacuum. The installation of the new more fragile liner has heightened this concern. This effort is an attempt to characterize the pressure loading on the cryopanel in the event of a beam window rupture. Also of interest is the time it would take the inrushing atmospheric air to reach the tangent tank where the fragile cryopanels are located. Fast acting values placed between sections D and E at the beam line tangent tank junction are being considered as a precaution