Kyle 

With the leak detector configuration as left yesterday, i.e. backing the Vertex MTP (100% of the turbo exhaust) the helium background had decreased from 1.3 x 10-8 torr*L/sec (as left yesterday) to 6.2 x 10-9 torr*L/sec today -> I vented the HAM5 and HAM6 annulus volume and decoupled the HAM5 aux. pump components leaving the pump port connection open to the room.  Then I let the HAM6 aux. cart diaphram backing pump pump air through the annulus, i.e. room air enters HAM5 pump port and routes through annulus volume and exits HAM6 pump port.  This was another attempt to expedite removal of any helium permeated in the annulus O-rings -> No help, too slow.  Next I calibrated our 2nd leak detector and swapped it in place of the initial leak detector -> No change.  It measured and behaved within 10% of the first.  This was done to rule out any instrument-specific inability the initial leak detector might have had in resolving helium ions from non-helium ions in the spec. tube (as the leak detector inlet pressure is relatively "high" baking the MTP).  This concludes my attempt to get the helium background to the nominal <2 x 10-9 torr*L/sec value.  

Moving on, I reconnected the initial leak detector and began testing CF joints on the output MC tube with a background of 6.2 x 10-9 torr*L/sec.  Two of the first three flanges I tested were 10-6 range leakers!! Ouch!!  Will have to continue tomorrow after this pumps away.