Kyle R.,  Rakesh K. 

Today we connected a 55 L/s ion pump assembly to the 1 1/2" UHV angle valve located at the bottom of CP1 (ECR E1700073-v2, WP #7189).  We assumed that the unpumped volume of the 2.75"-NW50 adapter was at rough vacuum.  As such, we sought to "burp" in a minimal amount of room air into this unpumped volume via slightly spreading apart the NW blank flange from the adapter while monitoring PT114B and PT124B to test the integrity of the closed valve (metal sealed).  As it turned out, this volume was at room pressure already - meaning that this valve had been closed when CP1 was initially pumped down (1998?) and has remained so to this day.  

Next, this adapter was removed from the valve and the ion pump assembly support table was adjusted so as to bring the two mating flanges together with good axial and parallel alignment and then the flanges bolted.  The ion pump volume was pumped with a temporary, locally mounted, turbo pump for a few hours and then the ion pump started.  Even after isolating the turbo pump, the ion pump current (pressure) fell off to 1 LED, i.e. excellent vacuum.  

We are observing a pressure rise consistent with a new leak or a change in the leak rate of the existing (known) leak as the result of today's activity.  Is so, it is likely the 2.75" joint on the CP1 side of the 1 1/2" valve.  We are monitoring for now.  

For tonight, I am leaving the turbo running but isolated from the ion pump and the ion pump pumping (albeit via a temporary power cord).