We are declaring victory on CP4 bake at MY! Rai Weiss and Dennis Coyne gave it their blessing. :)

Attached is a spreadsheet with RGA scans showing partial pressures of residual gases. Total pressure = 2.4e-9 Torr for the post bake scan. LLO’s CP4 scan at their EX serves as a reference/baseline (coincidentally we’re both changing states of our #4 CPs). I also included a scan of our CP4 before the bake, but after the LN2 was boiled away and ice pumped away (total pressure 2e-7 Torr) in Faraday mode. Not very useful, but it’s data. We baked our newly installed RGA in situ with the CP bake so we never captured a baseline.

Comparing LLO’s reference to our post-bake, the peaks relative to each other look good, expect maybe for AMUs 50-60. Note that LLO’s scan is from an SRS unit and ours is from a Pfeiffer unit. I don’t have Torr/A conversions for these units specifically. Based on VBO scans, we know that the Pfeiffer ion current correlates closer to pressure than the SRS:

Pfeiffer = 1.3 Torr/A of Ar

SRS = 367 Torr/A of Ar

I used these values to convert to Torr and included that plot as well.

We have a new peak at AMU 7. Probably from baking the old 10” CETEC valve with o-ring gate seal.

After the annulus piping is installed and GV electrical connected, we will open GV 11 first to expose the bake volume to CP3 and IP9 and collect an RGA scan and finally open GV12.