Since the pressure was 5E-7 Torr, I took some data with the RGA with the ion pump and turbo still on. See the attached graphs. Some takeaways: H2, H2O, and CO2 are about 2-3x the LIGO beam tube requirement (note the old date; maybe they require better now). N2 and CH4 are below LIGO's requirements. The total calculated pressure is 1E-6 Torr, 2x what the agilent pressure gauge reads. This could be because the RGA is at the end of a 7" tube, an angle valve, and a tee before it reaches the center of the 6 way 6" CF cross. The Agilent ion pump has direct line of sight to the center of the 6 way cross. It does not appear like there are significant hydrocarbon contaminants (they should appear at 12-16 amu (C, CH1, CH2, CH3, CH4) and above 40 amu). The Holometer desired a partial pressure below 1E-10 Pa (7.5E-13 Torr) which is the same as LIGO's hydrocarbon goal. I think we are far from this target, but in my amateur opinion we have met our vacuum goal.
