CARME and the interaction chamber have been pumping for ~26 hours, P=4.15e-7 mbar, attached figures show the current pump down plot in comparison to the two previous pumpdowns in the last 2 weeks and the pump down with the bare chamber in 2020. The gradient of the pressure reduction appears to be improving for each pump down, either due to conditioning of the chamber or the reduction in leaks.  

CARME and the interaction chamber were leaked tested again today. The base leak rate has reduced significantly from 1.5e-10 mbar l/s to <1e-12 mbar l/s. All flanges on the interaction chamber were tested. A leak is still visible on the gate valve, however the magnitude of the leak has decreased significantly from 2.2e-10 to 2e-11. No other leaks observed on the interaction chamber. 

All flanges on CARME checked again, no leaks observed on flanges or wire seal. Leak was observed on the bellows of the left hand side (inner ring) actuator arm. Leak is not on either the small flange box side or the large flange on the chamber, but on the bellows itself. Image attached. Leak rate is 2e-10 mbar l/s. The actuator was moved with the pneumatic motor once to observed any effects, no effect on leak rate or the chamber pressure.

 Replacing the bellows is very challenging and will likely require removing the detectors installed on the rod. Current plan is to continue with the baking and re-evaluate post bakeout. The bellows will be baked but should not experience the same temperatures as the flanges on the chamber. Future experiments do not require extremely forward angles so that the actuator arm can remain fixed in place to not cause a n increase in the leak, the leak rate can be compensated by the large neg pumping power.