Lab Book 2014_05_19 Hamilton Carter Summary Started work on leak checking a second fiberglass Dewar. So far, the jacket seems to be holding vacuum well. The auxiliary roughing pump was pumping more vapor into the system than expected. Once it was taken out of the circuit, the diffusion pump quickly pulled the jacket back down to a reasonably good vacuum. No leaks were detected in any of the vacuum junctions, or anywhere on the jacket. Testing a different fiberglass Dewar. I wire brushed the old Teflon tape off the vacuum port and and attached the lead detector after putting on new Teflon tape. Just pumping the hose up to the Dewar, it looked like there might be a leak. When the rouging pump was taken out of the system after a minute or two, the pressure went back up from about .05 to above .1 rather quickly. However, after letting the roughing pump work for 28 minutes, when the valve was closed removing the ro...