A couple of weeks of 17O3+ to DRAGON ended yesterday with a photo finish. Supernanogan went off at 10:00. Preparations for 18O began. Main event for yesterday: Replace IOS:TP7. Edi Dalla Valle reported that he had just received a V550 with Conflat flange. "Our timing was perfect." It is working well. The system was under vacuum again by around noon, and pumped overnight. This morning IG1 was ~5e-7 Torr and IG4 was ~2e-7 Torr, where those two gauges were the other way around previously. We attempted to do a leak check, but could not get it coordinated in time. So by 15:00 we chose to start the MWS and hand over the beam to the users.

Present MWS source gas setup: enriched 18O attached in two places; the straight-through path is open, while the calibrated leak is closed. We approximated the appropriate pressure on the regulator, allowed it to bleed down, then reset it to slightly under. The bottle valve is open. The bottle pressure is 150psi right now. At this rate, the cost of the source gas is about $200/day.