The second day back

The second day back after a holiday is way more trying than the first.

On the first day back, I generally expect it to be a bit of a shock, and work accordingly. On the first day back, the goal is to simply make it through a normal day without screwing anything up. All the tricky stuff is left for the second day.

So it is that second day back that requires trying to make up for all the time away. For me, that meant doing a month’s worth of deferred maintenance on the ICP- changing the cones and both lens stacks.

Yesterday, I was content to just get it up and running. It was only going at about 98% of our preferred minimal sensitivity, but that was close enough for the first day back. So I waited until today to tear everything apart and reassemble it. And when I did, I found that I only had 8% of the minimum sensitivity.

The trouble with changing everything at once is that it required going back in incrementally reverting, to locate the problem. So I pulled all the nice, shiny clean bits out, replacing them with the mangy ones that I had just removed. After that process, I managed to get back up to 30% of minimum. And this was the same configuration that gave me 98% yesterday.

So I banged my head on the wall, cried, and screamed at it. No change. Eventually, after a talk with my boss, I went outside and checked all the external bits- things completely unrelated to the maintenance that I did. And sure enough, one of the roughing pumps was down. The circuit breaker must have thrown when I pumped down after the first lens change. If only one pump dies, the vacuum degrades enough in the source to squelch the signal, but not enough to show up on the gauges. So it turns out that after tearing everything apart twice, all I had to do was reset a circuit breaker, and give it a few hours to pump down. I got everything fixed and checked out just in time to confirm that the scientist booked on the machine had given up and gone home for the day.

At least I got back to where I started.