Sunday, October 11, 2009

SciMon Diary: Day 1

Today saw my first day as an expert SciMon - the first of thirteen more days. It being the weekend there weren't really many people at the site, in fact for the most part it was just me and the detector operator (someone who actually knows how to run the detector!). During the shift was based in the control room at the observatory, which looks like this, and has a variety of monitors projected onto the walls - some of the most useful monitors show the current estimated range (the distance, in Megaparsecs, out to which we could observe a binary neutron star coalescence), the sensitivity curve, and a variety of seismometer channels (useful for seeing if there's been an earthquake).

The main (but not only) duty of a SciMon is to document when and why the detector falls out of lock - being in lock means that the interference pattern that the detector uses to sense length changes is held on held just off a dark fringe [I've updated this as I just got reminded that we no longer lock on the dark fringe, but instead use a system where we lock just off the dark fringe (a so-called DC readout) - this is to help us better control the detector] i.e. where the light from the two arms of the interferometer are almost completely cancelling each other out - during this state, and if the detector's behaving itself, it can be said to be in science mode and we can use that data for astrophysical analyses.

For the first half of my shift the detector was behaving itself nicely, and I thought we might make it through the whole 8 hours staying in science mode. But this hope was dashed when a reasonably local earthquake in Nevada knocked us out of lock. The disturbance from this lasted a while, but we got back into science mode and the end of my shift saw us back behaving well. There was also an unexpected interruption in the control room near the end of the run when a tour group came through to observe the detector in operation.

At the end of the shift I handed over to the next SciMon on the 4pm-12am shift, but I'll be back tomorrow. (Posts probably won't get much more exciting than this)