The detector was filled with gaseous argon for the first time today. The triplet scintillation peak is already clearly visible!
This is a plot (by Tom Caldwell, Penn) showing the centroid of the PMT hits from a low level coincidence trigger. The MiniCLEAN inner vessel (see pictures below) is running with vacuum. All 92 PMTs are operating and the DAQ system is recording the data. You can see that the centroids cluster at the PMT location in theta-phi, which is consistent with Cherenkov light from radioactivity in the PMT glass.
or on YouTube here: