During the last run, PMT North showed some weird noise.

The PMT was replaced by the deep UV PMT with small aceptance range (100-200nm) but there was still a lot of noise on the output channel in the Messhütte, see attached photo. The intensity of the noise signal was as strong as a normal signal count.

I replaced all cables and used other preamplifier channels. The noise is gone and the baseline is flat now. However, the timing of PMT north will be a bit different now, so we should use PMT middle for the laser/ion overlap as we did before.

Graziano opened the valves for the laser and turned off the vacuum gauges and emergency lights. The background of the UV PMT looks normal (Middle 10 Hz, North 1 Hz) so I think we are fine here.