Lance, Genevieve, Robert

PEM injections

We are redoing part of the formal PEM injection program, which took place for a week before the run, because the 75-60W change reduced vibration coupling by factors of 2 or 3. On Wednesday, during the commissioning slot, we finished acoustic injections at EY and started shaker injections at EY. Thursday we finished the main shaker injections at EY.

ETMY bias sweep with electronic ground injections

Fig. 1 shows that the ETMY bias setting that minimizes our electronic ground injection coupling has possibly changed a little, but not much, since January.

HVAC shutdown

I shut down the HVAC, site-wide, from about 15:23 to 15:37 Aug 17 UTC. The range increased by a little less than 10 Mpc to a little over 160 Mpc. Elenna posted a spectrum for the best part of the site-wide shutdown (see below). The shutdown and especially the re-start took time, so Fig. 2 shows just the effect of of the chilled water system at EX. Also, we shut down SF4 only (the fan pushing 11,000 CFM at the CS, from 21:18 to 21:32 UTC, but we did not see an improvement in range. We will continue with a focussed study tommorrow in order to better understand the locations of the problems.