Daniel, Stefan,

With the interferometer in a decent noise state at 25W, we went to both end stations with a calibrated rubber mallot (actually a shovel a rubber cover on the handle).

We first shuttered the PCAL lasers because we didn't want to short-circuit scatter measurments.

Upon banging the vacuum vessel the noise increased in a fairly broadband manner. On top of that some individual beaks at ~90Hz and ~110Hz also were rung up.

The worst spot in both end stations was the periscope supporting PCAL and camera. ETMX seemed to be slightly more sensitive.

Attached is a reference spectrum showing the sensitivity when we did the injections, including references from the best H1 the recent best L1.