This morning and in the afternoon (due to the ITF unlocks), a tapping campaign was performed in CEB. Specifically, tapping was applied on several flanges of each tower, on DET viewports, on SIB1 and SIB2 beam dumps, and on DET and INJ cryotrap vessels.

Only a few preliminary comments on what was observed during the tests (a complete analysis will follow)

SDB1 – South flange: Peak at 121 Hz and several additional lines.

Cryotrap – DET viewport (West side): peak at 315 Hz and various other frequencies

DET Cryotrap – Vessel: peaks above 400 Hz; clear peaks at 501 Hz and 843 Hz.

SR flange – East: peaks at 501 Hz and 840 Hz

SR flange – West: peak @ 120 Hz.

PR North flange (POP flange): peak at 730 Hz and minor lines around 93–105 Hz.

NI North flange: peak at 165 Hz, increasing and disappearing with delay  (~1 minute)

B1 viewport: Fluctuating line at 26.5 Hz, and peak at 66 Hz.

B1p Viewport: Strong broadband response: 115–120 Hz, 200 Hz, 322 Hz, and several additional lines.

Hartmann viewport: 66 Hz line shows slight breathing/modulation.

B5 viewport: responses above 400 Hz are more intense; additional lines at 101 Hz and 190 Hz.

EQB1 door: narrow peak at 951 Hz.

General observation: 
The 120 Hz line is persistently excited and fluctuating even without tapping, just by moving around the  SR -DET area.

Figures 1 and Fugure 2 show the spectrograms of hrec during the tappings performed in the morning and afternoon, respectively.

The time and the exact locations of each tapping are reported in detail in the attached file.

PS During the tappings in SIB2, we noticed a whistling noise caused by the compressed-air line (Figure 3). We informed Piernicola, who then contacted Antonio.