Motivation: the first scope is to study the sound transmission between the CEB hall and the two labs: in order to quantify the contribution from the CEB HVACs this time we first switch off the INJ and DET labs HVAC and THEN the hall and CleanRooms HVACs. Also, we perform a white noise injection with one of the two sub-woofer positioned in the DET terrace. The second purpose is to study the origin of the low frequency peaks at approximately 12 Hz and 19 Hz which are clearly seen by microphones when the INJ HVAC is off (previous investigations: elog https://logbook.virgo-gw.eu/virgo/?r=69148).
Preparation (this morning):
- we moved the GRAS microphone inside the laser bench room (the microphone was laid onto the fan coil at the left of the entrance). We positioned it on a tripod in the corner of the bench room at the right side of the entrance.
- we installed a second GRAS AZ46 microphone on a tripod inside the hall on the west side of the INJ tower (nearby the EEroom). In the attached picture.
Action times:
- 12:35 UTC - DET OFF
- 12:38 UTC - INJ OFF
- 12:45 UTC - CEB CLEAN ROOM OFF
- 12:50 UTC - CEB HALL OFF
- 12:58 UTC - acoustic injection in CEB hall (acoustic injection file: /virgoData/NoiseInjections/AcousticInjectionsO4/output/AcousticColored_NOISE_CEB_DetTerrace-1469278756.txt)
- 13:05:50 to 13:11:30 UTC - open (and kept open) the acoustic door between Atrium and LaserLab
- 13:11:30 to 13:13:00 UTC - open and close repeatedly the atrium door to generate sound pulses inside the INJ bench room
- 13:16 UTC - clean room ON
- 13:18 UTC - CEB hall ON
- 13:21 UTC - DET AHU ON
- 13:24 UTC - INJ AHU ON
The laser lab temperature increased by 1deg overall as shown in Figure 2. The weather conditions were good, with low wind (also in Fig.2). Analyses will follow.
