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taiki.tanaka - 17:22 Saturday 07 September 2019 (10405)

Hunting the 17 Hz noise

Miyoki, Yokozawa, Washimi, Taiki Tanaka

Today we measured vibration around SR3 to hunt the 17 Hz noise.

We found 17 Hz vibration in the silver color frame of SR.

And, we found the path that 17 Hz noise propagate from the frame to oplev cables by measurement at oplev cable. (pic.1, 2, measurement plot will be attached later)

We installed 4 PEMs to measure the 17 Hz noise in more detail.

K1:PEM:SENSOR_RACK_SR3_BNC8_OUT -> TEAC706 (placed under the oplev receiver table, pic.3)
K1:PEM:SENSOR_RACK_SR3_BNC9_OUT -> TEAC706 (placed under the oplev transmittance table, pic.4)

K1:PEM:SENSOR_RACK_SR3_BNC10_OUT -> Ultra-low frequency microphone (placed near the oplev transmittance, pic.5)

K1:PEM:SENSOR_RACK_SR3_BNC11_OUT -> TEAC710 (placed on the frame of SR, pic.6,7)

Images attached to this report

Comments to this report:

tatsuki.washimi - 17:51 Saturday 07 September 2019 (10406)

Spectrum of USB-ACC (left) and Temporaly sensors (right)

Images attached to this comment

takaaki.yokozawa - 7:32 Sunday 08 September 2019 (10416)

We investigated the which FFU was mainly cause the 17Hz vibration of the SR2/SR3 TM PIT oplev.

We investigated the effect of the FFU with turning on/off the PR2, BS, SR2, SR3, SRM, OMC ones.

SR2 ; Fig.1 When we turned on the PR2 FFU, 17Hz line noise appeared.

SR3 ; Fig.2 When we turned on the SR3 and SRM FFU, 17Hz line noise appeared.

It means 17Hz may not come from the resonant frequency of the clean booth frame, but FFU itself generated 17Hz noise and path via oplev cable.

Next, we want to investigate the vibration of the FFU itself.

There are no difference between FFU on and off of the SR3 oplev around 35Hz. This noise is not come from the FFU.

Images attached to this comment

takaaki.yokozawa - 12:10 Friday 20 September 2019 (10638)

We removed the following sensors from SR3 area due to prepring the next measurement