KAGRA Logbook

VIS (OMM)

tatsuki.washimi - 16:39 Monday 21 October 2024 (31389)

OMC Stacks connection and TF measurements

[RTakahashi, Aso, Mitsuhashi, Washimi]

Today's our work:

The anchor bolts securing (klog31381) by Kimura-san & Yasui-san
TF measurement by locating both 2 accelerometers on the Top
TF measurement: Bottom (Z) -> Top (Z/X/Y)
Lunch
Instration of the extended breadboards for the OMC shroud (klog31387)
TF measurement: Bottom (Z) -> Top (Z/X/Y)
Stack Connection
TF measurement: Bottom (Z) -> Top (Z/X/Y)
DCPD connection & Beam splot alignment check

The attached photos are of the connected stacks.
This connection work itself was done without any difficulties.

For today's TF measurements, we used a stand-alone FFT analyzer (similar to the TAMA tests).
Because the seismic level at KAGRA is smaller, we used the shaker on the floor (the final photo) to get enough coherence.

Images attached to this report

Comments to this report:

tatsuki.washimi - 16:50 Monday 21 October 2024 (31390)

2. TF measurement by locating both 2 accelerometers on the Top

Comparison for the 2 accelerometers (TEAC710Z, TEAC710).

After this measurement, the smaller one (single axial) was moved to the base plate.

Images attached to this comment

tatsuki.washimi - 18:13 Monday 21 October 2024 (31391)

We measured the OMC Stack TFs (Z -> Z/X/Y), for 3 times: morning time (before the installation of the extended breadboards ), before connection, and after connection.
By connecting the upper stages, the vertical TF changed from 3 to 2 modes, as expected.
(Some small structures are found between the 1st and the 2nd mode. Due to the things located on?)

I summarized the each peaks (Z -> Z) for before and after the connection.

	1st mode	2nd mode	3rd mode
before connection	17dB @ 23Hz	2dB @ 101 Hz	-18dB @ 166Hz
after connection	18dB @ 29Hz	-9dB @ 145Hz	-

At 82 Hz, the amplitude was changed from about -5dB to about -10dB.
At 92 Hz, the amplitude was changed from about -3dB to about -15dB.

Images attached to this comment

ryutaro.takahashi - 13:22 Tuesday 22 October 2024 (31396)

[Takahashi, Washimi, Aso]

We installed the new support bolts onto the optical bench. The old bolts projected from the optical bench. Two bolts at X- and X+Y- were replaced with shorter ones.

Images attached to this comment