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VIS (EY)
ryutaro.takahashi - 20:12 Wednesday 17 November 2021 (18927) Print this report
Preparation for accelerometers

[Takahashi, Sato]

We assembled the accelerometers for EY.

  1. Assembled the base plates with the adjustment screws.
  2. Set the folded pendulum bodies on the base plates.
  3. Removed the original position sensors (capacitors) from the bodies.
  4. Attached the LVDT coils onto the bodies.
  5. Replaced the coaxial LEMO connectors to the 2-pin LEMO connectors.
  6. Soldered the actuator coils to the connectors. Checked the resistance.
ACC Primary coil Secondary coil Actuator coil
Al-#1 #10 #10 54.4Ω
Al-#2 #11 #11 56.4Ω
Al-#3 #12 #12 53.7Ω

 

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ryutaro.takahashi - 17:59 Wednesday 05 January 2022 (19359) Print this report

[Takahashi, Sato]

We soldered the LVDT coils to the connectors. Checked the resistance.

  Primary[Ω] Secondary[Ω]
#1 45.2 52.5
#2 46.8 52.6
#3 44.8 53.0

 

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ryutaro.takahashi - 17:27 Thursday 06 January 2022 (19377) Print this report

[Takahashi, Sato]

We set up the LVDT driver and the coil driver in the rack.

ryutaro.takahashi - 21:51 Wednesday 12 January 2022 (19425) Print this report

[Takahashi, Sato]

We started the tuning of the accelerometers.

  1. Set up the LVDT-ACT distributor in the rack.
  2. Connected the accelerometers to the drivers using the in-vacuum cables.
  3. Adjusted the demodulation phase and the gain of the LVDT driver.
  4. Started the tuning with the ballast weight. The resonant frequency of ACC #1 reached 0.2Hz. The LPCD was used for ACC #3.
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ryutaro.takahashi - 20:54 Thursday 13 January 2022 (19464) Print this report

[Takahashi, Sato]

We continued the tuning of the accelerometers. The LPCD was replaced with the HPCD. The resonant frequencies of ACC #2 and #3 reached less than 0.3Hz. While their Qs are very small, the DC responses correspond to 0.2Hz resonance.

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ryutaro.takahashi - 20:08 Tuesday 18 January 2022 (19496) Print this report

I tried to lock ACC #1 to calibrate. The servo filter has not been optimized yet (oscillating at 2.3Hz).

The measured spectrum was compared with the seismometer's one.

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ryutaro.takahashi - 14:56 Friday 21 January 2022 (19524) Print this report

[Takahashi, Sato]

We attached the ballast weights onto the proof masses of the accelerometers.

  Weight [g]
ACC #1 67
ACC #2 178
ACC #3 296

 

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ryutaro.takahashi - 20:35 Wednesday 26 January 2022 (19586) Print this report

[Takahashi, Sato]

The ballast weight for ACC #3 was reduced by 7g. We checked the transfer functions. The measurement for ACC #3 was often failed as shown in the plots.

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ryutaro.takahashi - 14:32 Thursday 27 January 2022 (19596) Print this report

[Takahashi, Sato]

In order to investigate the unstable actuation in ACC #3, we swapped the channel of the coil driver and the cables for H1 and H2. The actuator of ACC #3 was still unstable. We checked the soldering for the actuator coil. It was easily cut. We soldered it again. The actuator became stable.

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