[Nakano, Ushiba]

We measured actuator efficiency of each stage of ITMX payload.

What we did:
Excite longitudinal motion of each stage from test point with following counts.
TM stage: 100 counts @ 10.5 Hz
IM stage: 1000 counts @ 10.5 Hz
MN stage: 100 counts @ 10.5 Hz

Then, we measured displacement signal by using calibrated DARM signal.
Results are following:
TM stage: 100 counts = 1.6e-13 m/count/rtHz @ 10.5 Hz
IM stage: 1000 counts = 8.2e-15 m/count/rtHz @ 10.5 Hz
MN stage: 100 counts = 6.1e-14 m/count/rtHz @ 10.5 Hz

So, ratios of actuator efficiency @ 10.5 Hz is as follows:
A_TM / A_IM = 19.5 @ 10.5 Hz
A_TM / A_MN = 2.6 @ 10.5 Hz

From the result above and SUMCON model, we can estimate actuator efficiency ratios @ DC.
A_TM / A_IM = 0.42 @ DC
A_TM / A_MN = 0.0024 @ DC

Since actuator efficiency of TM stage of ITMX is 5.45e-12 m/count = 8.9e-9 m/V, we can calculate as
A_IM = 2.1e-8 m/V (Design value: 2.1e-7 m/V)
A_MN = 7.7e-6 m/V (Design value: 5.1e-6 m/V) 
Designed value is referred from JGWdoc T-2011661

Note: I'm not sure details of Michimura-san's calculation. So, it might miss several factors.