Message ID: 8255
Entry time: Fri Mar 8 02:17:04 2013
In reply to: 8242
Reply to this: 8256

Author:

yuta

Type:

Update

Category:

LSC

Subject:

calibration of PRM actuator

[Manasa, Yuta]

We measured AC response of PRM actuator using PRM-ITMY cavity.
Result is

PRM: (19.6 +/- 0.3) x 10^{-9} (Hz/f)^2 m/counts

It is almost the same as in 2011 (elog #5583). We took the same procedure as what Kiwamu did.

What we did:
1. Aligned PRMI in usual procedure, mis-aligned ITMX and locked PRM-ITMY cavity using REFL55_Q_ERR. POP DC was about 18 when locked.

2. Made UGF of PRM-ITMY cavity lock at 10 Hz and introduced elliptic LPF at 50 Hz(OLTF below).

3. Measured transfer function from C1:LSC_ITMY_EXC to C1:LSC_REFL55_Q_ERR. Dividing this by ITMY actuator response(measured in elog #8242) gives calibration of REFL55_Q.

4. Measured transfer function from C1:LSC_PRM_EXC to C1:LSC_REFL55_Q_ERR to calibrate PRM actuator.

Result:
Calibration factor for REFL55_Q for PRM-ITMY cavity was (1.37 +/- 0.02) x 10^9 counts/m (plot below). Error is mainly from statistical error of the average.

Measured AC response (50-200 Hz) of PRM is below.

Next:
- Measure free-run length spectrum of PRM-ITMY cavity and compare with MICH free-run.