CAL group
We performed DARM calibration.
The measurement dir: CAL/current/measurement/2025/0407/
The measured files: 1454_*xml
Measured TF:
During the last measurement (ETMX_MN -> DARM), the lock was broken. Probably our excitation kicked a resonance around 40Hz.
The front-end calibration was updated with today's measurement results.
There is no large change in the actuator efficiency of TM from previous ones which was measured on Feb. 19th klog#32745.
Because we had large changes in the mirror temperature in Mar. it was not an enough evidence that actuator efficiency had been stable during Mar.
On the other hand, an assumption in recent OLTF measurement on Apr. 2nd (klog#33198) and updated on Apr. 4th (klog#33260 that 1.5dB change in OLTF came from optical gain (klog#33213) seemed to be almost correct. (Mirror temperature was ~80K in Feb. and Apr., but it changed as 80K -> 40K -> 80K in Mar.)
A change in the actuator efficiency of IM is slightly large but it's not so serious for sensitivity evaluation now. So it will be checked later.
Update of the front-end calibration was done at 18:58:26 JST.
So it's valid from an IFO lock at 19:08:59 JST.
Actuator efficiency of TM (Fig.1-2 shows measured TF to DARM)
old: 3.7791e-14 * (10Hz/f)^2
new: 3.7947e-14 * (10Hz/f)^2 (+0.4%)
Actuator efficiency of IM (Fig.3-4 shows measured TF to DARM)
old: 1.39319e-14 * (10Hz/f)^4
new: 1.62888e-14 * (10Hz/f)^4 (+16.9%)
Optical gain (Fig.5-6 shows measured OLTF)
old: 248.094dB
new: 247.993dB (-1.2%)
MN_LOCK_L (Fig.7 shows total filter shape of all FMs)
added 40Hz band stop filter at FM6
IM_LOCK_L (Fig.8 shows total filter shape of all FMs)
added 40Hz band stop filter at FM1
LSC_OMC_DC
removed +2dB and -2.08dB gains at FM2 and FM3, respectively.
Additional notes on the DARM calibration measurement on April 7, 2025
PRFPMI_RF_LOCKED and INCREASING_LAS_POWER, monitoring the ARM BPC signals.1350_*) was taken without performing OMC alignment.1454_*) was taken after OMC alignment.