aLIGO LHO Logbook

H1 General (CAL, ISC)

anthony.sanchez@LIGO.ORG - posted 15:06, Saturday 31 August 2024 - last comment - 09:23, Thursday 26 September 2024(79841)

ETMX Drive align L2L Gain changed

anthony.sanchez@cdsws29: python3 /ligo/home/francisco.llamas/COMMISSIONING/commissioning/k2d/KappaToDrivealign.py

Fetching from 1409164474 to 1409177074

Opening new connection to h1daqnds1... connected
[h1daqnds1] set ALLOW_DATA_ON_TAPE='False'
Checking channels list against NDS2 database... done
Downloading data: |█████████████████████████████████████████████████████████████████████████████████████| 12601.0/12601.0 (100%) ETA 00:00

Warning: H1:SUS-ETMX_L3_DRIVEALIGN_L2L_GAIN changed.

Average H1:CAL-CS_TDEP_KAPPA_TST_OUTPUT is -2.3121% from 1.
Accept changes of
H1:SUS-ETMX_L3_DRIVEALIGN_L2L_GAIN from 187.379211 to 191.711514 and
H1:CAL-CS_DARM_FE_ETMX_L3_DRIVEALIGN_L2L_GAIN from 184.649994 to 188.919195
Proceed? [yes/no]
yes
Changing
H1:SUS-ETMX_L3_DRIVEALIGN_L2L_GAIN and
H1:CAL-CS_DARM_FE_ETMX_L3_DRIVEALIGN_L2L_GAIN
H1:SUS-ETMX_L3_DRIVEALIGN_L2L_GAIN => 191.7115136134197
anthony.sanchez@cdsws29:

Comments related to this report

louis.dartez@LIGO.ORG - 16:20, Saturday 31 August 2024 (79845)

Link

I'm not sure if the value set by this script is correct. 

KAPPA_TST was 0.976879 (-2.3121%) at the time this script looked at it. The L2L DRIVEALIGN GAIN in H1:SUS-ETMX_L3_DRIVEALIGN_L2L_GAIN was 184.65 at the time of our last calibration update. This is the time at which KAPPA_TST was set to 1. So to offset the drift in the TST actuation strength we should change the drivealign gain to 184.65 * 1.023121 = 188.919. This script chose to update the gain to 191.711514 instead; this is 187.379211 * 1.023121, with 187.379211 being the gain value at the time the script was run. At that time, the drivealign gain was already accounting for a 1.47% drift in the actuation strength (this has so far not been properly compensated for in pyDARM and may be contributing to the error we're currently seeing...more on that later this weekend in another post.). 

So I think this script should be basing corrections as percentages applied with respect to the drivealign gain value at the time when the kappa's were last set (i.e. just after the last front end calibration update) *not* at the current time.

also, the output from that script claims that it also updated H1:CAL-CS_DARM_FE_ETMX_L3_DRIVEALIGN_L2L_GAIN but I trended it and it hadn't been changed. Those print statements should be cleaned up.

louis.dartez@LIGO.ORG - 09:23, Thursday 26 September 2024 (80304)

Link

to close out this discussion, it turns out that the drivealign adjustment script is doing the correct thing. Each time the drivealign gain is adjusted to counteract the effect of ESD charging, the percent change reported by Kappa TST should be applied to the drivealign gain at that time rather than what the gain was when the kappa calculations were last updated.