Summary of the DQ shift from Thursday 26th to Sunday 29th (inclusive), click here for full report:
- Very high duty cycles of 95% Observing. Range sitting around 68-70 Mpc.
- Range drops caused by; ETMY ESD overflows, glitches on the 100-200Hz band, and scattering of SUS-SRM_M1.
- IMPORTANT: Range reduced when broad excess noise below 70Hz was present. In one case this noise increased after running of A2L DTT script for dither-up. (see attached pic)
- NOTE: Presence of nonstationary narrow excess noise at around 70Hz causes small reductions of range sensitivity (few Mpc). In some case observed time agreement with increase in Pitch and Yaw motion of ITMX. (see attached pic)
- Not all lockloss understood. One was preceded by overflow of H1:ASC-AS_C_SEG2 and H1:ASC-AS_C_SEG4, this lockloss showed agreement with spikes on HAM6 X-Y acelerometers and with some erratic behaviour of the Corner building external temperature (see attached pic). Other nonunderstood lock losses had time coincidence with ground motion and wind activity.
- Violin modes have been well damped for the whole shift. And 2nd order harmonics (1kHz) have not been a proble either, specially since damping of these were added to the Guardian. Relevant is the damping of the ETMY modes at 1009.44 and 1009.49 Hz which have been associated to a high SNR glitch line at 2kHz.
- No lockloss after an earthquake Mag 5.8 EQ near Ragul Island, New Zealand.
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IMPORTANT: Coincidence of PyCBC? live newsnr of ~11 glitch with strong glitches on PEM channels for MAINSMON and MAG in all buildings.
(see attached pic) - Summary page issue: ODC Overview plots did not agree with the corresponding channels segment info --> This is now fixed and Summary Pages are being regenerated for the last year.
For reference:
I have learned that the H1:PEM-CS_ACC_HAM6 accelerometers while being not in vacuum but just beside the HAM6 chamber, they are sensitive to the shutter closing down in order to protect the output PDs after lockloss. Therefore the spikes in this channels will always be present during lockloss (see attached picture where I plot this channel together with the power built up on PR cavity so a good indicator of lockloss).
I also looked at the possibility that the overflow of H1:ASC-AS_C_SEG4 and H1:ASC-AS_C_SEG2 may actually have caused the lockloss (more to come from this analysis worthy of an aLog in itself), but notice that these signals are used, together with SEG1 and SEG3, to generate the aligment signals for SR2 and SRM mirrors.
Finally, in order to look at the possible effect that the A2L script caused on the excess low frequency noise I will run BruCo before and after the running the A2L script, which is run ocassionaly to recenter the beam into the mirrors. Sheila has mentioned that it should not affect frequencies above 25Hz though.
The Bruco reports before and after the A2L script was run. In each case I look at 600 seconds from GPS time 1169564417 for the case 'before' and 1169569217 for the case after and look at the frequency band between 40 and 100Hz, as an example this is the command used for the 'Before' case:
./bruco.py --ifo H1 --channel=OMC-DCPD_SUM_OUT_DQ --gpsb=1169564417 --length=600 --outfs=4096 --naver=100 --dir=~/public_html/detchar/O2/bruco/Before_at_1169564417_600_OMC_DCPD --top=100 --webtop=20 --xlim=40:100 --ylim=1e-10:1 --excluded=share/lho_excluded_channels.txt
Another look at accelerometers/seismometers.
In addition to the external (i.e. in-air) accelerometers, we also have in-vacuum seismometers (GS13s mounted within the Seismic Isolation [ISI]tables) which we can also look at. Attached is a look at one of the HAM6 ISI GS13s (H1:ISI-HAM6_GS13INF_H1_IN1_DQ) & a HAM6 (H1:PEM-CS_ACC_HAM6_OMC_X_DQ) in-air/external (probably mounted on the HAMdoor) accelerometer. So, when the lockloss occurs, the HAM6 Fast Shutter (referred to as "the Toaster") pops up & this shakes the HAM6 table (somes trips the HAM6 ISI). This motion is seen by the GS13 inside and accelerometer outside (which was a surprise to me).
