The violin mode monitor is now monitoring each fundamental mode indivudually, using the same band pass filters (and notch filters if there's any) from the SUS damaping filters. The RMS value of each mode should equal to the order of magnitude from the nominal observing noise floor. I haven't had a chance to check if that's true for every mode so there probably will be some changes to the gains in the future. At least it's usable and trust worthy enough for damp job.

Dave (on phone), Nutsinee

Concerned about locking issues, I looked into alignment changes and compared before the power outage to after the power outage and there's a few things that stand out.

IMC MC1-3 alignment changes:

changes of 8-24urad

Total angular change of each chamber:

Linear change at 16.4m (IMC length)

change due to ISI is in um range

change in IM4 Trans

change in IM1 alignment required to account for change in IM4 Trans

IM1 would have to move 11.64urad in yaw to account for the change on IM4 Trans.

IM1 hasn't move 11.64urad, so changes on IM4 Trans are coming from somewhere else

change in WFSA and WFSB yaw (before values are approximate)

diff value is not so much the problem

both WFSA and WFSB are close to or already railed in yaw, at -0.9 on a +/-1.0 scale

Gerardo, John, Chandra

Spent a good part of the day troubleshooting CP5 and surveying/fixing the other cryopumps after the electronic actuator install. CP5's LLCV needle coupling was not fully threaded. We tightened and may be seeing an improvement in the % open to % full (% open was approaching upper limit of 100% to maintain 92% full). 

We measured the pressure in the vacuum jacket of the LN2 supply line. The two ports measured 5 & 6 microns (good vacuum).

The top-end regen line connection at CP5 has an ice ball.

All of the posts are set in concrete.

Updated the de-macro'd PSL screens for FSS and ISS, restarted the MEDM web capture program.  Noticed that the status, PMC, FSS, and ISS screens didn't display properly because they had been edited and saved while far from the upper left of the display (the web capture program doesn't have a large screen area).  I edited the PSL_STATUS.adl, PSL_PMC.adl, PSL_ISS.adl, and PSL_FSS.adl files to move them to the upper left corner of the display.

Reran the de-macro script, and restarted the MEDM web capture program again, the screens now appear properly on the web pages.

Attempted to check in the modified MEDM screens, but failed.  Note that there are several MEDM screens with local mods in the userapps/release/psl/common/medm directory, these should be checked in by the responsible parties.

Peter, Sheila, Evan

We have been having trouble keeping the IMC locked when powering up (without the interferometer).

We found that the UGF of the loop was something like 110 kHz. During O1, we ran with a UGF that was more like 50 kHz. Recall also that the IMC loop at one point had some questionable resonance features above 100 kHz, so it is probably in our interest to keep the UGF on the low side (though we should confirm this with a high-frequency OLTF measurement).

We turned down the loop gain by 4 dB, giving a UGF that is more like 60 kHz. We were able to power up from 2 W to 23 W without lockloss.

Attached is an OLTF measurement after turning down the gain. As usual, the last point is garbage.

Jim, Sheila, Haocun,

Turning on the BS stage2 isolation loops sometimes causes locklosses.  These are the locklosses for which Hoacun found that there is a glitch in the BS side osem.  (27739)

The first attached plot shows the Z isolation loop gain coming on at t=-34 seconds, Jim tells me this comes on with a 10 second ramp, and you can see a small glitch in the Z CPS at around t=-24 seconds when the ramp should be finishing.  At just after t=-8 the gain for X, Y, and RZ isolation loops increase, which corresponds to a glitch visible in the CPS, GS13s, and top mass side osem, and optical lever.  This is the glitch that breaks the lock. 

For now I've rearranged the guardian graph so we won't be isolating the beamsplitter stage 2. 

WP5938

Evan, Dave:

h1asc model was changed to add REFL A/B WFS channels to the DAQ. 22 channels were added to both science and commissioning frames.

DAQ restart was somewhat messy, requiring mx streamer restarts on various front ends.

To make h1fw0 consistent with h1fw1 and LLO, the /etc/security/limits.conf file was edited to comment out the lines:

controls - rtprio 99
controls - nice -20

Note that the daqd processes on both frame writers are running with priority/nice values of 20/0
 

Added 184 channels. Removed 8 channels. (see attached)

IM2 shows more motion in pitch and yaw than IM1, IM3, or IM4. Below is a chart showing the p-p amplitude of the oscillations in the damping signals, in urad, for pitch and yaw.

• IM2 pitch is 3 times larger than IM4 in pitch.
• IM2 yaw is 4 times larger than IM3 yaw.

Attached is a power spectrum taken today showing OSEM LR, DAMP L, and COIL OUT LR for IM1 and IM2.

• red = OSEM, blue = damping in length (output, counts), green = coil out
• both plots have the same x axis range and y axis range
• both IM1 and IM2 damping signals have the 1Hz oscillation and additional peaks and a cluster of noise peaks
• for IM1, the noise in the length damping signal shows up in the OSEM signal at 278.34Hz, then the signal is quiet until the cluster of peaks between 526.34Hz and 570.3Hz
• for IM2, the noise in the length damping signal starts to shows up in the OSEM signal at 70.3Hz, and above that frequency, the 1Hz comb, individual peaks, and clusters of peaks are clearly visible in the OSEM signal

See also: alog #26502, alog #25955, alog #25811

C. Cahillane

I have revamped the uncertainty budget to include covariances between all stages of actuation and all time-dependent parameters.
I computed each parameter's covariances in real and imaginary coordinates to provide a consistent basis.  I then compiled an 6 x 6 Actuation Covariance Matrix C_A, a 2 x 2 Sensing Covariance Matrix C_S, and an 8 x 8 Kappa Covariance Matrix C_K.  Then I compile them into a giant covariance matrix C:

     _             _
    |  C_A  0   0   |
C = |   0  C_S  0   |
    |_  0   0  C_K _|     

Then, I multiply by some conspicuous Jacobian vectors J(f) to get the final 2 x 2 uncertainty matrix σ_R^2(f):

σ_R^2 = J * C * J'

where J looks like:

        _                            _
       |  d Re(R)    d Im(R)          |
       | ---------  ---------   ....  |
       | d Re(p_i)  d Re(p_i)         |
J(f) = |                              |
       |  d Re(R)    d Im(R)          |
       | ---------  ---------   ....  |
       |_d Im(p_i)  d Im(p_i)        _|

(I was able to use complex differentiation and Cauchy-Riemann here to make the derivatives easier.  Recall that R = 1/C + D*A.  Now I can compute dR/dA = D and dR/dC = -1/C^2 to form J(f), thanks to 200 year old mathematics)

Finally, to make the uncertainties readable by humans, I divide σ_R^2(f) by |R(f)|^2, rotate σ_R^2(f) by angle(R(f)) via a rotation matrix, and read off the square roots of the diagonal of the rotated σ_R^2(f) to get the magnitude and phase uncertainties plotted below.

I have plotted the uncertainty at GPSTime = 1135136350, the time of the Boxing Day Event.

The plot shows an overall increase in magnitude uncertainty of about 1% at low frequency.
Phase uncertainty increased by about 0.5 degrees at low frequency.

The effects are more dramatic at Livingston.  Check out LLO aLOG 26542.