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

Evan, Sheila, Stefan

For now we decided that we need to go back to a SRC alignment scheme similar to the O1 one - while not great it kept the machine running with the existing hardware. And we know that was at least reliable enough to do other work.

We started with SRC1_Y. The combination
        ezca['ASC-INMATRIX_Y_6_3']=-1.5   # AS_A36I to SRC1_Y
        ezca['ASC-INMATRIX_Y_6_7']=1      # AS_B36I to SRC1_Y
gave a reasonable error signal with about zero offset, and we could close the loop - with a gain of -30 for now.

As in the past pitch is a bit more tricky. AS_B36I has a nice signal but also quite the offset. We lost lock before finding a good value for this, and had an episode of lock losses most likely due to bad initial alignment. (below).
On the next round the following gains seemed to work for now:

       #set input matrix
        ezca['ASC-INMATRIX_P_6_3']=0 # off for now
        ezca['ASC-INMATRIX_P_6_7']=1 # good enough for now
        ezca['ASC-INMATRIX_Y_6_3']=-1.5
        ezca['ASC-INMATRIX_Y_6_7']=1
        ezca['ASC-INMATRIX_P_6_1']=0
        ezca['ASC-INMATRIX_P_6_5']=0
        ezca['ASC-INMATRIX_Y_6_1']=0
        ezca['ASC-INMATRIX_Y_6_5']=0

As mentioned, in the meantime we had a number of most likely initial alignment related locklosses. They first occured in the CARM ASC engagement, and later even DRMI phase..

I did a full  initial alignment, and also noticed that the QPD offsets on the red X TR photodiode offset was unreasonably high. I re-zeroed this offset.

With that the IFO saw a two Watts, DC readout for 2+h.

Next on the menu was more violin damping. I focused on EX, which currently has 3 moned intermingling; 505.587Hz, 505.707Hz and 505.710Hz.

505.587Hz: Damps with H1:SUS-ETMX_L2_DAMP_MODE1, FM1, FM4, gain=100.

The other two are simply too close to each other (beat signal of 5min!) - we need to damp with the same filter.. I focused on 505.710Hz., which is the big peak.
 I deleted the narrow bandstop filters, and significantly widened the band-pass filter FM1, and tried with

505.710Hz    H1:SUS-ETMX_L2_DAMP_MODE6, FM1, FM4, gain=200.

which seems to work.

The next mode (which actually grew while I paid attention to the other 3) is 507.194Hz, together with 507.159Hz.

507.159Hz seems to damp with H1:SUS-ETMX_L2_DAMP_MODE6 FM1 FM3 FM4, gain=50 (later gain=10). But currently 507.194Hz still bleeds through this filter, which makes it hard to damp.

I left 507.194Hz in H1:SUS-ETMX_L2_DAMP_MODE7 FM1, FM4 gain=50, which seems to provide a wee bit of damping.

After that, ITMY also needs more attention.

I leave the interferometer running at 2Watts - I would recommend focusing on getting the violins under control - they prevent other work.

The violin mode harmonics overlap with the ~15070Hz test mass bulk modes.  This may explain the mystery modes that have been rung up in the vicinity at Hanford alog27659 15063Hz and Livingston LLO alog20100 15085Hz.
This spectrum was taken from these measurements alog27743.  Two violin mode harmonics are visible between 15kHz to 15.1kHz and 15.5kHz and 15.6kHz.  Several test mass modes are also visible.  The violin modes were elevated and we were actuating on 15077Hz ITMX mode and 15072 ITMY mode (which are very large and far off the top of the plot).
 

Jenne, Sheila, Peter, Evan, Stefan

We had been using AS45I for SRM signal in the last two days, and they seemed to not work well for yaw today.  Peter and Jenne noticed that the violin modes showed up more strongly in some quadratns of the AS45 WFS than others, so we drove a line in DARM to check the balancing of the AS45 WFS. We drove DARM at 21 Hz, and  looked at the transfer functions to the individual quadrants before the phasing.  We set the gains so that the signal amplitudes would all match quadrant 1.  For AS A, we ended up with gains as different from 0 as 0.69

We then attempted to phase these signals in the same way that the LSC AS45 detector is phased, by turning on and off the DARM offset and making sure that all the DARM signal was in the Q phase.  To do this we changed some phases by up to 20 degrees.  We had to use a step size of 0.5degrees on AS A which is in loop for DHARD to avoid loosing lock.  

After doing this we tried moving the SRM alingment to see if the AS45 signals were better for SRM.  We saw that pit and yaw were cross coupled, and we didn't have much pitch signal at all.  We reverted these changes since we don't really think that the gains in the electronics can be this badly matched.  

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.  

Jenne, Peter, Jeff, Terra

We took charge measurements on the ITMs by driving 20.1 Hz into H1:SUS-ITMX/Y_L3_DRIVEALIGN_L2L_EXC with 100k cts and looked at the coupling to DARM. We stepped up and down the ESD bias voltage from zero and found the bias that gave zero coupling to get charge measurements, where V_charge= (20/2¹⁸) * bias * 40. ITMX zeroed with bias = 3k, ITMY zeroed with bias = 2.5k. See bias stepping ITMX and ITMY spectra attached. 

ITMX charge: 9.15 V,   ITMY charge: 7.6 V

ITMX: 

ITMY:

Approximating alpha: The first term in the expression for the force produced by the ESDs is the attractive force between the ESD fringe fields and the test mass: F = alpha(V_bias - V_signal)^2, where alpha is a constant of proportionality. With the known bias voltage V_b, signal drive voltage V_s, drive frequency f, and now the peak amplitude x_pp , we used the largest bias offset (100k) to approximate alpha for both ITMs. Work is attached. 

ITMX: alpha = 1.78 x 10^-11 N/V²,   ITMY: alpha = 1.85 x 10^-11 N/V²

Stefan, Nutsinee

So we found out that the ITMY vstop filter has been turned off. That's likely the cause of mysterious ring up of ITMY violin modes last night and tonight. I was able to damp the three highest modes (ITMY MODE2, MODE3, MODE5) with the settings on the table I confirmed on June 13. I haven't had a chance to re-comfirm all the settings. So until then I would either comment out IY violin mode damping guardian lines or just skip it for now.