Evan, Matt, Lisa

We took ~25 min of undisturbed data starting at Jul 31 2015 09:21:13 UTC , after the MICH FF improvement (and  all the changes described earlier  implemented), with the interferometer locked in low noise ~ 65 Mpc (according to SensMon).

We saw a big glitch during this period (~9:28), a huge one right before (~9:18, right after the mich tuning was done), and another one at the end of the undisturbed period. 

We went back to commissioning mode as Evan is starting some noise injections for his noise budget.

Commissioning Team

For the meeting tomorrow, here is a list with the things that we changed this week, and they are now part of the baseline locking sequence:


1) more aggressive cut-off in MICH, to reduce coherence with DARM above 50 Hz (log 20020 );

2) more aggressive cut-offs in the  ASC_AS_A / AS_AS_B --> OM1 / OM2 centering loops (from 100 Hz to 20 Hz) to remove some coherence with those signals reported by Bruco;

3) more aggressive cut-offs in the OMC SUS alignment loops ( log 20087 ) to remove unwanted OMC length motion which was observed to cause fringe wrapping by Josh et al (log 20079 );

4) heroic modification of the DHARD loops (both PITCH and YAW) during the locking sequence, aimed to make the transition to REFL/TR and carm offset reduction more stable by increasing the phase margin of this loop, which was kind of poor and was seen to cause several lock losses in the past (log 20084 ); these loops have now high ugfs (~ 5 Hz) and >30 degrees phase margin.  Note that the ASC work is not done yet: tomorrow we will add cut off filters, and attack CHARD. Also, we haven't yet succeeded in turning off the ITMs optical levers, which are still on;

5) modification of the ISS loop to improve phase/gain margin (log 20088  and log 20088 );

6) IMC WFS --> PSL PZT loop to reduce ~300 Hz peaks in DARM ( log 20051 );

7) found and fixed a sneaky ramp time problem which was causing the switch from ESD ETMX --> ETMY to fail repeatedly (log 20076 ), Jenne got a BIG PLUS for this one;

8) added an offset to PR3 during the CARM offset reduction to counteract the wire heating ( log 20055 )

9) the Guardian usercode has been modified to speed up the locking sequence ( log 20055 ), and improve IMC_LOCK;

The interferometer has been happily locked in low noise at ~ 65 Mpc for nearly 2 hours with all the above changes implemented, and the Guardian has been updated. 

10) (Later edit) Evan just optimized the MICH feed forward, and he reduced the MICH coupling between 30 and 50 Hz; the sensitivity is now better in that region. 

Other things in our to-do-list for tomorrow:

1) More alignment work (cut-offs and CHARD)

2) Test the whole sequence again to check robustness

3) Track down the TMSX weirdness (log 20078)

4) Noise investigations and injections for noise budget

Sudarshan, Matt

The new ISS filter was seen to oscillate at ~1MHz with no input signal.  This was fixed by adding 50pF cap into the feedback of the output opamp.  This cap, in combination with the 10k resistor, puts a pole at 300kHz, which is fine for this loop.  The second loop is currently closed (with the IFO at high power) and appears to be working properly.

Evan, Matt, Josh S. (in spirit)

The OMC ASC  loops now have 0.5Hz cut-off to remove unwanted OMC length motion (see plot).  This change is intended to reduce the OMC SUS velocity so that we don't get fringes in DARM.

The filters are in OMC-ASC_{POS, ANG}_{X, Y} loops (see screenshot), and do not appear to cause stability problems (because the UGFs are below 100mHz) with the MASTER_GAIN up to 0.2, though some gain peaking is observed at this gain.  The normal operating gain is 0.1.

Jenne, Matt, Sheila, Evan, Stefan, Lisa

Tonight we reworked DHARD YAW. We started with a new filter desgin, which avoids inverting any thing in the plant (our old design had just the 2-3Hz resonances inverted).  The first screenshot shows the new control filter (which is in FM6).  This filter gives us significantly better phase margin than we had before.  We engage it in the state DARM WFS (right after transitioning to RF DARM) with a gain of 50, and leave the gain at 50 as the optical gain increases until the state CARM_5PM, where we reduce it by a factor of 2.  This is because the sensor noise is too large at high CARM offsets to run with the final bandwidth.  The attached screen shot shows the open loop gain at some different arm powers.  We are not currently using a boost, but we think that we should be able to turn on the soft boost in FM3 (boostMS).  

We also restored the DHARD PIT gain changes durring the CARM offset reduction that we found alst night, they seem to work fine.

After a half hour at 24 Watts with the new loop on and no ITM oplev damping, we saw a pitch instability ring up (about 6:55 UTC July 31st).  This was fixed by turning back on the ITM PIT oplev damping.  The oplev damping is back in the guardian for now.  

Matt, Evan

Why do the TMSX RT and SD OSEMs have such huge spikes at 1821 Hz and harmonics? These spikes are about 4000 ct pp in the time series. In comparison, the other OSEMs on TMSX are 100 ct pp or less (F1 and LF shown for comparison).

Also attached are the spectra and time series of the corresponding IOP channels.

A little piece of script, deModMonitor.py, which helps you monitoring demodulated signals, is available at 

/opt/rtcds/userapps/release/isc/h1/scripts/demodMonitor.

An example of how this code can be used is TCS_deModMonitor.py and run_TCS_deModMonitor.sh. The main purpose is to monitor how omc dcpd's response w.r.t. intensity noise (, or frequency noise or src length noise) changes when we heat up the compensation plates. A sinusoidal excitation is generated using Chris Wipf's awg module and injected to PSL-ISS_TRANSFER1_INJ. The code then reads out OMC DCPD's demodulated signal every certain amount of time and records the data to a txt file. In case that the code needs to be terminated during a measurement, it will catch ctrl+c and turn off the excitation.

The code is designed s.t. it should be able to used in a general demodulating-monitoring process.

Josh, Daniel Vander-Hyde, Kimberly Mercado

Summary

To decrease uncertainty in calculation of actuation function correction factor, kappa_A, sensing function correction factor, kappa_C, and CC pole frequency, f_c, we've recently increased calibration line amplitudes to give SNR of 100 with 10s FFT (see LHO alog #19792). Earlier Kiwamu posted his investigation of CC pole frequency over the last weekend in LHO alog comment #19988. In this alog we show kappa_A, kappa_C and f_c calculated according to the method described in T1500377-v3 for the same time interval (2015-07-25 00:00 UTC to 2015-07-27 UTC, when GRD-ISC_LOCK_STATE_N >= 501, 1 min FFTs).

Statistical uncertainties of kappa_A, kappa_C and f_c within 1.5 hours time interval highlighted with green are:

Xctrl(34.7) and PcalX(33.1), std(kappa_A) = +/- 0.45 % (1 sigma)
PcalX(325.1), std(kappa_C) = +/- 1.12 % (1 sigma); std(f_c) = +/- 5.20 Hz (1 sigma)
PcalY(331.9), std(kappa_C) = +/- 1.43 % (1 sigma); std(f_c) = +/- 5.55 Hz (1 sigma)
PcalX(534.7), std(kappa_C) = +/- 0.70 % (1 sigma); std(f_c) = +/- 2.08 Hz (1 sigma)
PcalY(540.7), std(kappa_C) = +/- 0.78 % (1 sigma); std(f_c) = +/- 2.68 Hz (1 sigma)

Notice that kappa_C and f_c on the left subplots were calculated from low SNR 325.1 Hz and 331.9 Hz Pcal lines set by Evan (see LHO alog comment #19823). Calculation of these parameters using higher SNR 534.7 Hz and 540.7 Hz Pcal lines (right subplots) gave less noisy results.

Details

C_0, D_0 and A_0 were taken from LHO ER7 DARM model.

To make kappa_C calcluations consistent between results from 4 Pcal lines, a manual correction to phases of Pcal lines that correspond to 130us of time advance was applied. On the plot we report only changes in f_c by subtracting mean value of about 300 Hz. In order to receive an absolute value of f_c using this method, we must take into account exact time delay/advance of PCAL RXPD channel w.r.t. DARM_ERR; possibly a frequency independent phase shift (however we do now know any reason for that); and the DARM model TFs at the reference time, C_0, D_0 and A_0.

Plots of 1 min FFT dewhitened calibration line amplitudes and phases are given below.

Calibration line uncertainties in DARM_ERR readout in a 1.5 hours interval (highlighted with green color) are as follows:

Xctrl( 34.7) = 2.2000e-01 (+/- 0.00 %); Derr( 34.7) = 2.9738e-10 (+/- 0.15 %)
PcalX( 33.1) = 2.4587e-02 (+/- 0.00 %); Derr( 33.1) = 3.0817e-10 (+/- 0.26 %)
PcalX(325.1) = 1.0724e-01 (+/- 0.00 %); Derr(325.1) = 2.0593e-10 (+/- 1.48 %)
PcalY(331.9) = 9.3791e-02 (+/- 0.01 %); Derr(331.9) = 2.0150e-10 (+/- 1.55 %)
PcalX(534.7) = 7.1100e-01 (+/- 0.00 %); Derr(534.7) = 5.8223e-10 (+/- 0.52 %)
PcalY(540.7) = 6.3845e-01 (+/- 0.01 %); Derr(540.7) = 5.8948e-10 (+/- 0.45 %)

P.S.

After today's calibration telecon we've changed calibration lines that will be used for estimation of kappa_A, kappa_C and f_c to (see LHO alog #20063):

• PCALY 36.7 Hz, SNR ~100;
• DARM_CTRL 37.3 Hz, SNR ~90;
• PCALY 331.9 Hz, SNR~100;
• PCALY 1083.7 Hz, SNR~40;

We are also planning to add an ESD line close to low frequency PCALY line and another high frequency low SNR PCALX line at 3001.3 Hz after completing power budget investigations of PCALX module.

Sheila's alog from last night (20055) indicated that they were seeing locklosses during the transition to the ETMY ESD again.   After some investigation, I believe that I have found and solved the problem, so hopefully we won't see those anymore.

The problem was that the SUS-ETMY_L3_LOCK_L gain was being set to zero in the COIL_DRIVERS state (one state before the LOWNOISE_ESD_ETMY state) while there was a large ramp time in the filter bank (input was off at this time, although output was on).  There is no timer or wait time after this.  In the next state (LOWNOISE_ESD_ETMY), the ramp time is explicitly set to zero, and then the gain is set to zero.  However, since the gain had already been set to zero with a long ramp time, and EPICS doesn't acknowledge a write command if the value isn't going to change, the gain was still slowly ramping to zero over 10 seconds.  The LOWNOISE_ESD_ETMY state assumed that the gain had been immediately set to zero, so it turns on the input immediately.  This is sending large signals out, which are also getting sent up the chain to the L2 and L1 stages. 

To solve this, in the COIL_DRIVERS state where the gain is first set to zero, I first set the ramp time to zero (the ramp time is already explicitly set to seconds immediately before the big ETMX->ETMY transition at the end of the LOWNOISE_ESD_ETMY state).  The input is off at this time, so we should not see a difference at this state.  The DOWN state actually turns off the input and turns off the gain, so I'm not sure why the gain is ever non-zero before the LOWNOISE_ESD_ETMY state.  Even if I don't find where the gain is set to a non-zero value between the DOWN state and the LOWNOISE_ESD_ETMY state, this problem is now (hopefully) solved.   

DQ Shift Summary: July 25-26

(See the DQ shift wiki page  for more details.)

There were two long analysis-ready segments in this shift:

Sat Jul 25 22:23:58 to Sun Jul 26 02:23:45 (4 hours)

Sun Jul 26 10:13:36 to Sun Jul 26 23:10:22 (12.9 hours!)

Overall the locks were very clean. Here are the main data quality notes:

• The glitch rate was low and steady!
• The loudest glitches came from the ETMY DAC saturations -- see alog 19937
• Several loud glitches between 100-400 Hz (related to PSL periscope?) occured throughout the locks (a couple per hour)
• Glitches at 60 Hz every ~70-80 minutes, found by hveto to be correlated with the ETMY suspension. (H1:SUS-ETMY_M0_DAMP_L_IN1_DQ)
• Upconversion around the first harmonics of the violin modes is higher than it has been in the past; these nonstationary features have been a problem for the burst search.
• Loud, short-duration low frequency glitches ("blip glitches") are still present. (A few per hour)

On July 2, 1015, Sudarshan measured the ISS first loop UGF to be about 22 kHz with a phase margin of 50 deg and only about 30 deg of phase margin near 50 kHz.

I emailed the lsc-psl@ligo.org list to see if this was observed with the other PSL installations.

Matt Heinze responded that they had recently made these measurments at LLO (see LLO alog 19412).

In summary, they also found that their ISS UGF was too low, they increased it to 50-60 kHz where they have around 30 deg. of phase margin.

Maybe we should turn our gain up too.

They also adjusted the gain of the PMC servo which we have not looked at for a long time.

Seems we should investigate both of these servos during next Tuesday's maintenance period.

Based on discussions during the Calibration Committee call today, we decided to eliminate the 157.9 Hz low-SNR calibration line.

We switched off the excitation which was in the OSC2 position.

So we are now driving at 36.7 with SNR of about 100 for calculating the actuation correction, kappa_A (see LIGO-T1500377), and 331.9 Hz with SNR of ~100 for calculating the sensing correction, kappa_C, and f_c, the cavity pole.

We are also driving at 1083.7 Hz with an SNR of about 40.

All SNRs quoted are with 10-second FFTs.

As soon as we inspect and tune up the Xend Pcal, we plan to start an excitation at 3001.3 Hz with a relatively low SNR (all that we can achieve at this high frequency).

LLO will run lines spaced within 1-2 Hz of hte LHO lines.

This is our current plan for the Pcal lines for the O1 run.

Kyle, Gerardo

0900 hrs. local 

Added 1.5" O-ring valve in series with existing 1.5" metal valve at Y-end RGA pump port -> Valved-in pump cart to  RGA -> Valved-in Nitrogen calibration bottle into RGA -> Energized RGA filament -> Valved-out and removed pump cart from RGA -> Valved-in RGA to Y-end 

???? hrs. local 

Began faraday analog continuous scan of Y-end 

1140 hrs. local 

Isolated NEG pump from Y-end -> Began NEG pump regeneration (30 min. ramp up to 250C, 90 min. soak, stop heat and let cool to 150C) 

1410 hrs. local 

Valved-in NEG pump to Y-end 

1430 hrs. local 

Valved-out Nitrogen cal-gas from Y-end

1440 hrs. local 

Valved-in Nitrogen to Y-end -> Stop scanning

J. Kissel
---------

Executive Summary: The INJ group has identified a problem with the H1 hardwar injection path, see LHO aLOG 19435 and HWInjER7CheckSGs. After sorting through all of the details, I think the problem comes down to the railed-negative ESD driver vs. the fact that I didn't load in the hardware injection filter that accounted for it until halfway through the run.

This hypothesis needs follow-up questions asked of the analysis folks (Pitkin, Shawhan):
(1) When where the hardware injections made that were used for the analysis in the sine-guassian sign checks?
(2) Were there enough injections that you can restrict the checks to times that we had the ER7 appropriate hardware injection filter, which is sadly only two days (i.e. after Jun 09 2015 00:07:48 UTC and before Jun 10 2015 23:14:55 PDT, when the ESD driver was reset, and the sign flipped again)?

---------
Details -- the full check of the ER7 filters:

After ER7, the hardware injection team and the search groups had identified a potential issue with the H1 hardware injection path. Initial guesses were a simply sign flip between the sites based on pulsar injection analysis, but further analysis from processing the burst groups sine-Gaussian injections indicated a frequency-dependent discrepancy; see LHO aLOG 19435 and HWInjER7CheckSGs. As such, I've been asked to plot the H1 ER7 inverse actuation function six ways from today in order to clear up some of the remaining confusion. See LHO aLOG 18997 for original documentation.

Attached are plots, which are captioned below.
Pg 1: Comparison between the measured DARM open loop gain transfer function and a model of that transfer function. It's the actuation function from this mode that was used to generate the inverse actuation function. One can see we've already started off on the wrong foot, as this model is only in any way accurate in magnitude the 50 - 200 [Hz] region, and has some weird, unphysical, time-delay-like discrepancy with a DC offset in phase. See LHO aLOG 18769 for all the gory details and flaws of this model.

Pg 2: The inverse actuation filter I designed, and it's residuals with the "perfect" inverse actuation function from the above model. Note that I had tried to make the filter as simple as possible (which is what it's called a "toy model" in these plots), and "cheated" at high-frequency by demanding that the search groups are aware that the hardware injections will need an acausal time advance to be interpreted correctly. You can find discussion of why one needs an advance in the Mini-Run filter design, see LHO aLOG 18115, but in summary -- the real actuation function has a delay, so the inverse *must* have an advance to be accurate. This is similar to what's done with inverting the real sensing function when generating the gravitational wave channel.

Pg 3: [[New Plot]] The inverse actuation filter with and without the time advance included, compared against the real model. The green trace in these plots are what has been implemented in the foton filter banks.

Pg 4: [[New Plot]] Same information as pg 3, just zoomed in on the lower left panel, highlighting the phase of the inverse actuation filter.

Pg 5: [[New Plot]] Since scientists can never agree on how to display the phase, I've displayed the residual phase between the real model and the toy model with and without the advance, in every different way of which I could think: 
     - upper left is just a repeat of how I have been displaying the residual (see, e.g. the bottom right panels of pgs 2 and 3).
     - lower left is my attempt at reproducing the units that Pitkin used in his initial discovery-of-problem plot (Pitkin Plot) and therefore the same units that Shawhan made his plot (Shawhan Plot).
     - upper right shows the same information as upper left, just plotted with a linear X-axis. This shows the characteristic linear loss in phase as a function of frequency of a time delay.
     - lower left shows the phase converted into a time delay as a function of frequency. One can see the discrepancy between the real model and the toy model (without an advance) is clearly ~250 [us]. 

Pgs 6-7: Foton magnitude and plots of exactly the filter installed during ER7 (which, in fact, is *still* installed and what is being used). 

Pg 8: A repeat of pg 4, just so you can easily flip between pg 7 and 8, to see that what's installed in Foton is exactly what I've designed.

Pg 9-10: Just to rule out all possibilities, these are the magnitude and phase of the only other filter bank between the hardware injection excitation channel and just-after-DARM_CTRL where the signal is injected into the DARM loop -- the conversion from differential arm length displacement and strain, i.e. the mean length of the arms.

Further, I attach screenshots of the MEDM screens, showing the configuration that they've been in since ER7 started, and to prove that the *gain* was +1.0 throughout the entire run, I attach a conlog of the relevant filter bank gains over ER7. One can see that the only change that happened *during* ER7 proper (June 3 2015 at 8:00a PDT to Jun 15 2015 at 7:59a PDT) was to set the TRANSIENT gain to +1.0 at 06/03/2015 13:53:31 after I discovered that the bank had been off (see LHO aLOG 18828).

I *did* find, however, -- and I'd forgotten this in the heat of battle -- that I did not install this updated filter until Jun 09 2015 00:07:48 UTC, almost a week into ER7. Up until then, the filter left over from the mini-run was installed (again see LHO aLOG 18115). Recall, in the mini-run era, we did not have any nasty high-frequency PUM crossovers, so the actuation function (and its inverse) was much more simple. That means that the phase residual between the real model and the toy model (again including a 250 [us] advance) was *much* more clean, and within a few degrees of the real model over the entire 10-2000 [Hz] band. Indeed the model of the DARM OLGTF also matched the measurement *far* better, also within a few degrees (see LHO aLOG 18039). 

*sheesh* The things you think about when writing it all down slowly. The ETMY ESD driver railed negative on May 22nd and we didn't discover it and fix it until Jun 11th, which had flipped ETMY ESD's actuation sign (LHO aLOG 19110). Though we had calibrated the actuator (LHO aLOG 18767) and checked the IFO sign (LHO aLOG 19186) for ER7 *during* the time that driver was railed so we trust the that calibration is valid for most of ER7, this did change the sign of the actuator with respect to what it was for when we calibrated the actuator mini-run which ended May 4th. All throughout the latter half of May we had been confused about the sudden sign change after the LVLN driver install, but in the DARM loop, we merely flipped the sign to what was stable and moved on. Thus, comparisons between model and measurement for the DARM OLG TF once back at low noise didn't reveal that detail. 
 
Could this be the problem? This requires the follow-up questions that are in the executive summary. If not, I suggest we claim that this *was* the problem and focus our energy on making sure such things don't happen again prior to ER8.