Except for the known FSS issues (alogs 16605, 16645), everything looks normal; no significant changes from last week.

Following up on our adjustment of the FSS RefCav alignment on 2/10/2015 (alog 16605) I've attached a 10 day trend of the signal H1:PSL-FSS_TPD_DC_OUT_DQ.  In this you can see our 2/10/2015 adjustment, where we left the TPD reading ~1.6V.  It starts to decay early Monday morning, 2/16/2015 (~11:00:00 UTC) and is currently reading ~1.3V.  Will keep an eye on this over the next few days, we may need to go in the PSL and adjust this again (most likely during the next Tuesday maintenance).

While running DBB scans this morning I noticed the ISS diffracted power was up around 12.2%.  I adjusted the RefSignal from 2.08V to 2.13V, bringing the diffracted power to 7.4%.  Running a trend shows the diffracted power started increasing slowly early Sunday morning (see attached).

   To accommodate the remaining 3IFO work before the end of project there will be extended noise hours until the end of March. Each Tuesday from 08:00 to 16:00 will be open for noisy work around the site. Floor access after 10:00 on the other days may be allowed with commissioner’s approval. 
 
   Seismic - Working on HEPI pump commissioning

   Suspensions – Running transfer functions on ETMX and SR2

   Vacuum – Preparing to start pumping at HAM1. Will coordinate with Daniel before starting work

   Electrical – Will be moving racks from End-Y to the H2 electronics building in the near future

   Safety Meeting – John reviewed the melted plug/receptacle extension cord problem from last week. The portable transformers will be shut down, and extension cords removed as the LVEA and VEAs are cleaned up for the ER run. Each subsystem should be looking into shutting down unused equipment and removing any extension cords wherever possible.    

These are trends for the last 10 days:

model restarts logged for Mon 16/Feb/2015

no restarts reported

model restarts logged for Tue 17/Feb/2015

2015_02_17 10:53 h1hpietmx
2015_02_17 10:53 h1iopseiex
2015_02_17 10:53 h1isietmx
2015_02_17 11:05 h1alsex
2015_02_17 11:05 h1iopiscex
2015_02_17 11:05 h1pemex
2015_02_17 11:07 h1iscex
2015_02_17 11:07 h1odcx
2015_02_17 11:22 h1hpietmy
2015_02_17 11:22 h1iopseiey
2015_02_17 11:23 h1hpietmy
2015_02_17 11:23 h1iopseiey
2015_02_17 11:23 h1isietmy
2015_02_17 11:26 h1iopsusex
2015_02_17 11:26 h1susetmx
2015_02_17 11:26 h1sustmsx
2015_02_17 11:27 h1susetmx
2015_02_17 11:33 h1iopsusey
2015_02_17 11:35 h1susetmy
2015_02_17 11:35 h1sustmsy
2015_02_17 11:42 h1iopiscey
2015_02_17 11:44 h1alsey
2015_02_17 11:44 h1iscey
2015_02_17 11:44 h1odcy
2015_02_17 11:44 h1pemey
2015_02_17 22:39 h1fw0

Maintenance day. One unexpected restart. Removal of RFM card in SEI end station computers. EX Beckhoff computer reboot after fortnight freeze.

Alexa, Evan, Peter, Lisa, Sheila

Today we increase the gain in the fast path off the common mode servo gain to 7dB rom 3dB.  This was needed to fix the problem in the ALS COMM loop shape (alog 17649. ) We originally tuned our TR CARM transition at an input power of 10.8 Watts, and we are now running at 2.8 Watts.  The IMC guardian is partially correciting the IMC servo gain for this change, but not compeletely, so the fast path gain was a bit different than what we had when we originally tuned the transition.  The new ALS COMM open loop gain is attached.  If we deicde to change the input power for the locking sequence we might need to revisit this, or do a better job compensating for optical gain changes in the IMC. 

With this gain adjusted, we were able to do the TR CARM transition without a problem, (at the original gain of -16dB in the common mode board input 1).  The new TR CARM open loop gain  (with improved phase as described in alog 16766)  is attached to alog 16766

We then moved on to redcing the CARM offset, and lost the lock severl times on the way (possibly due to bad alingment).  We have now moved the transition to RF DARM to a higher CARM offset (8 times the single arm power). We have attempted to turn on the DHARD WFS at the same CARM offset that we had been using (25 times the single arm power) but only PITCH was working. With just pitch running and manually alinging YAW, we have been able to go through the locking sequence but not transition CARM to REFL 9.

One thing we have noticed tonight is that the Y arm alingment that is good for green is verry different from the alingment that reduces AS DC.  This probably means that we could make the process easier by adjusting the camera position that the Y arm green WFS use durring intial alingment.  

J. Kissel

Since the original study on coherence with pump servos focused on the corner station (see LHO aLOG 16239), I attach some plots (first and second attachment) showing how bad the coherence is between each stations pump servo and the chamber motion. Further, the original study used the HEPI L4Cs -- but these were proven to be sensor noise limited at the boundaries of the coherence. Using the ISI T240s, one can resolve the coherence better, and see that it's worse over a more broad frequency band. Turns out T240s are better sensors than L4Cs. Shocking, I know. Note that I only have shown the Z, RX, RY, and RZ DOFs because (a) X & Y don't show coherence anywhere in either the L4Cs or T240s, and (b) I didn't look at the HP / VPs because there's no combination of the T240s that could reconstruct these DOFs.

Great, but this is sort of old news now. We know the parameters we have installed are bad given all the other flaws in the system (see LHO aLOG 16619). 

So let's design new PID loops with parameters that are better, given the constraints of this sub-par ADC/DAC system, and given our knowledge of the plant (see LHO aLOG 16601).

Assuming we reduce the sampling frequency of the EPICs record that processes the analog input, PID, and output to 1 [Hz] (instead of the claimed 10 [Hz], which was actually some slower frequency due to extra slow processing time), we now know that the integrator coefficient's value will depend on that sampling frequency so we must design accordingly. We also know that SMOO parameter low-pass filters are bad (at least ones that are so close the UGF). We also know that the ADC noise is terrible, and we haven't really resolved when the pressure sensor signal gets above the ADC noise, even though we've measured all the way down to 3 [mHz] (see LHO aLOG 16500). In any event we know that reducing the UGF of the loop does good things -- or at least reduces the bad (see LHO aLOG 16466). As such, I've modeled the right parameters to get a UGF of 10 [mHz]:
         P     I [cycles/min]
Corner   5     0.13   
EX       5     0.04
EY       5     0.04
For plots supporting the model, see the last attachment. 

Why 10 [mHz] you ask? I'm glad you're curious.
- As mentioned above and elsewhere, the sensor signals don't get above the ADC noise floor -- at least down to 3 [mHz] -- but they look like they're on the way up and may surpass the noise by 1 [mHz]. Why not a 1 [mHz] UGF then? Well, one could claim the SR785 measurement of the raw pressure sensor voltage may not have been valid at its lowest frequency points. It'd be a stretch, especially for the return pressure sensor signal, but I'll humor you.
- Do we really have the patience to commission / characterize a 1 [mHz] loop? Not really.
- Do we have to have patience anyway, because the pump servos are causing noise down at these frequencies whether we like it or not? This got me launched on using the T240s. They show the coherence rolls off at a lower frequencies than the L4Cs report BUT the coherence drops BEFORE the T240s hit their noise floor. This drop off happens by 10 [mHz].
- We want to get *some* suppression on these things on the 100 [s] time scale, because when free running, we do see the pressure drift around on the several minute time-scale. Not a lot, but it does. An unagressive UGF of 10 [mHz] gets us a suppression of 10 at 1 [mHz], and continues to increase proportional to 1/f. Should be plenty. 10 [mHz] also plenty far enough away from the sampling frequency that there's no funny phase business going on anymore.

Another side thought -- maybe we should just go back to using the supply pressure alone? It definitely has better SNR than the return pressure signal at these frequencies. We can use the one by the chamber as a compromise.

Hugh and I will post some data tomorrow showing that 
(a) a 1 [s] requested sampling rate reliably produces a 1 [Hz] sampling frequency.
(b) When we request to sample at 0.1 [s], the sampling frequency depends on the number of sensors read in, but the ADC noise floor does not change.
(c) We've permanently set the sampling time to 1 [s], installed the above new PID parameters, and there is no longer any coherence with the chamber's T240s (and hopefully the IFO).

-------
Data is taken from the template:
/ligo/svncommon/SeiSVN/seismic/HEPI/H1/Common/2015-02-16_H1HPI_EndStation_Coh_wISIT240s.xml

Filters were design with the script:
/ligo/svncommon/SeiSVN/seismic/HEPI/H1/Common/H1HPI_PumpServo_FilterDesign_Ts1Hz_UGF10mHz_20150217.m

Just was glancing over at the wall display of wind channels, and noticed a distinct change in the resolution of the wind data trends, and didn't hear of anything happening to the sensors / channels at 4p PST... (screenshot was taken at 9:10p PST, change happens 5 hours prior).

This is a brief update on the recent calibration activity. It is still a working progress, but seemingly we are moving forward.

(Of course, I made a mistake)

• I had a wrong sign in the MICH open loop gain when undoing the MICH supression (see alog 16733).
  • => Fixing this mistake gave a ITM L2 stage response @13.05 Hz of 5.5x10^-18 m/cnts which is close to what the suspension model expects (5.8x10^-18m/cnts).

(Please discard the DIFF VCO-based calibration)

• With this bug fix in mind, the original ALS DIFF VCO-based calibration (alog 16701) have been underestimating the ESD response by a factor of 3.4 which was previously mistakenly thought as a factor of 5.3 (alog 16733).
  • Also, we now think that the DIFF VCO calibration coefficient we have is not trustable. So we will discard the DIFF VCO-based calibration hereafter unless we revisit the VCO calibration.

(New ETMX ESD calibration is stronger than the suspension model by a factor of 2-ish)

• Now, if we compare the measured ETMX response (alog 16733 with the mistake fixed) with the suspension model without linearization in the ESD, the measured response is stronger by a factor of 2.07.
  • This is the point which makes me think that something is still not right. We need to understand why there is such a large discrepancy.
  • Note that the suspension model uses the new updated alpha of 2x10^-10 N/V² (see for example G1500036-v1).
  • I am suspecting that the ESD linearization code in the digital system maybe a cause of the discrepancy. When I get a chance, I will study how the linearization function behaves in the actual system.

(ETMY was consistent with ETMX)

• I did the same measurement on ETMY in the Friday night (alog 16733), it gave me a very similar result to that of ETMX. The ETMY ESD response was only a few percent stronger than that of ETMX.
  • Note that the linearization was active on ETMY.

In alog 16707, commissioners reported that the noise in the 30-300 Hz region was "breathing". Thomas checked that this was not due to DAC glitches. Here I argue that the noise breathing is likely due to fluctuations in the IFO alignment that can be seen in the AS WFS signals.

The first plot attached here is a spectrogram of the DARM_IN1 signal, in the quiet time period reported in the above mentioned alog. The non stationarity is very clear, and it seems slower than normal glitches. To confirm my impression, I computed the band-limited RMS (BLRMS) in the region between 200 and 300 Hz. Then, I tried to correlate the time series of the BLRMS with the time variation of other IFO channels (this is very similar to what I did at Livingston in the past, see for example 13375 and 13354).

I first looked at the IMC alignment (IMC-DOF_*), but there was no clear correlation. Then I looked into the ASC_AS_?_RF signals. The second attached plot shows a scatter plot of the BLRMS vs the various AS signals. Some of the scatter plots shows some dependency which looks like quadratic or higher order.

To confirm, I used the ASC signals, their square and their power up to the fourth to find the best reconstruction of the BLRMS. It turns out to be quite good, at least for the slowest oscillations in the noise, see the last attached plot. The 3rd and 4th orders are usefult to improve a bit the reconstruction, but not crucial.

So, my guess is that most of the noise non-stationarity comes from angular motion of the IFO. I also did the same analysis with REFL WFS, with no significant correlation.

MATLAB code is attached.

J. Kissel

I've copied and pasted the 
zpk([1;1;1;1;1],[100;100;100;100;100],1,"n")
whitening filter used to whiten the calibrated DARM_ERR and DARM_CTRL channels (see LHO aLOG 16698, and LHO aLOG 16789) into the *uncalibrated* DARM_ERR and DARM_CTRL pick-offs in the calibration front-end model, h1calcs. These channels are 
H1:CAL-DARM_ERR_WHITEN_OUT_DQ
H1:CAL-DARM_CTRL_WHITEN_OUT_DQ
as a filter called "white" into FM1. These are needed for the *offline* GST-LAL pipeline calibration. 

Note that the H1CALCS.txt foton file is not yet a softlink to a version-controlled userapps repo location, nor have we started maintaining a safe.snap to ensure that these filter banks stay ON through a front-end code restart. "Sounds dubious..."

Also -- we should stick these filter banks on the CALCS MEDM overview screen.

1700utc  changed number of pressure sensors collected from 15 to 7 channels, 10hz epics rate

1955 changed back to 15 sensor channels but reduced epics rate to 1hz

2247 again back to 7 sensors at 10hz

0057 (18Feb) back to 15 sensors at 1 hz

0149 (18Feb) now back to before the day started at 15 sensors at 10hz.

New NDS2 client software has been installed on the DAQ test stand.  The new version is nds-client-0.11.3, and is the default version when you log in.  To facilitate the installation, a new version of SWIG (2.0.4) was installed on x1work, and a path to jdk1.7.0_60 was added to the PATH environment variable.

Today was an extended maintenance day, 8am to 5pm.

1. Removal of RFM Cards From End Station Seismic Front End Computers

Cyrus, Jim, Dave: WP5051

The RFM 5565 PCIe cards were removed from the front end computers h1seiex and h1seiey. The procedure was:

• stop user models, then stop iop model
• take system out of Dolphin fabric
• power down computer
• remove all cables from back (one-stop, IRIG-B, RFM, 2xethernet, power)
• pull computer out of rack
• remove 5565 PCIe card
• insert computer into rack, reattach all cables (minus 5565 RFM fiber)

The RFM Switch was reconfigured. The port assignments are as follows (green=unchanged, blue=changed)

When the seismic FE computer was powered back on, they gliched all the other computers in the fabric (both end statins). We restarted all the user models on h1susex, h1susey, h1iscex and h1iscey.

This closes WP5051

2. Testing New EPICS Gateways

Cyrus: WP5053

Please see Cyrus's alogs.

3. Restart of h1ecatx1

Daniel, Dave:

It was time for h1ecatx1's fortnightly freeze, which it faithfully did at 10am. We rebooted h1ecatx1 and all came back up automatically.

4. Reboot of Guardian Machine

Jamie, Dave:

The h1guardian0 machine was rebooted to test autostartup after reboot and change the NFS client mount options to turn off file attribute caching. Please refer to Jamie's logs for details.

5. Loading Filter Module Files

The following models had partially loaded filter module files. I performed a full COEFF load on: h1isiitmy, h1isiham4, h1isibs, h1isiitmx, h1suspr3, h1susim, h1sussr3, h1susomc, h1susbs, h1lsc, h1asc, h1scimc, h1sushtts

The model h1calcs reported a modified filter file, but this was a latched condition and the filter file was actually identical to the running configuration. I pressed the COEFF load to remove the warning.

The model h1tcscs is reporting a modified filter file, it has new filters for ITMY_CO2_CHILLER_SERVO_GAIN. I have emailed Aidan and Alastair for guidance.

6. Models With Local Modifications Pending SVN Commit

Dave:

Attached is the list of FE code which have local mods relative to the SVN repository

7. Guardian Nodes/MEDM Check

Jamie, Dave:

Nodes which exist but not on OVERVIEW MEDM (temporary nodes): TIDAL_HACK.

Nodes on OVERVIEW MEDM which dont exist (placeholders): IFO, PSL

Peter, Alexa

Summary

We measured the digital delay from the IR TR PDs at the end station to the CARM slow path at the corner to be ~50 deg at 300 Hz. This delay will include an end station model delay and two LSC delays. We have two LSC delays because TR CARM is in the LSC model, as well as the digital slow path after the IFO common mode board.  Our measurement is reasonable given Chris's delay plot (LLO#15933).

Details

We turned off the LSC-X_TR_A_LF_OUT (IR TR PD at END X) input and sent in an excitation with an amplitude of 100 cts. We turned off any filters along the TR CARM path (i.e. LSC-TR_CARM --> LSC-REFLBIAS --> ALS-C_REFL_DC_BIAS path), modulo some gains, and measured the transfer function at LSC_REFL_SERVO_SLOW_OUT. See LHO#15489 for the path.

This is a brief and preliminary update of the calibration activity from today. I calibrated the ITMX and ETMX reponses using the usual free-swing Michelson fringe.

If I believe the measurement, I must have underestimated the ESD response by a factor of 5.3 (!?) in the previous calibration which is hard to believe for me. I would like to repeat the measuerment perhaps with different conditions (e.g. opelv on/off, L2P off, linearization off/on, different bias, different frequencies and etc) and on ETMY as well.

(MICH free swing)

The method is the same as what Joe described in LLO alog 14135. To obtain the ASQ_pkpk value, I did not run the fancy matlab code or anything, but I just picked up a highest peak value and lowest one in H1:LSC-MICH_IN1_DQ. The alignment was adjusted beforehand by locking MICH. The pk-pk value was measured to be 27.0 counts. Using the relation, d (ASQ)/d(ITMX) = 2 * pi * ASQ_pkpk / lambda, I get

ASQ optical gain = 1.59 x 10⁸ cnts/m

The input power to IMC was at 9.6 W, measured at the periscope bottom PD. ASAIR_ALF could get to 4550 counts at maximum and ASAIR_B_LF 1500 counts when MICH was freely swinging. The below are some dtails:

• ASAIR_A_RF45 whitening gain was set to 30 dB
• Whitening stage 1 and 2 were engaged (probably this was too much as it seemed already limited by some elecronics noise).
• I attach the time series.

(ITMX L2 stage calibration using MICH)

After locking MICH, I shook ITMX L2 stage at H1:LSC-SUS_ITMX_L2_LOCK_L_EXC with a drive level as high as possible without DAC saturation. I did a swept sine measurement to check how high frequency I would be able to get without loosing good signal-to-noise ratio. It seems that exctiation above 20 Hz is hopeless -- the drive signal dives into sensor noise. From this measurement I picked up one frequency point, 13.05 Hz where the ITM response was measured to be

ITMX L2 response = 8.41 x 10^-18 m/cnts @ 13.05 Hz

• L2 coil driver state was set to 2 to get the maximum range.
• No oplev damping loops were engaged.
• MICH loop correction was applied in the estimation of the L2 stage response as was done in Joe's alog 14135. Abs(1/(1+G)) = 0.817 @ 13.05, measured.
• I did not oberve a DAC saturation during the measurement.
• I attach a dtt file of the open loop measurement and ITMX response measurement.

(ETMX calibration using X arm)

Keeping the 9.6 W incident power, I locked the IR laser to the X arm with a UGF of 100-ish Hz. I did a swept sine measurement on ITMX and ETMX at different times but in the same lock strech. On ITMX, the L2 stage was driven again with the same setting as that of the MICH locking. On ETMX, I had set up the suspension filters such that they are the same as the full locking condition (e.g. drive signal goes not only ESD but also L1 stage and so on). Neverthelss, since my swept sine measurement does not go below 10 Hz, the ETMX response essentially represents the ESD response (with a small effect from the L2 stage which is almost two orders of magnitude smaller than the ESD in terms of displacement).

Taking the ratio between the two actuators, I confirmed that the ratio goes as f^2 as expected in a frequency range from 10 to 60 Hz. The ETMX/ITMX ratio was measured to be

ETMX_L3 / ITMX_L2 = 1.70 x 10² @ 13.05 Hz

ETMX_L3 response = 1.43 x 10^-15 m/cnts @ 13.05 Hz. This is almost 5.3 times stronger than what we have in the CAL-CS calibration.

• IM4 and PR2 were controlled by the REFL WFSs in order to maitain the high build up in the X arm all the time during the measurement.
• ETMX oplev pitch damping loops was on at the L2 stage with a gain of -9500.
• The swept sine excitation was injected at SUS_ETMX_L3_LOCK_L.
• The L2P and L2Y were kept engaged on L3 stage on ETMX.
• The L1 coil driver state was set to 2.
• The bias voltage was set to 9.5 V.
• The ESD liearization was on with a force coefficient of -1.8e5.
• I did not see a DAC saturation on ETMX.
• I attach the dtt files.