[Ed, Yuta, Stefan, Arnaud, Sebastien, Jeff, Evan]

Temperature loop

On Sunday, Stefan helped me get a stable temperature loop going for the auxiliary laser PLL. The lasers now stay frequency-locked for about 5 minutes. We take the fast control signal, feed it into an SR560 for gain/rolloff control, then attenuate a bunch, and feed it into another SR560 which sums this signal with a trimpot-controlled DC offset signal. This signal then goes into the slow control of the laser. I suspect the short lock time is due to the fact that the SR560 has no integrating feature; right now I've just set it to have a DC gain; the pole of the temperature loop is set by the thermal pole of the laser. A diagram of the loop topology will be uploaded soon.

PRMI FSR sensing: no success

On Monday, the EE shop made me a 60-ft BNC cable with LMR-195. I used this to take the raw RF signal from REFLAIR_B and bring it over to the IOT2R setup. This signal is demodulated using the PLL offset frequency as the LO, and the resulting DC trace is monitored on a scope.

This afternoon, Yuta and I stole time from the green team in order to lock PRMI and try to see if the demodulated REFLAIR_B signal would show any kind of error signal in response sto the PLL offset being swept across an FSR of the PRC. We swept from 58 MHz to 62 MHz, but did not see a clear DC response from this error signal; the DC was between -1 mV and 0 mV, with an rms noise of a few hundred millivolts. If the offset frequency was set to be near a harmonic of 9.1 MHz, the error signal would become dominated by the beat of the harmonic against the offset frequency (as one would expect).

Next, we tried looking at POPAIR_B_LF to see if we could see a DC power buildup as a function of PLL offset. We didn't see anything; the DC power fluctuated between 70 and 90 counts at all times, and showed no change in response to the PLL offset.

Addendum on PRMI Iocking

Yuta tried for some time this afternoon to get PRMI locked. The biggest stumbling block was that PRY showed no fringes. Eventually, with the help of Arnaud, Sebastien, and Jeff, it was realized that

1. ISI target values (e.g. H1:ISI-BS_ST1_CPS_RZ_TARGET) change after each CDS reboot; they must be corrected by hand. BS ISI stage 2 Rz was particularly bad.
2. Changing the signal blending from 'Start' to 'TCrappy' for BS ISI stage 1 and turning stage 2 off helps locking PRMI. When ISI settings were wrong, power recycling gain showed large fluctuations at ~0.5 Hz (presumably from the microseism), with a modulation depth of about 50%.

Jim, Sebastien

We've been seeing some weird issues all day on BSC-ISI ETMX.

After restarting the models on all the BSC-ISI platforms this morning (see post here), we realized that the horizontal (X, Y, RZ) lvl3 controllers on ST1 were all equal to an empty zpk with a gain of zero

zpk([],[],0.000000000000,"n")

First mystery.

We successfully reinstalled those filters using the seismic scripts to do so (autoquack function).

Second mystery: when we turned the controllers lvl3 on, we noticed a huge drive on the horizontal DOFs, especially on ST1-H3 (~15000 counts according to the overview MEDM screen).

After some investigation, we can see some high frequency features in the closed cloop power spectra, especially at 718.875Hz (see plot attached).

This features show up on all the axis, especially in X (which explains the huge drive on H3), and only with the lvl3 controllers (looking at these controllers in foton, they actually look fine...).

My guess so far is that there is something wrong with our foton file. Arnaud is taking some measurement right now, so I'll continue the investigation later.

Lvl2 controllers are actually engaged on ST1 and ST2 (with Tcrappy blend filters)

The external epics gateway and the vacuum alarm emailer programs were restarted after OS patches were applied and required server reboots.

Because finding the statistical uncertainty in a transfer function data point, as a function of its coherence and how many averages were taken, comes up just about every few years (e.g. the last time I saw it was in the LLO eLOG), here it is quoted in the aLOG for the next generation: 

Relative uncertainty in transfer function magnitude: 
 
d|TF|           1 - C  
----- = sqrt ( ------- ) 
 |TF|           2 C N  
 
where C is the coherence, and N is the number of averages.

Absolute uncertainty in transfer function phase:
 
                  1 - C  
d <(TF) = sqrt ( ------- )   [rad]
                  2 C N   
 
where C is the coherence, and N is the number of averages, and is in units of radians.

Ref: Bendat and Piersol, "Random Data" 2nd Ed, p317.

I exited the LVEA about 1635 pst.  I've got the two Actuators on Corner3 (SE) connected.  Three corners to go.  HEPI is unlocked.

Results of todays look at the suspended optic:

Longitudinal using the same corner cube to optic offset as measured on the test stand (454.3mm) added to the EDM shot = 5629.3mm, desired distance 5629.8, error o.50mm. Tolereance of +/- 3mm

Latitude desired tolerance (beamline) +/- 1.0mm, measurement 1.4051mm Error correction .4051mm minimum. Needs to move south direction.

Vertical desired tolerance beamline +/- 1.0 mm, measurement -1.1054mm. Error .1054 mm minimum. Needs to move up.

Pitch: desired 639 urad up +/- 100urads. Error 275urads  (angle set at 89deg, 57', 48" = 0urads) optic needs to pitch down.I used an iris to prevent AR side clipping

Yaw: desired 270deg +/- 100urads. Error 1.0 mrads urads. ISI/SUS needs to rotate ccw

Looks like some HEPI tweaks are next and another round of measurements

7:30-12:25 Heading to Mid Y - Jodi
8:05 --> PSL Check List (OK)
8:25 --> Ace portable toilets on site for maintenance
8:52-9:20 Working at End X – Aaron
9:20-12:00 Heading to End Y (chassis installation) – Aaron
9:31-12:30 Going to End Y (Cleaning/Organizing) - Karen
9:48-10:29 Performing work on GV-6(PT-124) in LVEA - Kyle
10:12-11:00 Going to End X to do HEPI work – Hugh
10:00-10:15 CDs work(reverted h1 susitmy model back to original/h1 iscey model rebuilt and restarted) - Dave
10:15-12:06 Running cables by BSC2/BSC3 (LVEA) - Filiberto
11:04-11:39 Doing measurements at End X - Keita 
11:10-12:30 ITMs work (LVEA)- Betsy/Travis
11:31--> LN2 delivery to CP6 (Mid X) – Praxiar
11:36--> Vendor delivery on site (Water)
13:01-    HEPI work on HAM4 – Hugh
13:19-    Back to Mid Y – Jodi
13:26-    Going to End Y to work on illuminator – Filiberto
13:47-16:00 Heading to End Y (electronics testing) - Jax
14:59-     LVEA transitioned to Laser Hazard

Dave B., Patrick T.

122,128 channels are now monitored.

The list is in /ligo/lho/data/conlog/h1/output_pv_list/monitored_pv_list_2014mar04-14_44.txt.

Fil, Thomas

Since it was Tuesday maintenance day, I thought it would be a good time to try to improve/fix the ITM optical levers:

- The sign conventions for positive and negative directions now fully match suspension bias sliders. This solves the negative sign difference in Keita's ALOG-10331 between the OpLev and his coordinate system.  I will plan on doing this for the ETMs as well, but with the new damping loops that are initiated on the lower stage, I'm going to talk to Stefan before making a change.

- Arnaud's ALOG-10426 pointed out that the noise floor at high frequency (above 100Hz) for ITMY was different from ITMX and ETMX by two orders of magnitude.  I let him know that the main difference in electronics is the whitening/anti-whitening chain not being activated for ITMY because we don't have enough binary daughter boards for all the optical levers on site (they are being ordered by Mohana).  Since we are in need of this optical lever to be in its final configuration, Fil created a jumper plug to recreate the daughter boards to activate two levels of whitening to make all test mass OptLevs match.

Figure 1 shows that improvement of the noise floor of ITMY so that it's even better than ITMX now.

Figure 2 shows that we did activate 2 levels of 1:10 whitening.

Today's restarts tested my new model restart logger. Here are the contents of the file /opt/rtcds/lho/h1/data/startlog/2014/03/04/2014_03_04_model_start.log

2014_03_04 09:53 h1susitmy

2014_03_04 09:58 h1iscey

2014_03_04 11:46 h1isibs

2014_03_04 12:24 h1isiitmy

2014_03_04 12:25 h1isietmy

2014_03_04 12:44 h1lsc

2014_03_04 12:47 h1pemmx

2014_03_04 12:54 h1isiitmx

2014_03_04 13:10 h1isietmx

13:11PST performed DAQ restart. Was not a clean restart, the following frontends required a restart of their mx data stream: susauxex, susex, pemmx, susauxey, iscey, sush2b, sush56, susauxb123, susauxh34, susauxh56. As normal, h1psl DAQ flags went red/green during these resyncs.

DAQ restart was needed due to new models on: h1susitmy, h1iscey, h1isibs, h1isiitmy, hisietmx, h1lsc, h1isiitmx, h1isietmx.

DMT broadcaster was reconfigured to add one new channel: H1:PSL-PERISCOPE_A_DC_POWERMON

The models (master and local models), scripts and MEDM screens have been updated to support new changes made by the Stanford crew (see update list DCC T1400012).

Everything went well and has been committed.

J. Kissel, A. Pele

Following the same procedure outlined in LHO aLOGs 9453 and 9079, Arnaud and I balanced the coils on the PUM stage of H1 SUS ETMX. The final balanced gains in the L2_COILOUTF bank are

H1 SUS ETMX
Channel     Balanced COILOUTF Gain
L2 UL            +1.034
L2 LL            -1.014
L2 UR            -0.986
L2 LR            +0.966

The precision to which we could balance the coils was limited by the day-time ground motion (we saw an almost instantaneous loss in SNR once the day-time 1-10 [Hz] noise increased around 8:30a PT), but we believe the obtained values are good to within +/- 0.5%.

This balancing has reduced the L3 P and Y caused by a L2 pringle excitation at 4 [Hz] by
   DOF                  Reduction Factor @ 4.0 [Hz]
    P                          > 6.0      (peak below the noise, and totally incoherent)
    Y                          > 7.3      (peak below the noise, and only ~60% coherent)
The first attachment shows the result from which these values were obtained, comparing the optical lever ASD at 4 [Hz] driven from L2 at the same amplitude for both balanced and unbalanced configurations.

I checked the amount of fluid that has oozed from the H1 ETMX H2 Parker valve since 25 Feb.  It is maybe a couple teaspoons so we are safe for a few weeks before I need to clean it up again.

As part of WP4476 I rebuilt, installed and restarted h1iscey. Its safe.snap showed no "cannot connect" errors, but it is out of date and has only about 50% of the channels defined.

The new autoBurt.req has 15,666 entries. The safe.snap has 7,095 and the latest hourly autoburt has 8,520. So I'll keep it with the safe.snap restoration for now.

WP closeout waiting for DAQ restart and safe.snap update.

h1susitmy has been running a special HWWD test version built against RCG trunk since Jan 9th and did not get upgraded to RCG2.8.3 last Tuesday. Today I reverted the h1susitmy.mdl file back to the original code, compiled against 2.8.3 and restarted the model. The safe.snap is out of date, 673 PVs are not connecting. I burt restored the system to 9am today (local time).

Waiting on a DAC restart to close out WP 4475

I calibrated PRM actuation transfer function measured in alog #10450.
Measured PRY error signal is smaller by factor of 2 from the calculation and suspension model. This means that demodulation phase is off by 60 deg, or PRY modematch(including misalignment) is 50%, or suspension model is off by factor of 2 (or combination of all of them).

[Motivation]
We wanted to check the PRCL loop signal chain (We have done this for MICH loop already; see alog #10213).
Also, we need calibrated actuation TF for designing the compensation filter which does not saturate DAC.

[Method]
1. Made PRY simulink model (It lives in /ligo/svncommon/NbSVN/aligonoisebudget/trunk/PRMI/H1).

2. Change optical gain from PRM motion to REFLAIR_A_RF45_I to match the measured OLTF (which was measured in alog #10450).

3. Use this optical gain to calibrate PRM actuation transfer function.


[Result]
1. OLTF_PRCL_1077847156.png: OLTF compared with model and measured. Flat gain is fitted in the model and this gives the optical gain. The measured optical gain was 1.3e3 W/m.

2. From the REFLAIR signal chain in alog #10213, calibration factor for REFLAIR_A_RF45_I_ERR in PRY is 3.4e11 counts/m.

3. ActTF_PRM_1077847156.png: Calibrated PRM actuation transfer function. Red curve is plotted using zpk from LISO fitting of the measured TF (alog #10450) and divided by 3.4e11 counts/m for calibration. Blue/Cyan curve is from the suspension model using /ligo/svncommon/SusSVN/sus/trunk/Common/MatlabTools/TripleModel_Production/generate_Triple_Model_Production.m and calibrated using the numbers from ./MatlabTools/make_OSEM_filter_model.m (or LIGO-T1000061). M3 and M2 crossover and measurement look healthy. Note that the overall gain of the measurement agrees with model just because we don't have independent measurement of the optical gain. Even so, crossover frequency doesn't change.


[Discussion on optical gain]
Theoretical expression for PDH signal is

dPmod/dL = 2*8*pi/lambda*Peff*J0(beta)*J1(beta)*(t1**2*r2)/(1-r1*r2)

With

Effective input power: Peff = 7.3 uW * 4 /Tprm**2 = 0.032 W  (alog #10213; incident power on REFLAIR_A was 7.4uW when PRM and ITMY is misaligned)
Modulation depth beta=0.07 (alog #9395)
Amplitude reflectivity/transmissivity of PRM: t1 = sqrt(0.03)
Amplitude reflectivity of BS/ITMY compound: r2 = rBS*rBS*rITMY = 0.50

This gives dPmod/dL = 3.1e3 W/m (+/- ~10%). Here, Pmod is RF modulation amplitude of laser power, and dL is one-way length change of PRC, which equals to PRM motion. (Optickle gives 1.5e3 W/m since Optickle assumes demodulation gain of 1/2).

Even if I include the loss of the cable we measured(alog #10213), theoretical value is 2.5e3 W/m (= 3.1e3 W/m * 0.81), or 6.5e11 counts/m at I_ERR. This is factor of 2 larger than the measured.

Since theoretical value assumes perfect modematching and demodulation phase, actual value might be smaller. Also, note that measured optical gain is derived from the model which assumes that suspension model is acurate enough.

[How to solve this challenge]
 - Calibrate BS actuation transfer function using simple Michelson, and compare it using the measurement done in PRY. This will be an independent measurement of PRY optical gain.
 - Measure PRY modematching