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

Since the h1fw1 system has been stable for several days, the default NDS server has been changed back to h1nds1.  This should only affect new logins or new processes started from new shells or by opening desktop icons.

The HAM-ISI BLEND_SWITCH_ALL screen wasn't working properly at LHO: it was impossible to switch all the blends at once (white screen).

This issue has been fixed by the Stanford crew (see Hugo's SEI log: https://alog.ligo-la.caltech.edu/SEI/index.php?callRep=391)

I've 'svn up' and everything works fine now.

Attached is the 18 hours trend of the X arm WFS from last night.  Seems like it's doing something sensible. Happy periods are indicated by pink arrows at the bottom left.

• Before the WFSs were engaged it was quite aweful despite people manually aligning it. This is partly due to the tidal feedback going to the ETM top mass (we'd be better off going to HEPI).
• Then WFS was engaged, the arm was happy for about 4 hours.
• Sheila started Arnaud's measurement before she left, which made injections to both ETM and ITM.
• After the measurement was done, the arm came back on its own and enjoyed its happy life for another four hours.
• Then the arm locked itself to a higher order mode, which lasted for about four hours, then something shook ITMX for an hour or so, and after it's gone the arm relocked to 00 mode again.

PSL Check:
Laser Status: 
SysStat is good
Output power is 28.7 W (should be around 30 W)
FRONTEND WATCH is Active
HPO WATCH is red

PMC:
It has been locked 2 days, 15 hr 39 minutes (should be days/weeks)
Reflected power is 1.2 Watts  and PowerSum = 11.9 Watts.
(Reflected Power should be <= 10% of PowerSum)

FSS:
It has been locked for 0 d 9 h and 51 min (should be days/weeks)
Threshold on transmitted photo-detector PD = 0.55 V (should be 0.9V)

ISS:
The diffracted power is around 1.5 % (should be 5-15%)
Last saturation event was 0 d, 10 h and 1 minutes ago (should be days/weeks)

After Sheila and Alexa realigned the arm by hand (arm transmission ALS-C_TRX_LF_OUT about 700cts), we removed the dark offset of WFS demode output, confirned that RFAM is negligible by misaligning the ITM but aligning the ETM, then centered and engaged WFS, but it did not converge.

We had to refine alignment further (760 cts transmission), disable the PDH off-loading to the ETM (the length to angle coupling is large even at low DC),  recenter the WFS, engaged WFS, wait for a while, hold the WFS output, recenter the WFS, and it worked with all except one DOF (DOF2 PIT, which is the soft mode PIT).

For now the hard mode sensor for PIT and YAW are WFSB and WFSA, respectively, while the soft mode sensors for PIT and YAW are WFSB and WFSA. The WFSA and WFSB seem to be highly degenerate for PIT, and that's probably why it's very difficult to make both DOF1 and DOF2 PIT at the same time.

Anyway, after three DOFs are engaged the transmission went up to 860+ cts maximum. We left the arm with WFS on.

Note that it's still with very small bandwidth (basically just DC).

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

I have been investigating the wire length values used in the matlab model since the model fitting code results on ETMY from https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=10089 found a discrepancy in the UIM to PUM wire length. The value given by the model parameter file quadopt_fiber.m for this length is 
     330.8 mm. 
However, the model fitting code converged to 
     340.0 mm +- 2 mm.
About 9 mm longer.

I started investigating this discrepancy by looking at the drawings of the wire jig and the PUM assembly. Since the UIM to PUM wire is a loop, the equivalent length between the UIM and PUM needs to be backed out from these drawings. From these drawings, I calculate the length of wire between the UIM blade tip clamp and the PUM prism is 
     337.61 mm. 
The attached pdf, PUMwireLoopLength.pdf, contains the calculations and references for this number. The limiting assumption for this calculation is likely to be that the wire has an infinitely sharp bending radius going around the prism. In reality, a finite bending radius exists, which will tend to make this calculation a slight overestimate.

Still, the value is close but not quite there. Upon further investigation of the other wire lengths given by the model, I noticed that all the wire lengths are a few mm off from the values determined by the wire jig in D060516. My assumption has always been that the parameter file requires values referenced from the wire clamps (given by the wire jig), as it does for the d's. Thus, either all these values are out of date, or my understanding is incorrect. In particular, quadopt_fiber.m gives the top two stages of wire lengths as

pend.ln = 449.192 mm
pend.l1 = 308.585 mm

In contrast, the wire jig gives these as 

pend.ln = 453.0 mm
pend.l1 = 305.8 mm

Since the model predicts the measured longitudinal modes very well with the UIM-PUM fitting correction, I made the assumption that pend.ln and pend.l1 are correct as listed in the parameter file. Therefore, my previous assumption that the model file requires clamp-clamp lengths is wrong. So I searched for an algorithm (by guess and check more or less) that would take the clamp-clamp wire jig lengths and convert them to the listed numbers in the parameter file. What I found was this:

pend.ln = (wire jig length) + pend.dm/pend.cn  = 449.208
pend.l1 = (wire jig length) + (pend.dn + pend.d0)/pend.c1 = 308.521

The pend.d values are the distances from the wire clamps to the centers of mass. The pend.c values are the cosines of the wire angle from the vertical. With this, both lengths are within 10s of microns from the current quadopt_fiber.m values. Thus, this algorithm means that the wire lengths as given by the parameter file reference the center lines of the masses rather than the wire clamp positions.

Following this center line to center line convention for the UIM to PUM length, rather than clamp to prism we get:

pend.l2 = (clamp to prism length) + (pend.d1 + pend.d2)/pend.c3 = 337.61 + (pend.d1 + pend.d2)/pend.c3 = 338.924 mm

This value is about 1.1 mm from the value determined by the model fitting code, and it fits quite comfortably in the fitting code's +-2 mm error bar.

So, the good news is that the value determined by the model fitting code is consistent with the other metal wires under the assumption that the parameter file is working with center line to center line distances rather than clamp to clamp distances. 

However, ssmake4pv2eMB5f_fiber.m, which compiles the parameter file appears to be assuming the values are in fact clamp-clamp. For example, near the bottom of the ssmake script, the pend.stage2 corrections have 

ln = ln - 2*flexn/cn;
l1 = l1 - 2*flex1/c1;
l2 = l2 - 2*flex2/c2;
l3 = l3 - 2*flex3/c3;

where flex is the distance between the wire clamp and the effective flexure point and ln is equal to pend.ln (and so forth). Thus, it seems these corrections are assuming the parameter file references the clamp positions, not the center line positions. Additionally, higher up in the script around line 285 the vertical heights of the masses are calculated as

pend.tln = sqrt(pend.ln^2 - (pend.nn0-pend.nn1)^2) + pend.dm;
pend.tl1 = sqrt(pend.l1^2 - (pend.n0-pend.n1)^2) + pend.dn + pend.d0;
pend.tl2 = sqrt(pend.l2^2 - (pend.n2-pend.n3)^2) + pend.d1 + pend.d2;
pend.tl3 = sqrt(pend.l3^2 - (pend.n4-pend.n5)^2) + pend.d3 + pend.d4;

where the tl's are the 'true' vertical heights of the centers of mass, the n parameters represent the horizontal distance from the centers of mass of the wire clamps, and the d's again represent the clamp to center of mass distances. So for the top wire for example, 

sqrt(pend.ln^2 - (pend.nn0-pend.nn1)^2)

gives the vertical length of the top wire, and 

+ pend.dn + pend.d0

accounts for the clamp to center line distances for the stage above and below the wire. Thus, it seems again that the ssmake file is expecting clamp-clamp wire lengths from the parameter file.

However, putting clamp-clamp lengths into the parameter file does not provide the correct frequencies. So, the wire length mystery goes on...