Kiwamu, Sheila, Evan, Lisa, Daniel, Elli, Dave O., Dan, Alexa
On December 3rd 2014, 3:01 UTC we had the IR resonanting in all the cavities. MICH, PRCL, and SRCL were still on the 3f signals; DARM was on AS 45Q and CARM was on REFL 9 I at 0 pm. This is what we did:
Here are the REFL and arm powers for a few values of the CARM offset (controlled via TR_REFL9, the digitized REFL9I error signal). These were taken with tdsavg
and a 5 s average.
It appears that we are indeed sitting at a minimum of REFL LF and a maximum for the arm transmissions.
TR_REFL9 offset (ct) | TRX QPD sum (ct) | TRY QPD sum (ct) | REFL LF (ct) |
---|---|---|---|
−1.5 | 78 | 87 | 53 |
−1.0 | 100 | 112 | 45 |
−0.5 | 118 | 134 | 39 |
0 | 129 | 146 | 36 |
+0.5 | 129 | 146 | 36 |
+1.0 | 119 | 134 | 39 |
+1.5 | 101 | 115 | 45 |
+2 | 80 | 90 | 51 |
+2.5 | 56 | 63 | 60 |
This is a trend of relevant signals during the locking sequence. We are running ASC loops with low bandwidth on BS, PRM and DHARD. The transition to REFL_9I happens at time = 600 sec. The relative increase in the power build up is only 15%. Dan will post more precise numbers, but his first estimate is that we have a total of 280 mW at the AS port, 75% due to sideband power, 25% carrier. POP_DC only increases by a factor of 3 when the carrier is resonant..it should be more like 10-20.
Congratulations! Way to go. Now let's chase that buildup..
Excellent!
Here are the OLTFs taken at 0 pm CARM offset. The CARM loop has turned out kind of weird as it crosses unity, but it seems the phase bubble can support it. We might need to do some retuning.
We rung up the BS roll mode at 25.7 Hz
And we beheld, once again, the stars.
Here are some power calculations for the AS port and the TMS IR QPDs:
==== AS_C sum output (the channel that is used for the shutter logic) ====
quantum efficiency = 0.8, QPD transimpedance = 1000 ohms, sum output gets a factor of 1/4 from R23 (see D1001974) --> 200 volts / watt on the QPD
OM1 transmission = 5%, M6 is 50/50 splitter (see T1200410)--> AS_C gets 2.5% of the light entering HAM6
AS_C sum output is 1.4V when locked at zero CARM offset: 1.4 V * (1/200) * (1/0.025) = 0.280 W into HAM6
==== Transmitted power through the arms ====
Using the IR QPDs on the transmission monitor tables, H1:ASC-X_TR_A_SUM_OUTPUT and similar, and assuming the same QPD transimpedance electronics. (I am not sure of the calibration of the other PDs, like LSC-Y_TR_A_LF.)
These four channels currently have one stage of analog whitening and 18dB of gain --> 7.9x analog gain
Quantum efficiency = 0.8, QPD transimpedance = 1000 ohms, 2x from differential output, 32768 counts per 20V --> 2621440 counts per watt
On the TMS (see T0900385), M4 is 100% reflector for IR (assumed), M12 transmission is 5%, each QPD gets half of this signal --> TR QPDs get 2.5% of light leaving arm
The QPD signals were about 6000 counts (see attached). 6000 counts * (1/2621440) * (1/0.025) * (1/7.9) = 11.5mW leaving the ETMs
From the galaxy optics page the H1 ETMs have 3.6ppm transmission, this implies about 3.2kW in the arms.
The first figure attached is a striptool of the second lock of the evening; the second figure has trends of the TMS QPDs.
That's great, congratulations. LLO had high arm losses (maybe not this high) at one point from poorly centered beams on the test masses; that would be something to check if you haven't already.
Wonderful to see! and well-earned. Congratulations!
Great job, congratulations!
This morning, after my failed attempt to engage the new LLO-imported filters on the SR3 damping loops, Evan managed to be successful. Attached is spectra of the SR3 OPLEV PIT and YAW signals comparing the original state of the SR3 (LHO filters and gains, OL damping enabled) with engaging the filters. Note, I increased the gain to compliment the LLO ones a few hours after we switched the filters and added new spectra. It does not apear that the new loop filtering and gain are helping, but instead hindering. Hmm... I've since dropped the gains back to the original LHO values, and leave it to the commissioners to flip back the filters if they see fit.
Today the fire protection water tank was filled which required the well pump to be switched over to a manual mode. After the tank was filled I was unable to switch the well pump back to the "auto mode" therefore I manually turned the well pump off. The domestic water tank is completely full and there should be sufficient water through the night. We will address this issue in the morning.
I was checking on the HTTS today and noticed that the lockin oscillators for RM1 & 2 were enabled. It looks like these have been exciting the optics for the last three months. The plot attached shows the amplitude and frequencies; RM1 was a few Hz, RM2 was a few mHz. I've zeroed the amplitudes.
Sheila was asking about extra glinting showing up in HAM5 somewhere between the SRM and SR3 suspensions which sit almost side-by-side when viewed face-on from HAM4. I've dug through the log and have reposted below some HAM5 pics which confirm that
1) the SR3 HR baffle location and orientation look to match the L1 HAM5 position, and the specified mechanical layout drawings of HAM5 (phew)
2) the baffle does not appear to completely block the line-of-sight to the left edge of the SR3 suspension cage which appears to be light up
I also confirmed that according to E1200145, the SRM, SR2, and SR3 optics all have a vertical wedge, so no secondary back reflections in the cavity should be propogating from the SR optics along the yaw axis.
Although she was specifically asking about light just to the left of the SR3 optic, there are light splashes above the optic on the SUS cage and below the optic on the HAM table, outside of the baffle frame. It is difficult to see the right edge of the baffle and cage with the existing camera view. I supect this is just the low power, non-gaussian tail of the beam which the cameras are very sensitive to. Will have to watch to see if this correlates to anything bad the commissioners see twitching around in the cameras.
07:16 Cris into LVEA 08:06 Karen into LVEA 08:10 Jim B. reconfiguring fw0 08:46 Corey to squeezer bay for 3IFO ISCT work 09:21 Filiberto, Aaron and Sudarshan to end X to power up magnetometers 09:37 DAQ restart 10:03 Gerardo to H2 PSL laser enclosure to work on OFI 10:09 Dick G. to ISC rack 2 to test RF signals 10:36 Betsy taking transfer functions on SR3 10:37 Karen cleaning at mid Y 10:38 Keita to end Y to check cross cabling of green WFS 11:07 Dick G. done 11:30 Karen leaving mid Y 12:06 Corey out of LVEA 12:26 Aaron and Filiberto done, Sudarshan still checking channels 12:34 Sudarshan back 12:35 Keita done 12:56 Gerardo done 13:15 Let truck with portable toilets through gate 13:19 Dan and Rob working on ISCT6 13:32 DAQ restart 14:07 Dan and Rob back
Made programming change to one half of pump -> Will duplicate change on remaining half of pump tomorrow -> IP4 was at wrong HV value for pressure conditions -> Previous change attempts either not saved(?) or entry error(?)
Up to now, the ALS COMM
and ALS DIFF
guardians have been using some hard-coded frequency offsets in order to do the IR finding. This works alright while the offsets are fresh, but after a few days (or less) they become stale and no longer correspond to IR resonance. So then we go find the resonances by hand, hard-code fresh frequency offsets into the guardians, and start the cycle over again.
After discussion with Lisa, we are now starting to have the guardians update the frequency offsets by themselves. This will hopefully reduce the amount of time spent looking by hand for IR resonance, and the amount of time spent going through the fine-tuning states in the guardians.
In userapps/als/common/guardian
, I’ve created alsDiffParams.dat
and alsCommParams.dat
. Each guardian reads from and writes to its parameter file using the json
library. This keeps the parameter file human-readable (unlike, e.g., pickle
).
When loaded into the guardian, the parameters are contained a python dictionary.
So, for example, the COMM guardian loads its dictionary from the file like so:
alsCommParamsPath = '/opt/rtcds/userapps/trunk/als/common/guardian/alsCommParams.dat'
with open(alsCommParamsPath, 'r') as alsCommParamFile:
alsCommParamDict = json.load(alsCommParamFile)
Once it’s done modifying alsCommParamDict
, it dumps the dictionary back into the file like so:
with open(alsCommParamsPath, 'w+') as alsCommParamFile:
json.dump(alsCommParamDict, alsCommParamFile)
I have completed a full set of measurements checking for basic coherence of input/output of the Aux Channels for every suspension. Suspect channels were retested a number of days later. Those that failed in the same manner were labled as "bad" or "failed". Those that changed, either significantly or marginally were left to question. Below is a crude spreadsheet that illustrates my findings so far. The measurement technique is noted on the spreadsheet.
Apologies. The original post didn't include channel names.
All /trend/minute_raw files have been moved to /frames/trend/minute_raw/minute_raw_1101489341, and a new /trend/minute_raw directory has been created to accumulate new data. The h1nds0 nds server has been reconfigured to read the /frames/trend/minute_raw/minute_raw_1101489341 files as old data. Testing has been performed to check availability of old and new data, across file boundaries. This concludes WP 4955
Alexa, Kiwamu, Lisa Most of the day was lost in ALS land. We manage to start locking at 2am. Our success was pretty well correlated with Kiwamu changing the Y end VCO offset slider from -0.263 to -5.526 such as the X VCO goes away from the negative railing point when DIFF is locked. This was done because, even if the HEPI relief was on, we were seeing that at least some of the ALS lock losses were due to the X VCO railing (to be investigated). After that, we worked on ASC during the CARM offset reduction. So far we have been using AS_B_45Q for DHARD until CARM offset = -12, then we were opening it because we suspected that this signal was flipping sign when reducing the CARM offset further. Tonight we indeed established that by measuring the response to ETMX steps by comparing CARM offset -8 and -13. At the same time we checked the AS_A_45Q response, which is still sensitive to DHARD but it does not change sign. After measuring the relative gains, we transitioned from AS_B to AS_A at -13 CARM offset, and then we kept the loop closed while reducing the offset down to -16. Some parameters: - AS_A input matrix elements are +2e-6 for both P and Y (ugf ~50mHz). - We also reduced the SRCL gain by a factor of 2 (from -30 to -15) at CARM offset -15, and that reduced the broad gain peaking we were seeing in the SRCL spectrum at 70 Hz (we didn't really make any measurement). We are not updating the Guardian, as this needs further testing. Data: Dec 3, 11.15 UTC locking start, lost lock at 11.56 UTC while transitioning to -16
The guardian has now been updated to reflect what we found last night.
Kiwamu, Dave, Dan, Alexa, Sheila, Elli, Evan
We have been having trouble keeping ALS DIFF locked for the past few hours. Alexa finally figured out there was a large 10 Hz peak in DIFF error spectrum and the ESD drives.
We thought it might be either the ETMX or ETMY 9.8 Hz bounce modes, since these have previously given us trouble (LHO#15118, LHO#15247). However, by looking at oplev spectra, we determined it was actually ITMX and the frequency was 9.84 Hz.
So we copied over Matt’s ETMX damping filters (pass9.8
, which has the sharp gain, and phase9.8
, which allows us to adjust the phase) and adjusted the frequency to 9.84 Hz. Then I turned off the oplev filters and engaged pass9.8
, and played with the gain (originally −0.05) until I got damping (the necessary gain was 300). The mode was originally a factor of 5–10 above the ITMX pitch oplev noise floor, and after 10 minutes we were able to push it into the noise floor. The use of phase9.8
was not necessary.
I have restored the ITMX pitch damping, along with a 9.84 Hz elliptic stopband filter stop9.84
which is modeled after an ETMX L1 filter.
Attached is a fine-resolution spectrum of the ITM OpLev pitch signals. ITMX bounce mode = 9.8469 Hz, ITMY = 9.8315 Hz. Probably ITMY will be a problem someday, too.
The bounce mode peaks are very narrow - only about 2mHz wide. One theory (from Dave) is that there might be two modes very close to one another, and only one of them couples to the oplev feedback; the other stores energy and makes the mode difficult to damp. The list of suspension resonances says that the z2 and z3 modes are both around this frequency, but doesn't say if we expect them to be within 2mHz of each other.
The phase9.8 filter was designed to be used with the standard OpLev damping to prevent excitation of the bounce mode, not with the Pass9.8 (used with the 0:50 filter to damp the mode after it gets excited).
ITMX is supposed to be as bad as ETMY.
ETMY > ITMX >>>>>>>> ITMY > ETMX, in terms of bounce-to-length coupling.
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=14876
I want to clarify something Dan wrote. There is only one vertical resonance at ~ 9 Hz in the quad - it is the highest of the four vertical resonances, called modev4 in the list of resonances which can be seen at e.g. https://awiki.ligo-wa.caltech.edu/aLIGO/Suspensions/OpsManual/QUAD/Models/20140304TMproductionTM The reference to z2 and z3 describes the dominant motion in that mode i.e. which masses are moving and in which directions in that mode. The highest vertical resonance involves the penultimate and test masses moving out of phase with each other in vertical - hence the z2 ( which is PUM vertical motion) and z3 (test mass vertical motion). The numbering is historical from our original MATLAB models, based on extending a triple model- masses are 0,1,2,3 from top to bottom.
J. Kissel In summary: (1) Turn on X, Y, and Z sensor correction for HAMs 2 and 5, using the standard Hua Filter scheme (see T1200285), with tuned gains. (2) Use LLO's M1 OSEM Damping filters and gains. (3) Turn off optical lever damping so we don't have worry about maintaining optical levers to as great care. ------- This continues (and hopefully resolves) the study of why PR3 and SR3 (both HLTSs) are angularly noisy, began by Kiwamu (see LHO aLOG 15048), and continued in a prior aLOG by me (see LHO aLOG 15154). I had started today thinking that I would do the usual full modeling suite, and this time include the optical lever damping. But after a little bit of exploring, I found that the L1 HLTS, H1 PR3, and H1 SR3 were using in various, completely different damping schemes, the performance of the optical levers are radically different, so a noise projection would be difficult, and the L1 vs. H1 HAM ISIs perform significantly different. So, since a "representative" model seemed impossible, as did the thought of making an individual model for all four suspensions and comparing, I've just spent the time gathering proof of what we need to do to make them much better. Once we get all of the above three steps completed *then* I'll make a full model suite of the performance. Here's the details explaining how I can to these conclusions. They're supported by the first and only attachment. (3) Turn off optical lever damping. Pages 1 and 2 of the attached show the wide variety of performance on the optical levers. Page 3 and 4 show the H1 the levers are in loop, but only with a bandwidth from 0.4 to 1 [Hz] (see design for SR3 in LHO aLOG 14719). There seems to be some effort toward rolling off the noise, but it seems quite unrelated to the actually noise performance of the levers at high frequency. LLO *had* used optical lever damping sporadically on L1 PR3, but they're currently not using it and haven't since Oct 17 2014. Given that the damping is so much strong and the input motion is so much smaller, this makes sense that its not needed. Further -- even with L1 SR3 aligned, the location to which, presumably, the optical lever has been centered -- the performance of the optical lever spectra is not limited by residual ground motion of the optic. So it's most certainly unusable for control. Including optical levers in the local damping scheme complicates the remaining dynamics of the suspension (and perhaps more to the point, the subsequent modeling of it), and getting used to relying on them means they'll be left on and most certainly reinject noise above their bandwidth unless the loops are custom tailored to the ever-evolving optical lever noise. So if we can achieve the same level of local damping with the top mass OSEMs, and improve the performance of the ISIs, let's do it. (1) Turn on X, Y, and Z sensor correction for HAMs 2 and 5, using the standard Hua Filter scheme (see T1200285), with tuned gains. Pages 5 through 7 compare the performance of the HAM2 and HAM5 ISIs, highlighting the degrees of freedom which contribute to L, P and Y at the optic. Remember, the L at the suspension point is the dominant contributor to L *and* P at the test mass, at all frequencies (see pgs 5 and 33 of the second attachment to LLO aLOG 7907). In turn, X and RY (for PR3) and Y and RX (for SR3) are the dominant contributors to L at the suspension point. Y at the optic is all Y at the susp. point, which is all RZ of the table. Though I'm not sure what the H1 HAMs have worse performance than the L1 HAMs between 2 and 8 [Hz] (that should be investigated further), I certainly know that the *drastic* difference between 0.3 [Hz] and 1 [Hz] is because LLO has sensor correction for all DOFs turned on. Poking around at LLO, I've found that the sensor correction is nothing particularly fancy -- it's just the standard Hua filter scheme, with a single, gain only Match filter at the output to tune better match STS gain to the displacement sensors (those gains are a correction of ~10-20%, matched to a ridiculously high precision [where its unclear if the precision is needed]). HAM2 uses the HAM2 STS (STS A), and HAM5 uses the HAM5 STS (STS C), as expected. At the first L and P resonances of the HLTS, there's a possibility for the following improvement if we get to LLO's level of isolation: Frequency [Hz] Table DOF Performance Ratio 0.64 HAM2 X 6.23 / 0.11 = 56.6 HAM5 Y 5.29 / 0.08 = 66.1 0.74 HAM2 X 1.87 / 0.03 = 62.3 HAM5 Y 1.42 / 0.02 = 71.0 and as we know by now, its these lowest resonance frequencies that dominate the RMS motion of the optic. All this being said, except for between 0.2 [Hz] and 0.6 [Hz], LLO is kicking the snot out of the "requirements." Nice job! I'm very confident that we can do just as well here at LHO. The trick will be to get the HAM2 and HAM3 sensor correction up at the same time, so that we don't introduce and relative low frequency noise in the recycling cavities. P.S. There're some pretty nasty sharp features and associated harmonics in the L1 HAM5 ISI's RX and RZ spectrum ... we should get that fixed -- they're obviously electronic, particularly ugly, and might affect pulsar searches. (2) Use LLO's M1 OSEM Damping filters and gains. Pages 8 and 9 highlight the DRASTIC difference in damping loop filters. I hesitate to call the H1 HLTS filters a "design," because I know they were copied from the QUADs (hence the 0.43 [Hz] and 0.56 [Hz] resonant gains in the L and P filters, respectively). There's no reason at all we shouldn't just switch to the LLO design immediately -- these aren't under global control so we need not worry about changing any global control transfer functions, and though I haven't modeled it (yet) the increase in gain at just about all frequencies, especially what's focused at the *actual* first L and P modes of the HLTS. With the switch, we would get a factor of 16.2 increase in gain at 0.75 [Hz] in the L loop (which presumable will hit the same mode in P as well), and a factor of 44 increase in gain at the first, 1 [Hz], Y resonance. With steps (1) and (2) complete, that means we can expect to improve the Y and P motion at the optic, at the main resonances by as much as three orders of magnitude.
I attach a screenshot of the configuration the L1 HLTS damping filters are in that replicate page 8 of the above attachment. Note that there are two filters in FM6 and FM7, called "Plant" and "x[number]," where "number" is the equivalent EPICs gain. These are useful to copy over because they represent, well the plant and the EPICs gain. BUT there're never meant to be turned on in-loop, they're only for offline foton study. In page 8 of the attachment, for example, I have the "x[number]" filters on for both sites, so their overall gain can be easily compared. We can, of course, turn on the "x[number]" filters and keep all of the EPICs gain at -1.0, which I prefer, in the future.
I've added the Hua filters to all the HAM ISI's. There was a BSC script to do this that I spent some time modifying, so we now don't have to copy and paste from other chambers. Currently the top level script lives in the HAM4 control scripts folder (called Loading_Sensor_Correction_Filters_H1_ISI_HAM4.m), but there were some subroutines from the BSC that needed modifying to work with HAM, as well as a master FIR file in the HPI userapps filterfile folder, all of which I copied and made HAM specific. None of the original files were changed, I just made HAM specific versions. I'll try turning stuff on at HAM6 first, and get some plots, then talk to commissioners about times to try turning this on elsewhere and making measurements with cavities to try to optimize, if they'll let me.
Jim: we do *not* want to use Hua sensor correction filters in any DOF for the BSCs, see the third item in SEI aLOG 645. So, don't worry about getting them into the BSC filter banks.
As per Jeff's suggestion (2) above, and with the commissioning crew's approval, I have loaded new filters into the empty filter bank slots on all 6 Damping DOF's of both the PR3 and SR3 M1 stages. None of the new filters have been enabled, and the damping loops are currently unchanged. They/we might try enabling the damping filters later tonight or tomorrow. At Kiwamu's suggestion, I'll also look at gathering comparison data for the different damping regimes now that they are available here at LHO on PR3, as well as installing them on SR3. Attached are the screen snapshots of the PR3 and SR3 DAMP loops with the existing set of filters enabled, and new slots filled. Note, before they are used, the available gain filters in FM7 needs some tweeking as the LLO gains do not match the LHO loop gains.
I did not copy the FM1, FM2, FM5, or FM10 filters.
Betsy and I have enabled the new M1 damping filters (see attachment).
The gains have not been changed.
The SR3 oplev damping has been turned off. It may have to be retuned because of the M1 changes.