david.barker@LIGO.ORG - posted 12:38, Monday 17 October 2016 (30593)
CDS model and DAQ restart reports: Thursday 13th - Sunday 16th October 2016
No restarts reported over these 4 days.
No restarts reported over these 4 days.
Weekly Xtal - graphs show some strange power fluctuations in Amp diode powers starting on or around the 10th. Also, this can be seen in the OSC_DB4_PWR graph as well.
Weekly Laser - Osc Box Humidity reached a high point at about the same time (10th) but seems to have started an upward trend sometime between the 8th and the 9th. PMC Trans power looks pretty erratic. Included is a zoomed view of the Osc box humidity and the OSC Box Temp just for correlative purpose.
Weekly Env - nothing notable.
Weekly Chiller - some marginal downward trends in headflow for heads 1-3. Head 4 is eother crazy stable and good OR this data is trash. ??
Head 4, power meter circuit, and front end flows are "fake" due to force writing in TwinCAT.
I went to EX this morning to check on the wind fence after Friday's wind storm. The fence is still there, intact, and hasn't accumulated any tumbleweeds, which is one of the concerns Robert had about a fence. However, a couple of the posts have been twisted, probably by the wind load and moisture, and all of the poured concrete footings have started creeping in the sand. I dont think there is any danger of the fence collapsing, yet, but I'll keep an eye on this.
Attached photos are: a picture of the total coverage from a month or two back (this hasn't changed), a picture showing the worst twisted post (this is new, I didn't notice this the last time I looked) and a picture of the gap in the sand around one of the footings (not new, but it's been getting bigger).
Laser Status:
SysStat is good
Front End Power is 34.67W (should be around 30 W)
Front End Watch is GREEN
HPO Watch is GREEN
PMC:
It has been locked 0.0 days, 0.0 hr 48.0 minutes (should be days/weeks)
Reflected power is 33.57Watts and PowerSum = 126.8Watts.
FSS:
It has been locked for 0.0 days 0.0 hr and 42.0 min (should be days/weeks)
TPD[V] = 3.225V (min 0.9V)
ISS:
The diffracted power is around 6.695% (should be 5-9%)
Last saturation event was 0.0 days 0.0 hours and 51.0 minutes ago (should be days/weeks)
Possible Issues:
PMC reflected power is high
ISS diffracted power is High (This seems to pop up after power increases)
SEI - Testing out some new configurations to get ready for O2.
SUS - No report
CDS - Running (go catch it. Ha.)
PSL/TCS - All good
Vac - Kyle wants to do test with pumps at end stations with locked IFO.
Fac - RO system issues, but it is back and running.
Maintenance
CDS - FRS's to address, cable pulling, power up RGAs at ends.
PCal - Travis to do some work.
Jitter (alog 30237): 10-6/√Hz (level) to n x 10-4/√Hz (peaks)
IMC suppression (alog 30124): ~1⁄200
⇒ at IFO: 5 x 10-9/√Hz to n⁄2 x 10-6/√Hz
Fixed misalignment of RF sidebands: Δα < 0.3
DC power in reflection with unlocked ifo at 50W: REFLDCunlocked ~ 300 mW
Error offset in REFL = jitter * REFLDCunlocked * Δα
⇒ 5 x 10-9/√Hz * 0.3 W * 0.1 ~ 1.5 x 10-10 W/√Hz (low)
⇒ n⁄2 x 10-6/√Hz * 0.3 W * 0.3 ~ n⁄2 x 10-7/√Hz (high)
Frequency noise coupling into DARM (alog 29893):
⇒10-10 m/W at 1kHz (approx. f-slope)
at 1kHz: 10-20 m to 10-17 m
at 300 Hz: n x 10-18 m (high) with periscope peak n ~ 4.
This seems at least a plausible coupling mechanism to explain our excess jitter noise.
Some additional comments:
This calculation estimates the jitter noise at the input to the ifo by forward propagating the measured jitter into the IMC. It then assumes a jitter coupling in reflection that mixes the carrier jitter with a RF sideband TEM10 mode due to misalignment. The corresponding RF signal would be an error point offset in the frequency suppression servo, so it would be added to the frequency noise. Finally, we are using the frequency noise to OMC DCPD coupling function to estimate how much would show up in DARM.
If this is the main jitter coupling path, it will show up in POP9I as long as it is above the shot noise. Indeed, alog 30610 shows the POP9I inferred frequency noise (out-of-loop) more than an order of magnitude above the one inferred from REFL9I (in-loop) at 100Hz. It isn't large enough to explain the noise visible in DARM. However, it is not far below the expected level for 50W shot noise.
TITLE: 10/17 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Lock Aquisition
OUTGOING OPERATOR: Patrick
CURRENT ENVIRONMENT:
Wind: 45mph Gusts, 27mph 5min avg
Primary useism: 0.08 μm/s
Secondary useism: 0.36 μm/s
QUICK SUMMARY: As I took a seat in the chair, a large gust of wind could be heard from in the control and then lockloss...
Left in down while the earthquake subsided. Had a hard time getting through an initial alignment. The IMC kept losing lock in INPUT_ALIGN and PRM_ALIGN. Not certain what finally allowed it to stay locked long enough to get through these states. ISS and FSS still losing lock, but recovered on their own each time. IFO is in NLN but range has been dropping steadily. Starting shift with 6.9 magnitude earthquake reported 78km WNW of Kandrian, Papua New Guinea at 06:14:58 UTC. Jeff B. has put ISC_LOCK in down. 09:57 UTC Earthquake has subsided but wind is increasing 10:00 UTC Starting attempting to lock. Changed ISI config from EARTH_QUAKE_V2 to WINDY. 10:04 UTC Paused at LOCKING_ARMS_GREEN. Both are less than 1 on WFS. X is kind of jittery. No apparent glitches of ALS PDH control signals. Node is still waiting for arms to settle, won't proceed to locking ALS. Reluctantly moving TMS Pitch. Started with TMSX 67.8 and TMSY 127.5. This cleared the waiting for arms to settle message and allowed moving on. 10:25 UTC Lock loss waiting for DRMI ASC to converge 10:44 UTC Lock loss right after CARM_5PM. ISS in oscillation. Recovered on its own after about 140 sec. 10:48 UTC Lock loss during LOCKING_ALS. 10:51 UTC Lock loss during LOCKING_ALS. 11:03 UTC Check IR signals not stable. Starting to hear wind on building. 11:07 UTC Put in down 11:12 UTC Try locking again 11:27 UTC Lock loss at CARM_5PM 11:28 UTC Put in down 11:45 UTC Starting initial alignment ALS X arm randomly dropping out of lock. MC not stable on input align. Put IMC_LOCK to down. IMC_LOCK is in down, but IMC still seems to be trying to lock? 12:30 UTC Finally got to INPUT_ALIGN. Waiting for ASC convergence. Initial alignment past locking arms green seems to make IMC quite unstable. 12:54 UTC Initial alignment done 13:25 UTC NLN
Ops Shift Log: 10/16/2016, Evening Shift 23:00 – 07:00 (16:00 - 00:00) Time - UTC (PT) State of H1: IFO is unlocked. Intent Bit: N/A Wind: Light Breeze (4-7mph) 0.03 – 0.1Hz: All 0.09um/s 0.1 – 0.3Hz: All around 0.6um/s Outgoing Operator: TJ Incoming Operator: Patrick Activity Log: Time - UTC (PT) 22:50 (15:50) Checked TCS Chillers – TCS-X OK; Add 200ml to TSC-Y (6.5 to 8.5) 23:00 (16:00) Take over from TJ 23:10 (16:10) Initial Alignment and relocking 00:50 (17:50) Evan – Going into LVEA 00:55 (17:55) Evan – Out of LVEA 01:32 (18:02) Locked at DC_READOUT 01:35 (18:35) Evan - Measuring RF modulation depth 03:02 (20:02) Locked at NOMINAL_LOW_NOISE , at 44.5W, 64.7MPc 03:55 (20:55) Sheila – Going into the LVEA for CARM Loops 04:24 (21:24) Sheila – Out of the LVEA 07:00 (00:00) Turn over to Patrick Shift Details: Support: Evan Shift Summary: IFO broke lock after a 9.5-hour stretch. Having trouble getting past PRMI and DRMI, and the X and Y arms did not look that good. Run Initial Alignment. The alignment was having trouble getting PRM to converge. Tweaked up the PRM alignment, and completed Initial Alignment. After a couple of tries locked at DC_READOUT. Turn over to Evan for commissioning. Go up to high power; Shelia and Evan commissioning. Second half of shift mostly spent trying to relock. Damping Roll and Bounce modes that were ringing up. Also had issues with the ISS Autolock oscillating and the FSS PZT MON saturating. At the end of the shift a magnitude 6.9 EQ hit, bringing up the seismic to near 1.1um/s. Put on the SEI_CONFIG in EARTH_QUAKE_V2, but to no avail. Set the IFO to DOWN, and turning over to Patrick.
By driving a line in CARM at 400 Hz we saw that the 9 MHz demod phase was mistuned by 9° at 2 W of PSL power. We tuned the demod phase to within 0.5° and then powered up.
Once the interferometer reached its final power (44 W), we could see that the demod phase was again mistuned, this time by 5°. Over the course of 30 minutes it relaxed to ~0.5° of detuning.
Also, the REFL9I readback now agrees almost perfectly with the CARM control readback; not sure why (this was true even before changing the demod phase). The CARM error readback is still mostly junk.
I tried again to check for REFL sensing noise in DARM by reducing the CARM gain, it seems that we cannot reduce the gain enough to bring the ugf to a few hundred Hz without loosing lock. (I could reduce the gain by 8 dB, but not turn off the boost, the other day we turned off the boost first, were able to reduce the gain by about 4dB, then when we tried to reduce the gain by 3 more dB we lost lock.
TCS-X: Levels OK. TCS-Y: Added 200ml (low = 6.5, fill = 8.5)
TITLE: 10/16 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Lock Aquisition
INCOMING OPERATOR: Jeff
SHIFT SUMMARY: Locked for most of my shift, last 30min it broke. To keep it locked when the range has drifted to ~35Mpc, adjust SRM to minimize POP90. Seemed to help get a 10Mpc and keep it locked. Evan H. has been doing some work, and we are on our way back up now.
LOG:
I wanted to find out how much contrast defect light we have in DARM at the moment. It seems to be about 2.0(5) mA at the moment. Since we run with 20 mA of total photocurrent, this implies a homodyne angle that is mistuned by about 6° away from the nominal value of 90°. I did not check how stable it is over the course of several hours.
To measure the contrast defect, I watched the height of 332 Hz pcal line in DARM while varying the dc offset.
Also, I found that the DARM residual is microseism-dominated at 50 W of input power (the current blrms is about 0.5 µm/s). So I turned on a boost in FM6 of LSC-OMC_DC. We should incorporate this into the DARM filter modules.
Expanding more on Evan's methods here:
Optical gain values in [mA/pm] were obtained by taking the magnitude of the transfer function at 331.9 [Hz] between H1:CAL-PCALY_RX_PD_OUT_DQ (pre-calibrated into [m] / zpk([],[1,1],1)) and H1:OMC-DCPD_SUM_OUT_DQ (pre-calibrated into [mA] to ~10% accuracy).
Total light on the OMC DCPD values in [mA] were pulled directly from H1:OMC-DCPD_SUM_OUT_DQ (again, pre-calibrated into [mA]).
The DARM DC offset was varied by adjusting the "fringe offset" or H1:OMC-READOUT_X0_OFFSET (pre-calibrated into [pm] to ~20-30% accuracy). This EPICs record can be found on the "IFO DC READOUT" sub-screen (called OMC_DC_READOUT.adl) of the OMC_CONTROL.adl overview screen. The nominal value is 10.65623 [pm], and to obtain the above data Evan varied the DARM DC offset from 6 to 13 in 1 [pm] increments.
zeta = homodyne angle [rad] = arccot( contrast defect [mA] / total light on DCPDs [mA] )
where the contrast defect [mA] is the y intercept of the parabola.
The subsequent IFO optical gain vs. DC power on the DCPDs was then fit (by-eye) to blind/simple quadratic function with a DC offset. to arrive at the answer.
From Evan's presentation G1601599, which nicely distills the famous-yet-cryptic 2001 Buonnano&Chen paper, the response of a DRFPMI interoferometer using detuned resonant sideband extraction can be parametrized into a pair of complex poles (for the optical spring, at frequency |p| and quality factor Q), a pair of real poles (for the coupled cavity, or "RSE" pole, at frequency xi) and zero, at frequency z, which can potentially (and typically does for low detuning) cancel one of the RSE poles:
dP 1 + i f / z
-- = g * --------------------------------------- (5)
dL (1 + if/|p|Q + (f/|p|)^2) - (xi / f)^2
The zero, in his presentation, is composed of the following fundamental parameters,
cos(phi + zeta) - r_s cos(phi - zeta)
z = f_a * ------------------------------------------ (8)
cos(phi + zeta) + r_s cos(phi - zeta)
where f_a is the arm cavity pole frequency (assumed to be the same for both arms), phi is the SRC detuning phase, and zeta is the homedyne angle.
One of the outputs of the above measurement, is that, if the homodyne angle, zeta, is consistently 90 +/- 6 [deg], then we can used Eq. (8) to simply fix the zero frequency in the overall IFO response (5), assuming the arm cavity pole frequency and SRC detuning phase also remain constant. This would reduce the parameter space over which the calibration group would have to MCMC in fits to measurements of the overall response (e.g. LHO aLOG 28302).
However,
(1) This is, again, *one* measurement of the homodyne angle, zeta. We're going to have to measure it multiple times, and quantify the uncertainty in the estimate better, to make sure that we're confident it stays there.
(2) The SRC detuning phase, phi, and the arm cavity pole frequency, f_a, also need measuring with quantifiable uncertainty. These are also parameters believed to be fixed, but the question is always to what level. f_a has been measured before to be ~83 Hz, using several techniques (e.g. LHO aLOG 7054), but rarely with quantified uncertainty. Further, those measurements are typically taken of a single cavity, and there is worry that the pole frequency may change a bit in the full IFO due to different spot centering*. The detuning phase "can be determined by the spring frequency."
To me, this is quickly going down a rabbit hole of another independent MCMC parameter estimation fitting regime, but I'm still quite ignorant on the topic.
*word on the street is that LLO has a technique, once in full lock, of "kicking the SRM fast enough" such that full IFO remains locked but simple as an PRFPMI. I couldn't find an aLOG on it, and these discussions with Evan today were the first I'd heard of it.
Worth exploring!
Doing a real least square fit gives different results, depending on what you assume
TITLE: 10/16 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Lock Aquisition
OUTGOING OPERATOR: Travis
CURRENT ENVIRONMENT:
Wind: 21mph Gusts, 15mph 5min avg
Primary useism: 0.05 μm/s
Secondary useism: 0.44 μm/s
QUICK SUMMARY:
Looks like Guardian took it all the way up on its own after Travis left, and it has stayed locked for 2.5hrs. The range drift still looks the same.
Posted HEPI pump Trends (FAMIS #4525). Pressures for the 4 CS pump stations are flat around 100. The control voltage shows some fluctuations during the period, however day 1 and day 45 values are within a few 10ths of each other. Both end stations pressures and voltages are, by comparison, somewhat noisy. End X max pressure and min difference for the end points is 0.2. For End Y this same difference is 0.1. Between the measurement end points there is a more noise in both the min and max values. There is no apparent pattern to the fluctuations.
Sorry Jeff but these trends are just 10 minutes long.
Daniel points out that the behavior of REFL LF during the 9 MHz modulation depth reduction does not make sense:
One possible explanation is that the 9 MHz depth is a factor of 3 lower than we think it is. However, based on single-bounce OMC tests (described below), this seems to not be the case. So the discrepancy remains unexplained.
For the OMC test, I first turned up the modulation depth by 3 dB (the slider value is normally 16.8 dB during lock acquisition, so I turned it to 19.8 dB).
Then I locked the OMC on the carrier, and then each of the 9 MHz sidebands, and recorded the following data:
| Frequency |
PSL power (W) |
OMCR A sum (ct) |
OMC trans sum(mA) |
| Carrier | 9.8 | 600 | <0.01 |
| 82 | 14.6 | ||
| USB 9 | 47.2 | 2930 | 0.01 |
| 2860 | 1.07 | ||
| LSB 9 | 47.7 | 2920 | 0.01 |
| 2880 | 1.07 |
I assign an uncertainty of 10% to the OMCR and OMC trans sum values. The OMC visibility is not perfect here, but we can nonetheless roughly infer the modulation index. If the carrier measurement had been done at 47 W, we would have seen 70.6 mA of sum photocurrent. Since Psb/Pc ≈ Γ2/4, this implies Γ = 0.25 rad during this measurement. This implies a value of Γ = 0.17 rad during normal lock acquisition. This is within 30% of the old value measured with the PSL OSA (0.22 rad). In other words, we are not missing a factor of 3 in the modulation depth, so the behavior of REFL LF during lock acquisition does not make sense.
I am attaching more time series for what happens during 9 MHz modulation depth reduction.
The ~0.8% increase in the transmitted arm powers suggests a modulation depth during lock acquisition of about 0.13 rad. With this modulation depth, we'd expect a change of 2.0 mW on REFL LF during the reduction (instead we see 0.54 mW).
I made the following power measurements at 1.9 W:
| RF9 | RF45 | REFL LF (mW) | AS LF (mW) |
| 16.8 | 23.2 | 0.315 | 69.7 |
| 13.8 | 23.2 | 0.271 | 68.5 |
| 13.8 | 20.2 | 0.236 | 49.1 |
I made the following measurements at 44 W, after reaching some kind of thermal equilibrium:
| RF9 | RF45 | REFL LF (mW) | AS LF (mW) |
| 16.8 | 23.2 | 3.55 | 545 |
| 13.8 | 23.2 | 3.71 | 575 |
| 13.8 | 20.2 | 4.20 | 823 |
Note that (somewhat confusingly) REFL LF is calibrated into milliwatts on the diode itself, while AS LF appears to be calibrated into milliwatts exiting the AS port (i.e., before OM1).
We can use the REFL LF measurements to infer the carrier and sideband content both at 1.9 W and at 44 W. Here we assume the modulation depths have their nominal lock-acquisition values (16.8 dB for 9 MHz and 23.2 dB for 45 MHz, which based on old OSA measurements correspond to 0.22 rad and 0.28 rad of modulation depth). Additionally, we can scale the 1.9 W measurements to infer what we should see at 44 W, all other things being equal.
| 9 MHz (mW) | 45 MHz (mW) | Carrier (mW) | Total (mW) | |
| 1.9 W, from measurement | 0.088 | 0.070 | 0.157 | 0.315 |
| 44 W, from measurement | 0.64 | 0.84 | 2.55 | 4.02 |
| 44 W, scaled from 2 W | 2.04 | 1.62 | 3.64 |
7.30 |
Note the large 9 MHz discrepancy from the power-up.
I copied the RF slider values for the 44 W measurement wrong out of my lab notebook, so here is the corrected table:
| RF9 | RF45 | REFL LF | AS LF |
| 10.8 | 20.2 | 3.55 | 545 |
| 13.8 | 20.2 | 3.71 | 575 |
| 13.8 | 22.2 | 4.20 | 823 |
The algebra and resulting numerical values for the PD sideband content were done correctly, though.
J. Kissel, D. MacLeod Duncan had noticed that Omicron triggers for the H1 PCAL Y RX PD (H1:CAL-PCALY_RX_PD_OUT_DQ) had failed on Oct 13 02:51 UTC (Oct 12 18:51 PDT) because it was receiving too many triggers. Worried that it might have been a result of the recent changes in calibration line amplitudes (LHO aLOG 30476) or the restoration of the 1083.7 kHz line (LHO aLOG 30499), I've trended the output of the optical follower servo, making sure that it has not saturated, and/or is not constantly glitching. Attached is a 3 day and 30 day trend. There is indeed a feature in the trend at Oct 13 02:51 UTC, but it is uncorrelated in time with the two changes mentioned above. Indeed, the longer trend shows that the OFS has been glitching semi-regularly for at least 30 days. I'll have Detchar investigate whether any of these correspond with heightened period of glitching in DARM, but as of yet, I'm not sure we can say that this glitching in a problem.
The number of glitches seems to be definitely large and seeing them in OFS indicate it is real (and will be seen in DARM). Since Pcal interaction to DARM (at LHO) is oneway i.e, DARM is not expected to influence Pcal, it is probably originating in Pcal. At LLO we have seen glitches in Pcal when there were issues with power supplies (a-log LLO 21430), so it might be good to check those possibilities.
Evan G., Darkhan T., Travis S. We investigated these glitches in the y-end PCAL OFS PD more deeply and can fully explain all of the deviations. The excursions either due to DAQ restarts, line changes by users (including manual oscillator restarts, or by request to make transfer function measurements), shuttering the PCAL laser, or maintenance activities. See the attached 35 day trend of the excitation channel, shutter status, and OFS PD output (trends for both the 16 kHz and 16 Hz channels). What sets the limits on Omicron triggers? Should Omicron be set to allow a higher number of triggers for Pcal?
