Dave, Nutsinee
TJ spotted the DIAG_MAIN guardian EZCA error (fail to grab a HWS channel) since this morning but we thought it's going to resolve itself. By evening the problem still persisted. Then Dave found out that the hwsmsr computer was crashed. We restarted the machine and re-ran the HWS codes for both ITMX and ITMY. ITMX had low peak counts when we restarted it. I stopped the code, turned the camera and fram grabber off and on then re-ran the code. That seems to have fixed the problem. I attached the image of the ITMX HWS before (low peak counts) and after camera restart (taken when the code wasn't running).
The end station chiller cleaning is on going. We ran out of water at End-X before the second chiller could be completed so we relocated to End-Y. I have called for a water delivery but that is not expected until Friday. We are and have been only running one chiller at each end station and the idle chiller at each station has been cleaned so I have switched units at each station. Chiller 2 at EX and Chiller 1 at EY are the ones currently running.
TITLE: 03/28 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: Jim
SHIFT SUMMARY: Struggling to get past DRMI locking most of the day due to ASC issues. Jenne has been parked in the OPS station helping me out. An EQ before lunch didn't help and took ~2 hours to ring down.
LOG:
16:26 Jeff B to EX
19:00 Jeff B back
19:19 Karen leaving EY
19:44 Chandra to EX checking pump cart
19:57 Jeff B to EX
19:57 TJ done with charge measurements
21:18 Chandra back, going to MY with John, Bubba
21:26 Krishna and Michael to EY
21:39 Chandra done at EY
Moved pump cart from Ymid to LVEA to connect to RGA for testing
I took charge measurements at both ends today, they finished around 12:50 local. I'll post plots soon.
The four plots are here
There were a few weeks that were not placed into the long trend, but a large majority of the data seems to be bad. I took out what I saw was obviously bad but the error bars are still huge on many of the points. Plots are attached but it definitely needs a second look hopefully tomorrow.
Note, I think it is time to change the sign on both of these ETM ESDs. The ETMx has now migrated ~20-30 volts away from 0, albiet at a slow rate. The ETMY sign flip from last month needs to be investigated since it seems that charge is still growing (slowly) there. More to follow.
Following up on this earlier study, Weigang Liu has tried folding some of the corner-station magnetometer data in 8-second intervals, day-by-day, month-by-month and over nearly the full O1 run (excluding January because of commissioning work and October 20 for some channels because of anomalous data). Attached are the summary plots, while links to the daily & monthly plots are here: H1:PEM-CS_MAG_LVEA_VERTEX_X_DQ H1:PEM-CS_MAG_LVEA_VERTEX_Y_DQ H1:PEM-CS_MAG_LVEA_VERTEX_Z_DQ H1:PEM-CS_MAG_EBAY_SUSRACK_X_DQ H1:PEM-CS_MAG_EBAY_SUSRACK_Y_DQ H1:PEM-CS_MAG_EBAY_SUSRACK_Z_DQ As before, each figure has a top graph with the raw folded (averaged) data, a middle graph with the spectrum of the folded data, and a bottom graph which is the inverse FFT of the lowest 40 Hz. Remarks:
Laser Status:
SysStat is good
Front End power is 30.88W (should be around 30 W)
Frontend Watch is GREEN
HPO Watch is RED
PMC:
It has been locked 6.0 days, 0.0 hr 15.0 minutes (should be days/weeks)
Reflected power is 2.987Watts and PowerSum = 24.26Watts.
FSS:
It has been locked for 0.0 days 2.0 h and 26.0 min (should be days/weeks)
TPD[V] = 1.407V (min 0.9V)
ISS:
The diffracted power is around 9.374% (should be 5-9%)
Last saturation event was 0.0 days 2.0 hours and 26.0 minutes ago (should be days/weeks)
Tues. maintenance planned tasks:
TITLE: 03/28 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
Wind: 12mph Gusts, 8mph 5min avg
Primary useism: 0.14 μm/s
Secondary useism: 0.19 μm/s
QUICK SUMMARY: Arrived this morning to find the IFO unlocked with many things tripped (TMSX, TMSY, ETMY, EY ISI, EX ISI, IY ISI, IX ISI WDs tripped). It appears this was due to a pair of EQs in Mexico during the night. Reset all WDs and began initial alignment.
During Maintenance March 15th, IM1, IM2, IM3 and IM4 all shifted alignment for the same given alignment drive. The first shift was identified and restored, but the next two shifts were not, and IM2 pitch, H1's biggest shifter, jumped about 40urad in the same direction, so a total of about 80urad alignment shift in pitch.
I restored the alignments (including IM4) to the values before the alignment shifts March 15th. I did so by moving each optic and leaving some time between each, so I could get a reading of how much each optic (IM1-3) changed IM4 Trans QPD.
The results are that IM4 Trans QPD is:
This suggests that the tolerance for alignment shifts on IM1 need to be smaller than the tolerances we use for IM3.
Currently we're using a tolerance of 5urad on all IMs, and I would suggest tightening that up for IM1 to 1urad tolerance for both pitch and yaw.
This week:
Week 4/4:
J. Kissel Joe Betzwieser has created some new bit of "user" c-code in order to facilitate getting the ISI's GS13s, projected into SUSPOINT longitudinal, to the corner station to be further projected into the IFO's cavity length basis. The code serves to mux multiple low-sampling rate channels (in this case, SEI channels) into one high-sampling rate channel for shipping over the RFM IPC with less overhead. See T1600083 for details. To absorb this new code for incorporation into the PEM model (as per the plan, see LHO aLOG 26249 and ECR E1600028), I've updated the ${userapps}/cds/common/src/ directory of the local copy of the cds_user_apps repository. -------------------------- Exactly what has been received: jeffrey.kissel@opsws2:/opt/rtcds/userapps/release/cds/common/src$ svn up A LOW_FREQ_MUX.c A ccodeio.h A MAX_MIN_CALC.c A LOW_FREQ_DEMUX.c Updated to revision 12938. jeffrey.kissel@opsws2:/opt/rtcds/userapps/release/cds/common/src$
Pressures still falling: HAM 7/8: 5.6e-6 Torr (Friday=8e-6 Torr) HAM 9: 3.8e-6 Torr (Friday=6e-6 Torr) HAM 11/12: 3.5e-6 Torr (Friday=5e-6 Torr) Then turned available annulus IPs ON: HAM 8: 7 mA (pressure at cart jumped to 9.6e-6 Torr) HAM 9: full scale with red light (pressure at cart jumped to 5.5e-6 Torr) HAM 11: full scale with red light (pressure at cart jumped to 4.2e-6 Torr) Need power and signal cables for IPs on HAM 7 & 12. Power cord on HAM 8 is sketchy with tears in outer insulation. I've asked Phil to replace it. Continue to monitor pressures to detect any potential outer o-ring leaks.
Signal cables are flipped in HAM 7&8 and HAM 11&12
We did a little bit of ASC work today.
First, while Kiwamu was running a TCS test I started a script to automate phasing of the WFS. It uses the lockin, first runs a servo to set the phase of the lockin demod, then servos to minimize some signal. We have it set up right now to phase the refl WFS to minimize the PR2 pit signal in Q for both REFL 9 and 45, and to minimize the SRM pit signal in AS 36 Q. There is some code for exciting DHARD, but we need to test amplitudes, phases and gains for this. The current version of the script does its job although it is painfully slow, and is checked into the svn under asc/h1/scripts THe resulting phases are in the attached screenshot.
We saw that the instability in CHARD pit was becasue somehow the LP9 got turned on again, this is now off and CHARD seems fine.
We tried powering up, were fine at 10 Watts. We had an instability in PRC1 and PRC2 yaw at 13 Watts. I reduced the Q on the complex zeros at 1.1 Hz for PRC2Y, which gives us slightly better phase and gain near the point where we seem to be unstable. Attached is a screenshot of the OLG measured with white noise at both 2 Watts and 10Watts, we might need to do a swept sign to get a good measurement around 1 Hz.
After about 10 minutes at 12 Watts, we had the usual fluctuations in the recycling gain. So the high bandwidth PRC2 loops haven't totally solved the problem.
For the record, these are angle settings that give approximately good CO2 powers tonight, and the powers to aim for from Kiwamu's note:
X power (W) | X angle | Y | Y angle | |
unlocked | 0.5 | 76 | 0.23 | 82 |
10W | 78 | 79 | ||
20W | 0.3 | 0.1 |
We have twice had the rotation stage for CO2 Y go to an angle that was wrong by a lot (sending a few watts to the test mass for a few seconds).
I'm leaving the IFO locked at 10Watts.
Sheila,
Do you know how much power was transmitted at CO2 Y to any precision? Can you say what the upper limit was?
thanks
The first time H1:TCS-ITMY_CO2_LSRPWR_MTR_OUTPUT read back 3.2 Watts for about 20 seconds.
THe second time H1:TCS-ITMY_CO2_LSRPWR_MTR_OUTPUT read 3 Watts for about 10 seconds.
This morning I looked at some of the data from friday night when we had our usual CSOFT instability. (16-03-26 7:52:56 UTC)
First, I used the moment of interia here, and the calibration of the arm circulating power from the transmon QPDs here, to estimate i it is reasonable that radiation pressure due to the fluctuations in arm circulating power (on the order of 2.5% fluctuations on 35 kWatts of circulating power) could cause the angular motion that we see (0.1-0.4 urad pp on the test masses), and it is not, the miscentering that would be required is far too large.
I never attached the sreenshot of the PRC2 Y OLG to the original alog. Here it is.
Preliminary conclusion: the DARM cavity pole seems to be a strong function of the differential lensing. I was able to change it from 357 Hz to 220 Hz (!!!)
I will post more details tomorrow.
The cavity pole measurement is not valid until t=80 min. and also in the time band approximately between 230 and 250 min. The interferometer was locked on the DC readout with ASC fully engaged, The PSL power stayed at 2 W throughout the measurement.
Learning this behavior, I would like to do the followings in the next test:
By the way the second attachment is trend of various channels during the test.
Actually, Hang pointed out that SRM and SR2 showed much more visible reactions in their alignment. See the attached.
In particular, SR2 pitch seems to trace the lensing curve.
Also, looking at PRM and PR2, we did not see drift or anything interesting.
A simulation with substrate lensings as reported in the elog did not show a large variation of the cavity pole: about 1% or so. My suspect is that the change in differential lensing is causing the IFO working point to change: alignment or longitudinal offsets? In my simulation the longitudinal working point is obtained from simulated error signals, so I don't see any offset in the locking error signals.
The differential lens change is about 18 microdiopters. For what it's worth, there is ~2.3% of power scattered from the TEM00 mode on a double-pass through such a lens. Whether such a purely differential lens in the SRC would manifest solely as a 2.3% round-trip loss in the differential TEM00 mode of the arms is questionable. I still need to run the numbers for the effect on the DARM cavity pole if we simply added this loss to the SRM mirror.
Here are some more small points to note.
[Two cavity pole measurements]
At the beginning of the run before I started changing the CO2 power, I ran a Pcal swept sine measurement in order to get the cavity pole frequency. The DARM open loop was also measured within 10 minutes or so in order for us to be able to take out the loop suppression. In addition, I ran another pair of Pcal and DARM open loop measurements to double check the measurement. The attached below shows the transfer functions with fitting. The fitting was done with some weighted least square algorithm using LISO.
As shown in the plot, the shift in cavity pole is obvious. Also the optical gain is different between the two measurements.
[Evolution of the sensing function throughout the test]
The optical gain and cavity pole are negatively-correlated. The trend of the optical gain looks very similar to the one for the power recycling gain, but the variation in the optical is much larger-- the optical gain increased by 20 % at most relative to the beginning. As pointed out by Valera in the ISC call today, a fraction of the variation in the optical gain could be due to the OMC mode matching.
[Alignment drift]
As Gabriele pointed out in the comment, it may be possible that the CO2 lasers affected the alignment of the interferometer and changed the amount of losses in some parts of the interferometer or introduced some other impact on the cavity pole. Hang and I have looked at trend of optical levers during the time.
There are two optics that seemingly reacted to the differential lensing, that are BS yaw and ETMX PIT. The showed a kink point at the time when the CO2 power changed. In addition, ETMY pit slowly drifted by 2 urad and ETMY yaw moved by 1-ish urad. Other large optics also moved but were within 1 urad. From a naive point of view, the alignment does seem to explain the behavior of the cavity pole going down and up during the measurement because none of them clearly showed a going-up-and-down type behavior. However, it is possible that the true misalignment was covered by drift of the oplev itself.
[Online cavity pole measurement]
The cavity pole was measured by injecting a line at 331.9 Hz at the DARM output. The DARM loop is notched out at the same frequency. The measurement method is described in 18436.
Some simulations I did months ago for the MIT commissioning meeting (https://dcc.ligo.org/LIGO-G1500593) showed that the cavity pole is very sensitive to SRC matching. I therefore expect the cavity pole to be also very sensitive to SRC alignment, as seems to be sugegsted by the SR* mirror drifts.