I tuned the Xarm TCS, eventually down to 0W.  Recall that the Yarm TCS is already at 0W at high PSL power. 

This consistently made my frequency coupling and jitter coupling lines better.  My intensity coupling line went through a bit of a minimum, but didn't come up very far from that. 

We started the next lock with 0W TCS, and it still seems good.  When the SRM is optimally aligned to minimize POP90, the peaks around a few hundred Hz are a little smaller.  But, if the SRM moves even a bit, they come back to their usual height.  On the one hand, this is good, since it means the peaks are better when the sideband buildups are better (previously it has seemed like the peaks are better when the SRC is slightly misaligned).  On the other hand, it's not good that it's so sensitive to the SRM being perfect.  We definitely need to close some kind of loop around the SRM, even if it's just the dither loop.

I'm obviously at the limit of how low I can go with the Xarm TCS, but it will be good to try increasing the Yarm CO2 a bit, to see if that also helps.  I know it's a pain, but we may also want to think about increasing the ITMX ring heater even more, so that we have more room to move with the CO2.

In the attached plot, you can see my demodulated DARM signals (orange-ish yellow is demodulated DCPDs in all rows).  Top row is the frequency line at 900 Hz, middle row is intensity line at 860 Hz and bottom row is pitch jitter line in the PZT on the PSL table at 820 Hz. Bright yellow in all rows is the ITMX CO2 power.  You can see that things got a bit worse when I increased it from 0.24W nominal to 0.40W around -120 minutes, then better when I went to 0.1W around -80 min.  Things continued to improve, although not much, when I went to 0W around -30 min.  It's not clear why we lost this lock.  For the intensity line in the middle row, you can see that it went through a minimum around about -65 minutes.  Unfortunately I didn't have the demod-phase-zeroing servo on with enough gain for this loop until about -130 minutes, so we can't compare directly to the coupling that we had during nominal operation of 0.24W, but it doesn't get as bad as it was with 0.40W. 

[Jenne, JeffB]

After our lockloss this afternoon, we couldn't get the ISS to quit oscillating.  Eventually we were able to engage the loop using PD_B, and since the new PD_A location didn't seem to make a big difference in DARM, we left it on PD_B for this lock.  Someone may want to revisit this on Monday.

   Checked the TCS chillers. X was OK. Added 300ml water to TCS-Y Raised level in site glass from 6.8 to 8.5. The mesh filter was seated properly in place. 

   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.             

TITLE: 10/15 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 47.5928Mpc
INCOMING OPERATOR: Jeff
SHIFT SUMMARY:

• After the lockloss I couldn't get DRMI ASC to converge, clearing the excitations that were on seemed to fix that.
• When asking Evan Hall about the drifting range,  he said that there is no SRM control turned on. Adjusting it seemed to help a bit, but I'm not too sure how to tell what hurts it, and what helps.
• We've been locked for 4+hours

Summary

Daniel points out that the behavior of REFL LF during the 9 MHz modulation depth reduction does not make sense:

• The measurement implies that during lock acquisition, at 50 W of PSL power there is 0.76 mW of 9 MHz light on the REFL diode.
• On the other hand, assuming a 9 MHz modulation depth of 0.22 rad, and a splitting ratio of 0.0066 W/W for the diode, and assuming 100% of the 9 MHz light is reflected out of the interferometer, we should instead expect 8.0 mW of 9 MHz light on the REFL diode.
• Additionally, AS_C sum indicates that we have about 100 mW of 9 MHz light leaking out the dark port at 50 W of PSL power, compared to 1.2 W of 9 MHz light being sent into the interferometer (assuming 0.22 rad of modulation depth). So we are not losing a significant amount of 9 MHz light through the dark port.

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.

Details

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:

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.

ITMX roll was slowly ringing up since I got on shift, and the range has been driting down as well. I tried damping the roll mode but it only seemed to make things worse for not just ITMX. 

On the bright side, the wind is < 10mph and useism is on its way down.

TITLE: 10/15 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Lock Aquisition
INCOMING OPERATOR: TJ
SHIFT SUMMARY:  Struggled to get past DRMI locked for the first 5 hours of the shift due to various issues including wind, microseism, FSS issues that continue, Noise Eater resets, WFS running away, and ISC_LOCK going into error several times.  The good news is that microseism is slowly trending down and the winds have subsided some.
LOG:

13:13 Made it to NLN for the first time today, finally.  However, cannot go to Observing due to 3 excitations running (psliss, lsc, and ascimc) as reported by DIAG_EXC.  ODC-OBSERVATORY_MODE is set to Observing however.

Both of the locks during my shift have lost range since they started.  I'm not sure why this is the case.  There is also a lot of noise in the DARM spectrum below 30 Hz and between 200-600 Hz.
 

This afternoon Evan and I became suspicous that there is excess sensing noise in the IMC locking loop (alog with details coming in the next few days). After we realized that, I thought it would be a good idea to make some frequency noise measurements using the DBB in 4 configurations:

• FSS unlocked (open FSS screen and request the autolocker to off)
• FSS locked but IMC unlocked (request OFFLINE from IMC_LOCK guardian)
• IMC locked but IFO unlocked (request DOWN from ISC_LOCK)
• full IFO locked (weather permitting)

As Jeff B logged, we can't use the DBB tonight.  I've attached the screenshot of the DBB medm screen right now.  The problem could be the little counter in the operation mode box that (illegibly) says switching to standby mode in 177 minutes.  Every time we hit one of the buttons to request a mode, that counter gets reset to 240 minutes.  I'm not that patient.  I tried caputing 1 minute to that time, but that doesn't work.  Perhaps there is hope that the DBB could possibly be operable if people have the patience to wait four hours between button clicks.  Jeff B will try when the timer goes off to get some of the measurements.

Do any PSL experts have further insights into how to get this working?   

Jeff B is going to leave a print out of the DBB instructions at the operator station.  If any operator is able to make scans, in addition to saving the scans please log the times when you had the DBB PMC locked in different configurations. 

Thanks

   Wind and microseism were dropping through out the first part of the shift. Took advantage of improving conditions to run an Initial Alignment and then try locking. Made it up to DRMI_LOCKED before Lockloss. The wind started to come back up (gusts back into the mid 30s), and 0.1-0.3Hz microseism is still elevated. Have not been able to get past locking green since. 

   The winds are forecast to drop later in the evening. Went back to Down for a bit to see if conditions improve.   

   Sheila wanted to run a couple of DBB scans of Frequency Noise. From the DBB MEDM found could not switch from LOCAL to LOCK (or any other state). Per Peter's instructions; (1). Checked the DBB toggle switch was in the RMT state. It was. Cycled the switch, but no change. Could not switch from LOCAL to any other state. (2). Then tried recycling the DBB AI chassis, but still no change. 

      

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.

Since LHO is getting walloped by the remanants of a Pacific storm, the winds are high and the microseism is high, preventing locking. A while ago RichM had suggested that we try lowering the St1 RX blends when the wind was high, and it seems like this might be a good idea, under the right conditions. I started by switching ETMY, first attachment is ETMY ground vs ETMY RX during high winds, refs are 250 mhz (nominal, high)  blends, live measurement is with the 90 mhz, lower blends . There is a large improvement from .1 to 1 hz. We don't normally run this way because ground tilt is usually below T240 noise, but not today. To check that this wasn't making things worse at ETMY, I also checked the Y motion and it was similarly improved, second attachment, again, refs are 250mhz (nominal, high)  blends, live measurement is with the 90 mhz, lower blends. Again, there is some improvement in the .1-1hz band, low frequency doesn't seem to be any worse. If we look at the CPS as a low frequency witness (below the blend frequency) going to a lower blend doesn't seem to do anything bad, under these very bad, no good conditions, third attachment. Yet again, refs are 250mhz (nominal, high)  blends, live measurement is with the 90 mhz, lower blends. The brown trace shows the Y cps is moving somewhat less than the blue Y cps, so there is at least enough real low frequency signal that we are not injecting T240 RX noise into the Y loop.

Sheila and Evan were doing modecleaner measurements, so I didn't try to get any arm cavity signals. It would be nice if commissioners would give this configuration a shot while the environment is terrible.

I have left the ITMY and ETMY RX loops in these lower blends because it sounds like commissioners are probably packing it in. While winds and microseism are this high (20-50mph(?) wind, 95th percentile(?) microseism) I think we should try this configuration. When winds settle down the ITMY and ETMY ST1 RX blends should be switched back to the Quite_250 blends. 

State of H1:  breifly locked PRMI but unstable, Commissioners doing other work, currently Sheila has IMC at 50W

Details:

• IMC locking - lower stage running out of range before upper stage kicks in
• BRS EY rung up
• winds back to 15-40mph
• useism is now at 1.0 in the Corner Station
• dust in the PSL alarmed all day, so with JeffB's approval, I set the alarm level to 800 on 0.3um particles
• FSS and ISS have unlocked many times, sometimes turning the auto-locker off breifly will help
• NPRO Noise Eater has been reset at least 3 times today, not a surprise, but might need to be tonight
• locking X arm in green finicky and needed a lot of alignment help to get over 1.0
• handing off the JeffB
• Sheila has the IMC

State of H1: in Initial Alignment, struggling to lock arms in green, have only had breif locks of X arm in IR

Details:

• winds between 10mph and 45mph across the site
• BRS at EX and EY turned off
• X arm in green locked but dipping below 0.5
• IMC on relock is pushing on MC2 so much that it's wise to pause in Ready to let it settle
• NPRO Noise Eater had to be reset twice, this seems like a apttern, like possibly the first reset doesn't really restore the system to a nominal state, and another reset is necessary
• useism is high, attampt to change BRS to WINDY_USEISM but didn't work as expected, set X by hand, Y is rung up so not being used
  •  small guardian code issue resolved by TJ, guardian behavior resolved

Site Activities:

• 16:15-16:45UTC - Chandra to both EX and EY VEAs to colect serial numbers
• 16:40UTC - Bubba to EY to add glycol to equipment in the mechanical room
• 16:45UTC - EvanG injected into Pcal
• 17:15UTC - I reset the NPRO Noise Eater
• 17:29UTC - I reset the NPRO Noise Eater
• 17:52UTC - Bubba back from EY

J. Oberling, B. Weaver

I checked on the TCS chiller this morning and added 350mL of water to bring the level from 5.0 to 8.9.  I then noticed that the mesh filter seemed to by pushing up out of the reservoir by a good bit.  I reseated the filter and noticed the level had dropped to 6.3.  There was still 50mL of water in the cup, so I added that to the chiller and observed the mesh filter.  Sure enough, the filter puffed up.  There is a large air gap between the top of the water in the reservoir and the spot that the filter seats into.  What I think is happening is when we fill the chiller, that air between the water and the filter has no where to escape quickly (probably due to the amount of water moving through the filter).  This creates an air bubble between the water and the filter that then influences the fill reading on the front of the chiller (hence why the reading went down when I simply reseated the filter).  I have a suspicion that the chiller has not been losing water, we just haven't added enough since the system flush to completely fill it, and when we do top it off we're creating an air bubble that influences the fill level reading.  We then think we've topped the chiller off when in actuality we haven't; as that air bubble slowly works its way out the level reading "drops," thereby making us think we're losing water.

I ran this by Betsy and found she was starting to suspect something similar.  We went out and removed the mesh filter and then topped the chiller off, then replaced the filter.  It took 600mL of water to move the indicator from 6.3 to 8.3, which is much less than we've seen in the past; if you look at the log on top of the chiller it can be seen that there are instances where we fill w/ 250mL of water and move the indicator from 5.0 to ~9.0, which is much less than the 600mL is took to go from 6.3 to 8.3.  This suggests that what I wrote above is correct, we haven't been fully topping off the chiller but have been fooled into thinking we have by an air bubble of our own creation influencing the reading of the chiller fill level.  One of us will check the chiller at the end of the day to check the chiller water level and see if we still need to add water (water has been added every morning and evening for every day this week).

Total water added this morning was 1000mL, and this moved the indicator from 5.0 to 8.3.

Sheila, Jenne, Kiwamu

Attached is a spectra of IMC-F in different configurations.  (MC locked at different powers, DC readout, low noise)  From 100 Hz to about 1 kHZ, the spectrum of IMC F doesn't change much at all in all of these different configurations. So the IMC control signal is not dominated by REFL9 sensing noise in full lock, and probably represents the real frequency noise at the input to the IMC.  

We can do a better job later, but if we assume this is really frequency noise we can roughly calibrate this into Watts on REFL 9I:

At 1kHz:  0.1Hz/rt Hz Frquency noise arriving at IMC (which is roughly consistent with measurements in P1100192, Fig 8) Suppresion of IMC loop: 1/200 (alog 22188) Supression of CARM loop (alog 22188, our ugf is now more like 8kHz) roughly a factor of 1/30.  We can scale the DC optical gain of 0.017W/Hz used in 22188 by sqrt(2) to account for the factor of 2 increase in input power and the 6dB modulation index decrease since then.  Taking into account the coupled cavity pole at 0.5 Hz give another factor of 1/2000:

0.1Hz/rtHz(1/200 Hz/Hz IMC supression )(1/30 Hz/Hz CARM suppression) (0.024*0.5/1000)W/Hz  = 2e-10 Watts/rt Hz signal on REFL 9I or 1.7e-5 Hz/rt Hz of residual frequency noise expected.  

We can repeat this at 400 Hz:

0.03Hz/rtHz(1/600 Hz/Hz IMC supression )(1/300 Hz/Hz CARM suppression) (0.024*0.5/400)W/Hz  = 5e-12 Watts/rt Hz signal on REFL 9I or 1.7e-12 Hz/rt Hz of residual frequency noise expected.  

Comparing this to Evan's in loop measurement of the CARM noise using REFL control, (here) it is close at 1 kHz but not at 400 Hz.  You can also compare it to the transfer functions from REFL 9I to DARM posted here, and see that at 1 kHz the expected frequency noise is of the order of 5e-20 m/rt Hz at 1 kHz.  

The main message: It is probably worth making a projection for frequency noise in DARM using IMC-F to estimate the frequency noise after the ref cav, because a very rough estimate says it could be within a factor of 2 of DARM at 1kHz.