High dust count.

There was a pressure glitch on PT100B HAM1 cold-cathode at 07:25:15 PDT this morning. There was no corresponding glitch on any other corner station gauge as far as I can tell.

Pressure increased from 3.3e-08 to 4.0e-08 Torr, recovered in 4 minutes.

Sun Jul 14 08:04:08 2024 INFO: Fill completed in 4min 5secs

TITLE: 07/14 Eve Shift: 2300-0800 UTC (1600-0100 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
SHIFT SUMMARY: H1 remained down again for this whole shift, and we will not be attempting to lock until further discussion can be had on the recent alignment changes. This is planned for Monday morning, which means H1 will not be observing until at least then.

The main activities of the shift were in pursuit of diagnosing the output alignment changes seen in the IFO recently, including my SR3 moves looking for good power spots (alog79103), further diagnosis of abnormal fast shutter behavior from last night (alog79102), and Sheila's comments on this situation being similar to that of the output change in late April (alog79101).

I've gathered several trends comparing the before and after of the alignment shift the IFO saw in the past couple of days, likely on Friday the 12th.

On all of these plots, I use y-cursors to indicate the levels each signal was at the appropriate time leading up to the last lock H1 had fully up to Nominal Low Noise, which lasted from 10:14 to 16:45 UTC on July 12th, in order to compare to what was likely the last time H1 was behaving "well."

DRMI signals with OM1/2 OSEMs:

The last DRMI acquisition before NLN, POP18 was around 66 counts while POP90 was around 11 counts.

The most recent DRMI acquisition, POP18 has dropped to 42 counts while POP90 has risen to 16 counts. The only significant alignment difference I see is with OM1 Y being about 70 counts different.

Optic alignments during 10W single-bounce: (times all taken from when ALIGN_IFO was in the state SR2_ALIGN [58])

The last SR2 alignment before NLN (P/SRC optics; large optics), AS_C_NSUM signal was at 0.0227 counts.

The next time in this configuration (P/SRC optics; large optics), AS_C_NSUM signal had dropped to 0.018 counts. The most obvious alignment changes are with PR2Y, PRM, some SR2, and SRM.

The most recent time in this configuration (P/SRC optics; large optics), AS_C_NSUM signal had dropped again to 0.014 counts. The same optics are off in alignment as before, but PRM has now flipped to being off in the opposite directions for both pitch and yaw.

OFI and KAPPA_C:

I recreated trends like Camilla did in alog78399 to check the behavior of the OFI. See attached for multi-day trend, zoomed in on shakes during high-state locklosses, and zoom in on one of these shakes.

HAM6 vacuum pressure:

Out of an abundance of caution, I trended the pressure gauge on HAM6 since we've seen pressure spikes somewhat recently, and I don't see anything that hasn't been previously noted on a 21-day timescale (the pressure rise ~20 days ago was noted to be because of the OM2 thermistor in alog78829).

To help characterize the recent issues we've seen with IFO alignment that are familiar to the output change in late April, I moved SR3 in 10W single-bounce configuration with the SRC2 ASC loop on so that SR2 would follow (ALIGN_IFO's SR2_ALIGN state), much like in alog77694. I moved SR3 far enough in each direction (+/- pitch and yaw) to bring the ASC-AS_C_NSUM signal back up to our target value of 0.022, which I was successful doing in every direction except -Y, where I could only bring AS_C up to 0.018. In the three directions where I was successful, the beam spot on the AS AIR camera looked much more like the clear circle we're used to seeing and less like the upside-down apostrophe we have now.

It seems that our old output spot (starting place in TJ's alog) is still bad (-Y direction with SR3 from current place) since that was the only direction where I couldn't get the AS_C power back up.

Slider values of SR3 after each move:

Attachment 1 is the starting AS AIR camera image (and our current spot), attachment 2 is after the +P move, attachment 3 is after the -P move, and attachment 4 is after the +Y move.

Yesterday, the fast shutter test failed due to dark offsets in the AS WFS DC NSUM channels.

The guardian started running the TwinCAT testing code, which works as intended: it sends a close command to the trigger logic, which in turn fires the fast shutter. The fast shutter works fine as can be seen on the HAM6 geophones. The slow controls readbacks also indicate that both fast shutter and PZT shutter are closed no later than 200ms after the trigger. However 0.5sec after the guardians started the test, it checks the AS WFS DC NSUM outputs and compares them against dark offset limits of ±15. Since the dark offset on WFS B was over 30, the guardian then sent an abort command to the TwinCAT code and reported a failure.

For a summary of links related to the 22nd/23rd incidents, see

The first two screenshots show the AS air camera with 2W out of the PSL in single bounce, reflecting off ITMY.  This seems very similar to what happened on April 22nd/23rd, where the as camera image looked bad when we were centered on AS_C, but looks sort of normal when we were way off center.

The single bounce throughput is also low, similar to what we saw on April 23rd.  Jenne looked at some times when the initial alignment guardian did SR2 offload, and narrowed down when the single bounce throughput changed to sometime between 9:23 and 23:22 UTC yesterday. 

TITLE: 07/13 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY:

• 16:00 UTC MANUAL_IA I manualed to SRC align in INIT_ALIGN where I got stuck at SRY as I expected, so I misaligned SRM and touched SR2 to maximize the ASC-AS_A_DC signal. I had to move a lot in YAW, I realigned it and started on SRM next. AS AIR looks good now, the ASC SRC loops seem to be making it worse? It degrades it until it loses lock. I adjusted it by hand, went back and finished the IA parts I skipped then tried SRC again to the same result so I went out of IA and went back into locking. I ended up having to make the following moves:
  • SR2: P -7.0 --> 62.4, Y 2044.0 --> 2052.0 (Reverted)
  • SR3: P 438.8 --> 440.1, Y 122.3 --> 122.8
• 17:45 UTC The camera spot looked much better now, and DRMI flashes were good, now SRC2 loop killed the lock now (makes sense as I couldn't complete SRC align). Sheila and I then held at DRMI_PREP_ASC and I turned off DC3 & 4 and clicked TEST on the SYS asport_protection medm screen to check the fast shutter to confirm it was ok.  alog79097
• 18:43 UTC Held us in down as the R waves of an earthquake rolled in and we couldn't hold als
• 19:32 UTC I got to PREP_ASC again and ran the test again
  • The DC CENTERING loops killed it?
  • No SRC1 loop and I turned off all 4 DC loops as soon as they came on and same behaviour
  • PRMI, I adjusted PR2 a little bit and it made the camera better, we stayed locked through the PRMI to DRMI transition now
  • Both SRC1 and 2 were False and RF90 still oscillated and lost lock
• 22:08 UTC another earthquake shaking things up
• 22:19 UTC dropped to do another IA after touching PR3 a bit (less than a microradian)
  • SR2 align made the camera look bad again and put it back into its previous spot, Making the camera better moves us off center on ASC-AS_C?
• Into single bounce mode, where we recentered SR2 on ASC-AS_C

TITLE: 07/13 Eve Shift: 2300-0800 UTC (1600-0100 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Ryan C
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 14mph Gusts, 11mph 5min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.09 μm/s
QUICK SUMMARY: Work on our IFO alignment issues have continued today; Ryan has just finished an initial alignment and Sheila is supporting remotely.

• Wind is low and the last EQ has mostly passed
• All other systems appear nominal

STATE of H1: Corrective Maintenance

We're getting shaken by an earthquake right now, once it calms down I'm trying to lock DRMI in PREP_ASC to check on the AS_SHUTTER. My IA efforts seemed to have helped as AS AIR doesn't look so strange anymore and DRMI flashes looked good. I'm going to try to keep moving up the locking sequence.

Sat Jul 13 08:09:15 2024 INFO: Fill completed in 9min 11secs

The first attached screenshot shows a time when the fast shutter was tested on July 11th, and seemed to be working fine and passed the tests.  In that case, the light on AS_A and AS_B was blocked for almost 10 seconds during the test. 

The second screenshot shows one of the many times that we tried to manually hit the run test button last night while sitting in ISC_LOCK state 120 (check as shutter). The light on AS_A and AS_B were only blocked for 10ms. 

So, this wasn't a false alarm, something about the shutter really wasn't working correctly last night. 

I've placed an ndscope template people can use to check on the fast shutter in /ligo/home/sheila.dwyer/ndscope/SYS/check_fast_shutter.yam The fast shutter full tests only run if it has been 48 hours since it last ran, so I think that Ryan should rerun the test manually this morning and check this template to convince ourselves that the shutter is really working now, before we continue with locking.

TITLE: 07/13 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Corey
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 6mph Gusts, 4mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.08 μm/s
QUICK SUMMARY:

• We've been down since last night due various issues

In the observing stretch that started Monday around 8 pm, there was a drop in optical gain (by 4%), and power at AS port PDs (4% drop in AS_A sum, AS_B sum, AS_C sum, and OMC REFL).  There not at that time any change in circulating power in the arms, PRG, coupled cavity pole, or alignment of suspensions (shown are SR2, SRM, OM1+2, but we have also looked at many other suspension, ISI and HEPI related channels for this time 77382 ).  This time is shown by the first vertical cursor in the attachment. 

We were unable to relock the interferometer after that Monday evening lock (a new lockloss type appeared early Tuesday morning, 77359), and after the maintence window we were uable to lock with difficulties powering up (77363) and an AS camera imagine that had lobes whenever the beam was well centered on AS_C.  We locked that evening by adding large offsets to AS_C's set point, (77368).  This is the cause of the large alignment shifts seen in the screenshot on Tuesday evening to Wed morning, which allowed us to lock the IFO but created a large scatter shelf and resulted in a lower coupled cavity pole, and lower optical gain, and we did not have much squeezing that night. 

We do not think that Tuesday maintence activities are the cause of our problems, although some of the Tuesday work has been reverted (77350 77369).

Yesterday we spent much of the day with SRY locked, single bounce or using the squeezer beam reflected off SRM to investigate our AS port alignment.  77392, We are able to recover the same throughput of a single bounce beam to HAM6 by moving the alignment of SR2 + SR3 by a huge amount 77388, which also produced a round looking beam on the AS camera.  We haven't since tried to explore this aperture, to see if we could have also recovered this thoughput with a pitch move, for example.  We also saw that the squeezer beam does not arrive in HAM6 with a good transmission when injected with the alignment used previously, but that we could recover good transmission to HAM6 by moving ZM5 by 150-200 urad, in pitch or yaw.   With this shift in SRC axis, and squeezer alignment we were able to relock and not have the large scattering issues we had Tuesday night.

Today's time was spent recovering from a seemingly unrelated problem in the SQZ racks, and some commissoning aimed at recovering our previous (165Mpc) sensitivity with this new alignment.  This will continue during tomorow's commissoning time.

additional related information:

• (no SQZ, HWS, OFI voltmons)  77374
• Move of SQZ beam in lock to get squeezing: 77400
• OFI transfer functions: 77391
• other suspension health checks: 77383
• dark offset script: 77362
• SRM and SR2 beam positions after the shift: 77443
• Further look at powers on HAM6 PDs: 77441
• AS port fringe wrapping worse than Summer 2023: 77452