I will be in the Clean and Bake Lab today from 9am to 4pm.

The emergency lamps above the exit sign on the NW entrance to the control room are on. I tried opening and closing the door, but it remains on. Probably nothing to worry about, but noting here anyway.

It happened before too. Doesn't it say it has occasional self-testing or something?

True - it is now not on anymore.

The (masked) tech accessed all areas in the lab (office area, control room, VEA) between ~230pm-3pm. The laser safety goggles he used have been kept aside for appropriate sanitaiton.

1. I found that an EPICS channel wasn't reset to the correct value by burtrestore after the FE bootfest yesterday.
   • This cost me the whole of last night, found it finally tonight. 
   • I'll try and modify the locking scripts to better capture such errors, but ideally, we should just use Guardian or something since it's made for this purpose already.
   • Anyways, tonight I was able to re-acquire the PRFPMI lock in a completely scripted way.
2. Locking CARM on POX remains out of reach.
   • I think this has to do with the fact that the zero-crossing of the CARM and REFL error signals are dependent on the 3f PRCL/MICH error point offsets.
   • So even if the DC gain is right, the fact that we use POX for the digital AO path and REFL for the analog AO path is leading to some conflict I think.
   • Ran out of energy tonight, I'll try again tomorrow.

The DQ channels of the ETM coils were active tonight, so I'll make the coil driver actuation budget over the next couple of days.

I will be in the Clean and Bake lab today from 9am to 4pm.

There was a power outage ~30 mins ago that knocked out CDS, PSL etc. The lights in the office area also flickered briefly. Working on recovery now. The elog was also down (since nodus presumably rebooted), I restarted the service just now. Vacuum status seems okay, even though the status string reads "Unrecognized".

The recovery was complete at 1830 local time. Curiously, the EX NPRO and the doubling oven temp controllers stayed on, usually they are taken out as well. Also, all the slow machines and associated Acromag crates survived. I guess the interruption was so fleeting that some devices survived.

The control room workstation, zita, which is responsible for the IFO status StripTool display on the large TV screen, has some display driver issues I think - it crashed twice when I tried to change the default display arrangement (large TV + small monitor). It also wants to update to Ubuntu 18.04 LTS, but I decided not to for the time being (it is running Ubuntu 16.04 LTS). Anyways, after a couple of power cycles, the wall StripTools are up once again.

A technician came to the lab today at ~4pm. He entered the VEA (with booties and googles), and also the clean and bake lab. The whole procedure lasted ~10 minutes. I did not follow him around, but was available in the control room throughout the process. I think the whole episode went without incident.

BTW, this guy didn't ring the doorbell, I just happened to be here when he came by. I don't know if this is usual practise - are we happy with the technicians entering the VEA and/or clean and bake labs without supervision? AFAIK, this wasn't scheduled.

My power at home winked out for a second this morning, but it looks like either nothing happened in the 40m lab or else it rode it out.

MC is locked - lost lock around 11:25 AM and then relocked.

2PM: Arrived at the 40m. Started the work for the coupling of the RF modulated LO beam into a fiber. -> I left the lab at 10:30 PM.

The fiber coupling setup for the phase-modulated beam was made right next to the PSL injection path. (See attachment 1)

• For the alignment of the beam, the main PSL path, including the alignment of the 2" PO mirror, has not been touched.
• There are two PO beams with the optical power of 0.8mW (left) and 1.6mW (right). Both had been blocked but the right one was designed to be used for PSL POS and ANG. For the fiber coupling, the right beam was used.
• The alignment/mode-matching work has been done with a short (2m?) fiber patch cable from Thorlabs. The fiber is the same as the one used for LO delivery.
• I tried to have a mode-matching telescope in the LO path. I ended up having no lens for the best result. The resulting transmitted power is 1.21mW out of 1.64mW incident (~74%). These powers were measured with the Ophir power meter. (Note that Thorlabs' fiber power meter indicated 1.0mW transmission.)

Some notes

• After the PSL activity, the IMC locking was checked to see if I messed up the PSL alignment. It locks fine and looks fine.
  • The input shutter (left closed after Jon's vacuum work?) was opened.
  • The alignment was not optimal and had some pitch misalignment (e.g. TEM03).
  • After some MC SUS alignment, the automatic locking of TEM00 was recovered. Mainly MC3 pitch was moved (+0.17).
  • I've consulted with Gautam and he thinks this is with the level of regular drift. The AS beam was visible.
• The IMC and MI were moving so much, but this seemed just the usual Saturday night Millikan shake.
• During the activity, the PSL HEPA was turned up to 100 and it was reverted to 33 after the work.
• I have been wearing a mask and gloves throughout the work there.

15:30
- PSL HEPA was running at 33% and is now at 100%
- South End HEPA was not on and is now running
- Yarm Portable HEPA was not running and is now running at max speed: the power was taken beneath the ITMY table. It is better to unplug it when one uses the IFO.
- Yend Portable HEPA was not running and is now running (presumably) at max speed

Particle Levels: (Not sure about the unit. The convention here is to multiply x10 of the reading)

Before running the HEPAs at their maximum
9/10/2020 15:30 / 0.3um 292180 / 0.5um 14420
(cf 9/5/2020 / 0.3um 94990 / 0.5um 6210)
==>
After running the HEPAs at their maximum
The number gradually went down and now became constant at about half of the initial values
9/10/2020 19:30 / 0.3um 124400 / 0.5um 7410

M4.5 EQ in LA 2020-09-19 06:38:46 (UTC) / -1d 23:38:46 (PDT) https://earthquake.usgs.gov/earthquakes/eventpage/ci38695658/executive

I only checked the watchdogs. All watchdogs were tripped. ITMX and ETMY seemed stuck (or have the OSEM magnet issue). They were left tripped. The watchdogs for the other SUSs were reloaded.

the seismometers obviously saturated during the EQ, but the accelerometers captured some of it. It looks like there's different saturation levels on different sensors.

Also, it seems the mounting of the MC2 accelerometers is not so good. There's some ~10-20 Hz resonance its mount that's showing up. Either its the MC2 chamber legs or the accelerometers are clamped poorly to the MC2 baseplate.

Sun Sep 20 00:02:36 2020 edit: fixed indexing error in plots

* also assuming that the sensors are correctly calibrated in the front end to 1 count = 1 um/s^2 (this is what's used in the summ pages)

the EQ was ~14 km south of Caltech and 17 km deep

I'm amazed at how much higher the noise is on the MC2 accelerometer. Is that really how much amplification of the ground motion we're getting? If so, its as if the MC has no vibration isolation from the ground in that band. We should put one set on the ground and make the more direct comparison of the spectra. Also, perhaps do some seismic FF using this sensor - I'm not sure how successful we've been in this band.

Attaching the coherence plot from ldvw.ligo.caltech.edu (apparently it has access to the 40m data, so we can use that as an alternative to dtt or python for remote analysis):

It would be interesting to see if we can use the ML based FF technology from this summer's SURF project by Nadia to increase the coherence by including some slow IMC alignment channels.

I supplied a bottle of hand soap. Don't put water in the bottle to dilute it as it makes the soap vulnarable for cotamination.

There were two SUSs which didn't look normal.

- ITMX was easily released by the bias slider -> Shake the pitch slider and while all the OSEM values are moving, turn on the damping control (with x10 large watchdog threshold)

- ETMY has UR OSEM 0V output. This means that there is no light. And this didn't change at all with the slider move.
- Went to the Y table and tried to look at the coils. It seems that the UR magnet is detached from the optic and stuck in the OSEM.

We need a vent to fix the suspension, but until then what we can do is to redistribute the POS/PIT/YAW actuations to the three coils.

While I stopped by the lab this morning to pick up some things, I took the opportunity to continue the recovery.

• IMC suspensions were sufficiently misaligned that the autolocker couldn't re-acqurie the lock. I manually recovered the alignment and now the IMC is locked again.
• ETMY illuminator was left ON, I turned it off. In the process, I modified the illuminator ON/OFF script to be compatible with python3, but unfortunately, it was written in a way that doesn't permit backward compatibility, so now the illuminators can't be turned ON/OFF via the MEDM screen on pianosa (since the default python is 2.7 on that machine). But it does work on rossa, which I'm using as my primary workstation now (hence the change).
• ITMX watchdog trip threshold was manually reset to the nominal value - the rampdown script was working, but the threshold was ~1400cts (normally ~200 cts) even at 1130am this morning (>12 hours after Koji's work yesterday evening), so I just accelerated the process.
• Suspension realignment - using a mix of green and IR beams and the various cameras/photodiodes as diagnostics, I roughly restored the alignment of all the suspensions, except ETMY. I can see IR resonances in the X arm now.

At some point, we should run the suspension eigenmode routine (kick optics, let them ringdown, measure peak locations and Qs) to confirm that the remaining suspensions are okay, will also help in actuation re-allocation efforts on ETMY. But I didn't do this today.

Leaving the lab at 1150.

See Attachment #1.

• The original ETMY actuation matrix was the naive one so I simply retuned everything by adding the butterfly mode appropriately.
• The cross coupling between the DOFs has not been characterized, but the local damping, Oplev loops, POX/POY locking, simpel Michelson locking, and ASS dither alignemnt all seem to work so I'm thinking this is good enough for now.
• A copy of the ETMYaux.db file was made, and the slow bias voltage was redistributed among the three available face OSEMs - note that the magnet polarity has to be taken into account.
• The series resistance on the slow path was reduced from 430 ohms, 1W to 100 ohms, 3W, to allow DC alignment of the cavity axis to the beam axis.
• Vertex Oplevs were re-centered on their respective QPDs after locking POX/POY and running the ASS dither alignment.
• The AS spot was a little low on the camera - presumably the SR2/SR3 got macroscopically misaligned. I re-centered the beam on the camera on the AS table (by moving the camera, the beam path was not disturbed).

The beam spot on ETMY looks weird (looks almost like a TEM10 mode), but the one on ITMY seems fine, see Attachment #2. Wonder what's going on there, maybe just a focusing problem?

I came to the lab. The control room AC was off -> Now it is on.

Here is the setting of the AC meant for continuous running

Gautam reported that the PSL HEPA stopped running (ELOG 15592). So I came in today and started troubleshooting.

It looks like that the AC power reaches the motors. However, both motors do not run. It looks like the problem exists in the capacitors, the motors, or both.
Parts specs can be found in the next ELOG.

Attachment 1 is the connection diagram of the HEPA. The AC power is distributed by the breaker panel. The PSL HEPA is assigned to use M22 breaker (Attachment 2). I checked the breaker switch and it was (and is) ON. The power goes to the junction box above the enclosure (Attachment 3). A couple of wires goes to the HEPA switch (right above the enclosure light switch) and the output goes to the variac. The inside of the junction box looked like this (Attachment 4).

By the way, the wires were just twisted and screwed into a metal threaded (but isolated) caps (Attachment 5). Is this legit? Shouldn't we use stronger crimping? Anyway, there was nothing wrong with the caps w.r.t the connection for now.

I could easily trace the power up to the variac. The variac output was just fine (Attachment 6). The cord goes from the variac to the junction box (and then HEPAs) looked scorched. The connection from the plug to HEPAs was still OK, but this should be eventually replaced. Right now the cable was unplugged after the following tests for the safety reason.

The junction box for each HEPA unit was opened to check the voltage. The supply voltage came to the junction boxes and it was just fine. In Attachments 8 & 9, the voltages look low but this is because I just turned the variac only a little.

At the (main) junction box, the resistances of the HEPAs were checked with the Fluke. As the HEPA units are connected to the AC in parallel, the resistances were individually checked as follows.

The coils were not disconnected (... I wonder if the wiring of South HEPA was flipped? But this is not the main issue right now.)
 

By removing the pre-filters, the motors were inspected Attachments 10 & 11. At least the north HEPA motor was warm, indicating there was some current before. A capacitor was connected per motor. When the variac was tuned up a bit, one side of the capacitor could see the voltage. I could not judge which has the issue between the capacitor and the motor.

Dimensions / Specs

- HEPA unit dimentions
- HEPA unit manufacturer
- Motor
- Capacitor

I was in the lab from 1630-1830. I have located and visually inspected all the parts required for the magnet regluing / optic cleaning parts of the planned vent, except the fresh batches of scpectroscopic grade solvents. I was in the cleanroom part of the clean and bake lab from 1630-1700.

[JV, GV]

The HEPAs work again. After running the HEPAs for ~1 hour, I checked the particle count on the PSL table - the meter registered 0 for both 0.3 um and 0.5 um. So I decided to turn the NPRO back on, at ~1730 local time. The PMC and IMC were readily locke, so the basic interferometer functionality is returned, and we can now go ahead with (i) vent prep (ii) air BHD tests and (iii) IMC debuggin as was discussed on the call today. The earth is shaking, but nothing serious so far, I will resume alignment of the interferometer later in the evening when hopefully things have calmed down a bit more...

Procedure:

1. Turned off mains switch on the NW corner of the PSL enclosure. Then, disconnected the power cables from mains to Variac and from Variac to HEPAs. Made sure both HEPAs were set to "OFF".
2. With confidence that no AC power was reaching the motors, I removed the pre-filters, and removed the old startup capacitors. These don't have a polarity, but I marked the cable that was connected to the left terminal of the capacitor when the cap is viewed with the label facing you, in the interest of changing as few things as possible.
3. The two new capacitors were measured with the LCR meter - the meter registered ~7.5 uF, as expected. Unsurprisingly, the old capacitors that were removed didn't register any reading on the LCR meter. The terminals weren't shorted, but I don't know what the failure mode for this kind of capacitor is.
4. The two new capacitors were installed. Then, I tested the system by undoing all the changes in bullet #1. We found that the Variac needs to be set to 100% for the motors to startup.
5. The motor speed was found to vary as the Variac dial was turned. FWIW, at the "nominal" setting of 33% on the Variac (when we run the interferometer), I could see both fan blades were turning, but the flow was low enough that you couldn't hear any wind (at least, neither Jordan nor I could).
6. Turned off the mains agian, and cleaned up - restored the insulating rubber sleeve on the capacitor leads, and re-installed the pre-filters on the HEPA blowers. Then we turned both blowers back on. 

Note that the many other issues Koji noted in the preceeding elog (e.g. flaky wiring) have not been addressed.

Flow measurements:

Chub kindly provided us with an electronic anemometer. With the meter held directly against the HEPA filter inside the enclosure, we measured ~700 cfm of airflow on each of the two HEPAs, with the Variac set to 100% and the HEPAs themselves set to "High". With the Variac at 50%, the flow drops to ~160 cfm. At the nominal setting of 33%, the meter didn't register any flow. I don't know what the spec'd flow rate is for this combination of blower + filter, but Jordan says similar units in Downs register ~1500 cfm at the "High" setting. The two protable (similarly sized) HEPA units in the 40m, one at ITMY and one at ETMY, register ~900 cfm and ~1100 cfm respectively, when set to high. So we may want to revisit what the "nominal" HEPA setting should be, in case the filters have become clogged over time. 

Some photos of the HEPA blowers with the pre-filters off and the capacitors switched out may be found here.

it would be a good idea for us to have an auto-reminder to have us check the flow of all the HEPAs in the lab and elog it once a year so that we can replace filters and pre-filters appropriately.

The optomechanics stock in the lab was in a sad state. We have obtained the following from Thorlabs in the last two months:

1. 6 pcs each of DT12 and DT12B compact translation stages (for lens mode matching).
2. 3pcs each KM100PM + PM3 cube beamsplitter mounts (for polarization control).
3. 1 Post / spacer kit for height adjustment.
4. 3 pcs ea of K6XS + AD11F + F220APC for fiber applications.

I have used some of these for the ari BHD setup. The unused items are stored in the shelves that house the optomechanics ~halfway down the east arm. I'm wondering what's a good setup to document the stock of this stuff so we can always have a healthy stock of optomechanics (at least the non speciality ones like posts, spacers etc). It sucks to realize at 0000hrs that you're missing a 3mm shim or 250mm converging lens or something.

2x500 ml bottles of spectroscopic grade isopropanol were delivered. I marked them with today's date and placed them in the solvent cabinet. In the process, my shoulder bumped the laser interlock switch by the door to the VEA in the drill press area, which turned the PSL NPRO off. I turned it back on just now. The other NPROs are not connected to the interlock and so were unaffected.

Tue evening from 4pm~6pm, Koji made a social distant tour for Anchal. We were present around the PSL/AS/ETMX tables.

• UPS batteries
• 2x HEPA filters
• VWR chemicals (methanol)

These boxes were moved from the 40m hallway to the inside of the VEA so that we have some space to walk around. You can find some pictures here.

[JV, GV]

We cleared up some space in the 1Y1 electronics rack to install the 3 new FE machines. I removed the current driver and laser from 1Y1, they are now stored in the E10 cabinet. I will upload some photos to gPhotos soon.

1. I think it's good to have all these FEs in one rack (at least the new ones) - we should then hook it up to an ethernet power source, so that we can remotely power cycle them. I think we have long enough cables to interface to expansion chasses / dolphin switches, but if not, I think it's still a good idea to have these machines in 1Y1 as it is the least sensitive area in terms of immunity to bumping some cable during setup work and disturbing the rest of the IFO.
2. We found that the rails that the Supermicros shipped with the servers seem to be just a little too narrow - we mounted these in the rack, but had considerable difficulty sliding the server units in. Once they are in, they don't slide smoothly. Is there some special trick to installing these? 
3. I spent a few minutes trying to get Debian 8 installed on these machines, so that the rest of the setup work could be done remotely - however, there appear to be some firmware issues and so I'm not gonna dive into this.
   • I couldn't find a disk image for Debian 8.5 which is what the KT wikl recommends, so the OS I tried to install was Debian 8.11.
   • The error that comes up is related to a "stalled CPU" - apparently this is related to some graphics driver issue (there's another forum page that suggests upgrading the BIOS, but I don't think that's the problem here).
   • Anyways, this part of the process is only to install some drivers and do the initial setup - these machines will eventually run a diskless boot from the image on FB, so who knows if there will be some other driver issues/hardware-software incompatibilities there 😱 .
   • We should also make an effort to set these machines up with IPMI, but I think we first need to install an OS and a CLI to setup the IPMI. My cursory browsing of the manual suggests that the initial setup maybe can be done without installing an OS, and then subsequent work, including OS install, can be done remotely. If someone reads more in detail and can provide me a step-by-step, I can follow those instructions (if they aren't available to come into the lab). See here for some brief documentation of how to access the IPMI.

Per Koji's suggestion, I turned the PSL HEPA Variac to 50% just now, so that the power load through the burnt electrical cable is reduced by 75%.

I entered 40m today at around 1:20 pm and left by 1:45 pm. I entered 104 through the machine shop entry. I did the following:

• I took photos and videos of the PSL table with lights on.
• I uncovered the AP table, took photos and video, and covered it back.
• I went to the X End table and took a video without opening the enclosure.
• Apart from flipping light switches, nothing else should have changed.

The AC cord from the PSL HEPA variac to the junction box was replaced.
Now the HEPA is running at 70%

Showed up at the 40m at 7pm

Preparation

• Closed the PSL shutter.
• Closed the innolight shutter
• Turned off the HEPA mains switch
• Checked the HEPA fan rating: 115V 4.5A.
• Brought the thickest power cord from the wall stock: the rating is 125V 15A. This should sufficiently hold two HEPAs.

Cable Replacing

• Rechecked the wire connection. The new cord has green/black/white wires. And the colors agree with the color of the wires in the junction box.
• Removed the existing cord.
• Attached the new cord.
• Checked the variac AC plug. The terminals in the plug look normal and the AC plug looked sufficiently rigid.
• Checked the connection again. = OK

Testing

• Turned on the HEPA mains switch
• VairAC turned to 70%
• Checked the air flow - The HEPA fans are sucking the air = OK

Closing the work

• Closed the junction box.
• Cleaned up the roof
• Opend the innolight shutter
• Opened the PSL shutter
• Locked the PMC
• Locked the IMC  - found the transmission was ~80% of the pre-work due to misalignment of the PMC
• Aligned the PMC - this recovered the IMC REFL of ~5.2 when the IMC was unlocked

Leaving the 40m at 9:30pm

Memo: 40m wiring/Mask/Camera/Red Pitaya/Particle Counter

I entered 40m today at around 1:10 pm and left by 1:50 pm. I entered 104 through the machine shop entry. I took top view single picture photos of ITMY, BS, AP, ITMX, ETMX and ETMY tables. The latest photos will be put here on the wiki soon.

I set up an action cam (DJI OSMO Pocket) and brought it back to the 40m. The kit is now placed in the control room cabinet together with the Canon DSLR.

I might have left the USBC chaging cable at home this time. Will bring it back next time.-> The cable was returned to the kit on Oct 23rd.

I wanted to look into the ISS situation. Some weeks ago, I found the PD that was previously used as the in-loop photodiode. I wanted to use this and measure the open-loop RIN at a few places (to see if there's any variation and also to check its functionality). However, I didn't get very far tonight - for a start, the PD height is 3" (while our beam height is 4" everywhere outside the vacuum), and I needed to put together a circuit to supply the 5V bias and +/- 15 V since the transimpedance is done on the head. I was only able to do a low-level functionality test tonight, checked that the DC voltage output varied linearly with the incident power (calibrated against an NF1611 photodiode, data will be put up later). I didn't get to measuring any noise performance - is an incandescent light bulb still shot noise limited at ~10 Hz < f < 10kHz? Some notes:

1. The PD is DC coupled, and has a transimpedance of 1 kohm (inverting AD829 does the transimpedance).
2. Probably a daughter board should be made that supplies the DC power voltages and rotues the output signal to something more convenient like a BNC connector. This daughter board can then also implement a DC coupled path (for monitoring) and AC coupled path (for servoing, fc to be determined).
3. SR560 based ISS was implemented some years ago but I think the improvement was only seen above 100 Hz, and that too was marginal, the stabilized RIN was 10^-6 (monitored on an out-of-loop photodiode I think, but unsure). We'd probably want to aim for at least an order of magnitude better. Unclear at this point why more suppression wasn't possible back then, was it just insufficient loop gain, or was the sensing noise too high? To be investigated.

Unconnected to this work - this problem reared its ugly head again (i noticed it yesterday morning already actually). I don't have the energy to embark on a fix tonight, Koji is going to be in the lab all day tomorrow and so he will fix it.

that little PD in the black mount was never very good. The AD829 is not a good opamp for transimpedance and especially not good for low frequencies. Stefan Ballmer and I were able to get 2e-8 out of these (@100 Hz) many years ago.

I wonder if we have some of Zach's M2ISS photodetectors around, perhaps in QIL or Cryo. I doubt that any of them are in use now. Those had good performance nad BNC output.

Ok I was using the PD in the black mount because Rana recommended it a few weeks ago.

Regarding the M2ISS, I acquired the hardware from QIL some months ago, including a circuit board, and 2 PDs. These had LEMO outputs though (not BNC), and the mounts are not 4". These photodiodes are what I'm using as the airBHD DCPDs right now, and some photos are here - are these the photodiodes you mentioned? Or are there yet more M2ISS photodiodes? I remember Johannes had some custom mounts extruded to make them 4" high, do you mean those? Can I retrieve them his Cryo setup?

BTW, my elog scraping shows only one spectra from Stefan in the ATF elog, and the performance there is more like 1e-7/rtHz @ 100 Hz, and that’s using a dedicated high BW servo circuit, not the SR560. Am I just missing the measurement of 2e-8/rtHz?

1. Two arms / BS / PRM / SRM were aligned. (Attachment 1)
2. IMC was aligned by WFS and the WFS offsets were offloaded.
3. Suspension Status Snapshot (Attachment 2)
4. Oplevs are aligned (Attachment 3)
5. Xarm green was aligned in the daytime. Xarm green refl DC (C1:ALS-X_REFL_DC_OUTPUT) was 620 (aligned) ~1300 (drifted). When unlocked, it was 3750.
6. Yarm green: I saw no flash. We don't have functional PZT alignment since the ASY M2 PZT got broken. I went to the Yend. Something funky is going on with the Yend green. I struggled to have any flash of the cavity. The apertures were not so precise. I finally got TEM00 locked, but the modematching seems exteremely low (like 1/1000?). Basically I saw no power reduction of the refl when the cavity is locked. So at least the cavity was locked but we might need to revisit when we open the chamber
   ==> Gautam thinks it was not like that. So he will check the green alignment tomorrow (Thu).
7. Item checking: I familialized myself with the yend crane operation. Today I learned that there is a power switch on the wall (Attachment 4). The yend has two heavy door storages (Attachments 4/5). The slings to lift the heavy door are in the crane cabinet along with the y arm (Attachment 6). I didn't yet try to find the "hammer" to hit the door if the o-ring stuck too strong, although that's optional.
8. We want to reduce the PSL power. But Gautam wants to use the arm locking with the nominal power, it will be done tomorrow by him.
    
9. The last thing is to check the green trans power. I noticed that the green trans beams are blocked by an HWP for the BHD LO path on the PSL table. (Attachment 7)
   The HWP was moved and the process was recorded in the movie (Attachment 8). The fiber output was monitored by the BHD DC (aka AS110 DC) with the AS path blocked. The fiber output of 22.6mV (offset -2.5mV) was improved tio 29.1mV after the HWP move and the alignment adjustment.
10. Now the green transmissions are visible by the green PDs. Attachment 9 shows the trans and ref of each green beams with and without locking to TEM00. The questionable green TRY was ~0.3. If we compare this with the histrical data (Attachment 10), it is about 1/4 of the value in the past. It's not too crazy but still quite low.

At this point, I'm leaving the lab. All the suspensions (incl SRM) are aligned. PSL/GRX/GRY shutters were left open.

1. Oplev HeNe at ETMY was replaced, see here for my earlier discussion on this.
   • I thought this is a good idea since we want the Oplev as a coarse reference and it'd not be ideal if this HeNe dies during the time the optic is out of the chamber.
   • New HeNe had 2.8mW of power output as measured with Ophir power meter. This is in line with what is expected from these Lumentum heads.
   • I labelled the head with the power output and today's date, re-aligned the Oplev reflection onto its QPD. 
   • After this work, the Y-arm could be locked without the huge angular fluctuations that was visible earlier, 👍 .
2. GTRY anomaly
   • I actually judged that there is no anomaly.
   • The GTRY CDS indicator is actually quite useless - the ADC saturates at ~3500 cts (and not 32768 as you would expect from a 16 bit ADC but that's the well-known whitening filter saturation problem). This should be fixed, but this is a task for later.
   • I measured with a DMM the voltage when the TEM00 is locked to the cavity and GTRY is 0.3 (the nominal value these days), the DC voltage was ~5.6 V. The prompt reflection from the ETM registers ~6.5 V DC. So the mode-matching isn't stellar, but this is again a known issue, and can be fixed later.
3. Other pre-vent checks
   • The Oplevs had drifted significantly, I re-centered ITMs, ETMs and BS after aligning the arm cavities and green beams in the POX/POY lock state. See Attachment #1.
   • I locked the PRMI on carrier and used this config to re-center the PRM Oplev, see Attachment #2.
   • No further action was taken regarding SRM oplev.
   • I checked the ALS noise, see Attachment #3. The X arm ALS has excess noise at ~100 Hz that certainly wasn't there previosuly - sigh. There is nothing I can find about any changes made at EX in the elog.
   • Updated the "DriftMon" values, though I guess we don't even really use this anymore these days?
   • Re-relieved the IMC WFS offsets.
   • Cut the input power to the IMC from 1.007W to 100.1 mW (both numbers measured with Ophir power meter).
   • Replaced the 10% beamsplitter in the MCREFL path on the AS table with a Y1 HR mirror. Note that there is no beam on the IMC WFS in this configuration.
   • Was able to lock the IMC on low power to a TEM00 mode - need to set up the low power autolocker. The IMC autolocker is now set to the low power settings, and I've tested it locks a couple of times. Attachment #5 shows the low power lock in StripTool.
   • Walked around and looked at all the bellows - the jam nuts are up against their stops, and I can't move them with my hands, so I think that's okay.

If everything else looks good, I'll start letting the dry N2 into the main volume after lunch.

BTW, nice video! @ Koji, How difficult was it to edit it into this form? 

1. Jam nuts - checked that none of the nuts move by hand, which according to Steve, is sufficient. I recorded photos of all of them here.
2. Lab particle count - at the SP table, I measured 25,910 / cf @ 0.3 um and 1220 /cf  @ 0.5 um. Steve's guidance is that the latter number should be less than 10,000, so no issues there.
3. Valves - closed all the annuli off, and also closed VM1, VA6 and V1. The procedure calls for VM3 to be opened, presumably so that the RGA remains pumped, but I see no reason why we can't just leave that RGA volume valved off.
4. Started letting N2 into the main volume at ~3pm local time, by opening VV1. Attachment #1 shows the valve configuration adopted for this vent. Went up to 25 torr and then switched over to the "Ultra Zero" instrument grade air cylinders.
5. Aimed for 3-5 torr/min rate of pressure increase locally. The full vent trend can be seen in Attachment #2.
6. Stopped letting air into the main volume when P1a pressure was 700 torr, at which point I disconnected the cylinders from the main volume, and left VV1 open so that the IFO equilibriates to the lab air pressure. I used 4 full cylinders of the instrument grade air, which is par for the course. 
7. Since we anticipate opening the ETMY and output optics chambers, I also vented those annuli. The final state of the valves as I am leaving it for the night is shown in Attachment #3.
8. I re-aligned the IMC mirrors so that I could lock the IMC at low power once again. Indeed, IMC trans of ~1400 cts was realized (see Attachment #4), c.f. ~1500 earlier today, I thought this is fine and didn't optimize further. I think the policy is to not lock the IMC in air unless necessary, so I'm leaving the PSL shutter closed for the night.
9. The ITMs, ETMs and BS were re-aligned such that the Oplev spots are centered. I can see some higher order resonances of the green beams. The AS spot is fringing (the two ND=0.5 filters on the AS CCD camera were removed for better visibility). So this is fine as far as alignment is concerned.

We are now ready to take the doors off. I've already done the basic prep work (loosened bolts, cleaned chamber, carts for tools, fresh ameristat on portable HEPAs etc).

[koji, rana, gautam]

This morning, we did the following;

1. Removed the ETMY chamber heavy door. It is stored on the rack at the east end.
2. Removed OMC chamber heavy door. It is smaller than the other chamber doors, so doesn't sit on the standard size rack we have. So it is laid flat, on a clean sheet of ameristat, on a cart next to the NE corner of the PSL table.
3. After taking some photos of the chamber and making sure the position of the suspension tower was marked by some stops, we removed the ETMY cage and moved it to the cleanroom area. The optic was EQ stopped during the transport, and the OSEMs were removed. The ETMY Oplev HeNe was turned off and the PSL was shuttered to allow us to work without goggles.
4. The broken off magnet was retrieved from inside the OSEM. The shadow sensor voltage recovered a value of ~800cts, which means the LED/PD pair on the UR OSEM seems to work fine, and it was in fact the magnet blocking the PD that was the issue.
5. In the cleanroom area, we removed the optic from the wire loop and placed it on the magnet gluing fixture. The wire is intact (for now), so there is some hope of re-suspending it in the same loop.

The OSEMs remain in the EY vacuum chamber. The next set of steps are:

1. Clean the EP30-2 residue from the broken magnet joint - this will require some scrubbing with an acetone soaked scrub or similar implement.
2. Reglue the broken magnet.

We will most likely work on this tomorrow. At ~1615, I briefly opened the PSL shutter and tweaked the IMC alignment. We will almost certainly change the pointing into the IMC when we remove the old OMC and rebalance that table, so care should be taken when working on that...

To be a bit more clear about what we are going to do in the OMC chamber, I marked-up some photos, see Attachments #1 and #2.

1. OM5 will be rotated to bring the IFO AS beam straight out without any splitting to the OMC.
2. OMMT, OMC, DCPD, DCPD transimpedance amp, and all peripheral optics associated with these components, will be removed. Many of these components are mounted on a breadboard and so removing that breadboard will take care of it. These are marked with pink Xs.

I anticipate that after this work, the only components on the table will be 

1. IM1, to send the PSL beam to the IMC.
2. OMs 5 and 6 to bring the IFO AS beam out onto the AP table (in principle, we could try and eliminate both these optics, if the AS beam happens to exit through one of the viewports cleanly, we will not have any intervening objects in the way once the OMC and peripherals are removed).
3. MMT2 for mode-matching the IMC transmission to the interferometer mode.

Are we in agreement with this plan?

See #15656 for the updated photo

I believe the mirror next to IM1 is for the green beams to be delivered to the PSL table. I think we still want to keep it. Otherwise, the plan looks fine.

Good point - looking back, I also see that I already removed the mirror at the SW corner of the table in 2016. Revised photo in Attachment #1. There is an optic on the east edge of this table whose purpose I'm not sure of, but I'm pretty sure it isn't essential to the main functionality and so can be removed.

I got a call from Calum ~830am today saying some facilities people entered the lab, opened the south entrance door, and tripped the alarm in the process. I came to the lab shortly after and was able to reset the alarm by flipping the switch on the alarm box at the south end entrance to "Alarm OFF". Then, I double checked that the door is closed, and re-enabled the alarm. The particle count at the SP table is not unusually high and the lasers (Oplev HeNe and AUX X) were still on, so doesn't look like any lasting damage was done. The facilities people were apparently wearing laser safety goggles.

[koji, gautam]

1. Glued broken off magnet - curing overnight with lamp to slightly elevate temp for curing.
2. Remvoed material from OMC chamber as per the plan. This is all sitting wrapped up in foil on a cart for tonight, we should figure out a better storage plan eventually.

The IMC isn't resonant for a TEM00 mode at the time of writing - we are waiting for the stack to relax, at which point if the IMC isn't resonant for a TEM00 mode, we will tweak the input pointing into the IMC (we want to use the suspended cavity as the reference, since it is presumably more reliable than the table from which we removed ~50 kgs of weight and shifted the balance.

[koji, gautam]

1. Tweaked last steering mirror before PSL beam is launched into vacuum to get the IMC resonant for the TEM00 mode. Less than 1/8 turn in each Pitch and Yaw was required, and we recovered MC2T ~ 1300 cts (c.f. the expected ~1500 cts when the cavity is well aligned, but we didn't touch the IMC mirrors).
2. ETMY magnet re-gluing
   • Regluing was successful. Pickle picker came off smoothly. 
   • We performed the razor blade test on all 6 magnets, the integrity of the joints seems uncompromised.
3. ETMY cleaning
   • Applied F.C. to HR face, HR edge (to remove some residual stains) and AR surface (taking care to go around the magnets).
   • A fresh bottle each of spectroscopic grade acetone and isopropanol was dispensed into clean beakers for the work.
   • Curiously, in the lighting conditions of the cleanroom, both HR and AR faces looked surprisingly clean, even when illuminated with the green flashlight.
   • However, when we took it to the east end and looked at it again with the green flashlight, just before putting it into the chamber, we saw all sorts of stains and markings on the HR side.
   • The central aperture looks fine - the contamination did not happen during the transport so we feel confident not to futz around more with this and since we cleaned it extensively in the cleanroom, we opted not to do another round of cleaning in the chamber.
4. ETMY re-suspension (on the existing wire loop)
   • The back OSEM-holding plates were removed for access reasons.
   • The optic was rested onto the EQ stops. 
   • Patient nudging of the wire around the optic allowed us to eventually get the wire into the V-grooves in the standoffs.
   • The wire was not damaged! (at least, to eye, free-swinging test is going on now, we will see what the eigenfrequencies and Qs are)...
   • We confirmed that the wire is seated in the v-groove, and took some close up photos.
5. ETMY pitch balancing
   • A HeNe was brought into the cleanroom and mounted at 5.5" beam height.
   • Level-ness of the beam (i.e. parallel to the optic table) was done coarsely with a spirit level placed on the HeNe holder, and more fine adjustment was done by checking the beam height at the launch point, and again ~2 meters away.
   • All EQ stops were backed off to ensure the optic was really "free-swinging" - no OSEMs either at this point, since all this was done in the cleanroom.
   • The return beam hit the HeNe's output aperture, so we were satisfied that the pitch balancing was good to ~1mrad.
6. ETMY transport back to EY
   • Since we want to maintain some tension in the wires, the bottom EQ stops were not raised as much as they were when the tower was transported from EY to the cleanroom.
   • As a result, we felt it'd be better for a human (Koji) to carry the cage (rather than cart it, the idea being that there would be fewer vertical impulses due to bumps on the ground etc).
   • The transport went smooth.
7. EY chamber work
   • Optic was placed back in its original position (marked by some L-clamps).
   • In preparation for alignment work, I undid all the CDS changes I made to facilitate the temporary 3-magnet actuation. This necessitated a reboot of c1auxey VME crate.
   • OSEMs were inserted - best effort to half light as usual, and we tried to replicate the rotation in the mounts as closely as possible to what was the case before (using a photo from the last vent as reference).
   • Coarse alignment was done by making the Oplev return beam hit the QPD.
   • Better alignment of the Y-arm cavity axis was done using the green beam. 
   • IMC was locked - the beam alignment target was used to ensure the IR beam was hitting ETMY at the correct height (by moving TT2), and then the ETMY angular alignment was improved to make the return beam go back roughly collinearly.
8. Y-arm POY locking
   • Satisfied with the alignment, we returned to the control room (light doors back on EY chamber) - cavity alignment was tweaked further to make the TRY resonances as high as possible.
   • I could lock the Y-arm length to the PSL frequency using POY as a sensor - TRY was ~0.04-0.05 (since IMCT is 1/10th its usual value, we expect it to be 0.1, so this is not bad).
9. OMC chamber work
   • Tied down the balance weights that were previously placed after the OMC and peripheral optics were removed.
   • Checked the table leveling.
   • Checked that the AS beam is reasonably well centerd on OM5 and OM6. Took some photos.
   • Checked that the IMC could be locked after this work - it could.

So all the primary vent objectives have been achieved 🙌 . The light doors are on the chamber right now. I'm measuring the free-swinging spectra of ETMY overnight. Barring any catastrophic failures and provided all required personnel are available, we will do the final pre-close-up checks, put the heavy doors back on, and pump down starting 10 am Monday, 9 Nov 2020. Some photos here.

Attachment #1 shows the main result - there are 4 peaks. The frequencies are a little different from what I have on file for ETMY and the Qs are a factor of 3-4 lower (except SIDE) than what they are in vacuum, which is not unreasonable I hypothesize. The fits suggest that the peak shape isn't really Lorentzian, the true shape seems to have narrower tails than a Lorentzian, but around the actual peak, the fit is pretty good. More detailed diagnostic plots (e.g. coil-to-coil TFs) are in the compressed Attachment #2. The condition number of the matrix to diagonalize the sensing matrix (i.e. what we multiply the "naive" OSEM 2 Euler basis matrix by) is ~40, which is large, but I wouldn't read too much into it at this point.

I see no red flags here - the PIT peak is a little less prominent than the others, but looking back through the elog, this kind of variation in peak heights doesn't seem unreasonable to me. If anyone wants to look at the data, the suspension was kicked every ~1100seconds from 1288673974, 15 times.

Basic IFO alignment checks were done.

1. IMC could be locked - I tweaked the cavity alignment a little to maximize the MC transmission.
2. Y arm can be made resonant for a TEM00 mode of the main beam. I can't run ASS successfully in this low power config. I can see that the axis isn't great, the spot is visually off-center on ITMY, but we should have plenty of actuator range to correct for this with TT1/TT2.
3. X arm shows IR mode flashes in the TRX QPD. The green beam can be made resonant for a TEM00 mode, but that alignment doesn't yield the largest IR resonant peaks in TRX. I suspect it is due to the mis-alignment of the beam axis.
4. AS beam was aligned onto the CCD. I could see clean Michelson fringes by tweaking the BS alignment. On the AP table, I noticed that the beam on the first steering mirror after the AS beam exits the vacuum is a little high. We can easily resolve this by tweaking OM6 pitch a bit, but even if we don't I don't see any major issues as there is plenty of clearance w.r.t. the viewport when the beam exits the vacuum.
5. With the PRM aligned, I can see the REFL beam on the CCD, and it doesn't look clipped.
6. I didn't bother to align the green beams to the arm cavities or re-center the Oplevs - is this necessary? It is a step in the pre-close up checklist, so maybe we should do it... The green transmission does reach the PSL table...

Tomorrow, we should do some visual checks of the chambers / EQ stops on ETMY etc but I don't see any major problems at the moment...