After some digging for lost functions, I was able to run and collect data for the matlab long ISI transfer functions. Attached plots are the actuator to gs-13s most recent tf (first plot) and the previous 2014 in air HEPI locked tf. I don't see any evidence at this point that the baffles on HAM2 have affected the plant much. There are a couple little wobbles at 17 and 24 hz, but I think those are both from HEPI locked, as those feature are present in both tfs, and are huge in the CPS measurements (not pictured). The poor high frequency coherence is probably due to purge air, I'll probably want to do another tf during pump down.

I've updated the HAM-ISI model in the repo and it is ready for installation - this continues the BSC update from last week, which Dave installed last Tuesday.

recall- This change will update the HAM-ISI watchdog to make the ISI more robust during earthquakes. We have changed the model to increase the hold-the-damping-on-even-if-stuff-is-saturating time from 3 to 60 seconds.

The updated model and watchdog medm screen is in the userapps repo at SVN revision 16422

Installation instructions and more technical details are in technical note T1700481.

The approved ECR is E1700367

and the FRS is 9309
 

I've not pulled work permits.

-Brian

As mentioned here, the PMC transmission is currently lower than usual (and lower than during O2).  In preparation for the IO IMC bypass and CS alignment to take place later this week, I tweaked the beam alignment into the PMC to try to recover as much power as possible.  Unfortunately, I wasn't able to recover much power; with the ISS ON and diffracting ~3%, the PMC is transmitting 48.8 W, versus the 48.7 W it was transmitting before I started.  The likely reason for this is bad mode matching into the PMC due to the recent NPRO swap (which could change the mode content of the PSL enough to alter the required PMC mode matching scheme).  We are likely to stay in this configuration until the HPO is decommissioned and the 70W amplifier installed (currently scheduled for late January/early February 2018), unless there is an overwhelming need to improve the PMC transmitted power.

No obvious errors. Just had to select run.

Restarted. Screenshot attached.

1) Resonances of the ITMX elliptical baffle match peaks in DARM. Several peaks in DARM, (e.g 70 and 106 Hz), were thought to be due to the elliptical baffles, either or both ITMX and ITMY baffles. This is because, for different vibration injections, the amplitude of these peaks in DARM were best explained by the vibration level at ST0 of BSC2, and these baffles hang from this stage of the ISI ( https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=26016, https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=31886 ).  To make sure that this identification was correct, I measured the elliptical baffle resonances with an in-chamber accelerometer while tapping on them. Figure 1 shows that resonances of the ITMX elliptical baffle match the DARM peaks, but the ITMY baffle resonances do not. Betsy will check to see if the ITMX baffle down-tube is misaligned when the upgraded baffle is installed. 

2) Possible sources of scattering in BS chamber. Follow-up PEM injections showed that shaking the walls of BSC2 produced noise in DARM (https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=39121 ).

One long term concern in BSC2 is the TCS mirror 2 and its support structure that is attached to the BSC2 wall: https://alog.ligo-wa.caltech.edu/aLOG/uploads/9564_20140126161227_Figure2-ITMXcompensationPlate.pdf .

Scattering associated with the mirror could either be from the support region surrounding the mirror or from the nozzle and flange holding the TCS ports, visible in the mirror (see Figure 2 and https://alog.ligo-wa.caltech.edu/aLOG/uploads/9564_20140126161227_Figure2-ITMXcompensationPlate.pdf ). The region around the mirror could be baffled and the port could be baffled. I talked to Steven about the possibility of a port baffle that might also be useful at the P-Cal transmitter and receiver ports.

Another mitigation possibility is to damp the motion of the mirror. I tried a very simple method illustrated in Figure 3 that seems to have reduced the Q’s of some of the resonances by 2 or 3. I think we could do a lot better by wrapping the struts with more material.

A second possible source of the scattering noise are the BS chamber walls themselves, which are nearly normal to wide angle scattering from the beam spot as illustrated in Figure 3. 

A final possibility is the elliptical baffle: I wasn’t able to eliminate this possibility because in the 14-17.5 Hz band we haven’t made strong enough injections with HEPI to exclude ST0 (discussed here: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=39121).

3) Scattering at P-Cal ports. Nothing new to report beyond https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=39121, except that I discussed port baffle design with Stephen Appert.

4) HAM1-HAM2 septum not shielded from spot on beam splitter

Figure 4 shows that the HAM1-2 septum is visible from the BS through the structures on HAM2. The septum is a concern because of its high reflectivity and the fact that it is not seismically isolated like the reflectors on HAM2. The baffles are not yet all installed on HAM2, but I think the baffles will leave the upper regions of the HAM1-2 septum exposed to the BS. There is not an equivalent exposure of the HAM5-6 septum because the central part of the MC baffle in front of HAM5 remains in place, while the central part of the MC baffle in front of HAM2 has been removed.

5) “Temporary” floors should probably be removed for scattering reasons. The floors placed inside the chambers for working are sometimes left in place. Figure 5 shows that they may create scattering paths and should probably not be stored in place. I think Betsy was already planning to do this for charge imaging and other reasons.

Krishna,

The upgrade to capacitive actuation/damping is done for all practical purposes. The original plan was to install one capacitor plate under each arm of BRS-X. However, after opening up the vacuum can, we found the space insufficient to install two. Rather than take the thermal shields apart and machine them, we decided to install just one. Just one has proved sufficient for BRS-Y, so I think this was a reasonable call. The installation went well. The Beckhoff code/parts proved easy to install and worked perfectly, after some hiccups with incorrect directory paths,etc, which Patrick helped me out with. The damping works perfectly well. I will tune the Q value over the next few days.

I also reduced the 'd value', which is the distance offset between the center of mass of the beam and the pivot/suspension axis. Measurements I made on Monday had suggested that d was ~ 26+/- 2 micrometers (first attachment). The measurement was made by using a piezo stack actuator under the BRS-X platform and driving it with sinusoidal drives at different frequencies. The absolute value of the the relative tilt-transfer function is then calculated from the responses at these frequencies.

I added ~1.5 grams to the top part of the beam-balance. The resulting frequency was ~5.6 mHz. Measuring the transfer function turned out to be impossible to do in air due to thermal drifts. So I had to close up and pump down and restore thermal insulation. Luckily, my first attempt for mass adjustment turned out to be reasonably good. Latest measurements indicate d = -1 +/- 1 micron. For BRS-Y we got d = 0 +/- 1 micron, but I think this is good enough.

BRS-X was pumped down with a Turbo pump to ~2e-7 torr. I switched on the ion pump this morning and I have valved off the Turbo. The ion pump current is at ~0.5 mA and going down steadily.

Over the next few days, I will monitor the DC position of BRS-X and adjust the tilt-subtraction filter banks based on the new response functions.

Krishna

As described before, we are testing to see if the seismometer mounted on BRS-Y platform sees better coherence with it as compared to the ground seismometer. Latest measurements suggest this may finally be happening. The first attachment shows the coherence between BRS-Y and the ground seismometer (red) followed by that between BRS-Y and the platform seismometer (blue). For the first time, blue is slightly better than red in a few places. The next page shows the spectra. Note the increased motion at 10-70 Hz, as mentioned previously.

The next attachment shows the coherence/spectra that was commonly seen before we bolted the seismometer feet to the table/platform. Once again, note the spectra at higher frequencies. It looks like we may have reduced higher frequency motion by bolting the feet to the platform.

The improved coherence after we bolted the seismometer to the platform supports two possible explanations: a) high frequency motion was causing the seismometer to move/slip on the table, which would cause low-frequency noise or 2) high frequency motion was down-converting through other mechanisms in the seismometer (flexure non-linearities).

In any case, we can try to improve/restore the thermal shielding and see if we can get even better coherence in order to do better tilt-subtraction.

Edit: The pink line is the current tilt-subtracted ground super-sensor, which is the ground seismometer minus tilt measured by BRS-Y.

The new temporary earthquake stops installed as a trial run worked great, they will be replaced with the real batch when it comes out of clean and bake on Monday.  Also, it appears that during the move/install the OFI alignment/balance went out a bit, so we are going to need to work on it in situ.

J. Kissel

Since HAM4's construction / installation stuff for this vent is complete as of yesterday's HWS Scraper Baffle install (LHO aLOG 39266), and the debugging of SR2's M2 OSEM today (LHO aLOG 39277), I took the afternoon to start B&K hammering all of the new / old baffle equipment and HWS mirror / lens mounts. Note, I deliberately skipped the SR2 cage, since nothing has changed on it since it was originally measured in LHO aLOG 12089, and I trust that Betsy and Travis successfully re-dogged and torqued bolts when they finished the relocation a few days ago LHO aLOG 39240.

Will post pictures and results next week.

Dan, Dave:

The recovery of the raw minute trends onto the new compressed ZFS file system completed at 16:30 as predicted. This data path was added to daqdrc for both h1nds0 and h1nds1 (default nds) which were both restarted. I tested that I could trend the outside temperature back to 26 May 2017.

Dan has setup the copy of the lion's share of the minute trend data over the weekend, should be completed by Monday.

Attached plot shows 30 day look back before the recovery (oldest data 18th Oct) and after the recovery.

49 channels added. 14 channels removed. List attached.

We hymned and hawed and decided that we prefer to have two metal sealed valves in series as a redundancy so I vented CP1's 55 L/s ion pump and swapped a second 1.5" valve in place of the 1.5" elbow that connects the ion pump assembly to the 1.5" pump port valve which is part of CP1.  I then pumped the ion pump to down and leak tested the new joints.  

This completes WP #7205

Fil, Patrick, Dave:

Following a BRS related power glitch at EX at 14:52 PDT this afternoon, the h1iscex computer lost connection with its IO Chassis. The front end recovery process was: stop models, take out of Dolphin fabric, power down computer, power cycle IO Chassis, power up computer. The system recovered with no problems.

In addition to the h1iscex IO Chassis, the following are also powered by the 24V power strip in the ISC rack; the two RF-Oscillators and the three Slow-Controls Chassis (End Station 2, End Station3, ISC Common). The attached dataviewer plot  shows the IOP model going down at 14:52 PDT (and latching off until I rebooted) and a beckhoff temperature signal momentarily glitching and recovering.

Fil is investigating the power glitch.

TITLE: 11/03 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
LOG:

15:44 - 18:14 UTC TJ to HAM3
15:51 UTC Snovalley through gate
15:51 - 17:03 UTC Jason to LVEA cleanroom with part, then adjusting PSL environmental controls
15:51 UTC Krishna to end X to work on BRS
15:53 - 15:59 UTC Travis to LVEA West bay to look for cables for SR2 OSEM
16:25 - 17:13 UTC Hugh to end Y to center BRS colocated T240 masses
16:26 - 17:30 UTC Travis to HAM4 to swap cables for SR2 OSEM
16:39 - 17:30 UTC Jeff K. to HAM4 with CDS laptop to help Travis
17:23 UTC Tour in CR
18:04 - 18:12 UTC Jason to optics lab
19:18 - 20:51 UTC Gerardo to HAM5 to unlock the OFI and install EQ stops
19:41 - 22:02 UTC Terry M. to squeezer bay
Dave reports chiller alarm at end Y, Bubba notified
20:57 - 23:03 UTC TJ and Jim to HAM2 to build and install baffle
21:30 - 22:48 UTC Rakesh walking around LVEA
21:54 UTC HEPI L0 pump controller crashed, Hugh and Filiberto investigating
22:07 UTC Jeff K. to HAM4 to B&K hammer
22:16 UTC h1iscex IO chassis power glitched. Something Krishna might have done at end X. Dave went to end X and restarted the frontend.

The following summarises the characteristics of the output Faraday isolator.  The
power meter used was an out of calibration date, Ophir 1Z02411 power meter, S/N 73375
with filter 19603 S/N 132872.  Microwatt level measurements were done with the filter
removed.

    An incident laser power of 10 mW was used to avoid the possible saturation of the
photodiodes used.


  

    
 Item 
    
 photodiode 
    
 power meter 
  
  

    
 transmission 
    
 98.1% +/- 0.6% 
    
 94.8% +/- 0.1% 
  
  

    
 back-scatter isolation 
    
 657 ppm 
    
 610 ppm +/- 5 ppm 
  
  

    
 TFP AR reflection 
    
 N/A 
    
 N/A 
  
  

    
 isolation 
    
 61.1 dB - 58.9 dB 
    
 69.7 dB - 70 dB 34.9 dB - 35.0 
  
  

    
 backscattering 
    
 24.4 ppm +/- 0.5 ppm 
    
 N/A 
  
  

    
 squeezer path transmission 
    
 99.8% - 98.4% 
    
 93.3% - 93.5% 
  


Some notes about the measurements. The backscattering could not be measured with the power meter.
The beam reflected from the AR surface of the thin film polariser could not be separated from the
prompt reflection in the clean space available, and was only visible with a CCD-based IR viewer.


  

    
 motion 
    
 frequency 
    
 Q 
  
  

    
 vertical 
    
 1.49 Hz - 1.50 Hz 
    
 22 -/+ 1 
  
  

    
 longitudinal 
    
 0.62 Hz 
    
 22 
  
  

    
 pitch 
    
 1.05 Hz 
    
 17 
  
  

    
 yaw 
    
 1.05 Hz 
    
 20 
  
  

    
 side to side 
    
 0.63 Hz 
    
 15 
  



  Gerardo / Peter