[Thomas, Aidan]

Thomas and I tracked the source of clipping on the Hartmann sensor beam. The return beam from the ETM was hitting the edge of one of the mirrors in the back corner of the ALS table (see attached diagram). We tweaked the alignment so that the beam was centered on that optic.

The new beam profile on the HWS is attached. There is no sign of clipping now, but the beam quality is a poor Gaussian. There also appears to be horizontal fringes on the beam.

Max F., Keita K., Daniel S.

We had a hard time finding the beat node by adjusting the crystal temperature. Once we came close to the correct frequency the line would simply vanish. This seems to be related to mode hopping. The diode current was about 1.43A. We noticed that increasing the diode current by simultaneously adjusting the temperature to keep the beat frequency close to 40MHz allowed us to widen the acceptable temperature range and improved the beat node strength. Around 1.9A there was another mode hope, so we backed off the diode current to 1.666A. This re-adjustment of the diode current seemed to have increased the gain in the PLL. We had to reduce the common gain to -23dB (down by 3dB) to make it stable again.

We also found that the gain in the digital temperature stabilization servo only has a small range where it would work. Adding 10dB would make it unstable, whereas subtracting 10dB made it go to the rails. Even with the correct gain, we noticed that the PZT voltage would often go beyond +/-1V. Our readback has a gain of 10 and saturates just above 1V. (This readback is used as the error point of the temperature stabilization servo.) The following changes were made to the ASL common mode board, S/N S1102638 (H2 EY): 
R272 removed (from 374), 
R271 replaced by 0 Ohm (from 3.32K). 
The readback now has a gain of 1 and the temperature servo should work over the full PZT range.

The H2 SUS ETMY Simulink model was modified to incorporate the Optical Lever photodiode signals on the second ADC card of 'h2susb6'.  The EPICS library part was removed from 'h2susetmy.mdl' which imported the signals from the temporary H2 ETMY optical lever Simulink model.  The signals are read from the second ADC, ADC_1, on the H2 SUS ETMY front-end,'h2susb6'. After a few recompiles, the model was installed, along with the 'h2sustmsy' model.

(corey, eric, hugo, jim)  [this is an entry for work on Tuesday]

#6

Installing more walls, several iterations of balancing system, measuring Lock/Unlock values.

And yet more serial number info for cables

Corner1

• Actuator H:  S1106673
• Actuator V:  S1104096
• GS13:  S1106665
• L4C:  S1106653

Corner2

• Actuator H:  S1104097
• Actuator V:  S1106676
• GS13:  S1106670
• L4C:  S1104709

Corner3

• Actuator H:  S1104099
• Actuator V:  S1104101
• GS13:  S1104701
• L4C:  S1104602

#7

Started staging for Pitchfork/Boxwork assembly.

Helicoiled Outer Walls

(corey, greg, hugo, jim, mitch)

#6

Performed ISI tilt measurements.  While doing this it was discovered that H1 (s/n094) was not acceptable.  It was removed and was replaced with the one spare horizontal GS13 on hand (s/n 018).  Then continued with performance measurements on the ISI with new H1 GS13.

#7

Ribs were prepped for Stage1 Assembly.  These Ribs were individually installed on the Stage1 Floor (vs. pre-assembling the Pitchfork/Boxworks and installing them on Stage1).  Keel Walls were installed, and other parts were also set up on Stage1.  Should have Stage1 on Stage0 tomorrow.

Attached are plots of dust counts > .5 microns.

Burped GV5 gate annulus into aux. pump cart and switched from Turbo to Ion pump pumping on the YBM -> Didn't valve YBM into CP1 yet as viewport work is still taking place on the YBM (op levs, camera).  

The support table was removed from HAM5 first thing this morning then the condition of the chamber was documented. The support tubes were wrapped and brushing was started. The crew got about a quarter of the chamber brushed before the end of the day.

[Stuart A, Travis S]

A request was made from Matt H and Jeff K to provide the distribution of addable mass used on the LHO PR3 (HLTS) suspension. Unfortunately, in this instance the paper-trail (and ICS trail) quickly ran cold. The distributions had been captured for subsequent suspensions, just not unfortunately for the first assembled PR3.

It was therefore necessary to conduct a visual inspection, and with the assistance of Travis, we were able to determine the following:-

M1 addable mass:-
M1 (upper) = 100+100+20+10 = 230g (+ nut)
M1 (lower) = 100+100+20+10 = 230g (+ nut)

M1 sliding masses:-
M1 roll adjustment, protruding ~11-12mm towards LF side
M1 pitch adjustment, ~centred

M2 addable masses:-
LF (front) = 100+20 = 120g, RT (front) = 20g (refer to pictures for fixing screws & nut arrangements)
LF (back) = 0g, RT (back) = 100+20 = 120g (refer to pictures for fixing screws & nut arrangements)

M2 sliding masses:-
M2 pitch adjustment, protruding ~2mm towards back

Many pictures have been taken during this inspection of PR3, a choice selection of which can be found attached below.

Image 836, PR3 storage barrel re-located to a chamber-side clean-room.
Image 866, Storage barrel lifted and removed, revealing PR3.
Image 851, M1 and M2 masses taken from front of suspension.
Image 857, Close-up of M2 taken from front of suspension.
Image 862, Close-up of M2 taken from back of suspension.

N.b. naming convention used is consistent with M1 stage BOSEMs, which are fitted to back of the suspension.

Activities throughout the day:

SURF students to End-Y

Recompilation of the 'h2susetmy' user model.  Subsequent reboots of 'h2sustmsy' and power-cycle of 'h2susb6' front-end. (Dave B. & Jeff G.)

Richard out the End-Y for cabling of end station camera.

PEM model reboots by Dave B.

35W beam

After Jeff G made his changes to the h2susetmy model to ingest the Optical Lever quad photodiode signals from the second ADC, we experienced strange "DAC channels already in use" errors between h2susetmy and h2sustmsy. We checked the models carefully, no conflict was apparent. I have recompiled (but not installed) all H2 models this morning against RTS Tag2.5, so I suspect I was the cause of the problem. I rebuilt all models on h2susb6 against the Tag2.5 and the suspensions for ETMY and TMSY are now working.

200W beam

After a serious round of fit checking on Monday (going through the motions on the wrong optic), Danny yesterday in my absence glued the first primary prism onto MC2.  It cured at room temperature overnight.  The fixture was removed this morning and the prism is now under a heat lamp cure until ~3pm this afternoon.

The setup for the fixture which requires the ability to use a horizonally mounted height guage is still flat out dumb.  After ~7 mods to parts, I've recreated Danny's setup at LLO (kudos for getting the poor design to work at there!), but we still find that the multlitude of bolted together stages do not hold the long lever arm of the height guage steady enough.  As well, we are still hand pushing the jig fixture around to acheive the 0.1mm tolerance on the placement of the prism (no micrometers!!).  I do not see how we can continue to use the exsisting fixtures for 13 more optics (H1 and I1), without sacrificing serious efficiency (and my mental health).  So, I'm going to try the iLIGO gluing fixture on a spare optic, in parallel with fussing through the cobbled together setup we have now for the 2nd MC2 prism.

Part of the Assembly Validation testing of HAM-ISIs (that happens in the staging building) consists in taking power spectra with the ISI tilted. It allows us to check that the sensors, especially the seismometers, work in tilted position as well. To do so, spectra are taken with a 10kg mass set at each of the 6 corners of the optical table (Locations A to F in ISI_Tilted) 

This test revealed that GS13-H1 (Pod #94) was not functioning correctly. Symptoms are the same as observed on previous failing GS13s. The response of the instrument drops dramatically below 60Hz (ISI_Not_Tilted) which is characteristic of a stuck seismic mass.

This instrument was tested OK at reception from LLO. It is very likely that the tilting of the ISI induced the sticking of the seismic mass.

We have one last spare horizontal GS13 (Pod #18). It will be installed as replacement today. Testing of this unit will start over with sensor spectra, as soon as it is installed. 

Mode Cleaner Tube baffles in MC1 installation alignment was verified as accurate for both MCA and MCB ends.

MCA1 - Fasteners were loosen to reposition center plates. The missing center clip and all fasteners (x2) were installed and tightened. Installation is complete as designed.

MCB1 - Fasteners were loosen to reposition center plates. The missing brackets (x4) and all fasteners were installed and tightened. Installation is complete as designed. NOTE: one broken fastener in lower middle center plate and one galled screw was left unmoved in upper right.

Work was performed by Apollo crew (Mark Dodson and Caleb), Tim Nguyen and Lisa Austin.

We left the HWS running overnight. Despite not properly imaging the ETM yet, we took spectra of the prism/tilt measured by the HWS and compared it to the OSEM signals for the penultimate mass of the ETM. There is a strong correlation between the two spectra just below 1Hz, verifying that the HWS is actually recording a real signal.

LHO CDS:

I've added more medm snapshots to the LHO CDS web page:

https://lhocds.ligo-wa.caltech.edu/screens/

Due to a 27 screen limit per virtual frame buffer, I am now running three frame buffers on script0 which correspond to the H0, H1 and H2 systems.

HAM6 was placed into a shipping container around January 27th, Corey's alog, and purged with a Nitrogen boil-off from a dewar. To the best of my knowledge it has not been purged since that time. To determine what the humidity levels inside the container were like, a super elaborate no expenses spared contraption was developed to capture the exhaust from the container during the purge (photos attached). Data logging using a testo 645 dew point probe was started as soon as the purge began and ran for about 19 hours (graph attached).

Direct LN2 boil-off read at -48.5 td°C, 9.2 °C; while ambient LVEA readings were at 4.4 td°C, 20.1 °C. Purge rate is ~10 L/m with ~5,442 L of empty volume inside the container.