The reference cavity has been locked continusously, with no glitches for about 24 hours. It's not clear why, since yesterday no one even touched the FSS.
Anyways, we're happy about that and we hope it'll last.
Attached is a 24 hr trend of the cavity transmitted power. On the left end you can see the glitches that we were having before.
35W beam
Andres and I ran the first set of transfer functions on H1-PRM yesterday. The results are posted in the attached files. There is a problem with P, R, and V. We are checking the suspension for EQ stops rubbing, OSEM alignment, and Flag positioning and will rerun the transfer functions after taking corrective action. The first set of transfer functions were taken in the afternoon with no one in the Triples Lab (where the suspension is located) and only light assembly work (no forklifts, moving BSC plates, etc) underway on the ground floor. As a test, I repeated taking the transfer functions last night after everyone had left the staging building for the night. There was no difference between the TFs taken during the day and at night. Conclusion: As long as the Triples Lab is empty and there is limited activity in the rest of the staging building, we should be able to test suspensions during normal working hours.
This morning at 14:11utc (7:11am Pacific time) a couple of earthquakes reached us. This tripped both BSC8 & BSC6 ISI & HEPI. The initial quake was a 6.8 (13:43utc) & the aftershock was 5.2 (13:51utc). Attached is a trace of one of the SEI Watchdogs (i.e. BSC8 ISI Stage1).
During a cavity scan, a second modulation is applied to the laser frequency. The response of a Fabry-Perot cavity to laser frequency modulation contains information about the cavity parameters, including cavity length, free spectral range, modal spacing, and the radius of curvature of the cavity optics. The goal of cavity scans is to measure cavity characteristics and characterize their time evolution in response to heating of the optics.
While the 532 nm ALS laser is locked to the arm cavity, laser frequency modulations are injected into the Innolight Prometheus frequency-doubled laser through the laser frequency servo (Common Mode A) with an SR785 signal analyzer. These frequency modulations are transmitted into the 1064 nm beam used for PSL phase locking and the 532 nm beam used for arm cavity locking. The PSL phase locking beam does not interact with the arm cavity, and the signal from the RF photodiode is used as a proxy for the signal injected into the arm cavity. The arm cavity reflection photodiode gives the output signal, which the SR785 divides by the input signal to produce a transfer function.
Automation of SR785 measurements is necessary to perform and store transfer functions in quick succession over a period of hours. A Prologix GPIB-Ethernet controller is used for remote control and retrieval of data from the SR785. Scripts for performing transfer functions and retrieving data using the GPIB-Ethernet interface were created for use at the 40m interferometer, and were used for cavity scan transfer functions here. The Python script exttt{TFSR785.py} performs a single transfer function.
A bash script, exttt{autoTF}, was used to repeatedly call this Python script. This script was originally set to perform one scan from 30kHz to 80kHz, alternate smaller scans around the first-order modes (from 46-47 kHz and from 65.75-66.75 kHz) three times, then repeat until 12 hours elapses or the script is terminated. During the scan, it was found that the first-order peaks moved further than anticipated, so the script was altered to scan from 45-46 kHz and 66.75-67.75 kHz. In future scans, the smaller scans will be run from 45-47 kHz and 65.75-67.75 kHz for the duration. For all scans, the amplitude of the excitation was 10 mV, and 10 averages were used.
The ALS laser output power is 100 mW, and the SR785 excitation output current is 100 mA. Therefore, the modulation depth for these cavity scans is 0.1, or 1% of power in the modulation sidebands.
The attachment cavity_characterization.pdf contains a more thorough explanation of the motivation behind cavity scans, and some preliminary results. The attachment cavityshift.pdf plots a cold cavity scan and a cavity scan after 2.5 hours of heating on the same axes, showing the shift in modal spacing with ITM heating.
H1-HSTS-PRM is ready for Phase 1b testing. OSEMs have been centered and tested. Check the attached file for data on Open Light Values, Offsets, Gains, etc.
Attached are plots of dust counts > .5 microns in particles per cubic foot.
Kyle, Gerardo (initial) The two leaking 16.5" feedthrough assebmlies were removed from BSC1. A custom bracket was fabricated and utilized which allowed the assemblies to be removed with the crane (as a whole unit). NOTE: Ports are covered in UHV foil but BSC1 is not within a cleanroom and is reliant on properly adjusted purge air - please don't adjust the Vertex Volume's purge air.
Found h2susb78 locked up as of 21:02:43 PDT Aug. 28. Restarted, models ran about 3 minutes and communication between IOC and computer went away (one-stop card/cable issue). The IOC one-stop card was replaced with a new revision C2 card yesterday, so suspecting an early failure, the IOC one-stop card was replaced with another one. With this second new one-stop card, one of the main PCIe buses was not visible to the computer, and the duotone timing was off by 35uS. Gave up, and installed an old non-updated one-stop card back in the IOC. System came up normally, but will have to run without problems for about 3 days before confidence begins to be restored.
Restarted test stands after timing system work. Restarted IOP models, but no user models. Applies to tripleteststand, bscteststand2, and seiteststand2.
[Alex, Deepak, Cheryl, Giacomo] Yesterday we finished alignment of the remaining 2 HAUX. All 4 are aligned and hooked up. The optical lever setup is in place, but no pitch balancing has been done yet. Electronics is up and running, the model has been restored to a clean working state after reboot, and BURT saved: - all OSEMs offsets and gains set - Damping filter set to (what I think are) reasonable values (no much though on this as of now: they just work to damp the optic) and set to the off state - Hardware LP filter set to ON (but see later) - Coils TEST enable flag set to 1. - Master switches are off Note that although the hardware for binary IO is on, apparently there is no state change when we change the flags in the software. It is not clear if status is not changed, or if is changed but not reported. This will need to be investigated this morning.
Added missing (Binary) cables in rack SUS-C3, from IO chassis (FE IO Chassis 2 HAM-A Controls) to Binary Input and Output Chassis. This only solved part of the issue, since the Enable and Disable bits were not switching. Opened up HAM A Coil Drivers and removed jumpers for Disable / Enable. With the jumpers in place, the state would not change regardless of input. No jumpers should be installed in P3 and P4. All four HAM-A Coil Drivers had the jumpers removed. S1201163 S1201160 S1201158 S1201161
Attached are plots of dust counts > .5 microns in particles per cubic foot.
Throughout the day, the CDS group performed multiple updates (cf Dave & Vern ALOG for details). When the computers were handed back to the users, I encountered some difficulties to restore HEPI BSC6. First, I was surprised by the large offsets on the position sensors (>10K counts ~ 15mils). Then, I realized that the pump was turned off. But after turning the pump back on, the HEPI did not come back to its nominal position. Some tests are currently being performed to understand what’s wrong with the HEPI at the end station.
[Keita, Alberto]
Today we tried to look for a different temperature of the reference cavity laser in the attempt of making the FSS more stable. Unfortunately we had no success.
We locked the cavity with the laser set at 41, 44, 48, 52, 38, 35 degree C but the cavity kept glitching at each state.
As described in Work Permit #3425, we replaced the "One Stop" PCIe Fiber Link cards in the "aLIGO I/O Expansion Chassis" connected to the H1 and H2 front-end computers. This was to correct for a manufacturer's incompatibility with fiber optic cable sets. The following I/O Chassis had their cards exchanged:
Location computer Chassis s/n
EY h2susauxb6 S1103366
h2susb6 S1001132
h2tcsey S1102673
h2pemey S1001138
h2seib6 S1102608
LVEA h2tcsIO S1102672
h2susb478 S1001136
h2susb78 S1001137
h2susauxb478 S1103368
h2seib8 S1001135
H1Elect h1susaux34 S1104995
h1sush34 S1103886
h1h1susauxh2 S1103622
h1sush2a S1103890
h1sush2b S1103885
h1psl0 S1200685
About 50% of the H2 front ends were upgraded to RCG 2.5.1 last week, this week I cleanly rebuilt and restarted all H2 frontends against 2.5.1 in conjuction with the timing change.
All of H2's timing signals were moved from the old h2 timing master to the new h1 timing master. The old h2 timing master is being decommissioned.
errors in the burt restore of the safe.snap files were seen on h2peml0, h2tcsitmy and h2pemey (my problem, I'll fix these).
Problems with a large ADC input on h2hpietmy is being tracked to a HEPI pump issue at EY.
The 24MHz RF amplifier at EY is showing a timing problem on the fanout, and its fpga led is blinking red sometimes.
Fixed timing synchronization of the EY RF source by power cycling the unit.
All H1 front ends were rebuilt against RCG tag2.5.1 which provides an IPC Dolphin fix. Front ends were restarted in conjuction with the timing upgrade work. The following models obtained an ini file change in the upgrade
h1hpiham2, h1hpiham3, h1susmc2, h1suspr2, h1sussr2.
The H1 PSL had a complete code upgrade, making it identical to the L1 PSL code. Generic template models for ISS, FSS, PMC and DBB were applied. I also rearranged bus selector order to fix crossing connectors on the top level models. All PSL ini files showed a change. Some issue with creation and use of burt snapshot files was found and is being worked.
H2 DAQ was restarted to resync the ini file changes mentioned above.
We attempted to reproduce the slow epics problem by speeding up the backup of h1boot, but were unable to see the problem. When it appears again we have a suggested front end epics sequencer fix to try.
The H1 DMT broadcaster machine was installed by Alex. We are working some networking issues before testing this system.
some burt restore errors on the safe.snap files were seen on h1pslfss (mentioned above) and h1susim.
H2 Timing system was taken offline and moved to H1 timing system. Used main GPS antenna (used by H2) for H1 and placed a lighting suppressor before connecting to H1 master fanout chassis. When the move was done, had issues with the old H2 not locking. Richard was able to troubleshoot it by swapping the fiber ends (A and B) at the transceiver (chassis side).
Lots of reboots, and many other activities.
Other work:
Electronics were troubleshooted.
SEI and SUS models were arranged to allow un-tripping HAM2-ISI Payload Watchdogs.
HAM2 model was re-compiled, installed and re-started after that. It is now running.
Matrices were filled
Input and output filters are loaded
The latest version (Version_2) of the unit-specific control scripts were copied from LASTI. They were made ready for use on HAM2.
Spectra were taken on the ISI tilted. It is the worse configuration for GS13s and they all appear to be working fine (see attached plot).
Transfer function measurements are running overnight.
The transfer functions measured last night had features that are typical to mis-connected sensors/actuators. Deeper analysis allowed narrowing it down the the GS13s.
We made a program to check for "cross-coupling transfer functions" (e.g. drive on H1, response on H2). It revealed that:
H1-GS13 was read on the channel of H3-GS13
H2-GS13 was read on the channel of H1-GS13
H3-GS13 was read on the channel of H2-GS13
V1-GS13 was read on the channel of V3-GS13
V2-GS13 was read on the channel of V1-GS13
V3-GS13 was read on the channel of V2-GS13
We checked our model and did not find a cause for such behaviour there. We moved on the the electronics rack and spotted the issue: GS13 In-field cables were connected to the wrong inputs on HAM2 sensor interfaces.
We ran a quick TF measurement between 500mHz and 5Hz. It confirmed that the sensors were now all correctly connected. This quick measurement is also in good accordance with what we measured on HAM-ISIs in the past which is encourraging.
TF measurement are running overnight on HAM2. They will be over by 7am.
Note: A blinking notification was recently added to HAM-ISI overview MEDM screens (see attachement). It turns the green "measurement" button to blinking yellow when a TF is running. HAM2 overview screen can be seen on the Video6 monitor of the Control Room.
Hugh and I added screwdriver tips under the top payload mass of HAM2-ISI last week, before the chamber was closed. They helped prevent this big mass of ~600lbs from causing unwanted resonances. Befoire/After comparison plots are attached.
We compared the latest transfer functions with the ones taken on LLO HAM2-ISI during the same phase of testing (Intitial In-Chamber Testing). Plots are attached. Accordance is good. We are confident that the unwanted resonance seen at 96Hz comes from the top mass. We plan on ajusting its boundary conditions with the optical table once the doors of HAM2 chamber are open again.