WP 6069 The copying of raw minuted trend files from h1tw1 is complete and the copied files have been verified. The nds1 service on h1nds1 has been restarted with a new configuration to read the copied files from their new location.
[Stefan, Koji]
Quick Summary
Shutter timing test has been performed for the OMC PZT shutter and the fast mechanical shutter. Everything seems reasonable.
- The trigger logic fires at the PD input of +2V.
- The trigger logic reacts at 1.5us since the PD input thresholding.
- The PZT shutter detunes the OMC cavity at 4.8us.
- The fast mechanical shutter start blocking the beam at 1.7ms, reaches half blocking at 1.85ms, complete block at 2.0ms.
More about the test comes later.
HEPI BS Tripped few minutes before ITMX ISI. This is the only HEPI that tripped in the neighborhood of the large quake.
ITMY ISI tripped--timing (H1:ISI-ITMY_ST2_WD_MON_GPS_TIME) indicates stage2 tripped on ACTuators 1 second before Stage1 on T240s but looking at the plots, the Actuators have only registered a few counts, nothing near saturation/trip level. But the T240s hit their rail almost instantly. It seems the Stage2 Last Trip (H1:ISI-ITMY_ST2_WD_MON_FIRSTTRIG_LATCH) should be indicating ST1WD rather than Actuator. On ETMY, the Trip Time is the same for the two stages and Stage2 notes it is an actuator trip but again, there are only a few counts on the MASTER DRIVE; seems this too should have been a ST1WD trip[ indication trip on Stage2--I'll look into the logic.
On the BS ISI, the Stage1 and Stage2 trip times are the same, and the Last Trip for Stage2 indicates ST1WD. The Stage2 sensors are very rung up after the trip time but not before unlike the T240s which are ramping to to the rail a few seconds before trip. ETMX shows this same logical pattern in the trip sequence indicators.
On the ITMX ISI, Stage1 Tripped 20 minutes before the last Stage2 trip. This indicates the Stage1 did not trip at the last Stage2 trip.
No HAM ISI Tripped on this EQ.
Bottom line: the logical output of the WDs are not consistent from this common model code--needs investigating. Maybe I should open an FRS...
Attachment 1) Trip plots showing Stage2 trip time 1 second before the stage1 trip where the stage2 actuators do not go anywhere near saturation levels.
Attachment 2) Dataviewer plot showing the EQ on the CS ground STS and the platform trip times indicated.
It seems this is not a problem with the watchdog but a problem with the plotting script. It seems for ST2 Actuators, it misses a multiplier on the Y axis. It works correctly for ST1 Actuators and all the sensors; it does not work for other chambers as well for ST2 ACT. FRS 6072.
Actually, the plotting script is working fine. When the spike is so large that the plotting decides to switch to exponential notation, the exponent is hidden by the title until you blow up the plot to very large size. In an effort to eliminate the need to connect and disconnect shutter cables during vent we have moved the shutter logic controler to the rack from the table. Also replaced the BNC cables with Yellow BNC cables so they can be easily identified. See attachment.
Krishna,
Jenna and I had noticed that L4C 7 didn't appear to be working. L4C is close to the c-BRS, so it would have been good for comparison. In order to test if it was the instrument or the electronics, I temporarily swapped the cables with those of L4C 8 going in to the SUS rack at the LVEA. Now L4C "7" appears to be working and L4C "8" is not, indicating that the problem must be on the instrument side (or the pre-amp, I guess?). I'll swap it back in the afternoon.
Cables replaced in original configuration.
After looking at a different working L4C output (5), I think I was wrong about the instrument being faulty. It looks like the L4C was working when I swapped the cables, suggesting that the problem must be on the electronics side.
Posted below is a 45 day trend of the TCS laser power compared to operating temperature. There is a drop in power and temperature on 07/19/16 (aLOG #28506). During the HAM6 vent the RF driver was replaced (aLOG 28837) but was never tested due to lack of a beam. After the vent TCS-Y came back at ~16W with a temp of 22.
Dear Colleagues,
As of now, LLO is closed until further notice due to widespread flooding in the area that prevents access, including emergency access. I expect we will be able to reopen on Monday.
Any personnel or visitors on site now should immediately leave, taking US-190. Explicit permission from either myself or Richard Oram is now required to be on site.
More details will follow, but I did not want this message delayed. As always, liaisons should be in touch with your visitors to convey this message.
Joe
Joseph A. Giaime, Observatory Head, LIGO Livingston (Caltech); Professor of Physics & Astronomy (LSU).
phone at LIGO: +1 225 686-3169.
SEI: All back to normal after vent SUS: All Ok CDS: Looking into several read-back issues. Will need to do a restart of NDS1 this morning. PSL: OK. Looking into the low power from the TCS-Y laser. VAC: No report FMC: No report Relocking and commissioning work today.
I have taken camera images of the OMC R and ASAIR beam. This was primarily to compare the beam quality before and after the OMC swap. However, I did not find any obvious or significant change in the beam shapes. See the attached and compare them to the ones in 28718. Also the data is attached as well.
Stefan and Sheila working on shutter control logic. I helped resolve problems with h1ecatc1. Had to restart EPICS IOC and copy updated PLC2 to target. 23:32 UTC Gerardo to HAM6 area to check on vacuum equipment 23:39 UTC Gerardo back 03:05 UTC Joe to Y2-5 to watch meteor shower with telescope 04:30 UTC Stefan and Sheila done working on shutter control logic. Kiwamu starting work. 06:17 UTC Kiwamu to end X to investigate green laser electronics 07:00 UTC Kiwamu back I was able to get the Y arm green power to around 1 with LOCKED_NO_SLOW_NO_WFS, but if I put it on INITIAL_ALIGNMENT it would start to be driven away. Kiwamu was investigating the X arm.
Patrick, Kiwamu,
We are unable to engage the QPD servo for the X green injection beam. It seems to be an issue with the PZTs. We are leaving this issue until tomorrow.
Also, the readback of the POPX whitening settings don't match to the requested. This also needs to be fixed.
For the QPD loop issue -- after a through investigation today, it tuend out that it was not the PZTs but it was the QPD signals that were not functioninng. I drove to EX again today and found that the whitening chassis for this particular signal was physically switched off. So I switched it on by latching the switch to the on position on the back side of the chasis. The QPD servo now runs. Also, during the investigation I confirmed that the pzt mirros were functioning by sending some sinusoidal excitation and looking at the beam spots on the table.
After CO2Y was powered on today, we noticed that the laser power was as low as 16 W which should be nominally 60-ish W. See the attached. This is the one with the RF driver recently swapped (28837). Needs more investigation.
Jason is aware of this and plans to look at it Friday.
... why we did all this testing single bounce, and didn't try to lock anything:
There was a 7.2 quake, includiong some stron aftershocks, gently rocking the planet for the last 3h...
We triggered the fst shutter a couple of times by lowering the threshold (i.e. ensuring that the alanog electronics fires the shutter), and wee verified that we didn't see any bounce after 60ms to 100ms (as loged before in alog 28958 ).
Attached are plots for one trigger, on different time scales.
Here's a 2nd fast shutter test. Again, no bounce.
And another one.
And another one.
ANd a last one.
[Corey, Betsy, Fil, Peter, Calum, Stefan, Koji]
Summary
- The ISC portion of the HAM6 vent work has been completed.
- Shield isolation of the in-vacuum cables was confirmed.
- The fast shutter was reinstalled on the table after some modifications.
=> Ready for the SEI mass balancing and other exiting procedures. OMC PZT HV is still on. Remeber to turn it off before pumping down.
Some details
- Shield isolation: It is always confusing to check the shiels isolation on HAM6 because of several reasons.
We initially had several cables shorting to the chamber but all of them but one happened at the slack of the cables right inside of the flange. The last one happened on the DB25 cable before it climb up to the vertical wall of the ISI.
- The fast shutter modification / reinstallation
(Photos are supposed to come later.)
Photos From Yesterday's Fast Shutter Work
Photos are on Resourcespace here:
https://ligoimages.mit.edu/?c=1705
Cable Grounding Check
(Corey, Fil, Koji)
Documents of interest:
We went through as many of the ISC/SUS cables as we could, which is mainly all the DB25 connectors (most were on a single flange, D6). The non D6 cables [i.e. SUS OMC & WFS Heads] were checked at the CDS rack (east of HAM6) & the SUS rack (south west of HAM6). We did not check the RF WFS cables at D5 (not sure how to make check on these connectors, and Koji was worried about disconnecting the connectors since it could make things worse. We also did not check SEI since those cables were not touched and are nicely clamped & out of the way.
Some notes:
OMC Cables (D6: F1, F2, & F3): These cables all go to a harness on the OMC breadboard. Their sheilds are all tied to each other. Since we checked these cables at the flange, You must disconnect all three cables at the same time. Then you can do the ground loop check (otherwise, if you do one at a time, you will trick yourself into seeing ground loops, but this is because their sheilds are all connected).
For the Picomotor cables, I thought Koji said we should disconnect the cable from the picomotor and then check for grounding, but I can't remember if that is really necessary.
Bird's Nest!: We found some shorts. When one finds a short, the job is to go in chamber and then "wiggle" the cable in question until you no longer see the short. I believe we were able to do this in-chamber right next to the D6 flange. This is where there is a "bird's nest" of ISC cables (unfortunate...I reckon we could clean this up by carefully clamping ISC cables down to HAM6's Stage0.).
At any rate, whenver one fixes a cable with a ground loop, one must then re-check all cables! This is because all these cables are in this "bird's nest". And if you remedied one by moving it around, you don't know whether you made things worse for a neighboring cable in the "nest".
At the end of the day, we were happy with our ground loop checks for these cables.
OH, a To Do Item:
At the D6 Flange, it was easier for Fil to plug/unplug cables when he removed some protective bars were removed from the flange protector. At the nearest convenience, those bars should get re-installed.
Re the To Do Item--removal of the 'protective bars' aka strain relief, to make it easier to unplug cables. These should be replaced and returned to relieving strain by the remover. There is plenty of instances where this has not been done and I expect is the SOP, sadly. The job is always so much easier if you don't have to return to it later, after you've remembered it.
> For the Picomotor cables, I thought Koji said we should disconnect the cable from the picomotor and then check for grounding,
> but I can't remember if that is really necessary.
No. It turned out that the picomotors have no shields at the mighty mouse connectors and have no shorting the the table.
HAM6 CC wafer placement - it is now back in the same place as the last one was pulled from.
Shutter Test Setup (Attachment1)
- The PD signal from AS_C QPD was temporarily disconnected from the left PD port. Instead, a function generator (SRS DS345) was connected. The static offset of the func gen was used to mimic the PD signal.
- The output of the shutter logic unit (D1102312) was branched by a BNC-T.
- A thorlabs PD (PDA55, Si DCPD, BW ~10MHz) was placed on the ISCT6 to monitor the power at OMCT and OMCR for testing the PZT shutter and the fast mechanical shutter, respectively.
- The monitor signals were connected to an oscilloscope (TDS3034B). The yellow, blue, and magenta traces corresponds to the FG offset, trigger signal, and the optical power at OMCT/R.
Shutter Test Results
- The offset voltage of DS345 was manually swept from 0V to a positive voltage until the trigger fired. We confirmed that the trigger fired at 2V.
- The offset voltage was changed from 0V to 5V on DS345. This made the actual output voltage changed from 0V to ~9V. The output voltage was not so clean because the relay seemed to be switched upon the change. However this essentially does not affect the test.
- The oscilloscope traces showed that the trigger logic reacted 1.5us after the PD input crossed the threshold. (Attachment 2)
- The OMCT optical power started to drop 4.8us after the thresholding (Attachment 3) and reach 1/10 of the power after ~60us (Attachment 4). The trace for the OMCT power showed a decay curve. The half life was 10~20us depending on which part of the curve is taken. This corresponds to the cutoff freq of 5.5kHz ~ 11kHz, which is way to low and unlikely to be the cavity pole of the OMC (330kHz). It is more likely to be determined by the actual motion speed of the PZT.
- The OMCR light was used for the test of the fast mechanical shutter. During this test we didn't try to lock the OMC cavity to make the observation of the light drop easier to interpret. The shutter started blocking the beam at 1.7ms, reached half blocking at 1.85ms, completed blocking at 2.0ms. (Attachment 5). The observation in a longer time scale (~0.5s) showed that there was no boucing effect of the mechanical shutter any more. (Attachment 6)