Displaying reports 64121-64140 of 83294.Go to page Start 3203 3204 3205 3206 3207 3208 3209 3210 3211 End
Reports until 11:38, Thursday 16 July 2015
H1 SEI (SEI)
robert.schofield@LIGO.ORG - posted 11:38, Thursday 16 July 2015 - last comment - 10:02, Friday 17 July 2015(19682)
Wind tilt is very local and is lowest in the beer garden

Summary: the effect of wind in the sub 0.1 Hz tilt band is very local (little coherence between seismometers 20m apart) and more than a factor of two greater in the HAM 2 and 5 seismometer locations then in the beer garden. We may be less sensitive to wind if the sensor correction seismometer(s) are located only in the beer garden. Also, because tilt is so local, real tilt meters, like Krishna’s at EX, should be as close as possible to the chambers.

Wind tilts our buildings, which produces spurious control signals from servo seismometers and can make it difficult to lock or maintain lock.  A previous log showed that there was almost no wind tilt at a location 40 m from the EY building, making it clear that wind tilt is a local effect (Link).  As a result, Hugh and I have been wondering if the HAM 5 seismometer location is better because it is down-wind for most storms or if the beer garden is better because it is furthest from walls. With Hugh’s help, I looked at chance coincidences between wind storms and seismometer huddles over the last few months as well as data with seismometers in the 3 locations. I think the answer is that the beer garden shows substantially less tilt than either the HAM 5 or 2 locations.

Figure 1 shows how local tilt is. The blue seismometer traces are for “huddled” seismometers (about 2m apart) in the beer garden and show high coherence below 0.1 Hz. But the red seismometer trace shows much lower coherence in this tilt band between the beer garden seismometer and the HAM5 seismometer, only about 20 m away. During high wind, I also found low coherence in the tilt band between the beer garden and the HAM2 seismometer locations.  The local nature of the tilt has implications for true tilt meters used to correct the tilt signal from seismometers. The tilt meter at EX is about 4 m from the chamber and, in Figure 1 we saw very little coherence at 20m. While it may not be enough of a return to move this one, it may be best to try and place the next one even closer, and, to the degree possible, engineer the BRS so that it can be as close as possible or even under the chamber.

Figure 2a and b show that tilt is very different at different locations in the LVEA and, of the 3 locations, the beer garden is the best. In both horizontal axes, the tilt in the beer garden is at least a factor of two better than the best of the HAM2 and HAM5 locations. It is about a factor of ten better than the worst of the HAM2 or 5 locations. I checked the 3 windstorms during the period when all 3 seismometers were working and, for each time that I examined, the beer garden seismometer was better. Figure 3 shows the two seismometers that were available during the windy period that caused locking problems last night: the tilt noise was half as much in the unused beer garden seismometer than in the HAM5 seismometer that was used for sensor correction. So, a sensor correction seismometer in the beer garden may be better than in the HAM2 or 5 locations in the frequency band dominated by tilt instead of real acceleration (roughly below 0.5 Hz). This morning Jim switched sensor correction to the beer garden seismometer.

Finally, when we have two STSs available, I think we should do a more detailed study of tilt-band coherence length, and attenuation with distance from the walls.

 

Robert, Hugh

Non-image files attached to this report
Comments related to this report
brian.lantz@LIGO.ORG - 12:09, Thursday 16 July 2015 (19684)
Just to check - 
Are you sure that there was no activity in the LVEA during these data times? That will also cause local distortions of the floor and might confuse the results.
robert.schofield@LIGO.ORG - 10:02, Friday 17 July 2015 (19703)

Actually, people on the floor make very different spectral signatures than wind and would be easy to identify in any of the spectra. But, nevertheless, I did check for any anomolous spikes in the 30 to 100 mHz band of the PEM seismometers, or, for more recent data, the  new equivalent bands of the ISI seismometers. 

H1 PSL (DetChar, PSL)
edmond.merilh@LIGO.ORG - posted 11:36, Thursday 16 July 2015 (19683)
PSL DBB scans + ISS Scan
Non-image files attached to this report
H1 SEI
sheila.dwyer@LIGO.ORG - posted 11:07, Thursday 16 July 2015 (19681)
lockloss caused by an earthquake

For anyone who is interested in classifying locklosses, or in earthquakes, here is an example of a full low noise lock broken by an earthquake.  

Images attached to this report
H1 SEI
jim.warner@LIGO.ORG - posted 10:04, Thursday 16 July 2015 (19680)
Sensor correction in the corner station switched to STS-B

Hugh and Robert asked that all sensor correction for the corner station be switched to the ITMY STS. I've done this (because interferometry is being impeded by an earthquake) and accepted the changes in the SDF. I'm assuming Robert and Hugh have an imminent alog describing the need for the change.

H1 ISC (ISC)
stefan.ballmer@LIGO.ORG - posted 01:33, Thursday 16 July 2015 - last comment - 08:44, Thursday 16 July 2015(19675)
more ASC...
Jenne, Evan, Stefan

- Reverted the the ramp times in PREP_TR back to Monday's values - this seemed to be more reliable, and not produce any transients at that stage of the script.
- Repeatedly brought the machine up to 24W, but we still see a hint for the 0.41Hz CSOFT resonance, and occasionally a YAW gain oscillation at maybe 1.5Hz.
- The DC oplev PIT on SR3 was stuck on the limiter.
- We also cleaned up the Guardian flow chart. It now has a single flow line. (The previous spider web caused more lock losses than it was worth.)
- Since the 0.41Hz problem seems to come and go, we decided to kill it with a good CSOFT loop design - using a 2nd UGF at the resonance to damp it. Evan is still testing this filter.

Comments related to this report
evan.hall@LIGO.ORG - 04:39, Thursday 16 July 2015 (19676)

Just to summarize, we seem to be suffering from several issues at 23+ W:

  • The intermittent apperance of an 0.4 Hz instability seen in the arm powers, the sideband powers, and various ASC loops (but particularly common soft pitch). [Some people claim this will be fixed by tuning the cSoft loop appropriately.]
  • The intermittent appearance of a 2.5 Hz instability seen on the AS port camera and the yaw ASC loops. Confusingly, it sort of looks like a pitch instability on the camera. [Some people claim this is an ASC loop instability.]
  • Random, sudden locklosses after a few minutes. [Some people claim this is a slow alignment drift.]
evan.hall@LIGO.ORG - 06:27, Thursday 16 July 2015 (19678)

I was able to get a 30 minute lock at 23.7 W with the following:

  • dETM yaw gain increased from 14 to 22. I think this is what is needed to suppress the 2.5 Hz oscillations that we see at high power.
  • cETM pitch engaged with +20 dB filter and gain of -1. Unclear whether this helps or hurts us.
  • cETM yaw gain engaged with no +20 dB filter and with gain of -2. After 30 minutes I tried turning on the +20 dB boost, but this rang up the 2.5 Hz oscillation and broke the lock. So this loop configuration gets a thumbs down.
  • Common hard/soft actuation removed from the output matrices. I did this out of an abundance of caution. I'm not sure whether it is responsible for any of the high-power problems we've seen over the past 36 hours.

Other notes:

  • Over the past two days, I saw the following EPICS freezes:
    • 2015-07-14 04:31:00 Z
    • 2015-07-14 08:22:50 Z
    • 2015-07-15 12:26:36 Z
    • 2015-07-15 12:26:50 Z (this one lasted for about 20 s, and at the same time the SYS_DIAG guardian threw an NDS connection error)
  • Twice tonight we had locklosses when engaging the fiber mode damping in the Guardian.
  • Twice tonight we saw the DARM WFS fail to control the AS port spot during CARM offset reduction. This caused a lockloss both times. From the OPS overview screen, it seemed like the shutter was open both times.
evan.hall@LIGO.ORG - 08:44, Thursday 16 July 2015 (19679)

We were able to get two more stable locks at 24 W, this time in the full low noise state.

However, Patrick and I found that EY L2 was periodically saturating, with the quadrants having something like 50,000 ct rms, coming primarily from the microseism. So the EY L1/L2 crossover is now increased in the Guardian (the L1 filter gain was 0.16, and now it is 0.3). The rms drive on L2 is now more like 30,000 ct rms. L1 is 6000 ct rms, and L3 is 1000 ct rms.

H1 ISC (ISC, SEI)
sheila.dwyer@LIGO.ORG - posted 22:36, Wednesday 15 July 2015 (19674)
nearly recovered from maintenance, windy locking

Kiwamu, Stefan, Jenne, Matt, Evan,

We've almost recovered from yesterday's "maintenance".  Kiwamu found this morning that the X arm camera servo had been off, I think this was a miscommunication/mistake durring maintence recovery which probably lead us into some bad alingment last night.  Stefan/Kiwamu/Jenne did some realignment this morning and early afternoon, and we were able to lock with good recycling gain and were stable at 24 Watts. 

The gain of the OMC DC PDs was wrong this was picked up by the SDF put I am not sure what maintence acvitity would have caused that.  The ETMY ESD bias had the wrong sign.  Stefan added it in SDF.  

We were able to lock momentarily at low noise, and lost it for reasons that we don't understand yet, but might have been a slow alignment instability.  

About 2 hours ago the wind picked up, we have gusts up to 35-40 mph, forecast to stay this way until 1 am.  Our improvement to the offloading of DRMI has certaintly helped with windy locking, DRMI locking is still slow but it does lock and stay locked.  Stefan has rasied the gains that are used for acquisition, we can try to get some statisctics about DRMI lockign times.  Now we get to the next windy locking problem, which seems to be the handoff from ALS COMM to the transmitted arm powers for CARM.  

H1 GRD (CDS)
sheila.dwyer@LIGO.ORG - posted 21:49, Wednesday 15 July 2015 (19673)
guardian PV problem is getting worse, epics freeze

The guardian has been having an occasional problem where it cannot acces channels (the channels exist and are spelled correctly). One solution has been to reload the gaurdian a few times, just now I had to reload the DRMI guardian about 10 times.  Eventualy Stefan paused and reloaded it and the problem went away.  

Screen shot attached. 

We've also had some more epics freeze incidents today.  4:42:39 UTC Local 17:25:50

Images attached to this report
LHO General
patrick.thomas@LIGO.ORG - posted 16:01, Wednesday 15 July 2015 (19670)
Ops Summary
08:09 Ken working on GPS antenna on roof
08:46 Peter, Jeff B. to chiller room to look at chiller displays
08:52 Richard to roof
09:02 Peter, Jeff B. back
09:39 Travis to LVEA to look for part
09:45 Rebooted projector0 due to memory leak, Jim B. recreated credentials for seismic DMT
09:49 Travis back
11:26 Richard to DC power mezzanine to look at roof sections
11:32 Jeff B. to cleaning area
11:44 Richard back
12:17 Ken to electronics room to get measurements for drilling hole in building for GPS antenna cabling, then drill hole
12:58 Nutsinee to LVEA to take pictures of CO2 laser chassis
13:04 Nutsinee back
13:30 Ken done

Commissioners working on recovering IFO alignment.
H1 AOS
edmond.merilh@LIGO.ORG - posted 14:49, Wednesday 15 July 2015 (19669)
PSL Weekly Report - Past 10 day Trends
Images attached to this report
H1 CDS
david.barker@LIGO.ORG - posted 10:14, Wednesday 15 July 2015 (19667)
End Station SUS errors showing up

We are seeing large CPU max numbers on the IOP and SUS models at the end stations. In addition ADC errors are showing up on the IOP model, and intermittent Dolphin IPC errors on SEI and ISC receivers. I have just cleared out the warnings so we can see how often these appear.

H1 SUS
betsy.weaver@LIGO.ORG - posted 09:31, Wednesday 15 July 2015 - last comment - 20:04, Wednesday 15 July 2015(19666)
IFO ALign

The alignment settings of the IFO this morning are a bit different than they were according to the hourly burt snap files from ~midnight on Monday night when locking was ~good.  The slider values from Monday's good locking are consistent with the alignment values in hourly snaps from a few days before Monday as well.  Attached is the snap file from Monday at 11:10pm in the event the commissioners need to do a complete restore.  Commissioners report that it is confusing as to why to ASC systems did not recover the pointing even when the starting point was not quite right.  Evan is working on it now.

 

Most notably:

 

IM4 is 1400 uRad different in Pitch

IM4 is 200uRad different in Yaw

MC3 is 100 uRad different in Pitch

MC1 is 80 uRad different in Pitch

PRM is 30 uRad different in Pitch

PRM is 40 uRad different in Yaw

 

Images attached to this report
Comments related to this report
stefan.ballmer@LIGO.ORG - 20:04, Wednesday 15 July 2015 (19672)
Turns out the IMC slider values changed significantly, resulting in the IMC to hang at a different place. This caused a lot of the trouble we faced the last day.

Once we simply restored Monday’s alignment slider values, the IMC mirror positions moved pretty much back to where they were. This meant we also reverted the alignment references back to Monday's values. This includes the following settings:
H1:ALS-X_CAM_ITM_PIT_OFS       256
H1:ALS-X_CAM_ITM_YAW_OFS       340.9
H1:ALS-Y_CAM_ITM_PIT_OFS       303.9
H1:ALS-Y_CAM_ITM_YAW_OFS       433.5
H1:ASC-X_TR_A_PIT_OFFSET       0
H1:ASC-X_TR_A_YAW_OFFSET       -0.095
H1:ASC-X_TR_B_PIT_OFFSET       -0.11
H1:ASC-X_TR_B_YAW_OFFSET       -0.067
H1:ASC-Y_TR_A_PIT_OFFSET       -0.128
H1:ASC-Y_TR_A_YAW_OFFSET       -0.174
H1:ASC-Y_TR_B_PIT_OFFSET       -0.516
H1:ASC-Y_TR_B_YAW_OFFSET       -0.1
H1:ASC-POP_A_PIT_OFFSET        0.38
H1:ASC-POP_A_YAW_OFFSET        0.248
H1:ALS-X_QPD_A_PIT_OFFSET      0.2
H1:ALS-X_QPD_A_YAW_OFFSET      0
H1:ALS-X_QPD_B_PIT_OFFSET      0
H1:ALS-X_QPD_B_YAW_OFFSET      -0.05
H1:ALS-Y_QPD_A_PIT_OFFSET      0.1
H1:ALS-Y_QPD_A_YAW_OFFSET      -0.4
H1:ALS-Y_QPD_B_PIT_OFFSET      0
H1:ALS-Y_QPD_B_YAW_OFFSET      0.15
H1 ISC
evan.hall@LIGO.ORG - posted 08:55, Wednesday 15 July 2015 - last comment - 10:45, Wednesday 15 July 2015(19662)
Recovery update

Sheila, Jeff, Evan

We had repeated locklosses handing off the DARM sensor from ALS DIFF to AS45Q. We changed the guardian so that the handoff happens at a slightly lower CARM offset, and with a different DARM loop gain (we had previously used these settings back in late February). This new CARM offset makes the AS port more unstable during the DARM handoff, but it makes the transition successful.

We were able to make it to resonance on rf darm, but with a mediocre recycling gain (30 W/W). We spent some time manually steering the ITMs in order to bring the recyling gain up to more than 40 W/W. Then we updated the TMS QPD spot positions and the green alignment references (green QPD offsets and camera positions). It is not clear to us why we had to do this, since we restored all the suspension alignments from before the maintenance work.

We did an initial alignment starting with the new green references. Subsequently, we came into resonance with good recycling gain (>40 W/W) again.

We were able to engage the ASC with these new spot positions. However, at 17 W we saw the same 0.4 Hz resonance that we saw a few days ago, meaning we should not power up further in this configuration.

We redid the dark offsets for the TMS QPDs, since they seemed to be stale.

Comments related to this report
evan.hall@LIGO.ORG - 10:45, Wednesday 15 July 2015 (19668)

For now, the DARM handoff has been returned to its old CARM offset. I have left the DARM gain slightly lower than before (80 rather than 125).

The ITM QPD offsets have been reverted to yesterday's values. We are able to engage them as usual in the ENGAGE_ASC state, and they give a good recycling gain. However, at 23 W the interferometer unlocks suddenly after a few minutes. The transmitted arm powers seem slightly less stable than with the new offsets tried above (a slow oscillation with a few-second period can be seen in the arm powers, as well as POP LF), but there is no 0.4 Hz oscillation.

H1 SEI
hugh.radkins@LIGO.ORG - posted 15:20, Tuesday 14 July 2015 - last comment - 08:56, Wednesday 15 July 2015(19632)
LHO SEI HEPI Fluid System Accumulator Charge Check

All fifty (50) Accumulators were checked for charge today.  No Accumulator needed charging.  Only three accumulators showed a decrease in pressure since the last charge check on 21 April, see T1500280.  These were small decreases (few psi) and likely reflect loss from gauge pulloff (does the uncertainy principle apply?)  The acceptable range of 60-93% of operating pressure is quite broad and the lowest reading today was at 80%.

Given these results, and, the reservoir-fluid-level-indication of Accumulator charge which can be checked with the system pumping, this invasive, must have system off accumulator pressure check could be done just quarterly.  As long as the weekly check of reservoir fluid levels show no decrease, the accumulators can be assumed to be adaquately charged.  If a weekly check of the reservoir fluid indicates a volume loss, then the accumulators could be checked.

Comments related to this report
brian.lantz@LIGO.ORG - 08:56, Wednesday 15 July 2015 (19665)
good to hear that the accumulators are holding well. I like your plan
-Brian
H1 TCS
eleanor.king@LIGO.ORG - posted 12:50, Tuesday 14 July 2015 - last comment - 05:24, Thursday 16 July 2015(19624)
CO2X laser tripped this morning, now back on

CO2X laser RTD sensor alarm (H1:TCS-ITMX_CO2_INTRLK_RTD_OR_IR_ALRM) tripped at 14 Jul 15 17:15:00 UTC this morning (10:15am), shutting off the CO2X laser.  Folks were pulling cables near HAM4 this morning, which is probably why it tripped.  CO2X laser was restarted at 19:30:00 UTC, and is now running normally again.

Comments related to this report
jeffrey.kissel@LIGO.ORG - 20:38, Tuesday 14 July 2015 (19652)
Just adding some words, parroting what Elli told me: this temperature sensor (RTD) is nominally supposed to be on "the" viewport (HAM4? Some BSC? The Injection port for the laser? Dunno). This sensor is not mounted on the viewport currently, it's mounted on "the" chassis, which (I believe) resides in the TCS remote racks by HAM4. She's seen this in the past: even looking at this sensor wrong (my words, not hers) while you're cabling / electronics-ing near HAM4, this sensor trips. As she says, this was noticed and recovered by her before it became an issue with the IFO because recovery went much slower than anticipated.
matthew.heintze@LIGO.ORG - 05:24, Thursday 16 July 2015 (19677)

If I understand correctly the sensor I think your talking about then yes this should be on the viewport (the BSC viewport which the laser is injected in). The viewport sensor though is an IR sensor, but for some parts of the wiring in the control box (and thus on the MEDM screen) the IR sensor and RTD sensor are wired in together making it hard to know which one caused the trip.  Its supposed to monitor scattered light coming off that viewport. It is very sensitive and can be affected by humans standing near it, light being shown onto it (one of the ways to set the trip level is to hold a lighter up to it ), maybe also heat from electronics, etc. So just sitting in the rack I am not at all surprised that it is tripping all the time and causing grief.

My suggestion is to try to get this installed on the viewport if you can, otherwise if you can’t and it really is causing problems all the time, there is a pot inside the control box which you can alter to change the level at which it trips.

H1 AOS (ISC, SUS, SYS)
sheila.dwyer@LIGO.ORG - posted 22:48, Monday 13 July 2015 - last comment - 09:38, Thursday 23 July 2015(19570)
More OMC excitations

Jenne, Sheila, Evan

We locked at 10Watts with low noise, and redid the OMC excitations that Koji and I did in alog 17919.  We plotted the OMC L excitation against a model with a peak to peak motion of 36 um, and the result seems consistent with a reflectivity of 160e-7 that we measured on Friday by exciting the ISI.  This is slightly worse than what we measured in April.  

We made these excitations with the same amplitudes and frequencies that we used in April, but some of the velocities seem to be smaller.  Jenne is working on doing a more thourough comparision, but it seems that the scatter is better when we are exciting Yaw and Transverse, if a little worse for longitudnal.  

We used a frequency of 0.2 Hz for all excitations.  

DOF excitation amplitude (0.2Hz) time Ref
OMC L 20000 4:39:30 10
T 20000 4:43:51-4:47:00 11
V 20000 4:47:30-4:49:20 12
P 2000 4:51:38-4:53:20 13
Y 200 4:54:00-4:56:20 14
R 2000 4:56:47-4:58:00 15
       
Images attached to this report
Non-image files attached to this report
Comments related to this report
jenne.driggers@LIGO.ORG - 00:18, Tuesday 14 July 2015 (19611)

I'm concerned that the times from the April data for the Longitudinal excitation that Sheila is using aren't quite correct. This means that for the "L" traces we're integrating some "no excitation" time in with our "excitation" time, and using this muddled spectra as the measurement of the OMC scattering.

I have pulled the data from April, and adjusted the start time of each measurement to ensure that the excitation channel was fully on at the start (the [0][0] "time series" trace in DTT), and was still fully on for the last average (the [0][9] "time series" trace).  Since I only had to adjust the "L" start time, I think this is the only one that is affected.  With this adjustment, I see that the knee frequency goes down for L and T. It stays about the same for P, and is hard to tell (almost no scattering) for Y. The amplitude is a little bit higher for L and P, but not by a lot. Since the knee frequency is directly proportional to the velocity (eq. 4.16, Tobin's thesis), this seems to imply that even though we were actuating with the same amplitude and frequency, the true motion is slower now than in April. Is this because we are also pushing around the weight of the glass shroud? I'm not sure how the glass is mounted.

The times that I'm using are as follows:

  16-17 April 2015 (t0 UTC) 14 July 2015 (t0 UTC)
No excitation 23:33:39 04:49:57
L excitation 23:47:47 04:39:30
T excitation 23:59:00 04:43:56
Y excitation 00:31:00 04:55:00
P excitation 00:24:00 04:51:50
Non-image files attached to this comment
keita.kawabe@LIGO.ORG - 16:30, Wednesday 15 July 2015 (19671)

Another thing to add:

Since June 25 (right after shroud thing was done) and including the time this measurement was done, OMCR beam diverter has been open and nobody cared to close it.

Though it's not clear if this makes any difference, any comparison should be done with the diverter closed.

Images attached to this comment
betsy.weaver@LIGO.ORG - 09:38, Thursday 23 July 2015 (19861)

Regarding Jenne's comment above, "Is this because we are also pushing around the weight of the glass shroud? I'm not sure how the glass is mounted." - the black glass shroud is mounted to the OMC structure, not the suspended mass.  After installation, the ISI was rebalanced and retested.

Displaying reports 64121-64140 of 83294.Go to page Start 3203 3204 3205 3206 3207 3208 3209 3210 3211 End