S. Karki, C.Biwer

Used the single IFO time to do the regular DARMOLGTF  and PCALY to DARM sweep measurement for regular calibration purpose. We also did a sweep at PCALX and used the measurement to create inverse actuation filter.

The coherence dropped to .95 during PCALY sweep at around 35 Hz because I forgot to turn of the x_ctrl line. Oops!

The measurement files are committed to the SVN:

DARMOLGTF: /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O1/H1/Measurements/DARMOLGTFs/2015-10-01_H1_DARM_OLGTF_7to1200Hz.xml

PCALY SWEEP: /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O1/H1/Measurements/PCAL/2015-10-01_H1_PCALY2DARMTF_7to1200Hz.xml

PCALX SWEEP: /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O1/H1/Measurements/PCAL/2015-10-01_H1_PCALX2DARMTF_7to1200Hz.xml

S. Karki, C. Biwer, R. Savage

The factor of two that was missing from the pcal inverse actuation filter installed at X-end is now retrieved from a new transfer function measurement  and a appropriate new filter is ready to install. The filters we used previously were created by using the transfer function taken from PCALY. The two Pcal should in principle be very similar and we were working on that principle. 

Today in trying to troubleshoot, we took a transfer function between RxPD and EXC at Xend and used it to create the inverse act. filter. We were able to retrieve the missing factor and possibly the sign as well. This still doesnot explain why there is this factor of 2 in the pcal response between the two end. Will continue investigating on it.

The factor of two is not unexpected and should not impact the calibration. We pick off a small part of the laser light that goes to the ETM using an uncoated optic oriented close to Brewster’s angle.  The small fraction of the light reflected from this optic (less than 1%) is a strong function of the angle of incidence. The reflected light is directed to the Optical Follower Servo photodetector . The percentage of light reflected, along with attenuators installed in front of the PD, coupled with the diffraction efficiency of the AOM, could easily account for this factor of 2. The excitation signal generates an offset in the Optical Follower Servo that is compared with the light level from the OFS PD.  The OFS ensures that they are equal and opposite (in sign). We monitor the actual light that is directed to and reflects from the ETM and the calibration is based on this.

In the meantime, we will install this new filter at the next opportunity and do a test through a full transfer function as well as waveform injection.

Attached is a plot with measured TF and an appropriate fit.

Kyle, Gerardo 

Today we bagged the Y-mid vent/purge valve NW50-4.5" adapter and sprayed helium (Valve is/was closed)

Warmed up LD for > 30 minutes and calibrated (cal-gas on Tee at LD inlet) -> Helium signal 6.4 x 10-8 torr*L/sec with cal-leak valved-in, < 10-11 torr*L/sec when cal-gas valved out

1.4 x 10-8 torr*L/sec helium baseline when turbo initially valved-in to Y-mid -> Declined to 7.3 x 10-9 torr*L/sec over next 90 minutes -> bagged vent/purge valve's NW50-4.5" adapter, filled bag with 4 LPM helium flow for 100 seconds and again for 10s of seconds -> LD signal began to increase ~30 seconds after initial helium applied and peaked at 1.2 x 10-8 torr*L/sec -> Removed bag -> LD signal fell off to 6.4 x 10-9 torr*L/sec after ???? minutes -> Bagged adapter a second time only this time included the O2 sensor (with internal pump) -> Repeated exercise and achieved O2 < 1% -> Max signal 1.1 x 10-8 torr*L/sec. -> Removed bag and valved-out Turbo etc. when Y-mid helium signal < 8 x 10-9 torr*L/sec 

Conclusion: 
Turbo aperture ~75 sq. in., beam tube apertures (~1500 sq. in) x 2 = ~3,000 sq. in. >> Turbo "sees" ~ 3 % of actual signal -> Air leak rate 0.4 that for helium -> maybe can explain 1/10 of assumed air leak.

Adam M., Chris B.

We are going to be scheduling coherent hardware injections. Will update with schedule lines.

We had some trouble getting re-locked this last time. 

Several of the locklosses that we had while trying to get back online were due to MC2 M2 saturations, much like we saw in early September.  See, for example, aLog 21169.  It looks like this stopped being something that we were noticing, so we didn't put too much effort into determining the cause. Anyhow, we were able to lock, and are currently back in Observing mode, so maybe we should just sit tight and see if this happens again, or if it goes away again.

Back to Observing Mode @ 0:42 UTC.

Richard, Gerardo, Jim, Dave:

While the IFO was in commissioning we went to Mid-Y to investigate the h1pemmy failure which happened at 03:53 PDT this morning. We found that the IO Chassis was not powered up, but the +24V power supply was running. We found that the fuse in the fuse-units at the top of the DC power supply rack had blown for the +24V line. We replaced the fuse, powered up the IO Chassis and noted the DC power supply was drawing at steady 3.5A as expected. It was then we noticed the AA-Chassis was not on. It has a fuse on the +18V line which had blown. Putting a new fuse in caused a hot electrical odor from the AA-Chassis. The fuse was removed to de-energize the AA.

Initially we left all the systems down (computer and IO Chassis) and returned to the corner station. But with h1pemmy not running, the DAQ EDCU and CONLOG were red on the overview screen. We remotely powered up the h1pemmy computer, which then started the h1ioppemmy and h1pemmy models. Wtith the EPICS IOCs running, this has appeased EDCU and CONLOG. For now the two models have FEC and DAQ errors as they are not actually running, only the epics IOC is running. We will remain in this state until the AA Chassis is runnng again.

A trend of a seismic signal and the front end status shows they both went down at 03:53 PDT Thu 01 oct 2015. We presume the failure of the AA-chassis and the overcurrent of the 18V glitched the 24V line which in turn blew the fuse.

Activity Log: All Times in UTC (PT)

15:00 (08:00) Take over from TJ
15:05 (08:05) GRB Alert – Switch to Observing mode
16:33 (09:33) Jodi – Delivering storage items to mechanical building
16:59 (09:59) Jodi – Finished with delivery
18:31 (11:31) GRB Alert – In Observing mode before notice
20:47 (13:47) Switch to Commissioning mode – Commissioning work while LLO is down
21:26 (14:26) Kyle & Gerardo – Going to Mid-Y to start rotating pump and leak detector 
21:35 (14:35) Dave & Jim – Going to Mid-Y to check on PEM problem
22:31 (15:31) Filiberto – Going to Mid-Y to work on bad AA chassis 
22:45 (15:45) Lockloss – Commissioning activities
23:00 (16:00) Turn over to Travis


End of Shift Summary:

Title: 10/01/2015, Day Shift 15:00 – 23:00 (08:00 – 16:00) All times in UTC (PT)

Support: Sheila, Mike, 

Incoming Operator: Travis

Shift Summary: 
- 15:00 IFO locked. Intent Bit = Commissioning Mode. Wind is calm, no seismic activity. All appears normal. Sheila doing some testing while LLO is relocking.
    
- 17:05 (08:05) GRB Alert. Switch to Observing mode
- 18:31 (11:31) GRB Alert. In Observing mode 
- 23:00 (16:00) Relocking  

Just in case you're wondering why LHO sees two noise bumps at 315 and 350Hz (attached, middle blue) but not at LLO, we don't fully understand either but here is the summary.

There are three things here, environmental noise level, PZT servo, and jitter coupling to DARM. Even though the former two explains a part of the LLO-LHO difference, they cannot explain all of it, and the coupling at LHO seems to be larger.

Reducing the PSL chiller flow will help but that's not a solution for the future.

Reimplementing PZT servo at LHO will help and this should be done. Squashing it all will be hard, though, as we are talking about the jitter between 300 and 370Hz and there's a resonance at 620Hz.

Reducing coupling is one area that was not well explored. Past attempts at LHO were on top of dubious IMC WFS quadrant gain imbalances.

1. Environmental difference

These bumps are supposed to be from the beam jitter caused by PSL periscope resonances (not from the PZT mirror resonances). In the attached you can see that the bumps in H1 (middle blue) correspond to the bumps in PSL periscope accelerometer (top blue). (Don't worry, we figured out which server we need to use for DTT to give us correct results.)

Because of the PSL chiller flow difference between LLO and LHO (LHO alog, couldn't find LLO alog but we have MattH's words), in general LLO periscope noise level is lower than LHO. However, the difference in the accelerometer signal is not enough to explain the difference in IFO.

For example, at 350Hz LHO PSL periscope is only a factor of 2 noisier than LLO. At 330Hz, LHO is quieter than LLO by more than a factor of 2. Yet we have a huge hump in DARM at LHO, it becomes larger and smaller in DARM but it never goes away, while LLO DARM is deat flat.

At LLO they do have a servo to supress noise at about 300Hz, but it shouldn't be doing much if any at 350Hz (see the next section).

So yes, it seems like environmental difference is one of the reasons why we have larger noise.

But the jitter to DARM coupling itself seems to be larger.

Turning down the chiller flow will help but that's not a solution for the future.

2. Servo difference

At LLO there's a servo to squash beam jitter in PIT at 300Hz. LHO used to have it but now it is disabled.

At LLO, IOOWFS_A_I_PIT signal is used to suppress PIT jitter targetting the 300Hz peak which was right on some mechanical resonance/notch structure in PZT PIT (which LHO also has), and the servo reduced the noise between about 270 and about 320Hz (LLO alog 19310).

Same servo was successfully copied to LHO with some modification, which also targeted 300Hz bump (except that YAW was more coherent than PIT and we used YAW signal), with somewhat less (but not much less) aggressive gain and bandwidth. At that time 300Hz bump was problematic together with 250Hz bump and 350Hz bump. Look at the plots from alog 20059 and 20093.

Somehow 250Hz and 300Hz subsided, and now LHO is suffering from 315Hz and 350Hz bumps (compare the attached with the above mentioned alog). Since we never had time to tune the servo filter to target either of the new bumps, and since turning the servo on without modification is going to make marginal improvement at 300Hz and will make 250Hz/350Hz somewhat worse due to gain peaking, it was disabled.

Reimplementing the servo to target 315 and 350Hz bumps will help.  But it's not going to be easy to make this servo wide band enough to squash everything because of 620Hz resonance, which is probably something in the PZT mirror itself (look at the above mentioned alog 20059 for open loop transfer function of the current servo, for example). In principle we can go even wider band, but we'll need more than 2kHz sampling rate for that. We could stiffen the mount if 620Hz is indeed the mount.

3. Coupling difference

As I wrote in the environment difference, from the accelerometer data and IFO signal, it seems as if the coupling is larger at LHO.

There are many jitter coupling measurements at LHO but the best one to look at is this one. We should be able to make a direct comparison with LLO but I haven't looked.

Anyway, it is known that the coupling depends on IMC alignment and OMC alignment (and probably the IFO alignment).

At LHO, IMC WFS has offsets in PIT and YAW in an attempt to minimize the coupling. This is on top of dubious imbalances in IMC WFS quadrant gains at LHO (see alog 20065, the minimum quadrant gain is a factor of 16  larger  smaller than the maximum). We should fix that before spending much time on studying the jitter coupling via alignment.

At LLO, there's no such imbalance and there's no such offset.

Chris Biwer and other members of the hardware injections team will likely be doing coherent hardware injections in the near future, and these will hopefully be detected successfully by one or more of the low-latency data analysis pipelines.  Currently, we are still testing the EM follow-up infrastructure, so the "Approval Processor" software is configured to treat hardware injections like regular triggers.  Therefore, these significant GW "event candidates" should cause audible alarms to sound in each control room, similar to a GRB alarm.  The operator at each site will be asked to "sign off" by going to the GraceDB page for the trigger and answering the question, "At the time of the event, was the operating status of the detector basically okay, or not?"  You can also enter a comment.

For the purpose of these tests, if you are the operator on shift, please:
  * Do not disqualify the trigger based on it being a hardware injection -- we know it is!  So, please sign off with "OKAY" if the detector was otherwise operating OK.
  * Pay attention to whether the audible alarm sounded.  In the past we had issues at one site or the other, so this is one of the things we want to test.
  * Feel free to enter a comment on the GraceDB page when you sign off, like maybe "this was a hardware injection and the audible alarm sounded".
  * You may get a phone call from a "follow-up advocate" who is on shift to remotely help check the trigger.

Note: in the future, once the EM follow-up project is "live", a known hardware injection will not cause the control-room alarms to sound (unless it is a blind injection).  You should not write anything in the alog about alarms from GW event candidates, because that is potentially sensitive information and the alogs are publicly readable.

IFO has been locked at NOMINAL_LOW_NOISE, 23.0W, 72Mpc for the past 5 hours. Wind and seismic activity are low. 4 ETM-Y saturation alarms. Received GRB alert at 18:31UTC (12:31PT) - LHO was in Observing mode during this event      

The attached plot shows the 2 day trend of the RF45 glitches. There were no glitches in the past day. The large glitches 24 hours ago were us. This is not inconsistent with a cable or connection problem. No one should be surprised, if the problem reappears.

Title:  10/01/2015, Day Shift 15:00 – 23:00 (08:00 – 16:00) All times in UTC (PT)

State of H1: At 15:00 (08:00) Locked at NOMINAL_LOW_NOISE, 23.0W, 72Mpc

Outgoing Operator: TJ

Quick Summary: Wind is calm, no seismic activity. All appears normal. Intent Bit at Commissioning while LLO was recovering from a lockloss.     

I'm posting an early version of this alog so that people can see it, but plan to edit again with the results of the second test. 

Yesterday I took a few minutes to follow up on the meausrements in alog 21869.  This time in addition to driving TMS I drove the ISI in the beam direction to reproduce the motion caused by the backreaction to TMS motion. We also breifly had a chance to move the TMSX angle while exciting L. 

The main conclusions are:

• The motion that produces the noise in DARM while driving TMSX seems more likely to be due to motion of the ISI than motion of TMS.  The smaller, linear coupling from TMSY does seem to be due to transmon motion.
• Driving the ETMX ISI produces a broad peak in DARM, however based on the normal level of GS13 noise in the X direction you would not predict that this noise should not normally dominate DARM at 75 Hz. The same drive at ETMY does not produce any noise in DARM.  To see if this coupling can explain the noise from 77-80 Hz we should make injections at those frequencies (and with white noise) on the ISI in multiple directions to allow comparisons to the ambient motion of the ISI and let us make a projection of how much of our unexplained noise is due to this blinear coupling.
• driving the ETMX ISI in X produces a yaw QPD signal, but no pitch signal.  This seems counter intituive to me, and I wonder if it is a clue about the scattering/clipping or just something I don't understand about how TMS reacts to ISI motion.
• There is a ghost beam near X TRB which has about 0.5% as much power as the main beam.
• The coupling produced by the driven peak at 75 Hz is not very sensitive to changes in the TMS position or angle, although the sidebands on the peak do seem to change as TMS is moved.

Comparison of ISI drive to TMS drive for X and Y

The attached screenshot shows the main results of the first test (driving ISIs and TMSs).  In the top right plot you can see that I got the same amount of ISI motion for 3 cases (driving ETMX ISI, TMSX, ETMY ISI) and that driving TMSY with the same amplitude as TMSX resulted in a 50% smaller motion of the ISI.  Shaking the TMS in the L direction induces a larger motion measured by the GS13s in the direction perpendicular to the beam, than in the beam direction, which was not what I expected.  I chose the drive strength to get the same motion in the beam direction, so I have not reproduced the largest motion of the ISI with this test. If there is a chance it would be interesting to also repeat this measurement reproducing the backreaction in the direction perpendicular to the beam.  

The middle panels of the first screnshot show the motion measured by OSEMs. TMS osems see about a factor of 10 more motion when the TMS is driven than when the ISI is driven.  The signal is also visible in the quad top mass osems, but not lower down the chain.  For the X end, the longitudnal motion seen by the top mass is about a factor of 2 higher when the TMS is excited than when the ISI is excited (middle left panel), which could be because I have not reproduced the full backreaction of the ISI to the TMS motion.  However, it is strange that for ETMY the top mass osem signal produced by driving TMS is almost 2 orders of magnitude larger than the motion produced by moving the ISI. It seems more likely that this is a problem of cross coupling between the osems than real mechanical coupling. The ETMY top mass osems are noisier than ETMX, as andy lundgren pointed out (20675).  It would be interesting to see a transfer function between TMS and the quad top mass to see if this is real mechanical coupling or just cross talk. 

In the bottom left panel of the first screenshot, you can compare the TMS QPD B yaw signals.  The TMS drive produces larger QPD signals than the ISI drive, as you would expect for both end stations.  My first gues would be that driving the ISI in the beam direction could cause TMS pitch, but shouldn't cause as much yaw motion of the TMS.  However, we see the ETMX ISI drive in the yaw QPDs, but not pitch.  The Y ISI drive does not show up in the QPDs at all.  

Lastly, the first plot in the first screenshot shows that the level of noise in DARM produced by driving the ETMX ISI is nearly the same as what is produced by driving TMSX.  Since the TMS motion (seen by TMS osems) is about ten times higher when driving TMS, we can conclude that this coupling is not through TMS motion but the motion of something else that is attached to the ISI. Driving ETMY ISI produces nothing in DARM but driving TMSY produces a narrow peak in DARM. 

For future reference:

I drove ETMX-ISI_ST2_ISO_X_EXC with an amplitude of 0.0283 cnts at 75 Hz from 20:07:47 to 20:10:00UTC sept 29th

I drove 2000 cnts in TMSX test L from 20:10:30 to 20:13:30UTC 

I drove ETMY-ISI_ST2_ISO_Y_EXC with an amplitude of 0.0612 cnts at 75 Hz from 20:13:40 to 20:16:30UTC 

I drove 2000 cnts in TMSY test L from 20:17:10 to 20:20:10UTC

Driving TMSX L while rastering TMS position and angle

I put a 2000 cnt drive on TMSX L from about 2:09 UTC September 30th to 2:37 when I broke the lock. We found a ghost beam that hits QPD B when TMS is misaligned by 100 urad in the positive pitch direction.  There is about 0.5% as much power in this beam as in the main beam (not accounting for the dark offset).  I got another chance to do this this afternoon, and was able to move the beam completely off of the QPDs, which did not make the noise coupling go away or reduce it much.  We can conclude then scatter off of the QPDs is not the main problem.  There were changes in the shape of the peak in DARM as TMS moved, and changes in the noise at 78 Hz (which is normally non stationary) Plots will be added tomorrow.

Speculation

There is a feature in the ETMX top mass osems (especially P and T) around 78 Hz that is vaugely in the right place to be related to the excess noise in the QPDs and DARM. Also, Jeff showed us some B&K measurements from Arnaud (7762) that might hint at a Quad cage resonance at around 78 Hz, although the measured Q looks a little low to explain the spectrum of the TMSX QPDs or the feature in DARM. One could spectulate that the motion driving the noise at 78Hz  is the quad cage resonance, but this is not very solid.  Robert and Anamaria have data from their PEM injections that might be able to shed some light on this.

When DTT gets data from NDS2, it apparently gets the wrong sample rate if the sample rate has changed. The plot shows the result. Notice that the 60 Hz magnetic peak appears at 30 Hz in the NDS2 data displayed with DTT. This is because the sample rate was changed from 4 to 8k last February.  Keita pointed out discrepancies between his periscope data and Peter F's. The plot shows that the periscope signal, whose rate was also changed, has the same problem, which may explain the discrepancy if one person was looking at NDS and the other at NDS2. The plot shows data from the CIT NDS2. Anamaria tried this comparison for the LLO data and the LLO NDS2 and found the same type of problem. But the LHO NDS2 just crashes with a Test timed-out message.

Robert, Anamaria, Dave, Jonathan

The ext_alert.py script which periodically views GraceDB had failed. I have just restarted it, instructions for restarting are in https://lhocds.ligo-wa.caltech.edu/wiki/ExternalAlertNotification

Getting this process to autostart is now on our high priority list (FRS3415).

here is the error message displayed before I did the restart.

 File "ext_alert.py", line 150, in query_gracedb

    return query_gracedb(start, end, connection=connection, test=test)

  File "ext_alert.py", line 150, in query_gracedb

    return query_gracedb(start, end, connection=connection, test=test)

  File "ext_alert.py", line 135, in query_gracedb

    external = log_query(connection, 'External %d .. %d' % (start, end))

  File "ext_alert.py", line 163, in log_query

    return list(connection.events(query))

  File "/usr/lib/python2.7/dist-packages/ligo/gracedb/rest.py", line 441, in events 

    uri = self.links['events']

  File "/usr/lib/python2.7/dist-packages/ligo/gracedb/rest.py", line 284, in links  

    return self.service_info.get('links')

  File "/usr/lib/python2.7/dist-packages/ligo/gracedb/rest.py", line 279, in service_info

    self._service_info = self.request("GET", self.service_url).json()

  File "/usr/lib/python2.7/dist-packages/ligo/gracedb/rest.py", line 325, in request

    return GsiRest.request(self, method, *args, **kwargs)

  File "/usr/lib/python2.7/dist-packages/ligo/gracedb/rest.py", line 201, in request

    response = conn.getresponse()

  File "/usr/lib/python2.7/httplib.py", line 1038, in getresponse

    response.begin()

  File "/usr/lib/python2.7/httplib.py", line 415, in begin

    version, status, reason = self._read_status()

  File "/usr/lib/python2.7/httplib.py", line 371, in _read_status

    line = self.fp.readline(_MAXLINE + 1)

  File "/usr/lib/python2.7/socket.py", line 476, in readline

    data = self._sock.recv(self._rbufsize)

  File "/usr/lib/python2.7/ssl.py", line 241, in recv

    return self.read(buflen)

  File "/usr/lib/python2.7/ssl.py", line 160, in read

    return self._sslobj.read(len)

ssl.SSLError: The read operation timed out