Displaying reports 56221-56240 of 78078.Go to page Start 2808 2809 2810 2811 2812 2813 2814 2815 2816 End
Reports until 12:58, Monday 12 October 2015
H1 AOS (DetChar)
nelson.christensen@LIGO.ORG - posted 12:58, Monday 12 October 2015 - last comment - 20:03, Monday 12 October 2015(22441)
H1-L1 coherence over O1 so far
Here are the observed H1-L1 coherences as of October 12, 2015, as calculated by stochmon:
https://ldas-jobs.ligo.caltech.edu/~thomas.callister/stochmonO1/stochmon.html

Some plots attached.

100 mHz resolution. 1E-5 is the expected level of coherence due to uncorrelated noise.
Frequency, coherence
33.6 Hz, 1E-3
34.6 Hz, 2E-2
35.4 Hz, 1E-3
42.5 Hz, 6E-4 (barely above background, could be a noise fluctuation)
64.0 Hz, 2E-4 (barely above background, could be a noise fluctuation)
74.0 Hz, 5E-4 (barely above background, could be a noise fluctuation)
128.0 Hz, 1E-2
256.0 Hz, 2E-3
331.8 Hz, 3E-4 (barely above background, could be a noise fluctuation)
351.1 Hz, 4E-4 (barely above background, could be a noise fluctuation)
559.9 Hz, 2E-4 (barely above background, could be a noise fluctuation)
736.0 Hz, 3E-3 (23rd harmonic of 32 Hz)
1904.0 Hz, 2E-3 (119th harmonic of 16 Hz)
2160.0 Hz, 4E-4 (135th harmonnic of 16 Hz)
2376.0 Hz, 4E-3 (297th harmonic of 8 Hz)
2768.0 Hz, 7E-3 (173rd harmonic of 16 Hz)
2984.0 Hz, 7E-4 (373rd harmonic of 8 Hz)
3001.2 Hz, 1E-1 (calibration lines)
4928.0 Hz, 3E-3 (77th harmonic of 64 Hz)
5016.0 Hz, 3E-3 (627th harmonic of 8 Hz)
5144.0 Hz, 2E-1 (largest coherence, 643rd harmonic of 8 Hz)
5616.0 Hz, 2E-3 (351st harmonic of 16 Hz)
5624.1 Hz, 6E-3 


0.25 Hz, 4E-6 is the expected level of coherence due to uncorrelated noise.
Frequency, coherence
34.25 to 35.25 Hz, 1E-3
36 to 37 Hz, 1.5E-3
37.25 Hz, 2E-3
42.5 Hz, 2E-4
128.0 Hz, 3E-3
256 Hz, 6E-4
1904.0 Hz, 4E-4 (119th harmonic of 16 Hz)
3552.25 Hz, 2E-4
4163.75 Hz, 5E-3 Hz
4576.0 Hz, 2E-4 (143rd harmonic of 32 Hz)
5016.0 Hz, 7E-4 (627th harmonic of 8 Hz)
5144.0 Hz, 1E-1 (largest coherence, 643rd harmonic of 8 Hz)
5584.5 Hz, 2E-2
5655.5 Hz, 1E-3
Images attached to this report
Comments related to this report
nelson.christensen@LIGO.ORG - 20:03, Monday 12 October 2015 (22452)DetChar
Continues the study on the H1-L1 h(t) coherence to date for O1.

0.001 Hz resolution, 2E-3 is the expected level of coherence due to uncorrelated noise.

0.5 Hz harmonics are seen in the H1-L1 coherence, averaged over all of O1 to data. See figures. Various other lines to be seen as well.

Frequency, Coherence
18.50 Hz, 3E-2
19.00 Hz, 3E-2
19.50 Hz, 4E-2
20.00 Hz, 3.5E-2
23.50 Hz, 2.5E-2
25.00 Hz, 3E-2
25.50 Hz, 2.5E-2
32.00 Hz, 2E-2
36.7 Hz, 3E-2
42.5 Hz, 3E-2
43.0 Hz, 5E-2
48.0 Hz, 4E-2
61.243 Hz, 2E-2
71.0 Hz, 7E-2
71.50 Hz, 3E-2
100.00 Hz, 7E-2
128.00 Hz, 5E-1
256.00 Hz, 2E-1
896.0 Hz, 3.5E-2
952.0 Hz, 7E-2
1080.0 Hz, 1.5E-1
Images attached to this comment
H1 SEI (ISC)
jeffrey.kissel@LIGO.ORG - posted 12:14, Monday 12 October 2015 (22440)
Briefly Tried Switching Back to 90 [mHz] Blends, uSeism + Wind Still Too Large
J. Kissel, T. Schaffer, S. Dwyer

After loosing lock, "the plan" had been to switch back to 90 [mHz] blend fliters, after having switched to 45 [mHz] over the weekend (see LHO aLOG 22410). After loosing lock at 18:12 UTC, by ~18:30 UTC we had BSC platforms switched to 90 [mHz] blends. Sheila commented that motion is still too large, so we switched back to 45 [mHz] blends by 19:00 UTC, and we're resuming lock acquisition. We'll see how it goes -- the wind is on its way up...

I attach some relevant screenshots of the amplitude of motion over the past 12 hours.

Images attached to this report
H1 INJ (DetChar, INJ)
christopher.biwer@LIGO.ORG - posted 12:12, Monday 12 October 2015 (22439)
Summary of October 11 hardware injections tests
Summary:

Last night I performed a number of hardware injections see aLog 22424 and aLog 22426.

Waveforms:

The waveforms were provided by Max and Francesco on behalf of the Burst group.

The single-column ASCII files are located in the injection SVN: https://daqsvn.ligo-la.caltech.edu/svn/injection/hwinj/Details/Inspiral/${IFO}/ringburstinj*.out

The parameters files are located: https://daqsvn.ligo-la.caltech.edu/svn/injection/hwinj/Details/Inspiral/ringburstinj*.xml.gz

First Set of Injections:

Originally the plan was to space the injections 180s apart.

I used tinj to schedule the injections so they are all H1L1 coherent injections.

The following injections were successful:
1128657857 1 1.0 ringburstinj1a_1126259456_
1128658217 1 1.0 ringburstinj2a_1126259456_
1128658577 1 1.0 ringburstinj3a_1126259456_
1128658937 1 1.0 ringburstinj4a_1126259456_
1128659297 1 1.0 ringburstinj5a_1126259456_

Note that the GPS time above (first column) is the time the injection began. The end times are ~6s after this time. The exact end time can be calculated from the parameter files.

Also recall from aLog 21487 that all analysis should have a 255us advance.

The following injections were skipped, ie. not injected, because tinj couldn't inject signals every 180s. The following were skipped injections and thus not successful:
1128658037 1 1.0 ringburstinj1b_1126259456_
1128658397 1 1.0 ringburstinj2b_1126259456_
1128658757 1 1.0 ringburstinj3b_1126259456_
1128659117 1 1.0 ringburstinj4b_1126259456_
1128659477 1 1.0 ringburstinj5b_1126259456_

We then had an external alert during the test. The injection in the queue was canceled at H1 but the injection was not canceled at L1. Duncan, Peter, Alex are investigating why this happened. The following injection was not performed at H1 but it was performed successfully at L1:
1128659657 1 1.0 ringburstinj6a_1126259456_

I then deleted the future injections from the schedule since it did not seem like L1 properly ignored the last injection. See aLog 22425 for the lines that were deleted.

Second Set of Injections:

We continued the hardware injections later in the night after waiting so the external alert had a stretch of clean data. The injections were spaced 360s apart this time and there was no problem with tinj handling injections this frequent.

The following injections were successful:
1128666017 1 1.0 ringburstinj1b_1126259456_
1128666377 1 1.0 ringburstinj2b_1126259456_
1128666737 1 1.0 ringburstinj3b_1126259456_
1128667097 1 1.0 ringburstinj4b_1126259456_
1128667457 1 1.0 ringburstinj5b_1126259456_
1128667817 1 1.0 ringburstinj6a_1126259456_
1128668177 1 1.0 ringburstinj6b_1126259456_
1128668537 1 1.0 ringburstinj7b_1126259456_
1128668897 1 1.0 ringburstinj8a_1126259456_
1128669257 1 1.0 ringburstinj7a_1126259456_
1128669617 1 1.0 ringburstinj8b_1126259456_
1128669977 1 1.0 ringburstinj9a_1126259456_
1128670337 1 1.0 ringburstinj10a_1126259456_
1128670697 1 1.0 ringburstinj11a_1126259456_
1128671057 1 1.0 ringburstinj12a_1126259456_
1128671417 1 1.0 ringburstinj13a_1126259456_
1128671777 1 1.0 ringburstinj14a_1126259456_
1128672497 1 1.0 ringburstinj15a_1126259456_
LHO General
thomas.shaffer@LIGO.ORG - posted 11:16, Monday 12 October 2015 (22438)
Lockloss 18:12 UTC

We just lost lock at 18:12 UTC

H1 PEM (DetChar)
thomas.shaffer@LIGO.ORG - posted 10:23, Monday 12 October 2015 (22437)
Construction on route 10

Gerardo noticed a few semis driving along route 10, this is uncommon for this time of day.

There is also construction on route 10 about .5 miles north of the site entrance. Not sure what exactly they are doing but there are rumors that they are just filling cracks in the road.

H1 PEM (DetChar)
dale.ingram@LIGO.ORG - posted 09:32, Monday 12 October 2015 (22435)
Outreach activity report (from Saturday, 10/10/15)
LHO's second-Saturday public tour occurred on the afternoon of 10/10.  Arrival time at LSB = 1:00 - 1:30 PM.  Departure time = 3:30 PM.  Group size = ~30 adults.  Vehicles at the LSB = ~15 passenger cars.  The group was on the overpass near 2:50 PM and in the control room from about 3:10 to 3:30.  Site winds picked up substantially near 2:30 PM. 
LHO General
thomas.shaffer@LIGO.ORG - posted 09:01, Monday 12 October 2015 (22434)
Morning Meeting Minutes

10-12-15 Morning Meeting Minutes

·      SEI – Running 45mHz blends are running on the BSC ISIs, may need to change them soon.

·      SUS - Needs charge measurement tomorrow.

·      ISC – Needs noise measurement of LV esd

·      Vac – Leak testing, no N2 deliveries this week.

·      Fac – Work with the water tank, starting again on the crack sealing on beam tube sealing during Observing.

·      PEM – Completed tamper inj at CS, but still needs ends. Needs about a two hours for both end stations.

·      Maintenance items:

o   ESD measurement - Keita

o   Slow controls testing DAQ – JH

o   PCal calibrations X/Y ends (Needs ETMs aligned) – Pcal team

o   Copy HW Inj Infrastructure to PCalX – Jeff K

o   Return HEPI pump pressure sensors to norm – Hugh

o   PEM inj, possible gluing to mirror in PSL – Robert

o   Finish deinstallation of old roof cam - Richard

o   PEM temp sensors on chambers – Richard

o   Fire dept. maintenance on hydrants

o   Plumbing in the LVEA – Jeff B.

o   Phone identification signs in ends/mids – Bubba

o   Jim wants to take some transfer functions on HAM BSC (probably not yet)

o   Load from MY to staging building – Jodi

o   Pulling cables from ends to 250 mark for ion pumps – CDS

o   Sataboy, storage data for DMT, work - Carlos

LHO General
thomas.shaffer@LIGO.ORG - posted 07:15, Monday 12 October 2015 (22431)
Ops Day Transition
H1 AOS
cheryl.vorvick@LIGO.ORG - posted 07:12, Monday 12 October 2015 (22430)
Ops Owl Shift End
	Title:  10/12/2015, Owl Shift 07:00 – 14:30UTC (00:00 – 07:30PT)

State of H1: Locked in NOMINAL_LOW_NOISE at 73.2Mpc, in Observe for 21 hours.

Incoming Operator: TJ

Quick Summary: 

- Nothing to report since Chris Biwer finished his hardware injections 8:10UTC (see his alog)
	- Talked to LLO, and was told their GraceDB is still down, so call if we get an alarm.
- Still to try: Switch ISI Blend Filters after lock loss, and try the Quiet 90 filters on BSC chambers.
 
H1 General
cheryl.vorvick@LIGO.ORG - posted 01:12, Monday 12 October 2015 (22429)
Ops Owl Shift Transition
Title:  10/12/2015, Owl Shift 07:00 – 15:00UTC (00:00 – 08:00PT)

State of H1: Locked in NOMINAL_LOW_NOISE at 76.6Mpc. 

Outgoing Operator: JeffB

Quick Summary: 

Chris Biwer doing hardware injections - ending around 8:10UTC (see his alog)

Instructions to switch ISI Blend Filters after lock loss, and try the Quiet 90 filters on BSC chambers.

H1 INJ (DetChar, INJ)
christopher.biwer@LIGO.ORG - posted 01:09, Monday 12 October 2015 (22428)
Done with hardware injection tests
Finished with hardware injection tests. More details later.
H1 AOS
jeffrey.bartlett@LIGO.ORG - posted 00:24, Monday 12 October 2015 (22427)
Ops Evening Shift Summary
Activity Log: All Times in UTC (PT)

23:00 (16:00) Take over from TJ
02:30 (19:30) Jeff K. left the site
03:57 (20:57) Chris – Running hardware injections for the next 72 minutes. 
			Approved by Mike L., Notified LLO, Will not drop out of Observing
04:30 (21:30) GRB Alert – In one hour stand down
04:58 (21:58) ETMY saturation event during GRB stand down
05:30 (22:30) Finished one hour stand down. 
06:15 (23:15) Chris – Restarted hardware injections
07:20 (00:20) Turn over to Cheryl
	

Title: 10/11/2015, Evening Shift 23:00 – 07:00 (16:00 – 00:00) All times in UTC (PT)

Support: Jeff K, 

Incoming Operator: Cheryl

Shift Summary: 
- 03:57 – Chris running hardware injections. He has Mike’s approval and did not go out of Observing
- 04:30 Received GRB alert. Both sites in Observing mode. In stand down for 1 hour
Chris has stopped the hardware injections he was running.  Per Verbal Alarm - Last injection stopped at 04:28:17, the GRB was time stamped at 04:30:28.  
 	
Good shift. IFO locked in Observing for 14 hours. Low wind and seismic. There were several ETMY saturations. There were 3 mag 5 or greater earthquakes during the shift, but these did not noticeably affect the IFO.      
H1 INJ (DetChar, INJ)
christopher.biwer@LIGO.ORG - posted 22:57, Sunday 11 October 2015 (22426)
Starting hardware injection test again
We're going to continue with the hardware injection tests again after waiting for the external trigger.

The schedule will be updated with the following lines:
1128666017 1 1.0 ringburstinj1b_1126259456_
1128666377 1 1.0 ringburstinj2b_1126259456_
1128666737 1 1.0 ringburstinj3b_1126259456_
1128667097 1 1.0 ringburstinj4b_1126259456_
1128667457 1 1.0 ringburstinj5b_1126259456_
1128667817 1 1.0 ringburstinj6a_1126259456_
1128668177 1 1.0 ringburstinj6b_1126259456_
1128668537 1 1.0 ringburstinj7b_1126259456_
1128668897 1 1.0 ringburstinj8a_1126259456_
1128669257 1 1.0 ringburstinj7a_1126259456_
1128669617 1 1.0 ringburstinj8b_1126259456_
1128669977 1 1.0 ringburstinj9a_1126259456_
1128670337 1 1.0 ringburstinj10a_1126259456_
1128670697 1 1.0 ringburstinj11a_1126259456_
1128671057 1 1.0 ringburstinj12a_1126259456_
1128671417 1 1.0 ringburstinj13a_1126259456_
1128671777 1 1.0 ringburstinj14a_1126259456_
1128672497 1 1.0 ringburstinj15a_1126259456_
H1 INJ (DetChar, INJ)
christopher.biwer@LIGO.ORG - posted 20:54, Sunday 11 October 2015 - last comment - 21:38, Sunday 11 October 2015(22424)
Starting hardware injection test
Beginning hardware injection test. The schedule will be updated with:

1128657857 1 1.0 ringburstinj1a_1126259456_
1128658037 1 1.0 ringburstinj1b_1126259456_
1128658217 1 1.0 ringburstinj2a_1126259456_
1128658397 1 1.0 ringburstinj2b_1126259456_
1128658577 1 1.0 ringburstinj3a_1126259456_
1128658757 1 1.0 ringburstinj3b_1126259456_
1128658937 1 1.0 ringburstinj4a_1126259456_
1128659117 1 1.0 ringburstinj4b_1126259456_
1128659297 1 1.0 ringburstinj5a_1126259456_
1128659477 1 1.0 ringburstinj5b_1126259456_
1128659657 1 1.0 ringburstinj6a_1126259456_
1128659837 1 1.0 ringburstinj6b_1126259456_
1128660017 1 1.0 ringburstinj7a_1126259456_
1128660197 1 1.0 ringburstinj7b_1126259456_
1128660377 1 1.0 ringburstinj8a_1126259456_
1128660557 1 1.0 ringburstinj8b_1126259456_
1128660737 1 1.0 ringburstinj9a_1126259456_
1128660917 1 1.0 ringburstinj10a_1126259456_
1128661097 1 1.0 ringburstinj11a_1126259456_
1128661277 1 1.0 ringburstinj12a_1126259456_
1128661457 1 1.0 ringburstinj13a_1126259456_
1128661637 1 1.0 ringburstinj14a_1126259456_
1128661817 1 1.0 ringburstinj15a_1126259456_
1128661997 1 1.0 ringburstinj16a_1126259456_
Comments related to this report
christopher.biwer@LIGO.ORG - 21:38, Sunday 11 October 2015 (22425)DetChar, INJ
The plan was to do the injections 180s apart. tinj cannot do injections this close together so some injections were skipped.

The following injections were successful:
1128657857 1 1.0 ringburstinj1a_1126259456_
1128658217 1 1.0 ringburstinj2a_1126259456_
1128658577 1 1.0 ringburstinj3a_1126259456_
1128658937 1 1.0 ringburstinj4a_1126259456_
1128659297 1 1.0 ringburstinj5a_1126259456_

The following injections were skipped and thus not successful:
1128658037 1 1.0 ringburstinj1b_1126259456_
1128658397 1 1.0 ringburstinj2b_1126259456_
1128658757 1 1.0 ringburstinj3b_1126259456_
1128659117 1 1.0 ringburstinj4b_1126259456_
1128659477 1 1.0 ringburstinj5b_1126259456_

This injection was scheduled during the GRB alert. It was not injected at H1 but it wasn't stopped in time at L1:
1128659657 1 1.0 ringburstinj6a_1126259456_

A GRB alert happened so I removed the following injections from the schedule:
1128659837 1 1.0 ringburstinj6b_1126259456_
1128660017 1 1.0 ringburstinj7a_1126259456_
1128660197 1 1.0 ringburstinj7b_1126259456_
1128660377 1 1.0 ringburstinj8a_1126259456_
1128660557 1 1.0 ringburstinj8b_1126259456_
1128660737 1 1.0 ringburstinj9a_1126259456_
1128660917 1 1.0 ringburstinj10a_1126259456_
1128661097 1 1.0 ringburstinj11a_1126259456_
1128661277 1 1.0 ringburstinj12a_1126259456_
1128661457 1 1.0 ringburstinj13a_1126259456_
1128661637 1 1.0 ringburstinj14a_1126259456_
1128661817 1 1.0 ringburstinj15a_1126259456_
1128661997 1 1.0 ringburstinj16a_1126259456_
H1 General
jeffrey.bartlett@LIGO.ORG - posted 20:16, Sunday 11 October 2015 (22423)
Ops Evening Mid-Shift
Locked in LOW_NOISE at 22.2W, 68Mpc range. LHO has been in Observation mode for past 10 hours. LLO has also been locked with comparable range during this stretch. Wind is calm (1 to 3 Mph); Seismic activity has been quite during the shift. 

   There have been a few ETMY saturation events, but have not observed any problems with the RF45 EOM.    
H1 AOS
jeffrey.bartlett@LIGO.ORG - posted 16:10, Sunday 11 October 2015 (22422)
Ops Evening Shift Transition
Title:  10/11/2015, Evening Shift 23:00 – 07:00 (16:00 – 00:00) All times in UTC (PT)

State of H1: At 23:00 (16:00) Locked at NOMINAL_LOW_NOISE, 22.2W, 70Mpc. 

Outgoing Operator: TJ

Quick Summary: Environmental conditions are good. IFO in Observing mode. All appears to be normal.       

LHO General
thomas.shaffer@LIGO.ORG - posted 16:00, Sunday 11 October 2015 (22416)
Ops Day Shift Summary

Title: 10/11 Day Shift 15:00-23:00 UTC (8:00-16:00 PST).  All times in UTC.

State of H1: Unlocked, high winds and high microseism

Shift Summary: Locked until 21:24, haven't been able to relock since due to environment issue.

Incoming operator: Jeff B.

Activity log:

H1 DetChar
thomas.shaffer@LIGO.ORG - posted 13:20, Sunday 11 October 2015 - last comment - 13:53, Sunday 11 October 2015(22418)
~300hz line in the glitch gram

Jeff Kissel noticed a ~300hz line in the glitch gram on the control room wall. Seems like it started with this lock but has been getting worse. Screen shots attached.

Images attached to this report
Comments related to this report
andrew.lundgren@LIGO.ORG - 13:53, Sunday 11 October 2015 (22421)DetChar
Looks like the peaks from the PSL periscope. See this alog for some details. I don't think we need to do anything about them right now, since it seemed like the IFO was hard to lock. I haven't seen them causing many problems for the search.
Images attached to this comment
H1 ISC
paul.fulda@LIGO.ORG - posted 13:22, Tuesday 22 September 2015 - last comment - 08:16, Monday 12 October 2015(21792)
AS 36 MHz WFS sensing as a function of SR3 RoC (SRC mode matching)

Elli and Stefan showed in aLOG 20827 that the signals measured by AS 36 WFS for SRM and BS alignment appeared to be strongly dependent on the power circulating in the interferometer. This was apparently not seen to be the case in L1. As a result, I've been looking at the AS 36 sensing with a Finesse model (L1300231), to see if this variability is reproducible in simulation, and also to see what other IFO variables can affect this variability. 

In the past when looking for differences between L1 and H1 length sensing (for the SRC in particular), the mode matching of the SRC has come up as a likely candidate. This is mainly because of the relatively large uncertainties in the SR3 mirror RoC combined with the strong dependence of the SRC mode on the SR3 RoC. I thought this would therefore be a good place to start when looking at the alignment sensors at the AS port. I don't expect the SR3 RoC to be very dependent on IFO power, but having a larger SR3 RoC offset (or one in a particular direction) may increase the dependence of the AS WFS signals on the ITM thermal lenses (which are the main IFO variables we typically expect to change with IFO power). This might therefore explain why H1 sees a bigger change in the ASC signals than L1 as the IFOs heat up. 

My first step was to observe the change in AS 36 WFS signals as a function of SR3 RoC. The results for the two DOFs shown in aLOG 20827 (MICH = BS, SRC2 = SRM) are shown in the attached plots. I did not spend much time adjusting Gouy phases or demod phases at the WFS in order to match the experiment, but I did make sure that the Gouy phase difference between WFSA and WFSB was 90deg at the nominal SR3 RoC. In the attached plots we can see that the AS 36 WFS signals are definitely changing with SR3 RoC, in some cases even changing sign (e.g. SRM Yaw to ASA36I/Q and SRM Pitch to ASA36I/Q). It's difficult at this stage to compare very closely with the experimental data shown in aLOG 20827, but at least we can say that from model it's not unexpected that these ASC sensing matrix elements are changing with some IFO mode mismatches. The same plots are available for all alignment DOFs, but that's 22 in total so I'm sparing you all the ones which weren't measured during IFO warm up. 

The next step will be to look at the dependence of the same ASC matrix elements on common ITM thermal lens values, for a few different SR3 RoC offsets. This is where we might be able to see something that explains the difference between L1 and H1 in this respect. (Of course, there may be other effects which contribute here, such as differential ITM lensing, spot position offsets on the WFS, drifting of uncontrolled DOFs when the IFO heats up... but we have to start somewhere). 

Non-image files attached to this report
Comments related to this report
keita.kawabe@LIGO.ORG - 18:33, Tuesday 22 September 2015 (21819)

Can you add a plot of the amplitude and phase of 36MHz signal that is common to all four quadrants when there's no misalignment?

paul.fulda@LIGO.ORG - 10:01, Wednesday 23 September 2015 (21839)

As requested, here are plots of the 36MHz signal that is common to all quadrants at the ASWFSA and ASWFSB locations in the simulation. I also checked whether the "sidebands on sidebands" from the series modulation at the EOM had any influence on the signal that shows up here: apparently it does not make a difference beyond the ~100ppm level. 

Non-image files attached to this comment
paul.fulda@LIGO.ORG - 07:57, Friday 25 September 2015 (21895)

At Daniel's suggestion, I adjusted the overall WFS phases so that the 36MHz bias signal shows up only in the I-phase channels. This was done just by adding the phase shown in the plots in the previous comment to both I and Q detectors in the simulation. I've attached the ASWFS sensing matrix elements for MICH (BS) and SRC2 (SRM) again here with the new demod phase basis. 

**EDIT** When I reran the code to output the sensitivities to WFS spot position (see below) I also output the MICH (BS) and SRC2 (SRM) DOFs again, as well as all the other ASC DOFs. Motivated by some discussion with Keita about why PIT and YAW looked so different, I checked again how different they were. In the outputs from the re-run, PIT and YAW don't look so different now (see attached files with "phased" suffix, now also including SRC1 (SR2) actuation). The PIT plots are the same as previously, but the YAW plots are different to previous and now agree better with PIT plots.

I suspect that the reason for the earlier difference had something to do with the demod phases not having been adjusted from default for YAW signals, but I wasn't yet able to recreate the error. Another possibility is that I just uploaded old plots with the same names by mistake. 

Non-image files attached to this comment
paul.fulda@LIGO.ORG - 14:47, Thursday 24 September 2015 (21899)

To clarify the point of adjusting the WFS demod phases like this, I also added four new alignment DOFs corresponding to spot position on WFSA and WFSB, in ptich and yaw directions. This was done by dithering a steering mirror in the path just before each WFS, and double demodulating at the 36MHz frequency (in I and Q) and then at the dither frequency. The attached plots show what you would expect to see: In each DOF the sensitivity to spot position is all in the I quadrature (first-order sensitivity to spot position due to the 36MHz bias). Naturally, WFSA spot position doesn't show up at WFSB and vice versa, and yaw position doesn't show up in the WFS pitch signal and vice versa. 

For completeness, the yaxis is in units of W/rad tilt of the steering mirror that is being dithered. For WFSA the steering mirror is 0.1m from the WFSA location, and for WFSB the steering mirror is 0.2878m from the WFSB location. We can convert the axes to W/mm spot position or similar from this information, or into W/beam_radius using the fact that the beam spot sizes are at 567µm at WFSA and 146µm at WFSB.

Non-image files attached to this comment
paul.fulda@LIGO.ORG - 10:04, Tuesday 29 September 2015 (22058)

As shown above the 36MHz WFS are sensitive in one quadrature to spot position, due to the constant presence of a 36MHz signal at the WFS. This fact, combined with the possibility of poor spot centering on the WFS due to the effects of "junk" carrier light, is a potential cause of badness in the 36MHz AS WFS loops. Daniel and Keita were interested to know if the spot centering could be improved by using some kind of RF QPD that balances either the 18MHz (or 90MHz) RF signals between quadrants to effectively center the 9MHz (or 45MHz) sideband field, instead of the time averaged sum of all fields (DC centering) that is sensitive to junk carrier light. In Daniel's words, you can think of this as kind of an "RF optical lever".

This brought up the question of which sideband field's spot postion at the WFS changes most when either the BS, SR2 or SRM are actuated.

To answer that question, I:

  • Added 18MHz and 90MHz "WFS" to the Finesse model.
  • Phased these new "WFS" so that all the 18MHz or 90MHz "sum" signals show up in the I-phase (see first two plots).
  • Plotted the new "WFS" responses to BS, SR2 and SRM pitch and yaw (normalized by their "sum" signal), as a function of SR3 RoC (see the rest of the plots).

Some observations from the plots:

  • 90MHz "WFS" show much more response to SRC1 (SR2) and SRC2 (SRM) tilts than 18MHz "WFS". This is somewhat intuitive, because the 45MHz sidebands are resonant in the SRC and the SRC eigenmode may be more sensitive to SR alignments than a beam traced through "single bounce" style.
  • The 90MHz response to SRM/SR2 tilt remain very much in the I phase, with almost no signal in the Q-phase. 
  • 18MHz "WFS" show more response to MICH (BS) than the 90MHz "WFS". This is problably because a BS tilt causes a large coupling of 9MHz HG10/01 mode from the PRC to the SRC relative to the amount of 9MHz HG00 mode already in the SRC (due to high Michelson reflectivity + SRC non-resonance for 9MHz HG00). Since I normalize to the total sideband power, this looks like a bigger response in 18MHz than 90MHz.
  • The 18MHz response to BS tilt is mostly in the Q phase. I'm not sure exactly how to interpret this, but my naive guess is that it's related to the BS tilt being a "differential" mode tilt for the X and Y arms of the small Michelson.
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paul.fulda@LIGO.ORG - 08:16, Monday 12 October 2015 (22432)

I looked again at some of the 2f WFS signals, this time with a linear sweep over alignment offsets rather than a dither transfer function. I attached the results here, with detectors being phased to have the constant signal always in I quadrature. As noted before by Daniel, AS18Q looks like a good signal for MICH sensing, as it is pretty insensitive to beam spot position on the WFS. Since I was looking at larger alignment offsets, I included higher-order modes up to order 6 in the calculation, and all length DOFs were locked. This was for zero SR3 RoC offset, so mode matching is optimal.

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