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Reports until 16:50, Friday 12 June 2015
H1 SEI
hugh.radkins@LIGO.ORG - posted 16:50, Friday 12 June 2015 (19106)
Another look at TerraMon Earthquake arrival predictor

A 6.0mag EQ occurring in Tonga, 8700km distance is a better candidate than the 5.7 EQ in Miyako Japan (7400km) alog 19074, I looked at yesterday for evaluating Terramon.  Slightly further away but enough larger and it makes all the difference.  With the 5.7 EQ, I couldn't be sure there was anything on the seismos, the predictor estimated a velocity of 1.9um/sec for the R-wave.  For the 6.0 EQ, the estimate is 5.

The arrival at the site is clear on the ground STS2--see attached.  I've marked the 3 times from the predictor with thin lines and we clearly see the arrivals.  The P-wave arrival estimate is very good; the plot is 40 minutes long.  The S-wave arrival is 'late' tens of seconds and the surface wave arrives more than 5 minutes sooner than predicted.  These channels should all be calibrated in nm/sec

The second plot shows some GS-13 channels on the BS ISI stage2 and an IFO red power showing if the IFO is fully locked.  The Surface (R-phase) arrival (last arrival) does clearly change the motion on the GS13s--I've marked the apparent arrival of the Surface wave on the plots--the thicker line.  The two fat portions of the GS-13 signal correspond to locked DRMI periods, beginning and middle of plot.  So what can I say...

1) The arrival of this P-wave may have brocken the DRMI although it broke ~20+ seconds after arrival prediction.

2) Clearly, the DRMI can hold lock during the arrival of the S-phase: it arrived some 50 seconds after the middle DRMI lock section began.

3) This IFO lock break was not caused by the surface wave arrival: it broke ~6 minutes before the obvious surface waves hit-marked at thick line.

4) The DRMI did not lock while the Surface Waves had the BS GS13s rung up although later looks show the DRMI may not be soley resposible for the GS13 ring up.  Still need to understand better what the IFO state does to the ISI.  I've chosen BS GS13s as they are not in loop so maybe the most vulnerable.

5) The arrival velocity prediction is within a factor of 2 of that observed.

Images attached to this report
H1 General
jeffrey.bartlett@LIGO.ORG - posted 16:06, Friday 12 June 2015 (19104)
Ops Day Shift Summary
Observation Bit: Commissioning 

08:00 – Take over from TJ – IFO not locked 
08:07 Christina & Karen – First cleaning at End-Y 
08:10 Betsy – Running ETM charging measurements at End-X
08:31 – Beam tube cleaning crew start work on X-Arm
08:50 Christina & Karen – First cleaning at End-Y
08:55 Richard – Cabling work at End-X for ETM charging measurement
09:06 Filiberto – Going to Mid-Y to get cables
09:15 Peter – Transition End-X building to Laser Safe. Lasers are on, tables & viewports secured
09:15 Betsy – Finished with ETM charging measurements
09:30 Filiberto – Back from Mid-Y
09:45 Richard – Back from End-X
09:50 Peter – Transition End-Y building to Laser Safe. Lasers are on, tables & viewports secured 
09:55 GRB Alert – IFO not Locked
09:58 Christina & Karen – Finished with first cleaning at both End Stations
10:43 Robert – Going to End-Y 
10:52 Snack Vendor on site to restock machines
11:20 Robert – Back from End-Y
11:37 Robert – Going to End-Y
11:54 Beam tube cleaning crew break for lunch
12:18 Robert – Back from End-Y
12:53 Beam tube cleaning crew working 
13:43 Beam tune cleaning crew finished 
15:34 Robert – Going beam tube enclosure near Mid-Y
15:55 Robert – Back from Mid-Y
16:05 Hand off to Travis

H1 General (CDS, COC, DAQ, IOO, ISC, PSL, SEI, SUS, SYS, VE)
vernon.sandberg@LIGO.ORG - posted 12:59, Friday 12 June 2015 (19102)
Vent Plan for HAM6 – OMC Black Glass Baffle Install JUNE 2015

HAM6, Vent Master = Hugh Radkins
https://dcc.ligo.org/E1500267

APPROVED work to be done in order of importance:

Install OMC glass stray light baffle assembly (Matt, Calum, Kate, Dan)

Install in-vac accelerometers if available (Matt, Calum, Kate, Dan)

Acoustic coupling measurements (Robert, Hugh)

 

DCC Vent Documents referenced in this plan:

Additional Documentation:

 

SCHEDULE

 

TUES, June 16, 2015

1)    Transition to LASER SAFE

2)    Turn cleanrooms on around HAM6

3)    Clean area, door flange, and cleanrooms

4)    Start staging of supplies and equipment

5)    Confirm dust monitor is working

6)    Lock HEPI

 

WED, June 17, 2015

7)    Confirm purge air is on at HAM6

8)    Vent HAM6

9)    Remove door – Review and follow M1100039 “ Hanford checklist – HAM Door Removal”

10)  Entry chamber checklist items: Pick up floor CC wafers.  Take particle counter measurements and record:

11)  Perform acoustic coupling investigations

12)  SEI Lock ISI 

 

THUR, JUNE 18, 2015

13)  Start payload rework of ISI in prep for rebalancing after OMC baffle installation E1100742

 

FRI, JUNE 19, 2015

14)  Start prep of OMC stray light black glass shroud

 

MON, June 22, 2015

15)  Start install of OMC stray light black glass shroud as per E1500214

16)  Take particle measurements and record:

 

TUE, June 23, 2015

17)  Continue install of OMC baffle 

18)Take particle count measurements and record:

 

WED, June 24, 2015

19)  Continue install of OMC baffle 

20)  Install in-vac accelerometers if available – location TBD

21)  Take particle count measurements and record:

 

THUR, June 25, 2015

22)  Transition to LASER HAZARD

23)  Check alignment of beams in and out of OMC

24)  Transition to LASER SAFE

25)  Final rebalance ISI 

26)  Take particle count measurements and record:

 

FRI, June 26, 2015

27)  SEI test ISI

28)  OM SUS checkouts if needed (DAN)

29)  Chamber closeout – perform applicable exit checklist tasks E1201035.

30)  Put doors on, begin pump down.

 

 

·       Acoustic coupling measurement details (description from Robert):

Robert Schofield is interested in getting some vent time in HAM6 for investigating the resonance that promotes high acoustic coupling (we are only a factor of 2 above having ambient acoustic noise cause features in DARM (https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=18504)).

The plan would be to tap particular structures and monitor the frequency on the GS13s or on a temporarily mounted Class-A compatible accelerometer that we normally use. If we find a candidate, we will damp it using a Class-A compatible temporary damping setup, and measure the damping using an externally mounted shaker. Then we would remove anything that we put in the chamber and turn the chamber over to the next project.





 

H1 General (CDS, COC, DAQ, IOO, ISC, PSL, SEI, SUS, SYS, VE)
vernon.sandberg@LIGO.ORG - posted 12:56, Friday 12 June 2015 (19101)
Vent Plan for BSC10 – H1 ETMY Discharge JUNE 15, 2015

ETMY BSC10, Vent Master = Betsy Weaver
https://dcc.ligo.org/E1500266

APPROVED work to be done in order of importance:

Remove charge from ETMy (Travis, Danny, Gary, Betsy, Kate, Calum, tester Arnaud)

Install VE ports to enable mounting of TMDS and new pumps (Gerardo, Kyle)

Add Krytox to beam diverters on TMS, additional QPD strain relief (Corey, Keita)

 

DCC Vent Documents referenced in this plan:

Additional Documentation:

 

SCHEDULE

FRI-MON early morning time permitting, June 12-15, 2015

1)    Turn cleanrooms on

2)    Clean area, door flange, and cleanroom

3)    Start staging of supplies and equipment

4)    Confirm dust monitor is working

 

MON, June 15, 2015

5)    Transition to LASER SAFE

6)    CDS: Control systems need to be up and running through vent – confirm that normal TUES CDS maint does not interfere with controls.

7)    Confirm purge air is on

8)    Close gate valves

9)    Vent BSC10

10)  Remove door – Review and follow M1100039 “ Hanford checklist – HAM Door Removal”

11)  VE work – installation of 2 ports

 

TUES, June 16, 2015

12)  Entry chamber checklist items: Pick up floor CC wafers.  Take particle counter measurements and record:

13)  Inspect optic – Calum, Kate, Travis, Betsy, Danny, Gary

14)  Transition to LASER HAZARD

15)  Perform TMS work

QPD strain relief, rebalance TS and check alignment

Krytox on BD

Take particle counter measurements and record:

16)  Transition to LASER SAFE

 

WED, June 17th, 2015

17)  Discharge ETMy, noting details of measurements for alog, as per procedure T1500101.  Inspect all EQ stops at TM stage for proximity.  Take particle counter measurements throughout and record:

 

 

18)  SUS ETMy TF tests.

19)Chamber closeout – note, a truncated exit chamber checklist will be executed due to risk of recontamination of charge.

20)  Put door on, start pump down.

 

THUR, June 18, 2015

21)  Perform ESD/OL charge measurements.



 

H1 General (CDS, COC, DAQ, ISC, SUS, SYS, VE)
vernon.sandberg@LIGO.ORG - posted 12:54, Friday 12 June 2015 (19100)
Vent Plan for BSC9 – H1 ETMX Discharge JUNE 15, 2015

ETMX BSC9 - Vent Master = Betsy Weaver
https://dcc.ligo.org/E1500265

APPROVED work to be done in order of importance:

Remove charge from ETMx (Travis, Danny, Gary, Betsy, Kate, Calum, Tester Arnaud)

Install VE ports to enable mounting of TMDS and new pumps (Gerardo, Kyle)

Add Krytox to beam diverters on TMS, additional QPD strain relief (Corey, Keita)

Fix clipping on TMSx (Corey, Keita)

Remove most bias from ETMx (Betsy, Travis or Danny, Gary)

Swap ESD feedthru, time permitting (Richard, Betsy)

Check ETMx PUM UL coil/cable seating, attempt to fix excess noise

as per Bug 929, alog 13047 (Betsy, Travis or Danny, Gary)

 

DCC Vent Documents referenced in this plan:

Additional Documentation:

 

SCHEDULE

FRI-MON early morning permitting, June 12-15, 2015

1)    Turn cleanrooms on

2)    Clean area, door flange, and cleanroom

3)    Start staging of supplies and equipment

4)    Confirm dust monitor is working

 

MON, June 15, 2015

5)    Transition to LASER SAFE

6)    CDS: Control systems need to be up and running through vent – confirm that normal TUES CDS maint does not interfere with controls.

7)    Confirm purge air is on

8)    Close gate valves

9)    Vent BSC9

10)  Remove door – Review and follow M1100039 “ Hanford checklist – HAM Door Removal”

11)  Entry chamber checklist items: Pick up floor CC wafers.  Take particle counter measurements and record:

12)  Inspect optic – Calum, Kate, Travis, Betsy, Danny, Gary

13)  Transition to LASER HAZARD

14)  Start TMS work

QPD strain relief, rebalance TMS and check alignment

Krytox on BD

Possibly fix clipping, recheck alignment

Take particle counter measurements and record:

 

TUES, June 16, 2015

15)  Finish TMS work.  Take particle counter measurements:

16)  Transition to LASER SAFE

17)  VE work – installation of 2 ports

 

WED, June 17, 2015

18)  Debias ETMx via watching pointing on oplev, note removing ~300 counts will be good enough.  Check TFs to ensure full suspension after complete.  Take particle counter measurements:

 

 

 

19)  Check cabling to ETMx L2 UL AOSEM – lots of sensor noise

20)  Swap and reterminate ESD feedthru (maybe – will skip if not enough time to complete)

 

THUR, June 18, 2015

21)  Discharge ETMx, noting details of measurements for alog, as per procedure T1500101.  Inspect all EQ stops at TM stage for proximity.  Take particle counter measurements throughout and record:

22)  SUS ETMx TF test

23)  Chamber closeout – note, a truncated exit chamber checklist will be executed due to risk of recontamination of charge.

24)  Put door on, start pump down.

 

FRI, June 19, 2015

25)  Perform ESD/OL charge measurements.

H1 General (CDS, COC, SEI, SUS, VE)
vernon.sandberg@LIGO.ORG - posted 12:52, Friday 12 June 2015 (19099)
Vent plans for next week and contamination control plans

DCC References


ETMX BSC9
https://dcc.ligo.org/E1500265

ETMY BSC10
https://dcc.ligo.org/E1500266

HAM6
https://dcc.ligo.org/E1500267


Plan for Contamination Control prep for the End Stations vent:

(prepared by Jeff Bartlet and Betsy Weaver)

    1). Friday morning Christina & Karen will do the first cleaning.
    2). Sunday Kyle will turn on the cleanrooms.
    3). Monday morning Jeff will take dust readings near the roof.
    4). Monday morning Christina & Karen will do the second cleaning.
    5). Jeff will monitor the dust counts during the door removals.

H1 ISC (DetChar, ISC)
gabriele.vajente@LIGO.ORG - posted 12:33, Friday 12 June 2015 (19098)
A look at SRCL coupling stationarity

At Sheila request, I look into some of the long locks to see if the coupling of SRCL to DARM is stationary or not. In brief, as far as I can tell, it looks stationary.

I took 5 hours of data from 1118016016, and compute the coherence between DARM and SRCL with 0.1 Hz resolution (first plot). There is some coherence, especially in the region between 20 and 70 Hz. 

Then I computed the coherence and transfer function for short 10 seconds-long periods, with a resolution of 1 Hz. I computed the average and standard deviation of the coherence and the absolute  value of the TF. The second plot shows the coherence and the transfer function: the shaded regions correspond to the standard deviation. It seems to me that there aren't large flutuations as was the case in the past.

Images attached to this report
H1 AOS
jeffrey.bartlett@LIGO.ORG - posted 10:42, Friday 12 June 2015 (19096)
GRB Alert
09:55 Received a GRB alert. Unfortunately LHO was not locked at the time. The GRB alert alarm handler worked well.    
H1 SUS (SYS)
betsy.weaver@LIGO.ORG - posted 10:31, Friday 12 June 2015 - last comment - 11:24, Friday 12 June 2015(19095)
ESD OPLEV charge measurements

Leonid, Betsy

Between yesterday afternoon and this morning, we obtained 4 more good ETMx charge measurements using the optical lever.  Soon to be attached are the trends of the data compared to the previous JAN and APRIL measurements.  Note, as has been stated over the last few days, the LL quadrant of the ESD does not appear healthy, and therefore is the only data point showing a lot of scatter.  This morning Richard went to End X and found that it is shorted.  We suspect it is likely shorted at the feedthru which is still the "old" style.  We plan to swp the feedthru and re-terminate the ESD in-vac cable during next weeks vent - this will bring it up-to-date with the EY ESD and both L1 ESD connections.

Comments related to this report
leonid.prokhorov@LIGO.ORG - 11:24, Friday 12 June 2015 (19097)
ETMX data seems Ok, except LL quad (red points).
ETMY data are saturated and coherence is not too much. We have no response when using Hi-Voltage driver, so we used the low voltages and it is the possible reason for scattering of the data points. 
Images attached to this comment
H1 SEI
jim.warner@LIGO.ORG - posted 09:54, Friday 12 June 2015 (19093)
Matching blends on corner station BSCs and Mich control

On Wednesday night, because we couldn't get much past DRMI due to wind, I tried changing the St1 blend on the BS ISI to match the "windy" blend used on the ITMs. This is a change that the commissioning crew and I have agreed should happen for a while, but we didn't want to disturb the IFO during data taking. Previously the BS was running the 45mhz blends in X&Y, while the ITM's were running the 90mhz blends in the beam direction. Looking at CPS spectra, this meant that the BS was moving a lot more at low frequency than the ITM's (see first attached spectra, BS is red and blue, ITM beam directions are in purple and black). Now that I've switched the BS, it is moving the same as the ITMs. Sheila suggested I look at the ASC signals during the subsequent lock (I left the blends because it was still "windy") to see if this affected the angular control of the IFO. I think at low frequency this made an improvement in MICH (second and third plots, which are ASC yaw and pitch for MICH, green is before, brown after on both). I checked the ground at both times to make sure the input motion was the same and there are differences, but not huge (last plot, green and brown are before, red and blue are after, solid is Y, dashed is X). I don't show Z but it was even more similar.

Images attached to this report
H1 General
jeffrey.bartlett@LIGO.ORG - posted 09:39, Friday 12 June 2015 (19094)
08:30 Meeting Minutes
ER7 will end at 08:00 on Sunday the 14th.
 
The Vent prep work will start Sunday the 14th. 
	Betsy will be the vent coordinator for the End-X and End-Y activities 
	Hugh will be the vent coordinator for the HAM-6 activities
For the vent plan, see aLOG 19085

Beam tube cleaning continues on the X-Arm

Bubba - working on fan repairs in the Mechanical building

Kyle – Prep work for the vent. Goal is to have the doors ready to come off at 12:00 Monday the 15th

Peter – Will transition the end stations to Laser Safe by locking the laser enclosures and verifying all view ports are in place. The laser will not be shut down until Monday when the doors are ready to come off. 
LHO General
thomas.shaffer@LIGO.ORG - posted 07:52, Friday 12 June 2015 (19091)
Ops Report

Since my last post the wind is beinging to pick up again, not anything crazy but gusts above 20mph. I have gotten a few tries very close, at 607 I made it all the way to LOWNOISE_ESD_ETMY but something always seems to break it.

On my last attempt, ETMY and ITMX bounce and roll modes were badly rung up, I managed to damp them below 10^-11 and then as soon as I went to move on it broke lock.

Cleaning crew will be heading into the end stations in a few minutes.

Looks like I failed for tonight. Handing it off to Jeff here in a min.

H1 CDS (DAQ)
david.barker@LIGO.ORG - posted 07:51, Friday 12 June 2015 (19090)
CDS model and DAQ restart report, Thursday 11th June 2015

model restarts logged for Thu 11/Jun/2015

no restarts reported

LHO General
thomas.shaffer@LIGO.ORG - posted 05:10, Friday 12 June 2015 (19089)
Ops Report

The winds died down about 2.5 hours ago but locking has still been unsuccessful. Breaks lock consistantly at REFL_TRANS. I have tried a handful of initial alignments, but with the same results.  I eventually  got past REFL_TRANS by touching PRM a little, but at DRMI_ON_POP I couldn't recover RF90 and RF18, seemed like me touching PR2 made things worse not better like it normally would.

I have a few more ideas I will try before I wake someone up for help.

LHO General
thomas.shaffer@LIGO.ORG - posted 01:55, Friday 12 June 2015 (19088)
Ops Report

Walked on to a very windy site(40+mph winds) and no locking for about 10 hours. Since then, the winds have died down a little but locking is still not happening. I can't get it past DRMI, most often it will get stuck on LOCK_DRMI_1F for a very long time.

Here's to hoping the wind will die down some more.

H1 General
travis.sadecki@LIGO.ORG - posted 00:04, Friday 12 June 2015 (19087)
EVE shift summary

Sheila added a "Brief Version" of the initial alignment procedure to the OPS wiki page.  It is a the top of the IA wiki, above the more verbose version used by the operators up to now.  The idea is that as we become more familiar with locking the IFO, we'll need more of an outline of what to do than a step by step procedure with all the possiblilites spelled out.  She is hoping this will speed up the lock acquisition time and increase the duty cycle.

Struggled with wind all night.  Never got past DRMI 1f.  I did initial alignment several times (for practice and to make sure I wasn't missing something).  Good luck TJ.

Images attached to this report
H1 General
travis.sadecki@LIGO.ORG - posted 20:42, Thursday 11 June 2015 (19086)
EVE mid-shift update

Times UTC

11:00 Leo and Betsy still taking charge measurements

11:03 Robert back from Y arm beam tube enclosure

1:32 Leo done with charge measurements

1:42 returned ETMx and ETMy ESD to nominal states

2:00 started initial alignment

Winds have been mid-20 to low-30 MPH since the start of the shift.  Locking attempts have been unsuccessful, stalling at DRMI 1f so far.  I talked to Gary in the CR at LLO a couple of times now to give him a heads up that we are in for a tough evening.

H1 DetChar (DetChar, ISC)
andrew.lundgren@LIGO.ORG - posted 15:07, Thursday 11 June 2015 - last comment - 14:55, Friday 12 June 2015(19079)
RF beatnote whistles in PRCL
Andy, Jess

Since the 79.2 MHz fixed frequency source was powered off alog, we have not seen any RF beatnote/whistles in DARM at Hanford. We see them in DARM at Livingston, however, but the mechanism is much more complicated than Hanford. The mechanism is not the PSL VCO beating against a fixed frequency.

Since we still see whistles at Hanford in auxiliary channels, we thought we'd revisit them, to see if that gives us clues for L1. We looked at the lock of Jun 11 starting at 6 UTC. We see whistles in PRCL, LSC-MCL, and sometimes in SRCL. Choosing two times, we find that the whistles correspond exactly to a beatnote of the PSL VCO frequency with a fixed frequency of 78.5 MHz (or something within a few hundred Hz of that). So it's the same simple mechanism as before, just against a different frequency.

Attached are plots of two times in PRCL where we predict the exact shape of the whistle, using IMC-F as a proxy for the PSL VCO frequency. SRCL and MCL are similar. We'll go back and check other locks to see if there's any evidence for other frequencies or shifts in the frequency.
Images attached to this report
Comments related to this report
andrew.lundgren@LIGO.ORG - 14:55, Friday 12 June 2015 (19103)
First, a question. Is there something at 34.7 MHz in the center station? I see this frequency on channel SYS-TIMING_C_FO_A_PORT_11_SLAVE_CFC_FREQUENCY_4 - the PSL VCO is number 5 on this fanout. The numerology just about works with 2*34.7+9.1 = 78.5, i.e. that frequency gets doubled and is seen in the 9 MHz demod of the POP and REFL PDs.

Jeff wanted me to also post an expanded version of the whistles story that I had sent by email, so here it is:

To be clear, H1 *did* have whistles in DARM. Once we got the secret decoder ring that told us how to figure out the PSL VCO frequency, we realized that the whistles in DARM were precisely a beatnote of that frequency with 79.2 MHz.

As a result of that investigation, that fixed frequency was turned off, and the whistles in DARM went away. Huge success!

We also see whistles in SRCL, PRCL, and MCL. We haven't been worrying about them, since they're not in DARM. But just yesterday we decided to see if this is also a simple mechanism. As you can see from the alog, it is - at least at the times we've checked, the whistles are a beatnote against something at 78.5 MHz. 

I realized just a little while ago that these channels all come from 9 MHz demods, so maybe the actual frequency we're looking for is actually 69.5 or 87.5. We'll check whether these signals show up on POP or REFL at either LF or 45 MHz.

We know that LLO is a very different mechanism. Not only do they not have this particular fixed oscillator, but these whistles:

1. Come from multiple very different VCO frequencies.
2. The beat frequencies don't seem stable even within a lock.
3. The whistles do not follow the PSL VCO frequency. They are more like 4 to 7 times the VCO frequency. The multiplier doesn't seem stable, and sometimes the whistles seem to decouple a bit from the VCO frequency.
4. The whistles show at LF, 9 MHz, and 45 MHz PDs, on REFL and POP. Different crossings show up in different photodiodes and with different strengths.

So you can see why we want to tackle Hanford first. I was hoping it would be more complicated but tractable, and that would give us a clue to what's going on in L1.

In case you're wondering whether this is academic, the CBC search loves triggering on the whistles at LLO, and it's hard to automatically reject these because they look like linear or quadratic broadband chirps. I think these give the burst search trouble as well.
​
We'll probably spend another day nailing down the case at Hanford, then look over all ER7 to figure out what was going on at L1. 
H1 ISC (SUS)
daniel.hoak@LIGO.ORG - posted 08:19, Wednesday 03 June 2015 - last comment - 18:35, Friday 12 June 2015(18823)
bounce mode Q for ITMX

Dan, Travis

Tonight during our long lock we measured the decay time constant of the ITMX bounce mode.  At 10:10 UTC we set the intent bit to "I solemnly swear I am up to no good" and flipped the sign on the ITMX_M0_DARM_DAMP_V filter bank and let the bounce mode ring up until it was about 3e-14 m/rt[Hz] in the DARM spectrum.  Then, we zeroed the damping gain and let the mode slowly decay over the next few hours.

We measured the mode's Q by fitting the decay curve in two different datasets.  The first dataset is the 16Hz-sampled output of Sheila's new RMS monitors; the ITMX bandpass filter is a 4th-order butterworth with corner frequencies of 9.83 and 9.87Hz (the mode frequency is 9.848Hz, +/- 0.001 Hz).  This data was lowpassed at 1Hz and fit with an exponential curve.

For the second dataset I followed Koji's demodulation recipe from the OMC 'beacon' measurement.  I collected 20 seconds of DELTAL_EXTERNAL_DQ data, every 200 seconds; bandpassed at 9 and 12Hz, demodulated at 9.484Hz, and lowpassed at 2Hz; and collected the median value of the sum of the squares of the demod products.  Some data were neglected on the edges of the 20-sec segment to avoid filter transients.  These every-200-sec datapoints were fit with an exponential curve.

Results attached; the two methods give different results for Q:

RMS channel: 594,000

Demodulated DARM_ERR: 402,000

I fiddled with the data collection parameters and filtering parameters for both fits, but the results were robust.  When varying parameters for each method the results for Q were repeatable within +/- 2,000, this gives some sense of the lower limit on uncertainty of the measurement.  (The discrepancy between the two methods gives a sense of the upper limit...)  Given a choice between the two I think I trust the RMS channel more, the demod path has more moving parts and there could be a subtlety in the filtering that I am overlooking.  The code is attached.

Images attached to this report
Non-image files attached to this report
Comments related to this report
daniel.hoak@LIGO.ORG - 01:19, Thursday 04 June 2015 (18843)

I figured out what was going wrong with the demod measurement - not enough low-passing before the decimation step, the violin modes at ~510Hz were beating against the 256Hz sample rate.  With another layer of anti-aliasing the demod results are in very good agreement with the RMS channel:

RMS channel: 594,400

Demodulated DARM_ERR: 593,800

Images attached to this comment
norna.robertson@LIGO.ORG - 09:39, Friday 05 June 2015 (18890)
To see what we might expect, I took the current GWINC model of suspension thermal noise and did the following.
1) Removed the horizontal thermal noise so I was only plotting vertical.
2) Updated the maraging steel phi to reflect recent  measurement (LLO alog 16740) of Q of UIM blade internal mode of 4 x 10^4. (It is phi of 10^-4, Q 10^4 in the current GWINC). I did this to give better estimate of the vertical noise from higher up the chain.
3) Plotted only around the thermal noise peak and used 1 million points to be sure I resolved it.

Resulting curve is attached. Q looks approx 100K, which is less than what was reported in this log. That is encouraging to me. I know the GWINC model is not quite right - it doesn't reflect tapered shape and FEA results.  However to see a Q in excess of what we predicted in that model is definitely in the right direction.
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angus.bell@LIGO.ORG - 08:26, Friday 12 June 2015 (19092)DetChar, SUS
Here we take the Mathematica model with the parameter set 20150211TMproduction and we look at varying some of the loss parameters to see how the model compares with these measurements. The thermal noise amplitude in the vertical for the vertical bounce mode is tabularised around the resonance and we take the full width at 1/√2 height to calculate the Q (equivalent to ½ height for power spectrum). With the recently measured mechanical loss value for maranging steel blade springs of 2.4 e-5, the Mathematica model predicts a Q of 430,000. This is a little bit lower Q than the measurement here, but at this level the loss of the wires and the silica is starting to have an effect, and so small differences between the model and reality could show up. Turning off the loss in the blade springs altogether only takes the Q to 550,000, so other losses are sharing equally in this regime. The attached Matlab figures shows mechanical loss factor of maraging steel versus predicted bounce mode Q and against total loss plus the resonance as a function of loss.
Angus Giles Ken & Borja
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daniel.hoak@LIGO.ORG - 18:35, Friday 12 June 2015 (19107)SUS

Since there has been some modeling afoot, I wanted to post the statistical error from the fits above, to give a sense of the [statistical] precision on these measurements.  The best-fit Q value and the 67% confidence interval on the two measurements for the bounce mode are:

RMS channel: 594,410  +/-  26

Demodulated DARM_ERR: 594,375  +/-  1590

The data for the measurements are attached.  Note that this is just the statistical error of the fit -- I am not sure what systematics are present that could bias the measurement in one direction or another.  For example, we did not disable the top-stage local damping on ITMX during this measurement, only the DARM_CTRL --> M0 damping that is bandpassed around the bounce mode.  There is also optical lever feedback to L2 in pitch, and ASC feedback to L2 in pitch and yaw from the TRX QPDs (although this is very low bandwidth).  In principle this feedback could act to increase or decrease the observed Q of the mode, although the drive at the bounce mode frequency is probably very small.

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