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Reports until 11:53, Wednesday 08 April 2015
LHO VE
kyle.ryan@LIGO.ORG - posted 11:53, Wednesday 08 April 2015 (17748)
~1140 hrs local -> Adjusted output signal of PT110A -> Started leak detector near HAM5
GV5 spontaneously hard closed -> ~26 hours after 10psi soft-close -> This valve has done this before at 15psi 

A
H1 SEI
hugh.radkins@LIGO.ORG - posted 09:30, Wednesday 08 April 2015 - last comment - 11:43, Wednesday 08 April 2015(17746)
WHAM1 HEPI Sensor etc Condition

Yesterday ran Range of Motion and Linearity Tests.  Took Spectra as well and then ran TFs overnight.

For the ROM, which evaluates based on the free hang position, not from zero, H1- was limited to 0.8mm.  This is not necessarily running into anything as the sensor (IPS) was just running into the sensor max.  In other words, the sensor position could be adjusted (along with the cartesian Isolated-to position) if the true centering of the Actuator could tolerate that.  Also for V4-, it was hitting something and the range was limited to 0.7mm.  I have not investigated this.

The linearity tests are possibly within spec (don't have a number of what that should be) but here V4 is also an outlier having a lesser slope than the others.  See attached, V3 also looks weird here but the range of motion is fine for V3 which drives further than the linearity test so if it is running into something it must be compliant.

The new L4C looks good though.  Attached are Spectra from last October and Yesterday.  I collected Isolated spectra yesterday and the data from October is 'Undamped' but the improved health of this L4C is apparent.  I can get Isolated from a few days ago before the swap.

TFs to come.

Images attached to this report
Comments related to this report
hugh.radkins@LIGO.ORG - 11:43, Wednesday 08 April 2015 (17747)

Re Linearity & ROM.  Looked at V3 and V4.  From the free hanging position, it appears the platform is hanging low at V4 and the Actuator Plate will run into the Bellows Shield hence the low V4- ROM.  To fix this we'd have to get on the Big DSCW Springs and raise the platform.  I think the install process needs to change to ultimately address this: after Initial Alignment, run ROM and excitations etc. letting the platform settle to its ultimate resting place.  Raise the platform with the Springs and repeat until it sits where we want.

For V3, remember, the slope on the Linearity plot appears to roll over at the positive side of the curve.  I checked and although V3 also hangs low like V4, this is a positive (up) issue.  Looking closely, the top of the Foot at the back rib looked pretty close to the notch in the Rear Caging Brace.  For a vertical motion, this contact would be a glancing impact and the Foot could shift sideways and get further vertical displacement.  I raised the Rear Caging Brace and reran the Linearity measurement.  See attached and compare with the above plot.  The slope is restored and shows no roll over.  Nice when something works as expected.

Given the magnitude of these tests and the actual motion we need for ops, these interferences would not have impacted performance.  However, we could over time possibly walk the platforms to a point where it does matter.

Images attached to this comment
H1 DAQ
daniel.sigg@LIGO.ORG - posted 09:23, Wednesday 08 April 2015 (17745)
Fun with model restarts

I came in early to finish the model changes started yesterday. First, I restarted the LSC front-end. This failed with the error message "-1 Operation no permitted". Being stumped, I decided to restart the DAQ to update the channel list for the end stations ALS systems. This worked fine as far as the DAQ and the ALS systems were concerned. However, it also crashed sush2b with an IRIG-B error! At this point the DAQ overview screen looked like a Christmas tree. I am amazed.

H1 CDS (SUS)
james.batch@LIGO.ORG - posted 09:15, Wednesday 08 April 2015 (17744)
Restarted h1lsc, h1susim, h1iopsush2b, and streams on h1susauxb123
The h1lsc model would not restart and needed to have the burt restore button pushed (which is no longer on the GDS_TP screen).  

The data concentrator had been restarted earlier, which caused the mx_stream to fail on h1susauxb123. Restarted the streamers on the front end and the data was restored.

There was a large IRIG-B timing error on h1iopsush2b, so I restarted the models on the h1sush2b computer.
LHO General
patrick.thomas@LIGO.ORG - posted 08:48, Wednesday 08 April 2015 (17743)
Morning meeting summary
HAM6 in chamber work
Check grounding and fast shutter, transfer functions

SEI
HAM1 L4Cs replaced, looking at transfer functions
New isolation filters tested, not ready to leave in

CDS
LTS humidity sensors cabling

Jeff B. moving optics into desiccant cabinet
H1 CDS (DAQ)
david.barker@LIGO.ORG - posted 08:30, Wednesday 08 April 2015 (17742)
CDS maintenance Summary

RFM errors investigation

Jim, Dave:

during the Ham6 vent, we further investigated the LSC RFM receiving errors. We remotely bypassed several nodes in the Y-Arm RFM loop (except for the h1iscex sender and the h1lsc0 receiver). We found that the Y-Arm errors disappeared when h1asc0 was bypassed. We then bypassed h1asc0 on the X-Arm loop and ran for 50 minutes without a single LSC receive error (error rate is typically 50 per hour).

Bottom line, h1asc0 is somehow causing the ISC to LSC errors. We found that of the 16 RFM channels the ASC is sending per arm, only 8 have receivers. Clearly we should start by removing the 8 obsolete senders (per arm, 16 in total). We have scheduled this with Daniel for such time as when the DAQ can be restarted.

We are investigating this further on the DTS.

X1 DTS
david.barker@LIGO.ORG - posted 08:19, Wednesday 08 April 2015 (17740)
x1iscex front end added to DTS

Jim and Dave:

we added a new front end to the DTS, the x1iscex system. This completes all nodes on the DTS X-Arm RFM IPC loop. We will now see if we can reproduce the H1 LSC RFM errors on the test stand.

the x1iscex will also be used to make noise measurements using the new IO Chassis DC power supply board. For this purpose, an AA-Chassis was installed above it.

H1 ISC
koji.arai@LIGO.ORG - posted 07:44, Wednesday 08 April 2015 - last comment - 15:07, Wednesday 08 April 2015(17738)
HAM6 Vent ISC work

[Dan, Ross, Corey, Keita, Koji]

The ISC work for HAM6 was done mostly along with the procedure in this ALOG entry 17631

We first started from the steps which does not require the laser beam, and then moved on the steps with the beam.


Visual inspection of the fast shutter mirror

- The mirror on the fast shutter was checked. We confirmed that the mirror is well intact and did not show any sign of delamination.
i.e. The toaster does not seem to fly.

Beam diverter lubrication with Krytox LVP

- The two beam diverters (BDs) were removed from the table after marking their positions with dog clamps.
  Corey applied Krytox along with the procedure by Matt H.

- The additional mass is added to the moving element to ensure each BD flips to the ends of the moving range.

- The BDs were returned to the HAM6 table. Their positions were aligned in the later process.

- The motion of the BDs were confirmed with EPICS I/F.

QPD cable strain relief

- QPD cable strain relieves (D1101910&D1101911) were installed to AS_C/OMCR_A/OMCR_B DCQPDs.
Now there is no chance for their ferrules to touch metal parts around there.

Transition to Laser Hazard

- The input power at this point was ~3W.

Initial alignment

- Aligned the beam on the AS_C QPD with SR2
- Aligned the beam on the OMC QPDs
- Confirmed the beam is on the WFS QPDs

OM1 mirror replacement

- The hIgh transmission (T=5%) OM1 mirror was removed from the TT suspension.
- The new OM1 mirror with T=800ppm (E1100056 Type02 s/n15) was installed.

- The old and new mirrors were supposed to have the same dimensions. However, the mirror holder faced down significantly.
  This was actually the same situation as it was seen in LLO.

- I don't want to describe the detail of the TT story. In the end, the clamp units on the mirror mounts were shifted towards the face.
  This let us recover the proper alignment of the OM1.

- The alignment slider values were coarsely debiased by aligning the TT suspension structure.
- All the BOSEMs indicated that the flags are too deep inside the BOSEMs. This was fixed.
- We actually debiased the suspension at the end of the procedure again.

- The AS AIR/AS_C pathes were aligned. The beam was faint and we decided to inclease the input power to the IMC up to 7W.
The beam was aligned to hit the AS_AIR periscope mirror. The AS_AIR beam on the ISCT6 table should be aligned.

- The BD for AS_AIR was aligned. The reflection of the BS was also aligned.

90:10 BS insertion

- A 90:10 BS (E1500009) was installed in the OMCR path. In order to accommodate this new optic, the steering mirror just in front of this BS
was moved back towards the OMC. We made sure the beam is hitting the OMCR periscope mirror. This changes the angle of the beam on
the ISCT6 table. Therefore, the OMCR beam on the ISCT6 table should be aligned.
- A V-beamdump is installed for the reflected beam of this BS.
- The OMCR QPD sled path was realigned.

Power budget

- The optical powers at the various places on the table were measured. Also the AS_AIR and OMCR powers on the ISCT6 were measured.
These measurements allows us to estimate the optical powers in the chamber using the ones on the ISCT6 table.

Double checking

- The optical path was traced from the septem windows to the OMC, AS_AIR, AS_WFS, OMCR paths.

- The shutter mirror was lifted manually to see if the reflected beam is still properly dumped.

- Took photos of the table for updating the table layout.

Contamination control

- At the end, the partice level was checked in the HEPA booth. It shows 0 counts for all particle sizes.


Still to do before closing the door

- It should be checked if the picomotors and fast shutter are still working.

- It should be checked if there is any ground shorting.
Note that BDs are shorted on the table. Also the cable harness on the OMC shorts the shields of the OMC QPD/DCPD cables at the OMC breadboard.

Comments related to this report
keita.kawabe@LIGO.ORG - 08:23, Wednesday 08 April 2015 (17741)

Regarding 90:10 BS, note that a thicker 2" Siskiyou lens holder instead of mirror holder was used, as was the case at LLO.

evan.hall@LIGO.ORG - 15:07, Wednesday 08 April 2015 (17755)

Since we have 36 dB less power on the ASAIR diodes, I have compensated for this in the ASAIR RF filter modules.

ASAIR_RF_90 had 18 dB of analog whitening gain. It now is maxed out at 45 dB, and there is 9 dB of gain inserted into FM8.

ASAIR_RF_45 had 6 dB of analog whitening gain. It now has 42 dB of analog whitening gain. Since we are going to remove the ND filter in front of the PD, this will have to be redone.

In both cases I also retuned the dark offsets.

H1 AOS (TCS)
greg.grabeel@LIGO.ORG - posted 00:38, Wednesday 08 April 2015 (17737)
TCS X and Y CO2 table work
The malfunctioning RF driver on the TCS Y table was swapped today. Unit 210020-20710 was replaced by 208160-20510 which is now coupled with the 20306-204190 laser. A quick test showed > 50W while in pulse width mode. 

TCS X table had the AOM swapped to the Kepco power supply. Both AOMs are now powered from the Kepco power supply and are running at 25V. The X AOM continued to show a fault after it had been turned on, but unplugging and replugging it at the feedthrough cleared the problem  A quick check showed no significant changes in alignment. I'd like to make sure the rotation stage is still behaving like before. 

The laser power feedthrough on X was also bypassed like on the Y table from last week's work.
Images attached to this report
H1 ISC
koji.arai@LIGO.ORG - posted 00:03, Wednesday 08 April 2015 (17736)
HAM6 Vent ISC work (almost) done

Dan & Koji

We've finished most of the ISC work in the HAM6 chamber. Details are coming later.

The left-over ISC items are:
1) Cable ground short inspection
2) Checking  functionarity of the picomotors and fast shutter.

These should be done tomorrow before closing the door.

The PSL rotation stage was energized again.
The laser power incident on the IMC was returned to 2.8W.
The PSL laser shutter between PSL and HAM1 is closed.
But technically to say, the LVEA is still laser hazard until it is declared to be safe.

H1 SEI (DetChar, ISC, SEI)
jeffrey.kissel@LIGO.ORG - posted 17:40, Tuesday 07 April 2015 (17729)
H1 ISI ETMX Configuration Comparison with Wind at 10-20 [mph]
J. Kissel, J. Warner

In summary -- in the "windy" configuration that includes the BRS (described below) we can achieve better performance, as measured by the local T240s, than when just switching to 90 [mHz] blends at almost all frequencies. This is especially true in the 20 to 80 [mHz] band, where ALS lock acquisition is limited by end-station VCO range. In this study, the wind is a consistent 10-20 [mph]. Not necessarily "high," so we'll still need more data during those conditions to confirm if there's an upper limit to performance improvement, i.e. if / when the BRS saturates and it's corrective signal becomes detrimental to the platform motion.

Discussion & Details
---------

I took some more data with H1 ISI ETMX in several configurations, looking to supplement Krishna's data on the performance impact of the BRS during 5-10 [mph] winds (see LHO aLOG 16465), this time with a confirmed consistent wind of 10-20 [mph] and a more-typical ground translation from the microseism. Further, since Krishna's study, Jim, Hugh, and I have made significant improvements to the BSC-ISI performance from beating down unexpected noise sources (see e.g. LHO aLOG 17702, Integration Issue 1004, LHO aLOG 16818, etc.) the results are considerably less confusing. This also serves to show what we get when we'll eventually automate switching between these configurations (see LHO aLOG 17639).

I compare three different configurations of the ISI's ST1 X DOF sensor correction and blend filters, over a short, 2-hour window where X-End wind has a consistent, minute-trend, mean of 10 [mph], and a consistent, minute-trend, max of 15-20 [mph]. The three configurations of the ISI's ST1 X DOF are as follows:
(1) Nominal -- 45 mHz blend; DeRosa's 0.43 Hz only, narrow-band, sensor correction (NB SC); GND T240 alone used for sensor correction, no BRS
(2) Windy when BRS doesn't work -- 90 mHz blend; DeRosa's 0.43 Hz only sensor correction (NB SC); GND T240 alone used for sensor correction, no BRS
(3) Windy with a functional BRS -- 90 mHz blend; Mittleman's broad-band, low-frequency, sensor correction (BBLF SC); Tilt is subtracted from the GND T240 with the BRS, and the super sensor is used for sensor correction.

Recall that plots comparing the X direction 45 and 90 mHz blend filters can be found in LHO aLOG 17595.

Comments:
- Look at 2015-04-07_H1ISIETMX_SensorBlend_Config_Comp_X.pdf first. This shows the X direction.
   PG1: Performance of configuration (1) has a significant amount of gain peaking (about a factor of 4) from the 45 mHz displacement sensor blend filter from 25 to 80 [mHz], as expected. This the sacrifice made to get the awesome performance between 0.1 [Hz] and 0.4 [Hz]. When we move the blend frequency up to 90 mHz, to configuration (2), the factor-of-four gain peaking moves up as well to 40 to 120 [mHz]. However, this shift up an overall RMS displacement reduction of about a factor of 5. In doing so, we lose a factor of 10 in performance between 0.1 [Hz] and 0.4 [Hz], and also some loss between 1 to 10 [Hz]. In configuration (3), The BRS+STS super sensor coupled with the broad-band sensor correction allows us to claw some of that performance back, *and* reduce the gain peaking to essentially zero.
        The trouble with interpreting ASDs is that the contain in coherent noise of the platform as well. Of course (save where the measurement is readout noise limited) this is the real motion of the platform, but it's less easy to see what's going on. Hence, 
   PG2: Comparing the coherent, linear transfer functions in each state, we see much more clearly what's going on: configuration (1) has x4-5 gain peaking between 25 and 80 [mHz]. One might even argue that we could tune the narrow-band sensor correction better, because it's performance is best at 0.35 [Hz] instead of 0.43 [Hz]. When we switch to configuration (2), the performance follows the change in displacement sensor filter, as expected. Finally, in configuration (3) we're basically blending in the tilt-free, inertial ground super sensor at 20-30 [mHz]. So we win back all of the noise introduced when the noisy displacement sensor is used out to high frequency, and in the 0.1 to 0.4 [Hz] band, we're only at most a factor of 2 to 3 away from the best nominal configuration. In fact, the performance is *even* better than the nominal configuration between 0.4 and 2 [Hz].

- Now look at 2015-04-07_H1ISIETMX_SensorBlend_Config_Comp_X_SensCorrSignal_ASD.pdf
    Unfortunately, we don't record the pre-sensor corrected, calibrated, Cartesian displacement sensors. In fact, there isn't even a test point for these channels. As such, there isn't a good way to compare the performance of the NB SC filter and the BBLF SC filter, using the CPS. As a proxy, I took a look at the output of the sensor correction path, just *before* it's subtracted from the CPS. The two signals should be equivalent to the CPS in the band that we use the sensor correction modulo a sign which doesn't affect the ASD. We can see that Configuration (3) has the *least* amount of sensor correction request below 0.1 [Hz], because the BRS has subtracted out the tilt from the GND T240 of this region.

- 2015-04-07_H1ISIETMX_SensorBlend_Config_Comp_RY.pdf shows the RY direction.
    PG1: Shown merely to demonstrate that the ground tilt ASD was essentially the same for all three of these measurement configurations, as was the residual tilt of ST1.
    PG2&3: Shown because I can -- the transfer function between ground tilt and platform tilt. Because we've reduced the HEPI pump servo noise (II 1004) we see now that the platform's RY motion is limited by and coherent with ground RY below 0.2 [Hz] as originally expected. Good!
    PG4&5: This is the transfer function between ground tilt (RY) and platform translation (X). It's pretty scary, but I'm not sure I trust it. I'm not at all confident that DTT is able to handle calibrating the transfer function between these two correctly. Anyways, I include it, again, because I can. Aside from the magnitude, pg 5 does clearly show that platform X is coherent with ground tilt.

This data set settles the question of whether the configuration (3) is better than (1) in 10-20 [mph] winds, especially if just going to configuration (2) during these kinds of winds is enough to lock the IFO. Now we just need to perform the same study at even higher winds. Looks like this Saturday may be a good candidate!

The template and all of the plots for this entry live under
/ligo/svncommon/SeiSVN/seismic/BSC-ISI/H1/ETMX/Data/2015-04-07*
Images attached to this report
Non-image files attached to this report
H1 AOS
eleanor.king@LIGO.ORG - posted 17:21, Tuesday 07 April 2015 (17734)
HWS alignment at end stations

Nutsinee, Aidan, Elli

Today we worked at both end-X and end-Y, working on moving the HWS camera to the image plane of the ETMs.  In the morning we were at EY and in the afternoon we were at EX.  We were planning to make only a small adjustment to the HWS location, but after taking some measurements we decided that we will have make bigger changes to the HWS path.  Most likely we will move the lenses on the HWS path.We have measured the current optic locations and we plan to move the HWS lenses tomorrow.

 

Details:

We located the image plane by applying a 0.05mHz, 2 microradian yaw to H1:SUS-ETMX/Y_M0_OPTICALIGN_Y_EXC .  We took 200 images with the HWS camera at .5 second intervals.  The images are located in /ligo/home/eleanor.king/HWS_Pictures/HWS_image_plane_X and /ligo/home/eleanor.king/HWS_Pictures/HWS_image_plane_Y.   We plotted the centroid of the beam vs time the images using the script 'find_image_plane2.m', which is attached.  We need to move the camera to where the centroid of the beam moves by and amplitude less than 0.2 pixels.  With the current lens locations, we would need to move the cameras by ~0.5m, which we don't have the room to do.  Instead we plan to move the lenses on the HWS table to move the conjugate plane.

Curernt HWS optic locations:

EY table layout with optics names as per https://dcc.ligo.org/D1400241
-All units are in cm.
-M3 was measured from the back face of the optic.
The distances between the optics at EY are:
BS1:M1    10.7 (cm)
M1:L1       7.7
L1:L2        61.0
L2:M2      12.3
M2:M3     9.6    
M3:M4     82.5
M4:M5     6.3
M5:L3      8.5
L3:M6      55.9
M6:CCD1 33.9

----------------------------------------------------

EX table layout is not the same as that in https://dcc.ligo.org/D1201448.
-  The lenses L1 and L2 are in different positions.  L1 is between M1 and L2, L2 is between L1 and M2, L3 is as drawn in D1201448.
-All units are in cm.
-BS1 is measured from the front face.  BS2 is measured from the back face.  M5 is measured from the front face.
The distances between the optics at EX are:
ALS-M11:BS1 6.5 (cm)
BS1:M1      32.7
M1:L1        10.6
L1:L2          62.6
L2:M2         20.1
M2:BS2      11.3
BS2:L3        62.9
L3:M3         11.2
M3:M4        10.2
M4:M5        63.3
M5:M6        31.1
M6:M7        9.9
M7:CCD1    11.5

Non-image files attached to this report
H1 ISC
daniel.sigg@LIGO.ORG - posted 17:09, Tuesday 07 April 2015 (17727)
Slow controls software update

The tidal code has been changed by adding a delay trigger to the red lock trigger and by requiring a lock condition to go into the red lock state. This should avoid the problem where the tidal state machine keeps switching states upon cavity flashes after a lock loss.

Prepared a change in the LSC/IMC model to enable the common tidal from MC_F using a switch after the MC_F filter module. This way we can switch on the common tidal feedback independently when the tidal state machine is in the transition state.

New slow controls code was loaded into the remaining EtherCAT systems to support automatic screen generation.

A new feature was added to the auxiliary library to allow momentary switching of its binary outputs. This has been implemented for the ESD power on/off channel to avoid the problem with the 4 second auto-reset when the channel was left in the high state by mistake. A high transition will now generate a one second long pulse which returns to low automatically.

LHO VE
bubba.gateley@LIGO.ORG - posted 16:42, Tuesday 07 April 2015 (17732)
Beam Tube Washing
Scott L. Ed P. Chris S.

Relocated lights and equipment to X-1-8 double doors north towards mid station yesterday.

Tested 8 sections as opposed to the normal 6 as this is the last and somewhat longer section from the double doors to mid station. Vacuumed beam tube supports and cleaned those same floor areas. Heavily soiled areas.  Able to clean only 6 meters yesterday and 64 meters of tube today.
Beam tube pressures monitored by control room operator during cleaning operations.  
LHO VE
kyle.ryan@LIGO.ORG - posted 16:38, Tuesday 07 April 2015 (17733)
HAM6 vent
(Kyle, Gerardo, Bubba, Jeff B., Betsy, Richard M.)

Kyle -> Soft-closed GV5 and GV7 

Kyle, Gerardo -> Connected pump cart to HAM5 annulus -> Vented HAM5/6 annulus volume 

Kyle, Gerardo -> Vented HAM6

Richard M. -> Troubleshot and fixed cabling to PT110A 

Kyle, Gerardo, Bubba, Jeff B., Betsy -> Removed HAM6 East door
H1 General
travis.sadecki@LIGO.ORG - posted 16:00, Tuesday 07 April 2015 (17726)
OPS Shift Summary

8:05 Kyle closing gate valves in vertex

8:10 Gerardo to LVEA assisting Kyle

8:12 Jim loading new isolation filters on HAM 2,3,4

8:21 Fil to EX, EY working on OpLev wiring

8:25 Vern and Richard to LVEA

8:28 Doug to LVEA OpLev test bed, moving to EX

8:33 Elli to EY HWS work

8:33 Jeff B to LVEA dessicant cabinet work

8:35 Hugh to HAM1 for L4C work

8:48 HAM6 picomotors shutdown for vent

9:20 Peter K to H1 PSL enclosure with Corey

9:31 Richard to LVEA checking Pirani gauge

9:33 Jeff B done

9:43 Vern out

9:49 Porta potty service on site

9:49 Betsy to LVEA

10:02 Jeff B to HAM6

10:13 Corey out

10:20 Hanford FD to LVEA

10:27 Cris and Karn to ends

10:52 Koji, Dan, Ross to HAM6

10:54 OMC and OMs to SAFE, HAM6 ISI to OFFLINE

10:55 PR3 light pipe install and align

11:01 Andres to West bay

11:05 Peter K done in H1 PSL, moving to H2 PSL

11:08 Andres done

11:37 Peter K done

11:58 Doug and Jason done at PR3 OpLev

12:03 Hugh done

12:05 HAM6 open for business

12:07 Elli done at EY

12:20 Dan, Koji, Keita, Corey to HAM6

12:37 Fil installing dewpoint cabling LVEA

12:47 Elli to EX for HWS work

12:58 Betsy to HAM6

13:08 Richard to LVEA

13:09 Betsy out

13:33 Sudarshan to EY for PEM work

13:40 Jeff B to HAM6

14:30 Doug and Jason to EY for OpLev work

14:45 Fil to LVEA retreiving tools

H1 AOS
jason.oberling@LIGO.ORG - posted 12:28, Tuesday 07 April 2015 - last comment - 16:27, Tuesday 07 April 2015(17722)
Optical Lever Maintenance

D. Cook, J. Oberling

ETMx

We moved the recently tweaked oplev laser (SN 197) from our testbed at HAM3 to ETMx.  This laser will thermally stabilize over the course of the afternoon, then we will start monitoring it to perform, if necessary, the final tweaks.  While we were at End X we installed the 50 lb. lead damper assembly onto the ETMx receiver pylon.  Due to the laser swap and the damper install, the oplev needed to be realigned, so we did that as well.

PR3

At the request of commissioners we realigned the PR3 optical lever.  While out there, we installed the light pipe support assembly (see attached picture) to keep the light pipe on the receiver from sagging.

Images attached to this report
Comments related to this report
sheila.dwyer@LIGO.ORG - 12:53, Tuesday 07 April 2015 (17724)

great!  that will make life easier.

jason.oberling@LIGO.ORG - 16:27, Tuesday 07 April 2015 (17731)

ETMy

We also finished tweaking another laser and considering the ongoing HAM6 work, and with commissioner approval, installed that in ETMy (SN 138-2).  We also installed the lead damper (see attached picture) and realigned the oplev (like ETMx, the laser swap and the damper installation changed the alignment of the oplev).  We will monitor this one as well as ETMx to see if we need to make any small tweaks to the laser power to maintain stability.

Images attached to this comment
H1 ISC (PSL)
evan.hall@LIGO.ORG - posted 03:45, Tuesday 07 April 2015 - last comment - 16:16, Tuesday 07 April 2015(17712)
35 kHz CARM UGF

Sheila, Evan

Summary

By increasing the gains on the common-mode and IMC boards, we pushed the CARM UGF up to 35 kHz and saw a reduction in the high-frequency noise floor of DARM.

Some further loop tuning is required to make this viable as a long-term change.

Details

Based on Sheila's earlier measurement of the IMC OLTF, we felt it was safe to increase the gain at the IMC error point (both the error signal and the AO) by 2 dB. Then we increased the CARM gain by 6 dB (using the IN2 slider on the CM board). These changes gave a UGF of 35 kHz with 25° of phase. [See plot and zip file.]

This gave a noticeable improvement in the frequency noise as seen by REFL_A 9I, which is currently the out-of-loop CARM sensor. [See plot.]

Consequently, there was a small but noticeable improvement in the high-frequency noise floor of the DARM spectrum. [See plot with red and gold, taken while still feeding DARM back to ETMX.] In the full locking configuration, the noise floor now touches the GWINC curve from 300 Hz to 3 kHz [See plot with purple.]

Obviously this CARM phase margin is quite thin, and we don't want to run like this as a matter of course. In order to win more phase, perhaps we need to look at the IMC loop and the FSS. Peter K last measured the FSS UGF to be 200 kHz with 30° of phase (on the low end of the phase bubble). In comparison, at LLO the FSS UGF is 500 kHz with 60° of phase.

More details

Nominal gains are 0 dB for CM IN2 [the CARM error signal], 5 dB for MC IN1 [the IMC error signal], and 0 dB for MC IN2 [the AO signal].

The gains used here are 6 dB for CM IN2, 7 dB for MC IN1, and 2 dB for MC IN2.

At the start of the evening, REFL_A 9I had no whitening filters engaged and 0 dB of whitening gain. It now has 1 stage of whitening, 21 dB of gain and a −21 dB filter engaged in FM4 (I and Q). There is some saturation during the lock acquisition, but in full lock the I and Q inputs are now at least a factor of 5 in ASD above the ADC noise floor everywhere. I also changed the digital phase rotation from 77° to 90°, as was hinted at earlier.

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Comments related to this report
evan.hall@LIGO.ORG - 04:18, Tuesday 07 April 2015 (17714)

The above work was done as usual with CARM controlled by REFLAIR.

However, in-vac REFL will also work for controlling CARM. The following screenshot shows the settings required and an OLTF of the CARM loop.

This has the unfortunate effect of making the DARM spectrum worse at high frequencies; a broad lump appears between 2 and 5 kHz. More investigation required.

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evan.hall@LIGO.ORG - 16:16, Tuesday 07 April 2015 (17730)

A noise budget of this morning's lock is attached, and includes intensity and frequency noise. For the coupling TFs I used what Koji and I measured previously.

This isn't our most sensitive lock in terms of inspiral range, in part because of the bump around 100 Hz. This is new as of a few days ago, and we are hoping it's just the HAM6 cleanroom.

The intensity noise is taken from IM4 trans, and the frequency noise from REFL_A 9I.

From the spectra shown in the parent entry, the noise in REFL_A 9I from 40 Hz to 2 kHz is mostly flat, and does not scale with CARM loop gain. It could be that the CARM loop is limited by sensor noise (e.g., from REFLAIR_A), or that it is just masked by noise in REFL_A. So the frequency noise trace in this plot should be taken as an upper limit between 40 Hz and 2 kHz.

In the future, when measuring intensity noise we should perhaps do what Alexa suggested and use the ISS second loop PD array as an out-of-loop sensor, since it is acquired faster than IM4 trans.

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