Following up on Kiwamu's report, here is the summary page for the coherences during the low noise lock:

https://ldas-jobs.ligo.caltech.edu/~gabriele.vajente/bruco_1110961816/

As usual, here is my digest.

In brief: we need MICH/SRCL subtraction, check SRC angular controls, they might be injecting noise, better tune the IMC longitudinal offset if possible

More details:

• At low frequency, below 5 Hz, the most prominent coherence with with SUS-ETMY_M0_DAMP_L_IN1. However, I'm not sure about the origin of this signal, so it might well be that it's just a DARM control signal fed to the top stage.
• Below about 100 Hz and especially below 30 Hz there is a significant coherence with SRC angular signals, in particular: SUS-SR2_M3_LOCK_Y_IN1 and SUS-SRM_M3_LOCK_Y_IN1. My guess is that the SR2 and SRM control signals are very similar, after the implementation of the driving diagonalization 
• MICH is likely the dominant source of noise in the 20-100 Hz region. SRCL is showing large coherence up to 200-300 Hz.
• We still see coherence of SRCL and PRCL signals (and REFL/POP signals) at high frequency, up to kHzs. This is likely due to the IMC longitudinal offset. It seems to me that the situation is slightly better now.
• Coherence is high with IMC angular signals at the 200-400 Hz peaks
• At about 450-500 Hz there is a lot of coherence with ITMX_L2 signals, which I guess is due to the violin mode damping. It might be worth checking if this is re-injecting any noise
• Coherence with intensity noise is not very high, but neither very low. In particular there seems to be a line at 1080 Hz.

P.S. Why are you sending DARM signal into the CARM filter bank?

Commissioners were complaining of excess arm motion, so I've changed the blends on the beamline directions on St1, from the nominal 45mhz blends to 90mhz. To review for those not in the seismic know, this is done by opening the St1 Blend screen from the BSC ISI overview and clicking on the 90mhz blend in the appropriate direction (i.e. X for ETMX, Y for ETMY). Attached screens show overview with circled blend screen, St1 Blend overview, close up the blend X bank. It's not perfectly clear that we need to be using the 45mhz blend or if the 90mhz blend is good enough, but I've been talking to some of the commissioner about maybe doing an assessment when it's convenient.

Installation of the 5 channel ESD filter (D1500113) was completed at EY.  We removed the existing Current limiting box and Bias filter box and replaced it with this new box making sure to reconnect the cables the same as before. We then restored the system and verified voltage could be applied to the ESD driver.

Some notes related to the low noise actions that will happen today.

COIL DRIVER SWITCHING:

 -  Coil driver state description 

 - LLO log entry with description of  switching of actuator states , Evan is looking at Den's script to do the BS actuator switching one coil at the time

MICH/SRCL FEEDFORWARD:

-  Den's talk G1500281, page 11  (also attached): by implementing the feed-forward subtraction actuating on ITM L2, the feedforward paths for both MICH and SRCL are just a constant gain (MICH control is done through BS M2; SRCL is controlled by actuating on SRM M3, so you would need to filter the SRCL correction signal by ~f^2 to actuate on ITM L2, but the optical response goes as 1/f^2)

Following Keita's entry from last week, we are now running with the OMC in a lower-gain state to reduce the length actuation.  First plot attached is a OLTF measurement of the OMC LSC loop while in low noise; the current Guardian settings bring us to the blue curve, with a UGF of about 15Hz.  For the blue and green curves the OMC-LSC_SERVO_GAIN = 10, the red curve had a gain of 60 and a larger boost.  We thought about turning off the boost entirely, which would give us the green curve -- for now we've left it on.

This gave us a good improvement in the upconverted noise around the OMC length dither line, see second figure which is the noise from late Friday night.  (The areas of improvement compared to the blue reference, from Thursday morning, are annotated.)  There is still some upconverted noise, see third figure, and we could reduce the OMC length gain even further. 

To do: estimate the OMC length noise --> DARM coupling using Koji's noise measurements of the intrinsic length noise in the OMC to see how much length noise suppression we need.

PSL Status: 
SysStat: All Green, except VB program offline 
Output power: 31.9w  
Frontend Watch: Green
HPO Watch: Red

PMC:
Locked: 5 days, 23 hours, 1 minutes
Reflected power:    2.2w
Transmitted power: 22.7w 
Total Power:       24.9w 

ISS:
Diffracted power: 7%
Last saturation event: 0 days, 8hours, 6minutes 

FSS:
Locked: 0 days, 0 hours, 7 minutes
Trans PD: 1.6v

SEI - hoping to get a new isolation filter installed on BS stage2.

SUS- nothing to report

CDS - ESD filters will be installed

3IFO - Tuesdat activities will include tagging and bar-coding of TCS and ISC items. Calum will be on site next week. Bubba is continuing to connect piping o containers for N2 purging.

FACILITIES - BTE cleaning is ongoing. Semi-annual lubrication of axial fans for the ventilation sytems will start today with the mid stations and may move to the corner statinos by today. Filters will NOT be removed.

TJ asked me about the BRS this morning, as it was tripping an alarm he had set. When I opened the overview, the numbers were rather large and swinging rapidly (over a minute it was going from -40000 cts to +40000 cts, the transition was a couple seconds. The attached dataviewer trend shows it has bee doing this since the 21st, starting about 15:00 UTC. No clue what happened.

at 8:25 in an attempt to continue the locking sequence that had gotten "stuck" at engatge "ENGAGE_ASC". I selected "DC_READOUT_TRANSITION" to try and get it moving again. THis tripped the SUS RMS watchdogs on the ETMs. I was able to reset ETMY remotely but ETMX seems to need a PUM  coil driver power cycle.

model restarts logged for Sat 21/Mar/2015
2015_03_21 14:42 h1fw0

model restarts logged for Sun 22/Mar/2015
2015_03_22 11:28 h1fw1

both unexpected restarts.

The CDS web server cdswiki was dead this morning, and needed a reboot.  It started normally, no explanation for the failure.

Evan, Lisa

Evan started locking early in the afternoon.

He collected 10+ successful locking sequences in a row without manual adjustment (WOW!), see first plot. 

However, in order to keep the interferometer locked on the operating point, he had to open most of the alignment loops, keeping closed only DHARD and BS. We realized later that it was due to some low frequency oscillation in the CHARD loop, which was triggered by closing the SRM/PRM loops. We decided to keep those loops opened for now.

We then realized that the power build up has been consistently low for a while (second plot - the beginning of the plot corresponds to  March 9 , when a manual adjustment of the ITMs brought the arm power to its maximum ~ 1100 counts), so we decided to go through the initial alignment and re-look at the ITMs position..and an earthquake happened..


P.S.: All of the above happened with DARM locked on RF. 

Dan, Kiwamu,

Some reports from last night and a little bit from today.

(Non stationary behavior of noise floor in 20-100 Hz)

Last night we worked more on the L2 actuation in order to see what noise are below the ESD DAC noise. The recycling gain was as high as 27 and we could smoothly fully lock the interferometer multiple times. After we worked on the OMC trans fluctuation issue (see Dan's report), we transitioned to ETMY from ETMX. The L1 and L2 stages of ETMY were used. As we saw last time (alog 17367), the DARM spectrum showed a non stationary behavior in 20-100 Hz frequency band when small bias and quadrant voltages (< 100 V) were requested. The noise floor was breathing up and down on a time scale of ~10 seconds. We varied the ESD bias voltage to see if there is a "sweet spot", but because of the non stationary noise floor, we were unable to find it. On the other hand, having +380 V on ETMX ESD consistently brought us back to the previous noise floor. So this agrees with the hypothesis that we were limited by the ESD DAC noise. A funny thing is that changing the ETMY ESD bias did not seem to make the noise floor better or worse -- even with +380 or -380 V on the ETMY bias did not bring the noise floor visibly high.

At one point we noticed that the noise floor seemed to be correlated with DHARD YAW -- when the DHARD YAW deviates from the operating point, the noise floor in DARM seemed to go up. So we newly engaged a boost (to suppress 100 mHz variation) in DHARD YAW which seemed to somewhat reduce the non stationary behavior. We need to investigate this issue a bit more.

Here are some time to look at:

• Undisturbed starts at Mar-21-2015 8:30:00 UTC (locked on DC readout with ETMY L1 and L2. ETMX was disabled. Zero DAC request counts on the quadrant and bias on both ETM ESDs. PSL at 10 W.)
• Undisturbed ends at Mat-21-2015 9:00:00 UTC (started messing around. Engaged a boost in DHARD YAW which seemed to somewhat reduce non stationary behavior in 20-100 Hz.)

I attach a DARM spectrum starting at Mar-21-2015 8:30:00 UTC.

(Unable to damp ITMX roll mode)

Today I happened to be in the control room and so started locking. The recycling gain was as low as 24 today even though I went through the initial alignment. After reaching full resonance with RF darm, the roll mode of ITMX at 13.81 Hz was found to be as high as 10^-12 m/sqrtHz in the DARM spectrum again (alog 17293). Initially I tried the same damping setting on ITMX, but I was unable to damp. Then I even tried the minus sign and +-60 deg phase rotators, but did not have a good luck. I wonder if this is related to the fact that the initial alignment today was far from optimum (i.e. low recycling gain).

Dan, Sheila, ITMX

While testing the vioin mode damping tonight, we had an abrupt lockloss, and for a short period my bandpass filter at 501.094Hz was sending noise x120dB into the ITMX L2 coils.  This tripped the coil current watchdog, just like a previous event on ETMY a few weeks ago.  (There are now limiters on all the violin mode damping filters...)

Unlike ETMY we can't reset this watchdog by toggling the RMS Reset epics channel.  Anyone know how to clear this error?

We suspect something in hardware is preventing a software reset.  In the CDS highbay, the SUS Independent Watchdog electronics box has red lights that won't reset when we use the 'Fault Reset' button.

[Stuart A, Jeff K]

As was recently carried-out at LLO (see LLO aLOG entry 16663), during this mornings maintenance period I was able to roll-out independent switching of BSFM M2 stage coil driver BIO filter states, as outlined in ECR E1500045. Hopefully, this should provide commissioners with the capability to smoothly (without breaking lock) transition from acquisition to the low-noise state coil driver, just for the Beamsplitter M2 stage, which was problematic at LLO.

This was implemented as follows:

(1) Svn'd up the common library parts:
/opt/rtcds/userapps/trunk/sus/common/models/
U       STATE_BIO_MASTER.mdl
U       BSFM_MASTER.mdl 

(2) Svn'd up the common MEDM screens:
/opt/rtcds/userapps/trunk/sus/common/medm/bsfm/
U       SUS_CUST_BSFM_OVERVIEW.adl
U       SUS_CUST_BSFM_BIO.adl
U       SUS_CUST_BSFM_M2_EUL2OSEM.adl

(3) Rebuilt, installed and restarted the h1susbs model without incident.

(4) Noticed some white boxes on EUL2OSEM Ramping Matrix MEDM screen, which were site specific to L1, so I fixed these with a $(IFO) substitution and re-committed SUS_CUST_BSFM_M2_EUL2OSEM.adl to the svn.

(5) 4 new EPICS channels are present for the M2 BIO states, as well as an additional 4 for the test coil enable, all which need to be configured:
- All coil enables were set to 1, and the BSFM M2 BIO state was set to the 'default' of 1, as I was informed by Jeff K was being used by commissioners n.b. LLO 'default' acquisition is BIO state 2, and low-noise is BIO state 3 (see LLO aLOG entry 16565). 

Screen-shots below show an example use case for the EUL2OSEM Ramping Matrix. with green indicating a nominal state i.e. set values and current value are equal, red when a new value has been set, and yellow after activating the LOAD MATRIX ramping in over the required duration.   

Finally, I took a new safe SDF snapshot using the same front-end technique I use at LLO:

- Transition the Suspension to a SAFE state via Guardian
- On the SDF_RESTORE MEDM screen available via the Suspension GDS_TP screen select FILE TYPE as "EPICS DB AS SDF" & FILE OPTIONS as "OVERWRITE" then click "SDF SAVE FILE" button to push a SDF snap shot to the target area (which is soft-linked to userapps).
- This safe SDF snapshot was then checked into the userapps svn:
/opt/rtcds/userapps/release/sus/h1/burtfiles/
M        h1susbs_safe.snap

This should close ECR E1500045 and Integration Issue #1003 for LHO.