This is a summary of the thermal test we did yesterday (alog 20146) in which we changed the power of the CO2 laser for ITMX as a part of noise coupling study.

We were interested in four quantities as listed below together with some observations.

• Frequency noise coupling can be lowered by a factor of 10
• Intensity noise coupling does not dramatically improve. A factor of 2-ish at best if we tune the CO2X power.
• SRCL coupling was not sensitive to the CO2X power. It changed by 30% or so.
• DARM coupled cavity pole frequency was stable throughout the test. It seems insensitive to the CO2X power.

Here are some plots. All of them are pltos of time series data starting at 2015-08-02 22:35:00 UTC for 8 hours. The interferometer was locked at the first 10 minutes of the plots and kept locked for more than 8 hours. Our thermal test start at around t = 2.7 hours. The time stamps for important activities are written in Evan's alog (alog 20146).

[1 st plot]

This plot is meant for showing how the noise couplings evolved during the test. The middle panel shows the measured coupling coefficients using the LSC front end demodulators. The signals are measured as in- and q-phases which are demodulated with cosine and sine local oscillators respectively. Since the excitation were done by independent awgs, the i- and q- phase don't mean anything except that they are 90 deg apart. Meaningful data start several 10 minutes before the CO2 power was changed. The intensity noise coupling shows an abrupt change at around t = 5.2 hours because Stefan closed the 2nd loop to try out a configuration for the maximum intensity suppression (alog 20155). Similarly, the SRCL excitation was disabled at around t = 6.5 hours resulting in a sharp drop in the measured I and Q signals. The bottom panel shows quadratic sum of the I and Q signals for frequency, intensity and SRCL couplings. The definition of the quadratic sum here is sqrt( I^2 + Q^2) in order to show the absolute magnitude of the couplings.

The in- and q-phase signals of the frequency noise coupling experienced a zero crossing -- but at different times as shown in the middle panel. After the frequency noise was found to be overshot, Evan and Stefan tuned the CO2 power to 410 mW in order to bring the frequency noise back to a point where the coupling is minimized. This tuning attempt seems to be successful because the coupling settled to a small number and roughly a factor of 10 smaller than the one when we started.

Intensity noise coupling appeared to be sensitive to the thermal tuning as well. However it did not show a zero crossing. As far as the tested CO2 power range is concerned, the best reduction in the coupling was only a factor of 2, and the minimum point does not coincide with the one for frequency noise.

SRCL coupling initially appeared to be responsible to the thermal tuning, however it then behaved as if it was not as sensitive as before any more for some reason. In any case, the variation was only 30% or throughout the test.

[2nd plot]

This plot shows cavity pole frequency and arms' transmitted light in time series. As shown the cavity did not show a obvious change and in fact, it seems insensitive to the CO2X. A meaningul measurement starts at around t = 2.5 hours since we were setting up a demodulator for it right before the measurement started. 

As for the transmitted light, there was a slowly varying component which raised the power level as a function of time. Since the slow variation was present from the beginning, this might be some other component independently of our test. There was a jump in both TRX and TRY which coincided with the time when the 2nd loop ISS was closed. So this must be something induced by a slightly different diffraction power in the AOM of the ISS. So, I don't see any obvious sign of improvement or degradation in the power recycling gain.

[3rd plot]

Since there was a suspicion that the frequency noise coupling may have been modulated by some misalignment, I plotted the optical lever signals which did not show a significant correction with the thermal steps that we made.

J. Kissel
WP 5405

I've prepped, compiled, and committed changes to the QUAD_MASTER (and FOUROSEM_DAMPED_STAGE_MASTER_WITH_DAMP_MODE) library parts to incorporate the following changes:
1) Added ${IFO}:SUS-${OPTIC}_L3_CAL_LINE oscillator infrastructure for future tracking of the L2-PUM / L3-TST actuation strength ratio.
    ECR E1500329
    Integration Issue 1088

2) Added ${IFO}:SUS-${OPTIC}_L3_ISCINF_L_IN1 to the science frames at 16384 [Hz], as option 2 in 
    ECR E1500323
    Integration Issue 1085

3) Adding low-pass filter banks and log10 processing after the True RMS violin mode monitors as a final implementation.
    ECR E1500271
    Integration Issue 1066

4) Removing all residual, redundant EPICs records storing IPC error rates. I mention them here, but these changes were prepped last Friday (see LHO aLOG 20124).
    ECR E1500230
    Integration Issue 1054

Attached are the relevant screenshots of the changes. 

To absorb the first three of these changes at LLO, one needs only to update the following library parts:
/opt/rtcds/userapps/trunk/sus/common/models/
QUAD_MASTER.mdl
FOUROSEM_DAMPED_STAGE_MASTER_WITH_DAMP_MODE.mdl
Unfortunately, the 4th change requires pruning on every top level model, as described in LHO aLOG 20124.

I'll construct MEDM screens to go with these model changes once they're installed and running.

Attached is the whiteboard list of tomorrow's scheduled tuesday maintenance activites.  We'll start withnumerous model restarts and move into some hardware work.

Here are the list of tomorrow's maintenance day tasks organized as we intend to execute them chronologically, and prioritized such that the tasks with the most global impact on the IFO are done first (such that we have the most time to recover from them). As with previous Tuesday, all tasks, associated estimated times for completion, and responsible persons will be added to the reservation system when they are *actually happening*, and removed after the task manager has checked in with the operator and confirmed completion. PLEASE PAY ATTENTION TO THE RESERVATION SYSTEM. 

As always, please keep the operators informed of your activities as accurately as possible / reasonable throughout the maintenance day so the reservation list can be adjusted accordingly and remain accurate. We appreciate your cooperation!

1st Round:

Cabling of EOM Driver - will involve climbing on HAM1 and HAM2 chamber areas

Restart all ISI Models

Restart all SUS Models

Restart ASC and LSC modelsInstall TCSy CO2y temperature sensor on viewport

Revert Ey fast FE to slower machine to reduce glitching

Revert Ey BIOS

VE EX NEG Regeneration

PEM injection hardware setup

2nd Round:

DAQ Restart

TCS Ring Heater Filter Install

PSL PMC/ISS checkout

IO (in PSL) Documentation

Guardian Upgrade/restart

3rd Round:

ETMy UIM rocker switch fix

EX/EY PCAL Tune up and Calibration

LVEA: Laser Hazard
IFO: Unlocked
Observation Bit: Commissioning  

Times in UTC
15:00 IFO unlocked for Ops locking training
18:20 Hugh – Going to end stations to check HEPI fluid reservoir levels
18:28 Ed – Going to Mid-X to reinstall repaired AA chassis 
18:52 Ed – Back from mid station
20:45 Filiberto – Cabling work at Mid-Y
21:31 Daniel – Going into CER
22:08 Stefan – Going to ISC rack
22:10 Kyle – Going into End-X VEA to connect and start RGA bakeout 
22:25 Stefan – Out of the LVEA

Valved-in Nitrogen cal-gas into RGA volume (pumped by aux. cart) -> Energized RGA filament

Here is an update to 19908 and Dave's 19808.  See attached 21 days of trends: the SUS glitches are not tripping the ISI with the new model code.

WP 5396

ECR E1500325

II 1086

All the local ISI models have been successfully recompliled to svn rev 11156.  This update allows clearing of the saturation count separately from the WD reset.  Also, every minute, saturations older than one hour are dropped from the count total.  If there are no saturations for the past hour, there will be no saturations totaled.

These models will be installed and then restarted tomorrow.

Rana pointed out to me that the PR3 and SR3 suspensions may still have some shift due to wire heating during locks (which we won't see until a lockloss, since we control the angles of mirrors during lock).

Attached are the oplev signals for PR3 and SR3 at the end of a few different lock stretches, labeled by the time of the end of the lock. The lock ending 3 Aug was 14+ hours.  The lock ending 31 July was 10+ hours.  The lock ending 23 July was 5+ hours.  The lock ending 20 July was 6+ hours.

The PR3 shift is more significant than the SR3 shift, but that shouldn't be too surprising, since there is more power in the PRC than the SRC so there is going to be more scattered light around PR3. Also, PR3 has some ASC feedback to keep the pointing.  SR3 does not have ASC feedback, but it does have a DC-coupled optical lever.  SR3 shifts usually a few tenths of a microradian, but PR3 is often one or more microradians.  Interestingly, the PR3 shift is larger for medium length locks (1 or 1.5 urad) than for very long locks (0.3 urad).  I'm not at all sure why this is.

This is not the end of the world for us right now, since we won't be increasing the laser power for O1, however we expect that this drift will increase as we increase the laser power, so we may need to consider adding even more baffling to the recycling cavity folding mirrors during some future vent.

PSL Status: 
SysStat: All Green, except VB program offline & LRA out of range 
Output power: 32.4w  
Frontend Watch: Green
HPO Watch: Red

PMC:
Locked: 5 days, 2 hours, 3 minutes
Reflected power:    2.1w
Transmitted power: 22.8w 
Total Power:       24.9w 

ISS:
Diffracted power: 9.2%
Last saturation event: 0 days, 0 hours, 24 minutes 

FSS:
Locked: 0 days, 0 hours, 24 minutes
Trans PD: 1.384v
 

DarkhanT, RickS

We found that the DARM_CTRL excitation line reverted to old values on 7/31 (last Friday) at about 11:13 PDT, 18:13 UTC.  Perhaps this was the result of an errant BURT restore, but we didn't find a record of one in a quick survey of the aLog.

When we set the lines last week (see this link), we didn't update the SDF (our bad!).

Today, we reset the frequency of the DARM_CTRL line and adjusted the amplitude to give us SNR ~100.  We also adjusted the amplitude of the Pcal lines to adjust their SNRs to be near the design values.

The updated settings are:

Wanted to know before Tuesday whether there were any reservoir level=>accumulator problems.  All reservoir levels are unchanged.  No HEPI maintenance tomorrow.

Late entry from last Tuesday's SUS front end restarts, here are the results of the 18bit DAC AUTOCALs performed by the IOP model. One card fails autocal, two take an addtional 1.2S to complete.

h1susb123

H1 was locked when I got in, so I brought ISC_LOCK to DOWN to get some locking practice.

It went up to CARM_ON_TR before stopping and notifying  of "No IR in arms".

Sheila mentioned in a log a few weeks back to go to manual and then go back to the state PREP_TR_CARM, but that did not solve the issue and broke lock when I went back to CARM_ON_TR.

Brought it back up and got the same notification, and then I did exactly what I did last time.

While it was going up and down the last few times I was investigating some of the work the commissioners did last night, and I ended up using SDF to switch back some of the changes from alog20146

At this point I got Jenne involved and she worked hard trying to figure it out while I went to a training.

When Evan came in he admitted that he had forgotten to turn back on the Input to the H1ALS-C_REFL_DC_BIAS filter module.

This seemed to have solved the issue.

This filter module is not being monitored, so I added it to the SDF monitor and Jenne added it to the Guardian.

All seems to be good now, made it to COIL_DRIVERS before a commissioner accidentally lost lock.

Log Times – The time stamp on the headers of aLOG entries are in Local Time. After much discussion, the times in body of the log entries should be entered in UTC time, with a note to that effect. Example: “restarted XYZ at 15:45 UTC”.

Betsy is giving operator training on the SDF system at 10:00 in the control room.

The New LIGO Web page has launched.
 
Prep work for the Tuesday maintenance window: 
   Sub Systems are coordinating planned updates
   CDS: will swap a switch on the End-Y UIM Coil Driver
   VAC: will be regenerating the NEG pump at End-X
   FAC: will be moving several crates to Mid-X    

Matt E and I were talking about the broadband noise that is showing up coherently in the OMC DC readout, increasing the noise by 15% or something above shot noise, at frequencies above ~80 Hz. The observation is that this noise increases as the input power is increased (i.e., the watts/rtHz on the OMC DC PDs goes up with higher input power). Amplitude noise on one or more RF sidebands is a plausible source of this noise (not a new idea), and we wanted to suggest specific tests be done to look for RF sideband noise. For example:

• measure the amplitude noise on the 9 MHz and 45 MHz signals coming out of the RF distribution amplifiers in the LVEA that drive the IO EOM (not sure if there are any active devices between these distribution amps and the modulator crystal)
• measure the (AM) noise on the light reflected from the OMC, in full lock (if possible); this light has most of the carrier removed, so any AM on the RF sidebands should be relatively larger than in the OMC transmitted beam (the OMC REFL beam is typically blocked by a beam diverter in low noise, I guess; if the diverter is opened the beam should go to two QDPs in HAM6, if they are aligned)
• measure the RF sideband noise by locking the OMC to one of these sidebands (in DRMI, e.g.); I understand Stefan made an attempt at this already for a 45 MHz sideband -- ?
• of course if the new EOM driver is installed then you could try reducing the modulation index after transitioning to low-noise

There was a persistent excitation in:

H1:ALS-C_REFL_DC_BIAS_EXC

on h1lsc.  This was presumably from an awg process left running by Evan on operator1 workstation.

I killed ALL testpoints on h1lsc (dcuid 10):

jameson.rollins@operator1:~ 0$ diag -l -z
supported capabilities: testing  testpoints  awg 
diag> tp clear 10 *
test point cleared
diag>

Jamie, Sheila, everyone,

Over the past several days, TJ's verbal alarams have been warning us about ETMX software watchdog trips which aren't really happeneing.  This is interseting though, since we've noticed that sometimes this seems coincident with a huge glitch in DARM that can be seen in the spectrum.  The verbal alarm script is checking the channel H1:IOP-SEI_ETMX_DACKILL_STATE.  It sometimes jumps to a value of 3 for about a second and comes back to 0. 

Three incidents from Friday night happened in the 10 to 20 seconds proceeding these times (UTC):

8/1/2015 7:37:40, 5:32:10, 4:00:00

One of these incidents a huge glitch is visible in the DARM time series before the DACKILL state changed. 

Two questions probably need further investigation, is DACKILL behaving the way we want it to, and are the glitches in DARM cauing the DACKILL state to change or is something else causing both DARM glitches and the change in DACKILL state?