Continuing on from yesterday's TTFSS work.

All notches were removed, and the transfer function was measured (see NONOTCHS.tif).
The peak at ~760 kHz is of no big concern.  However the peaks at around 1.77 MHz are.
These were notched out with C50 (1-65 pF) and series with L2 (220uH).  C50 was adjusted
to suppress the two peaks.  The transfer function was re-measured (see OLTF.tif).  The
unity gain frequency is around 450 kHz.

Currently the common gain is set to 27 dB and the fast gain to 5 dB.  Should the
loop break out into oscillation, reduce the fast gain to 0 dB, wait until the oscillation
stops and then increase it back to 5 dB.





Rick, Peter

ER-7 is scheduled for mid-June. There will be a short “annealing” run just before the ER-7 run.

Seismic:
	Running TFs on BS and ITMX.

BRS:
	Software crashes about every two weeks. Ops will check the BRS status daily.

CDS:
	Finished connecting the Dew Point sensors for the 3IFO storage containers.

VAC/FMC:
	HAM6 is still pumping. Hope to transition Ion pump today.
	Beam Tube cleaning of the X-Arm is 25% complete.
	There will be a safety meeting at 15:00 in the LSB auditorium.   
	There will be painters on site working in the VPW, LSB, and OSB.

PSL:
	Work continues on the FSS.

Comm:
	Tuning and alignment work on the Mode Cleaner and the HWS.   
  

Koji, Evan, Sheila

Tonight we saw the shelf from 50 up to 100 Hz, however we are back to a range of around 35 Mpc.  We saw this last week and hoped that it was related to the HAM6 cleanroom.  We have done several things:

• It seems that the peak at around 250 Hz is related to the OMCR path.  The peak was reduced after the vent and replacement of the BS with a 90/10, and closeing the OMC refl beam diverter reduces it below the DARM noise floor.)
• closing POP and AS air beam diverters didn't seem to have any impact on the spectrum, the DHARD roll offs we added ddin't do much either.  
• We measured fringe wrapping by exciting the OMC and OM1.  Analysis coming tomorow, but at first it looks like the OMC backscatter should not be limiting the sensitivity.  
• We were locked at 15 Watts for a few hours, after this time we saw broadband noise in DARM and tried to use the 785 to check for PI.  We had used the 785 earlier in the lock, but the second time we weren't able to connect to it.  By reducing the power we stayed locked.  (An incorrect calibration around this time lead to a sensmon range of around 40 Mpc)
• ALS scanning is faster this week, since we added a fast scan durring the vent that checks the two most commonly found frequencies.  

Jeff, Sheila

This afternoon during an hour of winds consistently between 20-35 mph, we got a chance to use the three configurations Jeff described in 17729.  We hoped to get be able to make a clear statement about whether or not the BRS is helping us on windy days to reduce the motion of the optic, we see a modest improvement with the BRS on, which could also be due to reduced ground motion. 

We got at least 15 minutes of data with ALS COMM locked and common tidal runnng to ETMX (ugf set to 0.1 Hz) with three seismic configurations:

• configuration 1 (45 mHz blend, narrow band sensor correction, no BRS) from 23:49:51 April 14th to 0:06:36 Arpril 15th (black traces) (this is the configuration that we have been using as a nominal configuration when the BRS is not working, we know that it is not good when the wind is high)
• configuration 2 (90 mHz blend, narrow band sensor correction, no BRS) from 23:27:30-23:48:51 April 14th UTC (blue traces)
• configuration 3(90 mHz blend, broad band sensor correction, BRS on) from 0:43:43 to 01:08 UTC, a large glitch nearly broke the lock at 0:51:58 (red traces)

The IMC F signal, calibrated in kHz, is a readback of the X arm motion above 0.1 Hz in this configuration, with possible contamination from angular fluctuations.  The best performance was measured with the BRS on, where the rms is about 67% of the rms measured with the 90 mHz blends and narrow band sensor correction.  From the second screenshot, you can see that the ground motion also dropped when we switched to the BRS sensor correction, the rms of the ground is also about 62% lower for the red traces.  The third plot shows X direction GS13s for the three configurations.  

The last two attachements are the wind direction ( in degrees from north, this is mostly wind along the Y direction) and speed, and the seismic FOM for today.  

Evan, Kiwamu,

We had a difficulty in locking the IMC in this afternoon after the FSS activity (see alog 17875). It turned out that the signal in the IMC trans PD was too low to trigger the IMC-MCL filter. Note that the upper and lower thresholds have been set to 100 and 90 cnts respectively for the nominal 3 W operation. We could have simply increased the output digital gain of this path, but at the same time we noticed that the analog signal was pretty low to begin with. It was about 20 cnts at the ADC when the IMC was locked on a 00-mode. We went to the IOT2L table and checked whether there is a clipping or some stupid things, but we did not find anything obvious. Since I did not like an analog signal to be as low as several counts at the ADC, I decided to crank up the analog gain of the PD (PDA100A) from 0 to 30 dB. Now it detects more than 200 cnts when the IMC is locked on 3 W. Evan then adjusted the digital gain such that it keeps the same conversion. We did not get a chance to subtract the dark offset yet, but the IMC is now locking fine.

Note that it seems that the trans PD has been in this low-ADC counts situation since approximately Feb-25 at which point the signal in IMC-TRANS decreased dramatically for some reason. See the attached trend. Could this be due to the LSC/OMC model split (alog 16893) ????

In an effort to increase the unity gain frequency of the TTFSS, I had tried a higher resonant frequency but

broader notch filter comprising of a 30 uH inductor for L2 and a 1500 pF capacitor for C16.  After re-installing

the TTFSS, I found that the frequency no longer locked.  Thinking that it was my circuit modification that was

the root cause, I reversed the changes and found that the frequency servo still did not lock.

The error signal was present when the cavity was swept.  Each time the servo was engaged it did not lock

as the slow actuator ramp passed the resonance, which to me indicated that there was no feedback.  The

problem was traced to the loop switch not engaging, this in turn was a faulty opto-coupler in the FSS fieldbox.

Coincidentally, the same one that Evan and I had switched the other day.  Replacing both opto-couplers and

re-engaging the loop switch, the frequency servo locked.

The file M10P5.tif shows the open loop transfer function with the common gain set to -10 dB and the fast gain

set to +5 dB.  The presence of the peaks at ~770 kHz and ~1.8 MHz suggest I did not correctly solder in the

two notches.

At the moment the common gain is set to -10 dB and the fast gain to +6 dB.  If the loop starts oscillating -

indicated by a wildly oscillating reference cavity transmission of the PZT monitor plot on the MEDM screen

being a solid black, the fast gain needs to be reduced until the oscillation stops and then slowly restored.

The reference cavity transmission was ~1.45 V.

Peter, Rick

Pumpdown continues.
An attempt was done today to run the system with only the 500 l/s "main" ion pump (valved out the turbo pump), but the "controller" was not able to "keep up."
So we'll continue to use the turbo pump in parallel with the ion pump, we'll keep this configuration until the pressure is low enough for the controller to support the ion pump demand.
 

H0:PEM rename to H1:PEM [WP5153, ECR1500016]

Patrick, Jim, Dave:

The EPICS PEM systems which monitor the weather stations and dust monitors had their channel names changed from the prefix H0:PEM- to H1:PEM-.

The DAQ was stopped and the minute trends were offloaded to a temporary location on the SSD raid. A new blank minute trend area was created. The new H1 INI files were loaded and the DAQ was restarted. Later the NDS servers were configured to serve the offloaded minute trends (in their temporary location). Later they will be migrated from SSD to HDD raids.

The EPICS IOCs for Weather and Dust were modfied and restarted. New H1 targets were created, and safe.snap files moved. MEDM screens were modified.

This WP will remain open to cover the remaining DAQ work which is needed.

End Station SUS/SEI upgrade to RCG2.9.1 [WP5154]

Jeff, Jim, Rolf, Dave:

RCG Tag 2.9.1 was installed on h1build. The following models were upgraded to this tag: h1iopsus[ex,ey], h1iopsei[ex,ey], h1susetm[x,y], h1sustms[x,y], h1hpietm[x,y], h1isietm[x,y]. No DAQ restart was required.

This closes WP5154, future WPs will cover upgrading the rest of H1.

3IFO storage environment monitoring

Richard, Filiburto, Dave, Jim:

The EPICS monitoring system for the LVEA 3IFO storage system was started today. The EPICS channels were added to the DAQ.

J. Kissel, J. Warner

We noticed that the wind / tilt at EX was so large that the peak-to-peak amplitude of tilt as measured by the BRS was surpassing the level at which the BRS's gravitational damper turns on. Since we're trying to get data in these high wind conditions, we've gone to the X end and and turned OFF the gravitational damper from the laptop software.
Will turn on again some time soon when it's less windy.

Waiting to clear these until the OMC is shown to be able to handle the changes.

Again there is some 70urad RX (Pitch) and 15urad RZ (Yaw.)  Look at the SDF Diff Table (attached) to get an ideal of where to steer if alignment is suspect.  Do the Yaw on HEPI though to keep the ISI drive minimal.  I suspect the Pitching HEPI will not directly translate to the ISI.

Today's Maintenance Day started with PSL FSS work.  Unfortunately, they were not able to complete this work, because they spent a good chunk of the day recovering from the FSS attempt.  Due to this work, the PSL PZT Mirror swap was not attempted.  Below is a running tally of work.

• Before 8:00:  Peter K working on FSS Elec (~until 8:30)
• Before 8:00:  Elli/Nutsinee Hartman work ("Adjusting PZT Offset") using ALS (~2hrs)
• 7:30:  Jeff/Andres "measurements & pictures":  path for vac plumbing for dust monitors for another 30in & end stations
• 7:59:  Nutsinee heading to EX to turn on TCS Camera
• 8:10-10:07:   Mike/Fred giving tour (may go out again)
• 8:17:  Richard heading to PSL to give PK an elec box
• 8:40:  Gerardo out to check HAM6 Pump state (may take out Turbo today)
• 8:45:  Richard/Fil working on dewpoint sensors in West Bay/3IFO area
• 8:45:  Fire Dept on-site testing valves at Pump room
• 8:50:  Jeff/Andres heading to Outbuildings
• 9:00:  BRS turned OFF
• 9:08:  Dick RF measurements (for 3-hrs)
• 9:10:  Peter just called to say he'll need atleast 1hr to recover the PSL.
• 9:25:  Cheryl removed pesky MidStation FMCS alarms (which came up as MAJOR alarm for years)
• 9:30:  Cheryl LVEA DustMon#15 settings raised since no longer have chamber open
• 9:45:  Praxair truck onsite
• 9:45:  Jodi in LVEA for 3IFO
• 9:55:  Elllie/Nutsinee going to ISCTEX
• 9:57:  Gerardo/Kyle valving out Turbo at HAM6
• 10:15 Rick/Robert/Kiwamu Mirror Swap
• 10:19 Driver here to pick up pallet
• 11:00 Landry tour EY
• 11:05:  Andres checking exit/emer signs
• 11:06 Patrick doing weather station/dust monitor change
• 2:09  contractor picking up pallets (2nd visit of day)
• 2:16 Rick/Peter taking H1 PSL to Science Mode
• 2:33 Kyle to MY
• 3:30 Jim has the Yarm for ISI TFs until ~7pm
• 3:30 Robert heading out to EY (PEM work?)
• 3:15 ALSX aligned, IR Input aligned & handed over to Commissioners
• 4:06 Jeff/Jim heading to EX to turn off damping software for BRS

A while ago I wrote a script to calculate match gains for the BSC FF to match the ISI L4C's to the HEPI L4C's. This was based on Arnaud's script script to compute the match gains for the sensor correction, in alog 16208. The process was much the same, putting the St1 in 750mhz cps blends, turning off feedforward and sensor correction to the ISI and HEPI. I left the ISI's like that for 10 minutes, then calculated the transfer function between the HEPI and ISI L4C's, and took the average between .1 and .4 hz. The transfer functions all look somewhat like the attached one for the BS. Most match gains were are 1 +/-10%, but ETMY and the BS both had one value that was off by about 20%, X for ETMY, Y for the BS. Gains are installed, I'll get some performance data overnight. The script is in the SEISVN under /BSC-ISI/Common/Misc, it's called BSC_FF_gain_matching. You can see what the results look like by running (with the SEI paths loaded) BSC_FF_gain_matching('H1', 'ITMX', 1113079985, 600) and exchanging 'ITMX' for the other chambers.

J. Kissel, K. Izumi

Using the same model I described yesterday (see LHO aLOG 17847), I've now compared it against
(a) this weekend's measured DARM Open Loop Gain Transfer Functions (OLGTFs), which were taken out to 1 [kHz]:
     2015-04-12 Post UIM / TST Crossover Adjustment, Post HAM6 Vent, ESD Linearization OFF, at 10 [W] input power LHO aLOG 17834
     2015-04-13 Increase of input power to 15 [W], ESD Linearization OFF LHO aLOG 17835
and
(b) The previous measurements shown in LHO aLOG 17847.
They've solidified suspicions of we'd just barely begun to see -- there's definitely some funny business going on:
- We suspect that the frequency dependence of the sensing function (i.e. optical plant) cannot be simply described by a single-pole filter, but it could also be a flaw in model of the actuation frequency dependence.
- The optical gain has significantly reduced from 112e6+/-8% to 75e6+/-4%, even though Evan and Sheila have attempted to compensate for it in the DARM loop digital gain.

In the first attachment, I compare all of the measurements against a model with a fixed cavity pole frequency of 389 [Hz], the number calculated to be the ideal from L1 (see LLO aLOG 15923). 

In the second attachment, I compare all of the measurements against a model where I've adjusted the coupled cavity pole frequency to match the model / measurement discrepancy. 

From the comparison of these two models, one can see several things:
(1) There is a systematic difference in frequency-dependent discrepancy between the earlier, 5-300 [Hz] data and the later, post-HAM6 vent, data. This implies something systematic has changed in the time between 2015-04-06 and 2015-04-12.
(2) In order to fit the discrepancy's frequency dependence, I've had to move the DARM coupled cavity pole down to an unrealistically (??) low 320 [Hz] and 290 [Hz] for the earlier and later data, respectively. The ?? is because I'm not sure what is unrealistic.
(3) I've used the same time delay for *all* of the data sets. The 40 [us] was chosen *after* I'd shifted the coupled-cavity pole frequency down in order to get the phase to be flat as a function of frequency. We have no reason to suspect that the time delay would have changed over these 5 measurements, so I take this to be the residual unknown timing error (*not* the 93 +/- 30 [us] I'd said in the previous log).

There are several things think might be the cause of this (arranged in order of what we think is most likely)
- DARM coupled cavity pole is lower than expected because of SRCL offset, low power recycling gain, or IFO alignment
- ESD / SUS isn't exactly 1/f^2 at high frequency
- Some nasty frequency dependence of the linearization algorithm

Kiwamu's hard at work testing the first suspicion. Stay tuned!

This seismometer has given us problems for some time: alogs 15510, 14482, 9727.  JeffK may point to others too.

On the attached four plots, there are four successive days, Saturday thru Tuesday at 0100pdt.  The lower left panels are the Coherences between the HAM2 & HAM5 (STS-A & C) and the ITMY (STS2.)  The Upper Left, Upper Right, and Lower Right panels are the ASDs of the X Y & Z DOFs respectively of STS2 A B & C.

The take away is that in general the character of the ITMY (STS2-B) ground seismometer doesn't change like the other two instruments below 100mhz while the HAM2 & HAM5 instruments change more day to day and mostly look like each other.

Details:  The Z DOF is most obvious in that below 50 or 80 mhz, ITMY trends up steeply while the A & C seismos do not.  For the Y DOF, the HAM2 (STS2-B) signal seems to be the outlier but the day to day doesn't follow a patten between the instruments so I ...  The X DOF is pretty good with the A & C instruments tracking each other pretty closely while the B sensor kinda stays at the same power level, mostly.  So, like I say, a Case, maybe.