This week:

• ASC work
• Re-establishing 25W operations
• Laser intensity variation tests (e.g., ITM centering)

Week 4/4:

• PSL high power work
• POP_X signal chain  checkout
• HAM6 vent to install GS13 and spring blade dampers
• Currently not planned: Installation of high QE PDs and fast shutter replacement

J. Kissel

Joe Betzwieser has created some new bit of "user" c-code in order to facilitate getting the ISI's GS13s, projected into SUSPOINT longitudinal, to the corner station to be further projected into the IFO's cavity length basis. The code serves to mux multiple low-sampling rate channels (in this case, SEI channels) into one high-sampling rate channel for shipping over the RFM IPC with less overhead. See T1600083 for details.

To absorb this new code for incorporation into the PEM model (as per the plan, see LHO aLOG 26249 and ECR E1600028), I've updated the 
${userapps}/cds/common/src/
directory of the local copy of the cds_user_apps repository.

--------------------------
Exactly what has been received:

jeffrey.kissel@opsws2:/opt/rtcds/userapps/release/cds/common/src$ svn up
A    LOW_FREQ_MUX.c
A    ccodeio.h
A    MAX_MIN_CALC.c
A    LOW_FREQ_DEMUX.c
Updated to revision 12938.
jeffrey.kissel@opsws2:/opt/rtcds/userapps/release/cds/common/src$

Pressures still falling:

HAM 7/8:   5.6e-6 Torr (Friday=8e-6 Torr)
HAM 9:      3.8e-6 Torr (Friday=6e-6 Torr)
HAM 11/12:  3.5e-6 Torr (Friday=5e-6 Torr)

Then turned available annulus IPs ON:

HAM 8:   7 mA (pressure at cart jumped to 9.6e-6 Torr)
HAM 9:   full scale with red light (pressure at cart jumped to 5.5e-6 Torr)
HAM 11:  full scale with red light (pressure at cart jumped to 4.2e-6 Torr) 

Need power and signal cables for IPs on HAM 7 & 12. Power cord on HAM 8 is sketchy with tears in outer insulation. I've asked Phil to replace it.

Continue to monitor pressures to detect any potential outer o-ring leaks.

Michael, Krishna

Yesterday, we tested some soft rubber-like pad under the turn-table to reduce the impact of the vibrations in the BRS-1 damper (as discussed here). This was unsuccessful and today we went back to the previous configuration with some thin sheets of closed-cell foam. The arrangement works for now but will likely not be permanent.

BRS-2's vacuum can was completely closed yesterday and we hooked up the portable pumping station to it but couldn't figure out how to enable the safety interlock to start pumping. We will start pumping on Monday after talking to the vacuum experts. We also connected the Satellite box to the Beckhoff computer and the 24V DC power supply. No issues there.

Summary:

The high freqency calibration lines injected at the end of O1 (alog 24843) were analyzed to estimate the sensing function at those frequencies and compare it to the matlab DARM model. The calibration at frequencies above few kHz shows deviation from the model. The upward trend in the residual, as shown in the plot below, looks like the effect of the bulk elastic deformation of the testmass due to the misalignment of the pcal beams. However, this is not a definitive conclusion because the phase doesnot seems to suffer so much and also the error bars are too large to make a definitive statement. A set of measurement might be necessary to see if this effect is in fact reproducible.

Details:

The SLM tool was used to estimate the line amplitude with FFT duration listed below for each individual lines. The mean of the several data points was taken as the central value and the coherence of the measurement was estimated using magnitude squared coherence:

Coh = (A.B*)² / A² * B²

where A  and B are amplitude of DARM_ERR and PCAL_PD channels readout.

Freq    Amplitude    Start Time           Stop Time        Duration     FFT       Data points   Optical Gain
(Hz)           (ct)        (mm-dd UTC)     (mm-dd UTC)    (hh:mm)    (mins)      (#'s)             (kappa_C)
------------------------------------------------------------------------------------------------------------------------------------------
1001.3       35k         01-09 22:45     01-10 00:05         01:20         10           8                   0.995 

1501.3       35k         01-09 21:12     01-09 22:42         01:30         10           9                   0.995

2001.3       35k         01-09 18:38     01-09 21:03        02:25          10          13                  1.00

2501.3       40k         01-09 12:13     01-09 18:31        06:18          30          12                  0.995
 
3001.3       35k         01-10 00:09     01-10 04:38        04:29          30           8                   0.99-0.96 (Fluctuating)

3501.3       35k         01-10 04:41     01-10 12:07        05:26          30          10                  0.99               

4001.3       40k         01-09 04:11     01-09 12:04        07:55          60           5                   1.00

4501.3       40k         01-10 17:38     01-11 06:02        12:24          60          11                   0.99

5001.3       40k         01-11 06:18     01-11 15:00        ~9:00          60           9                    -----

These additional data points were added to one of the Pcal sweep done earlier during the run. In this case I picked the data from 2015-10-28. The optical gain during this sweep measurement was around 0.985 compared to 0.99-1.00 (from table above) during the high frequency injections. These optical gains were eye-balled from the detchar summary pages so I considered them within the margin of error and thus didnot do any correction.  A new parameter file is created to run this as a new set of measurement. The parameter file is stored at the following location:

ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O1/H1/Scripts/DARMOLGTFs/H1DARMparams_20151028E.m 

A script used make the plot attached above and save the output as a mat file is located here:

ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O1/H1/Scripts/DARMOLGTFs/make_sensing_HF.m 

The result of the the above script is saved at the following location and is also attached to this alog.

ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O1/H1/Resulta/DARMOLGTFs/2015-10-28E_H1DARM_HF_sensing.mat

1500 - 1510 hrs. local -> To and from Y-mid 

Exhaust check valve bypass opened, LN2 at exhaust after 2:47 mins with LLCV bypass open 1/2 turn 

Next CP3 over-fill to be Tues. before 4:00 pm hrs. local 

Daniel, Ed D., Ross, Dave B., Terra

In anticipation of more parametric instabilities as we go to higher power, we've set up the ESD PI damping scheme here (which has been successfully used at LLO so far).

Brief context: Figure below shows example relationship between blue mechanical modes of test masses and red optical TEM₀₀ and TEM₀₃ beat note peak (seen at LLO during O1; figure courtesy of Carl Blair). As red optical beat note peak moves left or right, it overlaps with the mechanical mode groups on either side, which can lead to PI. Each mode group has 4 peaks, one for each test mass. Simulations of surface deformations for each mode are shown near their respective peaks. Previously at LHO, PI was observed near 15540Hz and the ETMX ring heater was turned on, effectively moving the red peak leftward away from the 15540 mode group and towards the stable region as shown below. However, as we increase power, high mechanical mode density will mean smaller stable regions to tune towards; hence the need for an active damping scheme. 

Work this past week: ESD damping scheme is set up and ready for testing.  

We've updated end station pi models (h1susetmxpi, h1susetmypi) and added a corner station pi model (h1susitmpi) to allow for ESD driving; these now match LLO's PI models, with some extra downconversion options added. Note that LHO currently doesn't have ITM ESD drivers, so corner station model is just in anticipation.

I've overhauled the X and Y-arm PI medm screens (screenshot attached), located in userapps under /sus/common/medm/pi. For now, only X and Y arm PI screens exist - orange PI buttons on main sitemap. Screens shown in screenshot unfold clockwise from top left for ETMX. Main screen holds list of modes that will be identified over time. Each mode then has its own screen for it's damping parameters. 

The basic damping scheme for the ETMs is as follows: Arm transmission QPD signal carries test mass resonant mode information. QPD signal is passed through an analog 10K - 80K filter (see D1400419 for a rather enlightening PI hardware diagram). The 4-segment QPD vector is multiplied by INMTRX which selects for vertical or horizontal mode orientation. Band pass filter bank to pick out mode frequency; usually 2 x tight bandpass of <10Hz. Control filter bank to damp; gain of 100+, gain of -1 to damp, double zero1, pole 1000. All are shown in attached medm screenshot. Finally, PI has actuation control on two LNLV ESD drive segments: UR & LL. 

We're also temporarily recording the OMC DP PDs at 64K at H1:OMC-PI_DCPD_64KHZ_A and _B as these have the best SNR for PI modes (via the new h1omcpi model). After the ring heater test (discussed below), we'll change these to record at a slower rate. 

To do: There wasn't an available long lock > 10W while I was here so there's some testing of the system still to do.

1. Test ESD damping on known mode: As mentioned above, PI was previously seen at LHO at 15540Hz in ETMX at 15W. It was successfully avoided by turning the ETMX ring heater on; it has remained on since then at 0.5W requested power upper and lower. In an upcoming longer lock at ~15 W, the ring heater should be turned off to allow the 15540 mode to ring up and attempt to be damped with the new ESD scheme. 

2. Ring heater test: To match mode to test mass, we can step up the ring heater on each respective test mass and watch which PI mode shifts in response. We need to step up one ring heater at a time by 0.1 W (both top and bottom simultateously) for 10-15 minutes each.

3. Implement line tracker before damping filter: Ed and Ross have been working on a line tracker that will lock onto each somewhat-well-identified PI mode. It's in the last stages of testing and will be added to the model and sitemap (in between the BP filter and damping filter) asap. Ed & Ross have a more detailed alog about this in the works. 

The frame writers became unstable after the PI model changes Thursday 24th March. Attached is a plot of their restarts since that time. Initially fw0 was unstable, it then became stable and fw1 went unstable for periods of time. Note the regularity of h1fw1 restarts, roughly every hour around the 30 minute mark, with occassional restarts around the 45 minute mark.

The hourly restarts around the 30 minute mark have been correlated to the hourly running of the wiper script (crontab starts this at 23 minutes in the hour, it finished around the 30 minute mark). I was able to correlate this by changing the crontab time from 23 minutes to 03 minutes at 10:40 today. From that time onwards the restarts happened around the 10 minute mark. h1fw1 restart times for today are:

27_Sunday_March_2016_14:06:49_PDT

27_Sunday_March_2016_13:08:09_PDT

27_Sunday_March_2016_12:11:29_PDT

27_Sunday_March_2016_11:08:50_PDT

27_Sunday_March_2016_10:45:11_PDT

--------------------------------- cronjob changed 23 to 03 minutes

27_Sunday_March_2016_10:29:01_PDT

27_Sunday_March_2016_09:30:52_PDT

27_Sunday_March_2016_08:28:12_PDT

27_Sunday_March_2016_07:44:03_PDT

27_Sunday_March_2016_07:30:23_PDT

27_Sunday_March_2016_06:27:18_PDT

27_Sunday_March_2016_05:42:08_PDT

27_Sunday_March_2016_05:27:59_PDT

27_Sunday_March_2016_02:28:18_PDT

27_Sunday_March_2016_01:28:08_PDT

27_Sunday_March_2016_00:26:28_PDT

This suggests SAMFS disk access or NFS file sharing as a possible cause of the problem. I'll work with Greg and Dan tomorrow to see what diagnostics we can run on these file systems.

Ed, Ross, Terra, Jim, Dave

we have added code to the x1fe3tim16 model to test Ed's line isolation C-code. When this testing is complete, we will run the code on other test models running at different rates.

We installed the boot disk Keith provided into a new boot server called x1boot1. Thats to Keith's extensive prep work, the install was very quick. We moved the fast front end computer x1susey from the 2.6 boot server over to the new 3.0.8 server. Next tasks are to rebuild the models on this machine.

x1susey ~ # uname -a

Linux x1susey 3.0.8 #3 SMP Wed Mar 9 16:13:18 CST 2016 x86_64 Intel(R) Xeon(R) CPU E5-2690 v2 @ 3.00GHz GenuineIntel GNU/Linux

We did a little bit of ASC work today.  

First, while Kiwamu was running a TCS test I started a script to automate phasing of the WFS.  It uses the lockin, first runs a servo to set the phase of the lockin demod, then servos to minimize some signal.  We have it set up right now to phase the refl WFS to minimize the PR2 pit signal in Q for both REFL 9 and 45, and to minimize the SRM pit signal in AS 36 Q.  There is some code for exciting DHARD, but we need to test amplitudes, phases and gains for this.  The current version of the script does its job although it is painfully slow, and is checked into the svn under asc/h1/scripts  THe resulting phases are in the attached screenshot. 

We saw that the instability in CHARD pit was becasue somehow the LP9 got turned on again, this is now off and CHARD seems fine.  

We tried powering up, were fine at 10 Watts.  We had an instability in PRC1 and PRC2 yaw at 13 Watts.  I reduced the Q on the complex zeros at 1.1 Hz for PRC2Y, which gives us slightly better phase and gain near the point where we seem to be unstable. Attached is a screenshot of the OLG measured with white noise at both 2 Watts and 10Watts, we might need to do a swept sign to get a good measurement around 1 Hz. 

After about 10 minutes at 12 Watts, we had the usual fluctuations in the recycling gain.  So the high bandwidth PRC2 loops haven't totally solved the problem. 

For the record, these are angle settings that give approximately good CO2 powers tonight, and the powers to aim for from Kiwamu's note:

We have twice had the rotation stage for CO2 Y go to an angle that was wrong by a lot (sending a few watts to the test mass for a few seconds).

I'm leaving the IFO locked at 10Watts. 

TITLE: 03/26 Eve Shift: 00:00-08:00 UTC (16:00-00:00 PST), all times posted in UTC

STATE of H1: Planned Engineering

INCOMING OPERATOR: None

SHIFT SUMMARY:' Large tour group in the control room. Got a chance to really talk at length with some guests about my job and a little bit about various subsystems with a camera guided tour around the LVEA. Completed the last ofthe Sat Amp modifications. Did a little bit of re-locking for Sheila. She's going to be working on DRMI/TCS relationships for the remainder of the night.

LOG:

23:21 Chandra back from CP3 refill

00:15 Terra and Nutsinee to EY to do some signal injections

0:46 Terra and Nutsinee back

Michael, Krishna

This morning, we repositioned the EX_BRS-1 damper turn-table and restarted EX_BRS-1 software. The system worked normally and started to damp the balance but was unable to damp it all the way to small amplitudes (< ~50 counts/nrad). The reason seemed to be that the turn-table vibrations were driving up the beam-balance (see here). Looks like the foam sheets under the turn-table aren't effective at vibration damping any more. Later, Hugh handed us some soft polymer damping pads which we'll try out tomorrow. In the meantime, I've disabled the damper but the tilt data is available.

At EY, Carlos helped us to get the autocollimator software (in C#) working on the BRS-2 Beckhoff computer. We then proceeded with the vacuum can assembly and then aligned the autocollimator and adjusted the beam-balance position to get clear images on the CCD. By the end of the day, the angle data of the beam-balance was visible on the Beckhoff computer.

Plan for tomorrow:

1. Try out other vibration damping pads under the BRS-1 turn-table. Also try out some BRS-1 code changes to improve the software live-time, which crashes once in ~two weeks.

2. Continue BRS-2 vacuum can assembly. If possible, start pumping the vacuum can.

3. Hook up the SEI-Interfacing beckhoff modules.

This is a quick summary of today's TCS joy. I ran another differential lensing test today. I went to the other side of the differential lensing (CO2X goes higher power).

The highest cavity pole was 352 Hz in this test.

• CO2 X 500 mW --> 700 mW --> 500 mW
• CO2 Y 230 mW --> 80 mW --> 230 mW

This time, I also took many measurements of the intensity and frequency noise couplings periodically throughout the test using Evan's automated measurement script (20470). I will analyze and post them later. The second attachment is trend of some relevant channels.

In today's HAM6 vent meeting people asked if the shutter was working at all. It still works.

The first attachment shows that the shutter closed (green trace) last night when the IFO lost lock. Brown is the tirigger voltage, and the trigger threshold is 2V.

Red is the OMC DCPD, blue is the DC of ASAIR_A, vertical lines indicate where the shutter triggered.

Due to some strange timing problem of Ethercat signals transported to EPICS that was reported in alog 17445, you cannot compare the timing of the green and the brown trace with red and blue, so the trigger timing on this plot is just a guesstimate obtained as follows:

1. Trigger voltage (brown) is produced in ASC AS_C interface box by adding all four segments in analog, and the analog output is directly plugged into the shutter box. This voltage is just AS power, so is supposed to be proportional to ASAIR_A_LF (blue).
2. Before the IFO lost lock, trigger voltage was 0.12Volts, ASAIR_A_LF was about 1200 counts, so the equivalent trigger threshold for ASAIR_A_LF would be 20000 counts where the shutter should have triggered.

The second plot shows that the shutter has been firing all the time for recent 100 days.

One thing that is strange is that the LSC-ASAIR_C_LF_OUT_DQ is recorded on the frame at 16kHz but the input is grounded in the frontend. If my memory is correct Dan Hoak wanted to record the trigger voltage at 16kHz, and my guess is that ASAIR_C_LF was supposed to be used for this because it's not used, but nobody implemented it.

Preliminary conclusion: the DARM cavity pole seems to be a strong function of the differential lensing. I was able to change it from 357 Hz to 220 Hz (!!!)

I will post more details tomorrow.

The cavity pole measurement is not valid until t=80 min. and also in the time band approximately between 230 and 250 min. The interferometer was locked on the DC readout with ASC fully engaged, The PSL power stayed at 2 W throughout the measurement.

Learning this behavior, I would like to do the followings in the next test:

• Go further to the positive side of the differential lensing (ITMX's lensing goes larger than ITMY) to see if we can recover a high cavity pole.
• Search for optimum points for frequency and intensity noise couplings.

By the way the second attachment is trend of various channels during the test.