Top plot:

IM2 LR OSEM noise rises above other IM OSEMS around 135Hz.

At 570Hz, IM2 LR OSEM in blue in top plot is ~15x the noise of the IM3 LL, ~60x the noise of IM1 UR, and ~90x the noise of IM4 LR

Bottom Plot:

OSEM noise shows up in pitch signal

Kyle, Gerardo, Jeff B., Chandra

East door was installed on Thursday. North and South doors were installed today. Two of three are torqued. We will torque the South and start the rough pump down after late lunch. 

NOTES:  

1. North door has a questionable scratch along the o-ring sealing surfaces (but not wide enough to cross both o-rings at same time, we think). Scratch is in fourth quadrant (when looking at door).
2. Inner o-ring of South door was bad. We replaced with one from 1998 processed stock. 

We will leak check all doors before COB today.

Filiberto, Patrick

We did two things, and it is not clear which or if both were necessary. We swapped the transmit/receive fiber pair into the CU1521 media converter at X2-8. After that the link lights started blinking. At the end station we changed the rotary dial on the CU1521 media converter from 0 to 5. This dial sets the direction of the media converter as seen from the EtherCAT master. 0 is from fiber to copper. 5 is from copper to fiber. (pg. 22 of http://download.beckhoff.com/download/document/io/infrastructure-components/cu15xxen.pdf) So it had been incorrectly set as from fiber to copper. We then power cycled just the CU1521. We had checked the dial on the media converter at X2-8 and it was correctly set to 0 (fiber to copper).

I had to restart the Beckhoff controls and IOC again to scan and add the gauges. I called Cheryl from the end station and she ran a script on the vacuum computer in the control room to set the IOC values. She also set the CP LLCV control to manual. I just set it back to PID.

My watch on Operations: approx. 18:00-20:00UTC (11:00-1:00PT) - as of 20:56UTC:

• 18:11UTC - Kyle, JeffB, Chandra, 4th person - reinstall HAM6 North and South Doors - currently putting on the South door
• 18:30UTC - Fil and Patrick - EX-28 to look at fibers - done
• 19:00UTC - PSL team out for mid-day break - currently Jason and Peter are in the PSL
• 19:47UTC - Fil and Patrick to EX - vacuum controls, restarted Beckoff - currently Patrick is monitoring the PID for CP8

The h1nds1 computer died with a kernel panic.  I powered the computer off, then powered it back on at about 11:53 PDT.  Monit needed to be told to monitor the daqd process once the computer booted.

Corey and I did the last few ISI items this morning in HAM6. Check for tools, wiped down areas where people were working, pulled the septum cover, unlocked the ISI and closed the chamber. While we were doing that Evan, JeffK and Fil checked the operation of the beam diverter and fast shutter (Jeff just alogged that). I've now taken closeout ISI measurements and the ISI looks ok. I think my measurements are made a little noisy by high purge flow in the chamber, so I may take longer measurements after the chamber closes. But I think we are good to put doors on.

J. Kissel, E. Hall, F. Clara

As per this April HAM6 vent's plan, E1600092, we've confirmed the functionality of the AS AIR and OMC REFL beam diverters, as well as the HAM6 fast shutter. Details of the test below. The tests required turning on the HAM6 High Voltage for the shutter, but we since have turned it off again now that or tests are complete.  All mobile ISC components are functional; ISC is a go for chamber closeout.

------------------
Beam Diverters:
- The AS AIR and OMC REFL beam diverters did not need to be moved or disconnected at all during this vent, so testing their functionality was as simple as exercising the OPEN/CLOSE buttons on the corresponding Beckhoff MEDM screen and watching as the shutters cycled through the two positions. We were able to cycle both several times without issue.

Fast shutter:
To test the fast shutter we did the following (informed by LHO aLOG 17831)

This scenario: The chamber doors are open, the shutter is clearly visible, ISCT6 has been pulled away from the chamber, the trigger PD's input has been disconnected from the remote chassis, and the high voltage has been turned off.

Gather ahead of time: a portable DC voltage supply (it need only be capable of +5V) and associated BNC cable and adapter.

Process:
(1) Confirm that the HAM6 fast shutter remote chassis's power is OFF (both that the front-panel "HV Enable" little silver dip-switch is set to "disable", and the back panel power rocker switch is OFF). This chassis is located in the field rack just -Y of HAM6 at the bottom of the rack.
(2) Turn on the high voltage power supply in the Computer Electronics Room (CER) Mezzanine. Since the voltage and current adjust are analog dials, they are typically left at the right setting, so one only needs to turn on the power switch to the power supply. Once on, the voltage readback should show 250V, and the current readback should be hovering just above 0 A (i.e. *very* little current should be drawn).
(3) Return to the field rack, and turn on the back panel chassis power rocker switch.
(4) On the front panel, you should see the +/-15V light green, the computer screen light up, and after a few seconds the fault light will go red.
(5) Enable the HV from the front panel silver dip switch. The computer screen will indicate that the capacitator is charging up for ~10 sec or so. The fault light will remain on.
(6) Connect the DC voltage supply (with no voltage output) to the Fast Trigger Input. 
(7) As soon as you give the voltage supply 5 V, the shutter should pop up, and the fault light will go off.
(8) Cycle the 5V a couple of times to confirm expected functionality. If the shutter pops up and down as expected, then the shutter is functional.
(9) Disconnect the 5V voltage supply, flip the sliver dip switch back to "disable," turn off the power to the chassis via the back panel rocker switch, and turn OFF the high voltage power supply in the CER mezzanine.

NOTE This only tests the mobility of the shutter, it does not test the shutter logic or the timing. This requires ISCT6 to be in place, and light on a trigger PD, as per LHO aLOG 17831 cited above. We will test these critical components as soon as possible.

The Diagonal Volume is currently being pumped by the Turbo, IP7 and IP8.  IP7's voltage setting is not optimal, I'll fix it later.  Unless otherwise directed, will leave this way over the weekend and shut down the Turbo Monday.

I put the TwinCAT system into configuration mode at end X and scanned for devices. The media converter and X2-8 EtherCAT gauge did not show up. I put it back to run mode. The LLCV is in manual mode until the PID recovers.

PSL – The leaking coolant manifold was replaced yesterday. Coolant has been circulating since then with no apparent problems. Today efforts will concentrate on getting the PMC relocked. 

SEI – The new hardware has been installed and tested. The crew is closing out some final cleanup tasks; then will run a final set of transfer functions. If everything checks out OK, the plan is to hang the last two doors after lunch.

Vac – Pumping will start on HAM6 as soon as the doors are back on. Gate Valves should be opened on Monday. 

FRS – Reviewed and closed out completed FRS tickets.   

The output of the 4 flow sensors - one per laser head - from the past 24 hours is attached.
The sensor for head 1 was replaced yesterday.  Not obvious to me why it did not settle down
as rapidly as the other 3 sensors.  But we will keep an eye on it.

The crystal chiller water level was lower this morning than what it was yesterday afternoon.
This might be due to the air bubbles working its way out of the plumbing.  We will continue
to monitor for leaks.

J. Kissel

As per this April HAM6 vent's plan, E1600092, I've checked that the SUS have not been affected by this week's vent activities by measuring all DOFs of all SUS in the chamber -- the OMC and OMs 1 through 3. Attached are the results of the transfer functions compared against the last in-vacuum results. All SUS are A-OK; SUS is a go for chamber close out.

New data sets live here:
/ligo/svncommon/SusSVN/sus/trunk/OMCS/H1/OMC/SAGM1/Data/2016-04-08*.xml
/ligo/svncommon/SusSVN/sus/trunk/HTTS/H1/OM1/SAGM1/Data/2016-04-08*.xml
/ligo/svncommon/SusSVN/sus/trunk/HTTS/H1/OM2/SAGM1/Data/2016-04-08*.xml
/ligo/svncommon/SusSVN/sus/trunk/HTTS/H1/OM3/SAGM1/Data/2016-04-08*.xml
Note, I've improved the OM templates by tuning the drive and adding a boost to the low-frequency drive. The OMC's template didn't need it.

J. Kissel, J. Warner

Based on the results of B&K hammering the H1 ISI HAM6 blades before and after installing the new blade tip and flexure dampers, I've retuned and re-installed the pre-existing tuned-mass dampers. Lots of details, results, discussion and techniques below. As Jim mentions in LHO aLOG 26482, this concludes the installation of the HAM-ISI damping mechanisms for H1 ISI HAM6. 

Thanks to all who've have helped!

We will close up the chamber tomorrow as planned.

Details
----------------------
Blade Characterization

Over the past few days, as we've been installing the new Blade Tip Dampers (D1500469)
 and Flexure Dampers (D1500200) -- see LHO aLOGs 26482, 26473, 26456, and 26452 -- we've been gathering before-and-after B&K transfer function of the blade-spring & flexure system without the eLIGO tuned-massed dampers.

The results of the this characterization are shown in the attachment 2016-04-07_H1ISIHAM6_DampingInstall_BandKResults_BladeSpring_UndampedvsDamped.pdf. (Recall, for your convenience, which blade is which from the attachment HAM6ISI_Sensor_and_Blade_Names.pdf).

As expected, all three blades' first bending mode has moved down from ~153 Hz to ~139 Hz due to the extra mass of the blade-tip damper. Note, sadly, only Corner 3's "after" measurement has any coherence above ~300 Hz because we didn't starting using the B&K hammer's hard tip until that last corner. That means we don't have a quantitative metric for how much the dampers reduced each blade's higher frequency modes we expected to damp (at ~450 Hz and ~900 Hz) -- but at least we can see the end result from corner three. However, we have no reason to believe that these dampers aren't working at these frequencies as expected. Once pumped down, we'll make a comparison between the GS13 ASDs before and after the vent, and that'll be our final assurance that all has gone well.

We definitely need to use the hard-tip on the B&K hammer for all future installs and characterization of ISI damping mechanisms.

Tuned Mass Damper Tuning

Once we'd identified the new first bending mode frequency, the smaller, narrow-band tuned mass dampers needed retuning. I took them into the optics lab, set up a crude shadow sensor system with a HeNe laser and On-Trac QPD, hooking up the output to an SR785. See attachment 2016-04-07_TMDTuningPics.pdf for pics of the setup. 

The tuning itself was pretty easy. I went in armed with a set of calipers to try to a priori predict the increase in length needed to decrease the resonance to the desired frequency, but the tightening of the restraining bracket turned the frequency tuning to a guess-and-check game regardless. Pre- and Post measuring after tuning was finished showed an increase in length of 0.6+/-0.015 [in] to 0.66+/-0.015 [in]. 

A comparison of the resonant frequency and Q is shown explicitly in 2016-04-07_H1ISIHAM6_BladeTMD_Tuning.pdf. I was able to preserve the Q of about 10, and moved the frequency down to 139 [Hz] as desired. Given that I knew the frequency of each blade's first bending mode, and the resonance of each tuned mass damper, I matched each blade to the appropriate TMD and they're thus annotated in the legend by on which blade they were installed.

Tuned Mass Damper Installation

Nothing much to report here, the installation went smoothly. With the TMD in hand, I reached through the outer wall and "picture" access panel to secure the magnetically attached device to the blade. It took a few pictures and adjustments to get the final location "right" as shown in 2016-04-07_TMDInstalledPics.pdf (though they probably don't *have* to be so precisely oriented and located). Installing the TMD on Corner 1's blade was the "most difficult," in that it's a little uncomfortable and awkward climbing in chamber, sitting down, and reaching into the ISI, but it's totally doable even for someone of my stature.

To help identify potential scattering sites.

Miriam, Evan G, Evan H

*SUMMARY*

We investigate the possibility that there occurs a saturation or a slew rate problem somewhere in the analog electronics of the sensing chain causing (or resulting in) a blip glitch. This investigation finds no issue with either of these for a sample of the four loudest blip glitches in O1 data.

*DETAILS*

We investigate four different times: 1128085613.28, 1128221842.47, 1128264648.20, 1130156793.54

1. Get the data from OMC-DCPD_A_OUT_DQ and OMC-DCPD_B_OUT_DQ. These data have undergone some digital filtering to undo what the analog filtering did before the ADC. It is our best estimate of the photocurrent from the OMC DCPD. The units are in mA.

2. Convert the data into Volts (V=IR), where R=400 Ohms (see DCC:D060572) 

3. Following the schematic of the in-vacuum OMC DCPD, there are two zpk filters, each with one zero at 8Hz and one pole at 80Hz (we ignore the 15.9kHz pole, as it is far out of the frequency band of interest), and there is a gain of 2 at the differential output. We apply this filtering to the DCPD data (in V). The resulting time-series has to be within +/-15 V to not saturate. In the selected times of blip glitches, we obtain voltages that are well within this bound (see attached document, "preamp" plots) 

4. Continuing with the signal chain, the whitening chassis (DCC:D1001530). The whitening gain setting has a nominal value of 0 dB. In addition, only a single whitening stage is applied with one zero at 1Hz and one pole at 10Hz. The resulting time-series has to be within +/-15 V to not saturate the whitening op-amp, and within +/-20 V to not saturate the ADC. In the selected times of blip glitches, we obtain voltages that are well within these bounds (see attached document, "whitch" plots).

5. Typical slew rates for the op-amps used in these circuits are 2.5 or 5 V/us. None of the times selected show such high slew rates.

6. Note that the plots in the attachment are dominated by the low frequency content of the signal, that has an amplitude much greater than blip glitches. Only after whitening the time-series, the blip glitches become dominant.

*CONCLUSION*

The analog electronics in the sensing chain do not appear to be responsible for blip glitches. 

HV cable was pulled in from VEA mechanical room to X2-8 beam tube by Richard and Gerardo this morning. Connectors were terminated at both ends this afternoon.

J. Oberling, P. King

Spent today installing and testing the new HPO water manifold.  The mainfold is now installed and the valves for the MOPA, PWR, and Laser Head water circuits are set to provide the proper flow rates.  While we were doing this we figured it was a good idea to implement ECR E1500408; this ECR is for installing valve on the outlet side of the Laser Crystal water circuit.  This is now also complete.  A picture of the new water manifold and valve is attached.  This completes this ECR.

Once everything was installed and verified that it wasn't leaking, We noticed the flow sensor for laser head #1 (part of the Laser Head water circuit) had stopped reading.  Opening up the HPO box we saw that the turbine was not spinning.  We drained the circuit and removed and replaced the flow sensor.  Before installing the new flow sensor, Peter found an ~1/2" piece of black plastic (looked like a piece leftover from cutting the threads on the main water manifold.  Recall we pulled out a bunch of these yesterday while prepping the new manifold.) sitting in the output side of the flow sensor (in the small black manifold that sits above the HPO resonator cavity).  We installed the new flow sensor, turned on the chillers, and watched for leaks.  After several minutes no leaks were observed, so we left the crystal chiller running overnight to test the system (the diode chiller is still OFF).  The HPO and FE lasers are both OFF.  Will continue in the morning.

Related alogs 26264. 26245

I did some follow-up tests today to understand the behavior of the DARM cavity pole. I put an offset in some ASC error points to see how they affect the DARM cavity pole without changing the CO2 settings.

I conlude that the SRC1 ASC loop is nominally locked on a non-optimal point (when PSL is 2 W) and it can easily and drastically changes the cavity pole. The highest cavity pole I could get today was 362 +/- a few Hz by manually optimizing the SRC alignment.

[The tests]

This time I did not change the TCS CO2 settings at all. In order to make a fair comparison against the past TCS measurements (26264, 26245), I let the PSL stay at 2 W. The interferometer was fully locked with the DC readout, and the ASC loops were all engaged. The TCS settings are as follows, TCSX = 350 mW, TCSY = 100 mW. I put an offset in the error point of each of some ASC loops at a time. I did so for SRC1, SRC2, CSOFT, DSOFT and PRC1. Additionally, I have moved around IM3 and SR3 which were not under control of ASC. All the tests are for the PIT degrees of freedom and I did not do for the YAWs. During the tests, I had an excitation line on the ETMX suspension at 331.9 Hz with a notch in the DARM loop in order to monitor the cavity pole. Before any of the tests, the DARM cavity pole was confirmed to be at 338 Hz by running a Pcal swept sine measurement.

The results are summarized below:

• SRC1, offset = from +400 to -300 cnts, cavity pole = from 350 Hz to 275 Hz
• SRC2 , offset = from +0.2 to -0.2 cnts, no change
• DSOFT, offset = from -0.03 to 0.03 cnts, no change in cavity pole, but a noticeable drop in the power recycling gain (41 --> 39).
• CSOFT, offset = from -0.03 to 0.03 cnts, no change in cavity pole, but a noticeable drop in the power recycling gain (41 --> 38-ish).
• PRC1, offset = from -0.1 to 0.1 cnts, no change in cavity pole, but a noticeable drop in the power recycling gain (41 --> 38-ish).
• IM2, some large offset, no change in cavity pole.
• SR3, offset = +/- 50 urad, no change in cavity pole or recycling gain.

The QPD loops -- namely CSOFT, DSOFT, PRC1 and SRC2 loops -- showed almost no impact on the cavity pole. The SOFTs and PRC1 tended to quickly degrade the power recycling gain rather than the cavity pole. I then further investigated SRC1 as written below.

[Optimizing SRC alignment]

I then focused on SRC1 which controlled SRM using AS36. I switched off the SRC1 servo and started manually aligning it in order to maximize the cavity pole. By touching PIT and YAW by roughly 10 urads for both, I was able to reach a cavity pole of 362 Hz. As I aligned it by hand, I saw POP90 decreasing and POP18 increasing as expected -- these indicate a better alignment of SRC. However, strangely AS90 dropped a little bit by a few %. I don't know why. At the same time, I saw the fluctuation of POP90 became smaller on the StrioTool in the middle screen on control room's wall.

In order to double check the measured cavity pole from the excitation line, I ran another Pcal swept sine measurement. I confirmed that the DARM cavity pole was indeed at 362 Hz. The attached is the measured DARM sensing function with the loop suppression taken out. The unit of the magnitude is in [cnts @ DARM IN1 / meters]. I used liso to fit the measurement as usual using a weighted least square method. 

By the way, in order to keep the cavity pole at its highest during the swept sine measurements, I servoed SRM to the manually adjusted operating point by running a hacky dither loop using awg, lockin demodulators and ezcaservos. I have used POP90 as a sensor signal for them. The two loops seemingly had ugf of about 0.1 Hz according to 1/e settling time. A screenshot of the dither loop setting is attached.

This is an update of the DCPD cross correlated spectra. This time I have added the one from Livingston which was integrated over 1266 hours using the O1 data. High noise durations (e.g. LLO 23453) are excluded from the integration.

The fig and mat files are attached.