re WP 3999

We swapped the Parker Valve on BSC2 NE Vertical Actuator.  It went smoothly with little mess.  This Vertical Actuator remains in bleed mode for a time, at least an hour or several.  This means vertical drive of this corner is not possible.  If the HIFOY crew can not proceed come early afternoon, we'll forgo any further bleeding and put it back to Run mode for driving.  Otherwise we'll put it back into Run mode first thing tomorrow.  At the moment this disturbed position is not critical for the HIFO crew.  Attached are trends of the global position, it sure would be nice if the frames had the units contained...  I believe the units presented are nanometers & nanoradians.  So the horizontal positions are back: X, Y, & RZ; but, the vertical dofs are not.  Again though, currently, the HIFOY crew can work with it the way it sits.  If you think about the location of the corner we have disturbed, it's likely we have tilted the table around the barrel of the optic and therefore possibly have only rolled it.  Looking directly at the vertical IPS readouts of corners 2 & 4, (not plotted) there is a total pitch about the NW-SE axis of 1.5mm over the ~4m distance between the diagonal piers giving a roll of ~0.4mrads.

Noticed pressure increase on X-arm this morning -> Found that one channel of IP10 had shut off -> Turned channel back on and OK now -> Took this opportunity to change "STEP" values from 7000V-5000V-3000V to 5000V-5000V-3000V 

h1fw0 is currently offline for its upgrade, adding a local RAID storage device for raw minute trend archival. This means that h1nds0 does not have access to recent frame files. Most NDS clients are defaulting to h1nds1 and will not be impacted by this work. If you are using h1nds0, please switch to h1nds1 for the duration of this work.

[Matt, Lisa, Chris, Kiwamu, Alexa]

(This alog pertains to work done last night).

Last night we went to EY and adjusted several settings in both the PLL and PDH loops.

PLL LOOP:

We changed the settings on CMB_FIBR to increase the UGF of the loop. In particular, we turned off the output gain and decreased the input gain to -6dB. In addition, we turned the generic filter on. The settings are now as follows:

Common Compensation: ON

Boost one:  ON

Fast Option: ON

Generfic filter (in common path): ON

Input gain: -6dB

With these settings, the UGF is now 29kHz (up from 20kHz). We also measured the error signal spectrum and saw a peak at 28kHz.

PDH LOOP:

We also made changes on CMB_REFL. In particular we increased the input gain to 12dB. The settings are now as follows:

Common Compensation: ON

Boost one: ON

Input gain: 12dB

Output gain: 0dB

In addition, we altered the temperature control to reduce oscillations of the signal; on the PLL autolocker we reduced the slow frequency servo UGF to 0.01 from 0.035. We also tried using a 4dB attenuator on the RF modulator to see if that would reduce the oscillations; however, this did not seem to help.

With these settings, the UGF is now around 3kHz (down from 9kHz). Again, we measured the error signal spectrum and saw a peak at 28kHz. Clearly, we were seeing the features of the PLL loop in the PDH loop.

Additionaly, we saw that H1:ALS-Y_REFL_A_DC_POWER was oscillating vary rapidly from 50 counts to zero counts. As we misaligned the PD, the oscillation continued but reduced to 20 counts. If we completely blocked the beam, the signal dropped down to zero counts and remained so. As of last night, we left the PD slightly misaligned to reduce the oscillations in the PDH loop.

Attachments:

The attached pictures are as follows:

1) PLL transfer function

2) PLL error signal spectrum

3) PDH transfer function

4) PDH error signal spectrum

5) CMB_FIBR (as of this morning)

6) CMB_REFL (as of this morning)

(Corey, Keita, Lisa, Matt, Virginio)

In-Vacuum ISC Table

Lisa & Matt finished up laying out optics on the table (this included installing the mirror on the Beam Diverter, and installing the High Power Beam Dump [although one of the ceramic legs broke & will need to be replaced]).  This afternoon they were approaching point of aligning optics.

Setting Up Alignment Laser & Telescope Work

Virginio & Keita worked on setting up the alignment laser.  Before using it, they wanted to measure the beam profile of the laser.  The Telescope Assy was suspended from its tooling.  Made an Ameristat "tent" to enclose the Telescope and the Ag-plated mirrors when they are ready to be installed.  The mirrors will be insalled when the desiccant packs arrive on site. 

Clean Up, ISC-ing, Photos, Feedthru, & Humidity

Continued putting hardware away, and working on making ICS Assy Loads for the TMS.  Continue to upload photos of progress, here.  Helped Filiberto install the final roof-side cable to the TMS feed-thru.  The humidity in the Lab was 34-40%.

Filiburto DC powered the IO Chassis for h1iscex, Jim and I started the IOP model. We found that the IO Chassis appears to be the PEM MY (one ADC, one 18bit DAC) rather than the ISC EX Chassis (3 ADC, one 16bit DAC). 

• Corey and Virginio at EX working in TMS lab
• Filiberto hooking up cables at EX
• Jim Batch at EX troubleshooting network issues
• Gregorio at MX dropping off parts for iLIGO PSL
• Dominick at MY storing parts for Filiberto
• Rick, Craig, Pablo, Colin in H2 PSL assembling PCAL periscope

Last shift at LIGO. It's been fun!

Valved-in YBM turbo @ 0930 hrs -> 6.5 x 10-7 torr*L/sec

Valved-out YBM turbo @ 1600 hrs. -> 4.3 x 10-7 torr*L/sec

Just before lunch, I moved, unplugged and replugged back in the dust monitor at X-end.  It had been sitting in the large cleanroom over the chamber, but since the the chamber is closed with the hard-covers, the more fitting place is for it to monitor near the ETMx optic.  So, it is now in the cartridge assembly cleanroom.

Following the activation of jumbo frames on the EX DAQ switch, the IOP models h1iopsusex, h1iopsusauxex and h1iopseiex were successfully started with no negative impact on the DAQ system. The IO Chassis for h1iscex is not connected or powered, and so that front end is not running at the moment.

Here is the current status of the aLIGO SEI work regarding the HAM chambers. Everything in bold is to be completed for HIFO-Y. Everything in red is a change from last week's status. Everything in green is available.

Here is a plot from last night showing the VCO stability using the slow servo to keep it at nominal. 
The standard deviation of the distribution is about 16Hz.

None of the end-x front end computers had correct BIOS settings, so all have been changed to disable as many "features" as possible, and to enable PXE boot option ROM loading.  New BIOS settings resemble those of h1susb123 in the BIOS settings document (T-1300536).

The HEPI model at the end station (H1HPIETMY) was recompiled to receive the LSC lenth signal.

Changes since https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=6595

BSC1
ISI: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=6832
HEPI: Locked

BSC2
ISI: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=6834
HEPI: Unlocked - Valve of actuator V4 will be changed on June 25th.

BSC6
ISI: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=6768
HEPI: Unlocked - Controlled in position and with IPS-L4C blend
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=6709

STS2
STS-2 are connected at the corner station and at EY. Their locations are specified in:
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=6456
For now, only HEPI ETMY and ISI ITMY respect the convention. Other models will be changed at the next "boot fest" to follow the convention.

This is a log from this past Friday:

The goals of the day were (1) to measure a calibrated CARM signal and (2) to try switching the frequency sensor to the PFD (Phase Frequency Discriminator). The former was achieved but the latter was not.

Calibration of the CARM signal

 The VCO-based PLL, which is our frequency sensor for the CARM, was calibrated by an IFR RF generator so that one can evaluate the CARM fluctuation in a meaningful unit. The output signal from the PLL gets into an SR560 which does a signal amplification (pole at 100 Hz and gain of 10 ) and then is branched to the common mode board and an ADC through an RFPD interface box for monitoring the CARM signal. This channel is called H1:ALS-C_COMM_A_RF_I. Since this doesn't go through the common mode board the calibration is independent of the common mode board gain, which is good. Anyway according to a measurement where a known RF signal is injected to the RF input of the PLL a calibration factor of 176.2 Hz/ counts was obtained. This number was currently put in the gain of ALS-C_COMM_A_RF_I.

Calibrated CARM in-loop signal

The plot below is a measured CARM in-loop spectrum.

The residual fluctuation was measured to be 23.66 Hz in RMS integrated from 10 mHz to 7 kHz (shown as dashed line). However we are aiming a residual RMS of 8 Hz in order to confine the PSL frequency well within the arm resonance whose linewidth is approximately 80 Hz. So we are still far from the requirement by a factor of 4-ish but this is not surprising since we established the CARM control very recently.

Some notes on this plot

• The loop configuration is the same as the one we established in this past Tuesday (see alog 6801) except for the following two parts :
  • the gain of the end PDH loop was increased by a 4 dB (see alog 6835).
  • Matt added a Pomona box right after the second SR560 for low passing the CARM signal at 13 kHz.
• RMS of 23.66 Hz is inconsistent with what we observed in the transmitted light of the infrared beam (see alog 6801)
  • The arm cavity currently should have a linewidth of 168.14 Hz if T_etm = T_itm = 0.014 is assumed. The fluctuation of 23.66 Hz is not big enough to explain the 20 % fluctuation of the transmitted light.
  • The observed fluctuation may be due to an angular fluctuation happening somewhere. We need a better sensor which is more insensitive to the angular degrees of freedom i.e. length RF diode or a single PD on ISCTEY table (?).
  • Also if the sensor noise is high, the actual fluctuation observed at the transmitted light may be higher than 23 Hz.
• The RMS is dominated by high frequency components mainly above 1 kHz. Noise source is not identified yet.
• The 2.5 Hz peak wasn't always prominent. Depending on the time you are looking at the peak sometimes disappeared.
• The high frequency cut off at 5-6 kHz is probably due to a down sampling filter. Though I haven't confirmed if this was true. Note that the signals are recorded in 16 kHz.
  • Anyway it is possible that there might be some significant residual components above 6 kHz. An analog measurement is also necessary.

Alignment drift in the arm cavity

It seems there was an alignment drift which turned out to be big enough to prevent us from a long term measurement (say more than 30 min.). This looks due to a longitudinal to angle coupling in the ETMY top mass actuators. We have used an length offload scheme that relieves the end PDH signal from the low frequency saturation by branching the signal to the arm length via the ETMY top mass actuation. According to Matt the One-Arm-Test people used to offload this signal to HEPI rather than the ETMY or ISI, but recently we ended up with this ETMY scheme for some reason. Anyhow I think we have to go back to the old school -- offloading to the HEPI rather than the ETMY suspension for more rock solid lock.

The time series attached below is a trend during the CARM was locked. The CARM loop was closed right after the end PDH was engaged and then it was brought to the arm resonance several minutes later. I was tweaking PR2 and IM4 in the first 5-ish minutes after the IR became resonant. Then I stopped messing around afterward and simply let it locked. Obviously the oplev was seeing drift in both and YAW and PIT of ETMY by 0.3 urad or so over 20 minutes. Eventually the lock was lost (probably the end PDH first and then every loop lost their lock) due to the bad alignment. Once the length offload was shut off the alignment came back perfectly --- this strongly suggests a length to angle coupling in the ETMY top mass actuators at low frequency.

CARM control with PFD

Still unsuccessful --- I tried to close the CARM loop without using the PLL frequency sensor that we recently have been using but this basically destroys the IMC lock. One big reason is that there is a big gain discrepancy between the frequency sensor and phase sensor modes. This complicates the control scheme. Another reason is that it seems difficult to confine the PFD within its phase sensor mode by feeding the CARM signal to the MC2 suspension. The MCL control bandwidth can be 100 Hz or so, but probably this is not good enough to confine it within the phase range in the first place. Hmmm ....  Also, I tried to confine the sensor close to the phase range by feeding a low frequency signal to the ALS_comm VCO through the Beckoff by using ezcaservo but this turned out that the slow control is too slow for this job, plus everytime the sensor enters the phase sensor range it gives a large signal and somehow kicks the VCO frequency away from it instantaneously.

The last thing we can try is a transition from the PLL frequency sensor to the PFD once everything is locked with the frequency sensor (though we need to establish some kind of fast switching since the CARM signal is mainly processed in the analog land).

Beatnote lost and found -- it was BS HEPI alignment

As reported (see alog 6835) the beatnote had been lost at the corner station. This turned out to be due to mainly an alignment of the BS HEPI and indeed the beam was hitting the mount of one of the 1 inch mirror on ISCT1 before the beam gets combined with the PSL green light. Vincent told me that the BS HEPI had been stack since the last Monday (correct me if wrong) and he suggested me to recover the position of the HEPI by introducing biases in the actuators. We tried this and it worked -- the beam came back to a good position on ISCT1 and we became able to see the beatnote again. It is still unclear why the BS HEPI alignment changed between Wednesday to Thursday even though it was stack. Although the alignment was mostly recovered, later on a fine tuning of the green beam alignment was done by tweaking PR3.

Giles report from yesterday's work:

(Travis, Mark, Jason, Doug, Giles)

After leaving the PUM hanging overnight there was no further development of the crack. We then proceeded to re-lock the PUM and hang the ETM to perform modal measurements. Using the autocollimator we measured the longitudinal, pitch and yaw modes. We then setup and optical lever to measure the transverse, bounce and roll modes. Finally we measured the 4 fundamental violin modes. The modal data gathered was:         

Longitudinal    0.656 Hz

Pitch  1.09 Hz

Yaw  1.09 Hz

Transverse 0.656 Hz

Bounce 6.75 Hz (this will be sqrt(2) higher when the PUM is free)

Roll 9.6 Hz (this will be sqrt(2) higher when the PUM is free)

FR  505 Hz

FL  506.5 Hz

BR  506.5 Hz

BL  505 Hz

We finally installed the fibre guards and covered the entire lower stage.

(Corey, Keita, Lisa, Matt, Virginio)

ISC Table Layout Has Begun

I roughly laid out the QPD Sleds, High Power Beam Dump, & Beam Diverter.  Matt & Lisa started laying out all the rest of the optics (which required brining all the hardware from the Corner Station and then building each component, and then laying it out.)  Most of the optics are now on the Table.  Matt & Lisa will finish off laying them out and then begin aligning everything next week.

Telescope:  Staging & Tooling

Virginio & I unwrapped Tooling for suspending the Telescope.  Virginio is staging to start using our alignment laser.

Continuing To ICS

Continue to start making Assy Loads and accounting for all parts used for this installation.

EX TMS Weather

Relative Humidity started at 30% in the morning and went to 35% in the afternoon.  We will receive desicant packs and hygrometers on Mon/Tues.

HAM HEPIs 4 and 5 were brought into run mode yesterday, June 20th. 

current HEPI Status: