Over the last week, we've made a few tweaks to the SUS DriftMon such that it can be a quick tool to use when checking for drifting or misaligned suspensions.  I've linked a smaller, more user friendly version of the monitor to the sitemap which can be tucked in a corner if useful.  If channels are yellow or red and further investigation is needed, pop open the larger screen via the button in the lower right corner.  From the larger screen you can also update the alarm levels to capture latest-and-greatest alignment.  I have updated the monitor to a full lock time from this last weekend (2/09 14:10 UTC, 1107526216 GPS).

I have adjusted the alarm thresholds of the SUS channels such that they tell you:
YELLOW = you are close to the previously saved alignment, so likely just need some minor alignment tweaks
RED = you are too far away from the previously saved alignment.  

If values are RED, and you are starting an initial alignment, it might mean:
- The GUARDIAN for the SUS is in a misaligned state
- WFS pointing offsets or FM integrators have been left on and need resetting
- Possible temperature change in the VEA

Note, RM1,2 and OM1,2,3 thresholds are pretty wide so I wouldn't expect them to go into alarm.  These suspensions are not used to point beams into the IFO but instead direct beams onto WFS/PDs so we are more forgiving of their pointing.  The OM chain might see more commissioning so we will tweak these alarm levels as needed.

The following maintenance tasks have been approved by Daniel for tomorrow:

1. restart h1susetmx model (attempt to fix decimation problem)
2. add some slow channels to TCS corner station model (h1tcscs)*
3. update PEM DAQ channels to list approved by Peter Fritschel*
4. add missing PCAL channels*
5. add ALS models test points to DAQ*
6. patch and reboot all CDS Linux workstations
7. reboot h1guardian0 machine (patch and remove NFS client file attributes caching)

* - task requires DAQ restart

We have had several reports of user accounts whose applets on the top right menu bar of their desktops have disappeared. We don't know why they disappear, but we know how to bring them back.

Attached is an image of what the top right should look like. If you are missing this, follow this procedure

1. Position mouse in top menu bar, not on an icon.
2. Press 'ALT' keyboad key and right-hand mouse key at the same time
3. Select  'Add to Panel...'
4. Scroll down, select 'Indicator Applet Complete'
5. Press 'Add' button

If the applet icon is not in the correct position, move it by positioning your mouse on the icon and pressing 'ALT' + right-hand mouse button

1. Select 'Move'
2. left mouse on the desired location

no restarts reported. Conlog reports not available.

Items for Monday by Subsystem

SEI:  Hugh/Jim reporting:  Test Blend Filter changes, Feed Forward Filters ready to go,

SUS:  no report

CDS:  no report

3IFO:  Richard reporting:  Working on Baffle PDs in LVEA

facilities:  Tumbleweed clean up until 10am inquired about for the week (Daniel mentioned tumbleweeding didn't affect too much)

PSL/Pcal:  Rick reporting:  EY visit for Pcal, ITM camera image work (work permit being made)

TCS:  3IFO inventory work

Items for Maintenance Tuesday (tomorrow)

• Daniel inquired about any possible bootfests tomorrow in the hopes for a quick recovery & being ready for Commissioning as soon as Maintenance ends at nooon!
• HEPI Pump Control (SEI)
• Capacitor checks (SEI)
• Seismometer [STS2] on floor (Richard),
• Current fluctations on HAM4/5 system (Richard)
• Oplev enclosure for BS (Doug)
• Long term storage container work (Bubba),

Sheila, Alexa, Evan

Summary

We have transitoned CARM from digital normalized REFLAIR9I to analog REFLAIR9I, with a 4 kHz bandwidth and 50 degrees of phase. An OLTF is attached [the last data point is spurious, so ignore it]. This lock started at about 2015-02-09 12:24:00 UTC. We are leaving the IFO locked.

There is plenty of phase to push the bandwidth higher, but we have encountered large offsets induced by switching on the common-mode and summing-node boards.

We can also improve the low-frequency fluctuations of the CARM error signal by introducing an integrator somewhere; we need more dc gain.

Details

Analog REFLAIR9I is plugged into input B2 on the summing-node board (SNB), with polarity "off". The output of B goes into input #2 on the common-mode board (CMB), with positive polarity. Digital normalized REFLAIR9I is plugged into input A1 on the SNB, with polarity "on". The output of A goes to input #1 on the CMB. [See LHO#16489 for a review.]

According to our reckoning, the shape of the digital CARM loop at the start of the transition is roughly 1/f above a few hertz. At a few hertz and below, it has a number of boosts and integrators which make it tricky to engineer a stable crossover with the analog signal.

Transition procedure is as follows, starting right after the guardian has brought the interferometer into resonance.

• With the B2 gain at 0 dB on the SNB, input B2 engaged on the SNB, and the input #2 gain at 0 dB on the CMB, we engage input #2.
• Step up B2 gain to 8 dB on the SNB.
• Turn off double integrator in digital CARM path (FM2 in REFLBIAS: it is two zeros at 2 Hz and two poles at 0.01 Hz).
• Step up B2 gain to 14 dB on the SNB.
• Remove zero-pole pair in digital CARM; it is a 1.6 Hz pole and 20 Hz zero. We remove this pair by engaging FM1 on REFLDCBIAS.
• Step up B2 gain to 17 dB on the SNB.
• Engage analog compensation filter in the CMB. It is a pole at 40 Hz and zero at 4 kHz.
• Ramp down digital CARM gain all the way to zero using the input matrix.
• Increase the analog CARM gain by 10 dB using the CMB slider. This is the point at which we saw disconcertingly large offset jumps. The total jump was 6 ct of REFLAIR_A_RF9_I_NORM. For comparison, the peak-to-peak fringing of this signal during digital CARM is 6 ct pkpk.
• We also saw a huge offset jump when turning off A1 on the SNB, which analogizes the digital CARM loop. In retrospect, this is probably because we had an integrated history on the output of this loop (since we turned the loop off at the LSC input matrix, not at the loop's output).
• To tune the error signal offset to zero, we have shifted around the common offset slider on the CMB

Also, the use of DHARD WFS (pitch and yaw) has removed the need for touching up the ETMs. However, since the AS36Q WFS feedback to the BS has not worked for the past couple of days, the BS had to be touched up by hand every so often.

Evan, Alexa, Lisa, Ryan, Sheila

Today we were able to lock about 7 more times todat, for at most a half hour.

• The gain needed for the transisition to RF CARM changed from an 8 in the input matrix to a 5.  We checked several settings, but found no explanation for this change.  The arm transmitted powers today have been 5-10% lower than on saturday morning.  
• The guardian now takes us all the way to on resonance, in about 15 minutes most of the time.  It fails often, maybe about half the time we drop the lock durring CARM offset reduction. 
• We were able to measure the ratio of the in vac refl 9I signal to the normalized (digitized) signal, using a 785 with an exictation into the CM board and test points in the summing junction (plot attached). The gain on the in vac path was 31dB, while the normalized path had a gain of 0 dB (these gains are both before the measurement point).  We made several attempts to transition to this signal, but haven't suceeded so far. 
• DRMI lock acquisition has been much faster today than in the past, probably due to the BS limiter.  
• We adjsuted the dark offsets in AS45Q
• ITMX oplev still seems to have significantly more drift than other optics, screen shot attached. If this is real motion it is too much for us to stay locked with, this is about a half a micron drift in less than 10 minutes. 
• We haven't been using the WFS to servo the BS alingment, we stopped doing this because engaging the WFS would sometimes cause mode mopping and lock losses.  Without the WFS we have slow drift tof the beamsplitter (as seen in AS 90) which might be causing some of our lock losses.  
• We drove a line in DARM at 43.1 Hz and measured the response in ASAIR 45 and saw that the signal in Q is only 5 times larger than I. Evan tried to adjust the demod phase to improve this, but the situation didn't change.
•  We added a boost to RF DARM, an integrator with a 2 Hz zero. The guardian turns this on before transitioning to CARM to REFL.  We are also no longer using FM4 (which was a low pass with extra gain around the suspension resonances, which seemed unusable on friday night.)  This needs further investigation.

We have many examples of locklosses from today.  We have added lock loss states to the guardians, so we should be able to get a list of these off the Detchar summary pages or the command line utility.  

Summary

Now we have a faster DHARD yaw loop during CARM offset reduction, analogous to the fast DHARD pitch loop that Elli, Ryan and I commissioned last week (LHO#16544, LHO#16520). Injecting a step response at the error point shows a loop time constant of a few seconds.

Details

With the loop open, I injected ASC-DHARD_Y_EXC with bandlimited noise from 0 to 3 Hz and measured the transfer funcion ASC-DHARD_Y_EXC → ASC-DHARD_Y_IN1. Since we have no yaw oplev damping on the ETMs, the optomechanical plant has two moderately high-Q resonances, which I estimate to be at 0.6 Hz with a Q of 18, and at 1.36 Hz with a Q of 45.

The attachment shows the plant measurement, along with the analytical system used for the plant inversion. Here I've intentionally lowed the second Q from 45 to 20, to avoid excessive ringing in the filter step response.

Just to be clear, these are not truly DHARD loops, since we're not actuating on the ITMs. Really it's just the differential angular motion of the ETMs.

Both DHARD loops are meant to be engaged with FM3, FM4 (giving a 1/f shape overall), FM8 (plant inversion plus high-frequency rolloff), and F10 (30 Hz elliptic low-pass). For pitch, gain is 16 ct/ct, and for yaw, gain is 200 ct/ct. In contrast to what I said in LHO#16520, nothing should be engaged in the ETM L2 lock filter modules.

Additionally, these loops currently require us to disable the M0 and L1 pitch/yaw lock filter banks on the ETM suspensions. This prevents the DHARD control signals from being offloaded to the upper stages.

model restarts logged for Sat 07/Feb/2015
2015_02_07 10:29 h1fw1

Unexpected restart. First fw restart since 03Feb (4.8days)

During the early steps of the CARM offset reduction last night it was observed that the ALS DIFF bandwidth was a little low, causing lock losses around the arm power where the transition to the tranmsission QPD sums takes place. To continue locking work the gain was doubled, but it was noted that this should not really change. Today, the ALS diff loop was re-measured, and found to be close to the expected value (under nominal gain settings), so its not clear what happened. At the same time, it was noticed that the length control was ringing at 1.56 Hz, which is sometimes associated with mismatched L1/L3 crossover. A quick measurement of this did not reveal any problem, and somewhat incidentially it was discovered that the alignment of the reaction chain has a significant effect on the length control at this frequency (the reaction chain had previously been adjusted for a different test), potentially due to angular cross-coupling. This should be investigated further.

A core switch in the OSB hung up over night. A reboot of the offending switch returned service to wired network, wireless, and phones at approximately 12:35PM PT.

After the reboot, the firmware was upgraded to the latest release of the same major version due to multiple candidate causes of the issue we are seeing having been fixed.

The HWS on ITMX was running during last night's 1 hour lock. It saw a lens of ~6 micro-diopters (double-passed) form while the IFO was locked. The transient data is in the attached plot.

HWSY is not currently operational.

At the moment, I can't reliably estimate the absorption coefficient, but the absorbed power is about 1.06 mW per micro-diopter (double-passed), so roughly 6mW of power was absorbed.

If I go with 2W requested from the PSL rotation stage and do the same calculation we did at LLO:

2W (input power) * 30 (recycling gain) * 0.5 (beam splitter) * 286 (arm cavity gain) = 8.6kW stored arm power,

which yields

  ~700 parts per billion absorption in ITMX coating

I would definitely take this number with a healthy grain of salt ... I'd still like to run some diagnostics on the ITMX HWS following yesterday's code update.

(Also, the data in the attached plot was rescaled in dataviewer, by 0.00326, to what is currently displayed to account for the fact that the HWS magnification was set to 1x at the time of this measurement, rather than 17.5x. The spherical power scales as 1/M^2 = 1/17.5^2 = 0.00326).

This came up a couple of times this week, and Aidan and I just figured out how to do it, so for those that don't already know:

You can scale data in plotted in dataviewer by going to menu: Data->Transformations->Geometric transforms...

Ryan, Lisa, Evan

We have been locked for more than 1 hour with CARM controlled by digital REFL9I (at 0 pm offset) and DARM controlled by ASAIR 45Q. The power buildup is 1100 times the single-arm buildup, giving an interferometer recycling gain of 33 W/W. The REFL_A_LF power is 1.35 ct, compared to 21 ct with the arms held off resonance. This means the interferometer visibility is about 94%.

The new element today was a higher-bandwidth DHARD pitch WFS loop. The loop time constant is a few seconds or so, and is fast enough to suppress the appearance of the microseism in ASAIR 45Q. Next steps are probably to close the analogous yaw loop. Ryan had to adjust ETM differential yaw by hand several times to keep the AS beam reasonably round. Also, Ryan had to add a DC-coupled oplev servo to ETMX L1 pitch in order to keep the optic from drifting.

Details will be posted later.