As was described in alog 13761 (see the addition to that entry) it seemed as if what we see in the POP sled QPDs are not what we expect.

As it turned out, the sled was badly off in YAW such that the beam doesn't come to the sled without using picomotors. I needed to use "magnum" step for moving picomotor in YAW. What we "saw" previously seems to be a lobe of severely clipped beam.

Anyway, using a straight shot beam I'm already getting 1551 counts of H1:ASC-POP_A_SUM_OUT and 1450 counts B (whitening gain 45dB), while the maximum we should get is about 1540 counts assuming 10W through IMC, 3% PRM, 229ppm PR2, 10% through attenuating BS, 1k transimpedance, 45db whitening and 0.8A/W responsivity.

(I'm not using "toW" filter, so these SUM numbers are raw counts.)

Note that centering on QPDA is sort of reasonable, so you should be able to use that reliably for the carrier buildup measurement, but on QPDB the beam is only on one quadrant (S3). I'll continue centering tomorrow.

Sheila, Kiwamu, Rana, Lisa

This plot corresponds to one of tonight PRMI carrier locks (Sep 11 around 3.50 UTC). The recycling power fluctuations are larger than 50%.  PR3 PIT is causing the motion at 700 mHz, ITMX YAW is largely dominating around 100 mHz .

Jim, Sebastien

For the past couple of days, we were seeing extra motion below 100mHz on the ITMX optical lever (especially in Yaw -> almost 1 microradian at DC)

Jim and I spent some time looking at the BSC-ISI, and finally ended up with a better configuration: the motion in Yaw has been reduced by one order of magnitude below 100mHz

New configuration:

- TSheila blends everywhere on ST1

- T750mHz blends on ST2. GS13s in high gain mode.

This improvement should be good enough for tonight. However, those are some premilinary results and there is still some work to do to fully understand what's happening.

It seems (this is just a guess for now) that we were reinjecting some noise by using the GS13s in low gain and  the wrong blends (too aggressive).  We'll have a better look at the ISI performance in different configurations tomorrow.

We also have to compare those results with the other chambers and see if we see consistency. Plus, it would be nice to work on damping the 0.7Hz resonance seen in Yaw.

Work in progress!

As logged here by Kiwamu, there was a reported problem with the BS oplev.  I've now gone through several hours of data and have found no instances of these small (on the order of 20 - 30 counts) changes in the QPD SUM causing the oplev pitch/yaw outputs to behave badly.  After reading this alog, it sounds as if the BS oplev is behaving.  In light of this I'm going to leave the oplev as is.  I will continue to keep an eye on it, and if any problems are noticed during commissioning efforts please let me know.

Dan, Jim, Dave

h1fw0 was becoming unstable (4 restarts today). We stopped h1fw0 and unmounted the file system. Dan upgraded h1ldasgw0 Solaris and rebooted. We restarted h1fw0, here is the data gap in the frame record"

-rw-r--r--  1 controls controls 1232710812 Sep 11 15:40 H-H1_C-1094510336-64.gwf
-rw-r--r--  1 controls controls 1232554615 Sep 11 16:22 H-H1_C-1094512896-64.gwf
 

08:17 Richard and Bubba to the end station chiller yards to look at new VFDs
11:20 Gerardo to the LVEA west bay to move the optic used for the electrostatic charging tests
13:18 Travis to the LVEA west bay to retrieve parts for the staging building
14:20 Jeff K. to end Y to swap cables for the ISI STS
14:45 Jeff K. back from end Y, did not swap cables, fixes need to be made in the model
15:39 Dave shutting down fw0 so that Dan can restart the Solaris box

Dust alarms at monitor #6

Permanent/dedicated AC receptacle for BSC5 annulus ion pump was wired yesterday and now need to get annulus on line

Advanced LIGO Conlog was introduced. The full presentation is available in the DCC. The document number is G1401113.

Some highlights:

* It provides a means to access historical values of control settings. This is accomplished by monitoring and recording EPICS process variables to a database. Searches on this database are made available through a web form and command line client.

* It is designed to retrieve values at a given instant, or changes over an interval (as opposed to continuous trends like dataviewer).

* It can help answer questions like: "I know it was working before, what changed?".

* It is currently available only on the internal CDS network. The web page is at 'h1conlog'. The command line client is called 'conlog_search'.

* There are three different search types available:
1. Return the value, alarm status and alarm severity at a given time:
The value, alarm status and alarm severity of each process variable at the given time is returned.

2. Compare the value, alarm status and alarm severity at two given times:
If the value, alarm status or alarm severity of a process variable differed at two given times, the differences are returned.

3. Find changes in the value, alarm status and alarm severity between two given times:
If the value, alarm status or alarm severity of a process variable changed between two given times, the changes are returned.

* Its status is indicated on an medm screen named CONLOG. This screen can be accessed from the sitemap under the CDS menu.

Please give it a try and don't hesitate to inform me of any issues that you encounter.

It occurred to me last night that instead of doing measurements, I could figure out the gains from comparing the results of one measurement I remembered the settings for (because it was recent, but wrong) to a more distant measurement that was "right"(or at least things work). The GS-13's have to be run in low gain, or the St1 actuators will saturate them, so they are known. Looking at my data from the 14th (or 4th) of Nov, 2013 (first 2 plots, with "unknown" but "correct" gains) and comparing the magnitudes with the measurement I took on the 6th of this month (plots 3 & 4, with L4C and T240 in low gain) indicates that the T240 should be in high gain, L4C and GS-13 in low gain. 

(Kiwamu, Alexa)

We adjusted the PRM M3 L2P drive align gain to -1.36. This reduces the coupling of length drive to pitch. We deduced this by driving PRM_M3_LOCK_L at several frequencies and seeing the effect in ASC_REFL_B_DC_PIT.

I have been checking the whole ASAIR_A and _B electronics chain all the way from the diodes to the ADCs.

In summary:

• ASAIR_A has a smaller transimpedance gain at 45.5 MHz than that of the test document.
• ASAIR_B looks healthy.

Note that I used the old calibration coefficient for estimating the amount of amplitude modulation in the AM laser (see alog 9630).

ASAIR_A_RF45 (S1300523)

Remarks:

The transimpedance seems smaller by a factor of two than that of the test sheet at 45.5 MHz. All the signal chain after the PD looks healthy.

According to the test sheet from Caltech (S1300523), the transimpedance of the high-rf output should be 803 Ohm. However, it seems that the AM signal I obtained was smaller than the expected by a factor of two. If I we blame the transimpedance for this discrepancy, the transimpedance is smaller by a factor of two.

• DC laser power = 120 mV / 100 Ohm / 0.67 A/W = 1.79 mW
• Expected AM signal when driven by 0.1 Vdrivepp = 5.13 mW x (1.79 mW / 1 mW) x 0.1 Vpp x 0.67 A/W x 803 Ohm = 494.0 mVpp
• Measured AM signal at the SMA jack of the RFPD enclosure = 248 mVpp
  • This is smaller by a factor of two.
  • If we blame the transimpedance, it must be 403 Ohm rather than 803 Ohm.
• Hereafter, I ignore the PD response and use the 248 mVpp signal to check the electronics chain in the downstream.
• Expected IF signal at I-mon = 248 mVpp x 10.9 x 1/2 (single-ended) = 1.35 Vpp
• Measured IF signal at I-mon = 1.42 Vpp
  • good agreement with a small discrepancy of 5%.
• Expected ADC counts = 248 mVpp x 10.9 x 2^16 counts /40 V = 4428 counts pp
• Measured ADC counts = 4060 counts pp
  • This is within 10% deviation. The signal chain after the PD is healthy.

ASAIR_B_RF18 (S1200242)

Remarks:

The signal chain looks OK. The demodulated signal at the ADC is bigger than the expected by 12%. Good enough.

The demod board has a special one where it has a diplexer upfront. According to the test sheet (S1001003), the conversion gain of the whole demodulation box for 18 MHz is 13.8.

• DC laser power = 823 mV / 2k Ohm / 0.4 A/W = 1.03 mW
• Expected AM signal when driven by 0.1 Vdrivepp = 5.13 mW x (1.03 mW / 1 mW) x 0.1 Vpp x 0.4 A/W x 1.6k Ohm (see the plot from alog 9719) = 338.0 mVpp
• Expected IF signal at I-mon = 338 mVpp x 13.8 x 1/2 (single-ended) = 2.33 Vpp
• Measured IF signal at I-mon = 2.8 Vpp
  • this is too big by 24 %.
• Expected ADC counts = 338 mVpp x 13.8 x 2^16 counts /40 V = 7642 counts pp
• Measured ADC counts = 8577 counts pp
  • This is bigger by 12%. Good enough.

ASAIR_B_RF90 (S1200242)

Remarks:

The signal chain looks OK. The demodulated signal at the ADC was smaller than the expected by 13%. Good enough.

According to the test sheet (S1001003), the conversion gain of the whole demodulation box for 91 MHz is 11.4.

• DC laser power = 1.03 mW
• Expected AM signal when driven by 0.1 Vdrivepp = 5.13 mW x (1.03 mW / 1 mW) x 0.1 Vpp x 0.4 A/W x 1.2k Ohm (see the plot from alog 9719)= 254 mVpp
• Expected IF signal at I-mon = 254 mVpp x 11.4 x 1/2 (single-ended) = 1.45 Vpp
• Measured IF signal at I-mon = 1.32 Vpp
  • this is 9% smaller.
• Expected ADC counts = 254 mVpp x 11.4 x 2^16 counts /40 V = 4744 counts pp
• Measured ADC counts = 4210 counts pp
  • This is smaller by 13%. Good enough.

Transimpedance measurement of resonant-type RFPDs

To investigate the too-low-transimpedance in REFL_A(S1300523). I measured the transimpedance of S1300523 and S1300526 (whic is a spare, ) to make a comparison. Of course this measurement relies on the AM laser calibration. I believe that the calibration of the AM laser calibration is better than a factor of two and therefore I claim that the transimpedance is actually lower than 803 Ohm as measured.

I used HP4395A and the AM laser. The calibration of the data was done such that the transimpedance of S1300523 becomes 403 Ohm at 45.50298 MHz. The same calibration coefficient was applied on S1300526. The plot below shows the results. The vertical and hrizontal line indicates 45.5 MHz and 403 Ohm respectively.

From this measurement, I conlude that S1300523 is behaving fine. Also the two RFPDs consistently showed lower transimpedance gain by roughly a factor of two than that reported in the test sheets at 45.50 MHz. A possible explanation I can thinkg of at this point is that the test sheets were somehow consistently overetimsted the transimpedance gains.

model restarts logged for Wed 10/Sep/2014
2014_09_10 10:24 h1hpiham2
2014_09_10 10:24 h1hpiham3
2014_09_10 10:24 h1iopseih23
2014_09_10 10:26 h1isiham2
2014_09_10 10:26 h1isiham3

no unexpected restarts. h1sieh23 was dac-locked and needed a restart.

Peter Bojtos, Robert S, Dave Barker

This was a test carried out on two microphones at CS and one at EY with three DAC Box associated with these microphone. I left EX untouched because that setup is working and I am using that as a baseline to check everything else.

 My initial conclusion after looking at the power spectrum and time series plot:

1. MIC S1400302 (at CS) seems to be working with every DAC Box (named B, G and Y). This was not the case when I tested it on Monday. I only tested with DAC B and G and it worked with DAC G but not B. Fishy.

2. MIC S1400299 (at CS) seems to be little arbitrary but may be still working. This was tested with all three DAC Box.

3. MIC S1400300 (at EY) is not working with any DAC Box.

4. Also, the AA chassis that takes the microphone at CS seems to have 10X additional gain compared to EY.

The power spectrum plot and time series plot are attached for comparison.

Lisa, Sheila, Rana, Kiwamu

One of the goals for tonight was to test out the PR3 low frequency oplev servo to see if it improves the long term locking stability. And it helped.

We could keep the carrier PRMI locked for more than 30 minutes which is long enough to perform some studies.

The highest recycling gain we obtained tonight was roughly 15. Still too low. The investigation continues.

(Angular drift)

The PR3 oplev was engaged all the time during the commissioning tonight. We used the pitch loop and left the yaw loop off all the time. This was good enough to keep the PRMI locked for a long time.

On the other hand, we did not have to pay attention to the BS oplevs -- the BS angular drift is not significant or maybe it is not drifting in the carrier lock condition. Indeed, we did not observe a significant long term degradation in the dark port beam pattern. I attach a vide of the dark port when the carrier PRMI was locked. Note that the BS oplev loops were engaged all time time, which take care of only damping. So there was no control at low frequencies via the opelv.

(Some attempt for a better alignment)

The highest build up we obtained tonight was about 3000 counts in POPAIR_A_LF. Compared with the simple MICH configuration, this is 500 times brighter light (it was about 6 counts when a simple MICH was locked with PRM misaligned.) If we ignore a mode-matching effect, this corresponds to a recycling gain of 15.

However, when the intracavity power was maximized, we noticed that the REFL beam had a terrible beam shape -- the prompt reflection from PRM and the leakage fields were far apart. I will post a video of the REFL beam later. So we suspected a large misalignment in IMs.

We then tried moving a combination of IM3 and IM4, and a combination of IM1 and IM4 to see if we can make both the build-up and refl beam better. This was not successful. We could not optimized both at the same time. Tomorrow, we will check out the ABCD matrix for the IMs to make sure we are moving the right degrees of freedom.

(Some loop studies)

In parallel to the low-recycling-gain study, we measured the open loop of the length loops. The UGF of PRCL was about 40 Hz and MICH was 8 Hz. The phase looked OK. We will quantitatively cross-check the loops with models tomorrow.

I readjusted the demodulation phase of all the REFL WFSs. This time, instead of using a IMC excitation techqnue, I simply used a free swinging PRX signal and minimized the q-signals. The phases were adjusted such that every segment has the same sign.

In the process, I found that five RF cables disconnected from the field rack. Bad. This explains why we did not have a good signal in REFL_A_RF9_SEG4. I plugged them back in. Now they can see reasonable signals.

=======

J. Kissel, J. Rollins, S. Dwyer, A. Staley

While Sheila and Alexa began to lock PRMI on carrier, the HAM2 and HAM3 HEPI and ISIs tripped for an unknown reason. We'll leave this to people offline to figure out what happened. See attached actuator trip plots from the ISIs.