During the laser shutdowns last night, we acquire the background values for the CO2 laser QPDs.

The following adjustments were made to CO2 QPD EPICS channels to enter (and activate) the offsets and to add in the correct coefficients in the  PIT/YAW/SUM summing matrices

caput H1:TCS-ITMX_CO2_QPD_A_SEG1_OFFSET -171

caput H1:TCS-ITMY_CO2_QPD_A_SEG1_OFFSET 17.7

caput H1:TCS-ITMX_CO2_QPD_A_SEG2_OFFSET 74.3

caput H1:TCS-ITMY_CO2_QPD_A_SEG2_OFFSET -22.8

caput H1:TCS-ITMX_CO2_QPD_A_SEG3_OFFSET 131.3

caput H1:TCS-ITMY_CO2_QPD_A_SEG3_OFFSET -451.5

caput H1:TCS-ITMX_CO2_QPD_A_SEG4_OFFSET -419.5

caput H1:TCS-ITMY_CO2_QPD_A_SEG4_OFFSET 446.9

caput H1:TCS-ITMX_CO2_QPD_B_SEG1_OFFSET 150.2

caput H1:TCS-ITMY_CO2_QPD_B_SEG1_OFFSET 53.95

caput H1:TCS-ITMX_CO2_QPD_B_SEG2_OFFSET -854

caput H1:TCS-ITMY_CO2_QPD_B_SEG2_OFFSET 238.1

caput H1:TCS-ITMX_CO2_QPD_B_SEG3_OFFSET -197.1

caput H1:TCS-ITMY_CO2_QPD_B_SEG3_OFFSET -366.9

caput H1:TCS-ITMX_CO2_QPD_B_SEG4_OFFSET -181.7

caput H1:TCS-ITMY_CO2_QPD_B_SEG4_OFFSET -68.4

caput H1:TCS-ITMY_CO2_QPD_A_SEG1_SW1 8

caput H1:TCS-ITMY_CO2_QPD_A_SEG2_SW1 8

caput H1:TCS-ITMY_CO2_QPD_A_SEG3_SW1 8

caput H1:TCS-ITMY_CO2_QPD_A_SEG4_SW1 8

caput H1:TCS-ITMY_CO2_QPD_B_SEG1_SW1 8

caput H1:TCS-ITMY_CO2_QPD_B_SEG2_SW1 8

caput H1:TCS-ITMY_CO2_QPD_B_SEG3_SW1 8

caput H1:TCS-ITMY_CO2_QPD_B_SEG4_SW1 8

caput H1:TCS-ITMX_CO2_QPD_A_SEG1_SW1 8

caput H1:TCS-ITMX_CO2_QPD_A_SEG2_SW1 8

caput H1:TCS-ITMX_CO2_QPD_A_SEG3_SW1 8

caput H1:TCS-ITMX_CO2_QPD_A_SEG4_SW1 8

caput H1:TCS-ITMX_CO2_QPD_B_SEG1_SW1 8

caput H1:TCS-ITMX_CO2_QPD_B_SEG2_SW1 8

caput H1:TCS-ITMX_CO2_QPD_B_SEG3_SW1 8

caput H1:TCS-ITMX_CO2_QPD_B_SEG4_SW1 8

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_3_1 1

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_3_2 1

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_3_3 1

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_3_4 1

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_1_1 1

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_1_2 1

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_1_3 -1

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_1_4 -1

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_2_1 1

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_2_2 -1

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_2_3 -1

caput H1:TCS-ITMY_CO2_QPD_A_MTRX_2_4 1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_3_1 1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_3_2 1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_3_3 1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_3_4 1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_1_1 1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_1_2 1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_1_3 -1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_1_4 -1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_2_1 1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_2_2 -1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_2_3 -1

caput H1:TCS-ITMY_CO2_QPD_B_MTRX_2_4 1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_3_1 1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_3_2 1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_3_3 1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_3_4 1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_1_1 1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_1_2 1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_1_3 -1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_1_4 -1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_2_1 1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_2_2 -1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_2_3 -1

caput H1:TCS-ITMX_CO2_QPD_A_MTRX_2_4 1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_3_1 1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_3_2 1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_3_3 1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_3_4 1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_1_1 1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_1_2 1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_1_3 -1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_1_4 -1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_2_1 1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_2_2 -1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_2_3 -1

caput H1:TCS-ITMX_CO2_QPD_B_MTRX_2_4 1

Evan G. and I have restarted CW hardware injections, using the
old iLIGO actuation scheme, where the correction for the actuation
function is done directly, frequency by frequency, for each of
the 15 injected pulsars individually, without using a time-domain
inverse actuation filter. That filter is now no longer in the
path between H1:CAL-PINJX_CW and H1:CAL-PINJX_HARDWARE. We have
verified that the new envelope of the H1:CAL-PINJX_HARDWARE channel
is close to what it was before and that the spectral heights of
the injected signals look about the same (we don't expect perfect 
agreement). 

The injections will be left running for at least 24 hours, to verify
that the sidereal-day envelope agrees with what it was before,
within expectation, and that same-sidereal-time spectral snapshots 
agree reasonably well.

For reference, a new subdirectory O2test has been created in
the hinj Details/pulsar/ directory for this test and the
symlink RELEASE redefined to point to it. The only differences
between the files in O2test and O1test are the addition of
Evan's actuation function posted here and new in.N (N=0-14)
command files with the makefakedata actuation argument turned on.

Once we are satisfied the new injection actuation is working
as intended, the svn directories will be updated. One other
change I'd like to make is to use an actuation function file
that takes into account the extra time delay for the excitation
channel itself. Evan will consult with Jeff on approval for
that swap.

BSC5 annulus IP is flickering between red and green state. 

BSC8 aIP was in the red a few days ago, but seems to have recovered. 

many CDS workstations experienced a mini-freeze at roughly 14:10 this afternoon. The freeze up lasted only 10 seconds or so. Unlike the one reported several weeks ago, no "/ligo unavailble" errors were logged, in fact no errors of any type were logged at the time.

Transitioning over to the new, improved inverse actuation filters (see LHO aLOG 27176), I removed the old filters from PINJ_HARDWARE and installed the new inverse actuation filters into the PINJ_TRANSIENT bank. Since the CW injections will apply the inverse actuation function to condition their signals before sending it to the PINJ path, we don't want the filters in PINJ_HARDWARE any longer.

CW injections are running right now using this new actuation function. Keith R. and I made a test of this earlier to verify the output was roughly correct (Keith will post an aLOG about our work). He wants to see this running over the next few days to gain confidence that the injections are operating normally.

Peter, Jeff B, Dave, Kiwamu, Nutsinee

Quick conclusion: They work now.

Details: This morning we troubleshoot the cause of TCS chillers failure last night. All the channels in the chiller servo was requesting the right number (20C, no crazy gains). We went to the chillers and realized that the set point was 5 degree C for both TCSX and Y chillers instead of its nominal (20C). We tried to reset the set point at the chiller and it would come right back to 5C. This suggested that the front end was sending out some bad number to the chillers. This was confirmed further by measuring the voltage between pin 6 (ground) and pin 7 (temperature control) at the connector pinout and we were able to change the temperature setpoint when we unplugged this connector. Later we found out that H1OAF DAC went bad yesterday 19:18 PT. This forced the IOP to send out 0 values and caused the chiller setpoint to change to the lowest temperature possible. 10 minutes after DAC failed the chiller interlocks tripped because the chiller temperature was to low. Accordning to Sheila this happened when the temperature reached about 15 deg C. Below I included the plot of CO2 laser temperature, which is slightly higher than the actual chiller temperature but it's a good indicator of what happened to the chiller temperature (I couldn't find a channel that would report the actual chiller temperature).

We don't know what caused this DAC error. Dave also mentioned that this is quite rare.

Totally unrelated note to what happened, TCSY chiller is really nasty. I've attached a picture of inside the chiller Peter took earlier today.

I did an svn update of C:/SlowControls/TwinCAT3/Vacuum/LHO/MEDM on each computer and ran C:/SlowControls/TwinCAT3/Vacuum/LHO/MEDM/Source/create_medms.py to regenerate the screens.

Completes WP 5900.

I added the BSC5 AIP and BSC6 AIP to the vacuum overview. The BSC5 AIP is not physically connected, so is flashing red occasionally.

Diode Chiller on the bottom did not have a red LED alarm, so did not add any water to it.

Crystal Chiller was topped off with about 235mL (although a minute later it looked like it dropped a little from "MAX" level, but I just left it as is.)

This CLOSES FAMIS#4152.

Added 903 channels. Removed 390 channels. List attached.

The staging building chiller has been replaced with a new unit and appears to be cooling the building very well. Pictures attached show the old chiller being removed and the new chiller ready for install.

Evan, Sheila, Ed, Nutsinee on the phone

Both TCS lasers tripped off within 20 minutes tonight, apparently because of a low temperature alarm on the chillers.  We called Nutsinee and used the wiki to reset the chillers and lasers, but the lasers didn't come on although the lights on the controller were lit. The chillers tripped again within 15 minutes of being reset.  

We tried setting the TCSX guardian to Down and resetting the chiller again, but the temperature dropped quickly and the chiller started beeping and had a low temperature warning message, so we shut it off using the power button.  

In the attached screenshot the bottom screen is a time machine image of the laser screen from yesterday, the top screen is right now.  We tried enabling the output of LZR_HD, but that didn't work.  

Nutsinee wondered on the phone if this could be related to some bad settings after todays model restart.  I laoded the burt that was created by the model restart, but there are no diffs so that seems OK. 

I tweaked all the PUM pitch/yaw notch filters for the quad bounce and roll modes so that we can have a slightly better gain margin on the hard angular loops.

The bounce notch was tuned slightly too low given our bounce mode frequencies (9.73, 9.77, 9.81, and 9.85 Hz according to our bounce monitor filters). The roll notch seemed too wide. (Are we supposed to see Shapiro effect when driving the PUM close to the bounce and roll modes?)

I changed both notches to 3rd order elliptic filters, so the filter ripple should not extend above the 0 dB mark (previously, it went as high as 2 dB). I retuned the stopbands to give >30 dB attenuation at the bounce and roll mode frequencies (previously, the highest bounce mode frequency was only notched by 16 dB). This reworking has the added benefit of giving us 10° of phase back at 8 Hz.

These filters were installed and seem to work fine in full lock at 2 W.

Below are the past 10 day PSL trends. THe chiller woes are still apparent in these. The spare chiller has since been substituted while the former is being addressed.

It seems that the contrast defect degrades as a function of the PSL power when we power up according to the data from last night. This is not surprising.

However, this could be a cause of the recent behavior where the power recycling gain decreases as we power up. Tuning up the differential CO2 at a high PSL power can be an interesting experimental option to try out.

[An offline analysis]

I have looked at the data from last night. There were two good periods where the interferometer was locked stabily at different powers within the same lock stretch.

• 24-May-2016 6:26 UTC, locked with a 17 W PSL power, DC readout
• 24-May-2016 6:50 UTC, locked with a 31 W PSL power, DC readout

Because our OMC/DARM servo automatically maintains the same amount of the DC carrier light at the dark port (20 mA in DCPD SUM), increasing the PSL power from 17 to 31 W must have changed the DARM offset by sqrt(17/31) = 0.74. If there was no contrast defect, the amount of intensity noise at DCPD SUM should not change because it is only the local oscillator field who carries the intensity noise audio sidebands to the dark port and the absolute size of the local oscillator field is maintained to the same value by the OMC/DARM servo. In contrast, the intensity noise conveyed by the contrast defect simply scales with the PSL power and therefore one might expect an increase by a factor of 2 ish in the coupling coefficient for the case of the contrast-defect-induced intensity noise (assuming that the contrast defect does not change.)

The attached below shows a spectrum of the DCPD SUM for the two different power configurations.

As shown, the spectra above 100 Hz are (roughly speaking) almost always intensity noise limited. The variation of the spectral shape below 100 Hz might be due to different ASC settings which Sheila and Evan tried on the fly. The intensity noise increased by a factor of 4.5 or so rather than a factor of 2 at around 1 kHz as we powered up the PSL power. This likely means that the contrast defect became worse by a factor of 2 or so in its field strength power at the dark port. Although it is unclear how much this degradation of the contrast defect contributes to our recent low power recycling gain, it may be interesting to tune up the differential CO2 to see if we can get back to a high recycling gain.

Sheila, Haocun

We are trying to compare the amplitudes of 90MHz and 36MHz modulations at the AS port.

1. Using gpib connected to Agilent 4395A to measure the spectra of photo-current signals. The measurements are 1E-7 V/rtHz for 36MHz, 6E-8 V/rtHz for 45MHz, and 7E-8 V/rtHz for 90MHz. 
   All three signals are at the similar level.
2. Using RF detectors to check the input signal of demodulator, which are -18dBm for 36MHz, -12dBm for 45MHz, and -28dBm for 90MHz. 
   The 90MHz is lower, about 1/4 of 36MHz.
3. From measurements coming out from the demodulator are: 2943 counts for 36MHz, 2557cnts for 45MHz, and 17cnts for 90MHz (after being divided by gains).
   The factor drops to < 1/100.

These results are not consistent with each other, and we will check by changing the whitening gains and the demodulator.

Summary:
A new, better inverse actuation filter has been made for the x-arm Pcal, but it has not yet replaced the old filter. This was constructed using knowledge of the Pcal OFS-AOM gain coefficient (see LHO alog 27155), the suspension model, and models of the digital/analog AI components. The AI components had to be approximated since the injection model runs at 16k. Also, the actuation function delays couldn't be included in the filter, so all waveforms using the attached actuation function or using the inverse actuation filter should assume a timing advance of 225 us. Another aLOG will be posted once the new filter is in place.

When including this timing shift, the new actuation function/inverse actuation filter match the real values to within 5% in magnitude and 5 degrees in phase up to 2 kHz. Above 2 kHz, the deviations from the true actuation function are significant due to the approximations chosen for the analog/digital AI filters and a rolloff filter being applied.


Details:
The continuous wave hardware injections would like to use the Pcal actuation function instead of an inverse actuation filter for O2. Meanwhile, the transient injections will continue to use an inverse actuation filter. The actuation function is nominally modeled as follows:
PCALX_EXC --> IOP-15 --> 16k-64k AI(D) --> DAC (V/ct) --> ZOH 7.5 --> AI(A) --> OFS --> AOM --> N/W --> Norm. SUS --> 1/f^2 --> DC SUS (m/N) --> 1/L (h/m) --> strain
Legend:
IOP-15 = 15 us delay from the IOP
16k-64k AI(D) = digital anti-imaging filter (using the new RCGv3.0.2 filter, see LHO alog 27173)
DAC = digital-to-analog converter
ZOH 7.5 = zero-order-hold, 7.5 us delay
AI(A) = analog anti-imaging filter
OFS = optical follower servo
AOM = acousto-optic modulator
N/W = power-to-force coefficient = 2*cos(theta)/c (Note that this does not include rotation-induced errors, with 1-sigma uncertainty of 0.4%, see LIGO-L1600018)
Norm. SUS = normalized suspension transfer function model which has been multiplied by zpk filter with 2 zeros at 1 Hz
1/f^2 = zpk filter with 2 poles at 1 Hz
DC SUS (m/N) = suspension force-to-length "DC" coefficient
1/L (h/m) = inverse of the mean arm length

The OFS-AOM system has a wide-bandwidth (UGF ~50 kHz) and a gain of 0.0923 W/V for H1 ETMX Pcal (this is watts impinging on the ETM per volt of drive sent to the OFS, LHO alog 27155). The SUS file used is in the SUS repository:
/ligo/svncommon/SusSVN/sus/trunk/Common/SusModelTags/Matlab/quadmodelproduction-rev7652_ssmake4pv2eMB5f_fiber-rev3601_h1etmx-rev7641_released-2015-08-07.mat
However, in order to construct an *inverse* actuation filter, some of these components cannot be included because a delay would turn into an advance (breaking causality). In addition, the model runs at 16k, so the inverse AI digital filter must be approximated. The high frequency components of the inverse actuation filter need to be rolled off using additional filtering. Thus, the *inverse* actuation filter model is constructed as follows:
strain --> L (m/h) --> 1/DC SUS (N/m) --> f^2 --> 1/Norm. SUS --> W/N --> 1/[OFS * AOM] --> 1/AI(A) approx --> DAC (ct/V) --> 1/AI(D) approx --> Ellip. rolloff --> 3 7kHz poles --> PCALX_EXC
Here, there are two approximations made: the analog/digital AI filters are modeled to roughly match the magnitude (see comparisons in figures 1 and 2), as well as removing the IOP and ZOH delays. Note that two rolloff filters are used to suppress high-frequency content, a 3rd-order elliptic filter and 3 7kHz poles. The phase error in the approximations is accounted for with the expectation that waveforms using this inverse actuation filter will need a timing advance of 225 us.

The analog AI approximation is one zero at 5160 Hz and 2 poles at 7100 Hz (e.g., [5160:7100,7100])--see figure 1. The digital AI approximation is 4 zeros at 7000 Hz, and 2 complex pole pairs (e.g., [7k,7k,7k,7k:pair(4300,30),pair(7000,50)])--see figure 2. The elliptic rolloff filter is given by the Matlab function myellip_z2(6900,3,.4,10,10)--6900 Hz knee frequency, 3rd-order, 0.4 dB ripple, 10 dB stopband, and zQ of 10.

The final Pcal actuation function and comparison to the real value is shown in figure 3 with the delay included, and figure 4 is the inverse actuation function with the advance included. Figure 5 shows the impulse response of the inverse actuation filter (no delay included).

The attached H1PCALXactuation.dat file is the actuation function sampled every 0.125 Hz.

Code that produced these results is located in
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/DARMmodel/Scripts/pcal_actuation_function_quack.m

Next steps: replace the old inverse actuation filter, move the inverse actuation filters from the PINJ_HARDWARE bank into the PINJ_TRANSIENT bank so that the CW injections (which will use the Pcal actuation function manually) will not pass through the inverse actuation filter.