TITLE: 03/15 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 68Mpc
INCOMING OPERATOR: Jim
SHIFT SUMMARY:

Windy night with H1 Range all over the place, but have been locked for almost 8hrs.
LOG:

• 23:14 OBSERVING
• 23:20 School group visiting the Control Room (via Amber)
• Breaks from Observing due to TCS at 0:17:05 & 0:23:44 (alogged earlier)
• 4:30:  Random PI Mode 23 rung up....I switched phase from 90 -> 60, but it might have went down on its own.  I had not seen this mode rung up before.

We tried to simulate the effects of differential ITM thermal lens on SRM sensing. The idea of differential ITM thermal lensing is motivated by alog 34853. 

In the attachments we considered 4 different SRC geometries corresponding to G={0.76, 0.80, 0.83, 0.86} or one-way gouy phase={20.1, 18.6, 17.0, 15.3}, respectively. Note that here G=(A+D)/2, which is different from the stability g=arccos(gouy phase) = sqrt((A+D+2)/4). 

*In each plot, the top panel showed the recycling gain relative to nominal (we defined the gain as the ratio of E_{-9}^ast E_{9} inside/outside PRC).

*The left two panels showed the AS36 signal as function of AS port gouy phase, with the upper panel showing the abs of AS36 to SRM pitch response, and the lower panel the difference of SRM and BS demodulation phase. The orange trace is for the nominal setting (based on the finesse input file T1300904), and the blue trace when differential ITM lensing introduced. 

*The right two panel show an anatomy of the AS36 signal, i.e. the beat note of <9_00, 45_01>, <9_02, 45_01>, <9_01, 45_00>, <9_01, 45_02>. For conciseness we do not show the contribution from the negative sidebands. 

==================================================================

Some thing might be interesting to note:

1. When the ifo is at its nominal setting, the dominating AS36 signal comes from the beat between <9_00, 45_01>. This pair stays roughly constant w.r.t. different ITM diff lensing. However, because 9_00 is weak, when we add differential lensing, both <9_02, 45_01> and <9_01, 45_00> can be as large as, or even larger than <9_00, 45_01>, making the AS36 signal very messy. 

2. If SRC gouy phase >~ 18 deg, if we happen to put the two WFS at AS gouy phase around 35 deg and 125 deg, we would basically have no srm signal at all. If this is indeed the cause, increasing SR2-SR3 distance alone might not be sufficient to solve the sensing problem. 

3. If SRC gouy phase <~ 18 deg, the SRM signal becomes stronger as we adding diff lensing. However, it also becomes more degenerate with BS signal whose response is ~ 100 greater than SRM. If non of the WFS are placed at AS gouy phase [75, 140] deg, the SRM signal, despite higher amplitude, will also be lost due to degenerate demod phase with BS. 

4. The diff lensing can reduce recycling gain. For ~75 km extra lens added to ITMX, the recycling gain decreases by ~5%. 

5. Bad centering loops might not be necessary in explaining the bad srm sensing. As argued in T0810007, the carrier doesn't see ITM RoC mismatch to 1st order whereas the sidebands do. The effects due to carrier junk might not be as significant as sideband homs. 

Wee bit of a windy night.  Right now we are riding through 30mph sustained winds here at the Corner Station (can hear gusts in Control Room).  

H1 is still locked, but range definitely following the winds.

Recent Laser Setpoint Values Different From Lock To Lock:  Keep ACCEPTING or NOT MONITOR?

Over the last few days it has been noted that there have been TCS Diffs from lock to lock & they have simply been ACCEPTED in SDF.  These Differences have been tiny changes (e^-15) for the (H1:TCS-ITMY_CO2_LASERPOWER_SETPOINT & ...CO2_LSRPWR_SET_POINT_OFFSET).  

TCSx Servo Changes Knocking Us Out of OBSERVING Tonight:  Known Issue

Tonight, we have been bumped out of OBSERVING twice to some automatated servo changes being made to the TCSx.  Drops from Observing were:

• 0:17:05 - 0:19:30
• 0:23:44 - 0:25:26
• Channels in question:  H1:TCS-ITMX_CO2_CHILLER_SERVO_GAIN, H1:TCS-ITMX_CO2_PZT_SERVO_GAIN , H1:TCS-ITMX_CO2_PZT_SET_POINT_OFFSET

Basically it looks like the Input, a couple of filters, & output for two TCS ITMX CO2 filter banks are toggled, and then the offset for the TCSx PZT setpoint is ramped.  

(Currently messaging Nutsinee & she mentions this is a known issue & has been brought to Aidan/Alastair's attention.)

Following Betsy and Nutsinee's efforts to clean up the alignment of the ITMX_HWS probe beam yesterday, we reinitialized the HWSX code. The code has been running continuously since then. Last night there was a lock-loss in the IFO (at 1173593679) after being locked for about 2 hours. 

I pulled the HWS gradient field data from that time and have plotted it in the attached movie. I have rezeroed the HWS so that the reference wavefront was taken about 600s before the lock-loss, i.e when the IFO is hot. All subsequent gradient fields are plotted in reference to this initial state.

I then plot the difference in the gradient field from this reference time at intervals of 60s. Therefore, any thermal lenses you see in the gradient field appear as the negative of what would appear during a lock-acquisition (and when the cold state of the IFO is used for a reference wavefront). However, the heat flow is a linear process with regards to the input power, so analyzing the lens decay is fine for determining absorption.

From the point at which the lock-loss occurs:

• what physically happens is that ITMX starts to cool down and any residual thermal lenses start to vanish.
• what we see on the HWS gradient field is a strong negative lens form.
  • The lens is about 1cm - 2cm in diameter,
  • it seems to form to full size within a minute or two.
  • These two features, although qualitative, are very characteristic of a point absorber on the optic.

Notes:

1. there are few errant spots out near the edges of the HWS FOV. These are noise - just ignore them. I've not had an opportunity to remove them from the data
2. At the time of the lock-loss, you can also see a bulk pitch towards the top left - this represents a tilt change in the optic.
3. By and large, the gradient field shows no systematic noise on it, indicating that this measurement is quite clean.

The gradient field is shown above. The numerically integrated wavefront is shown below. There is some residual tilt in this wavefront.

The lens scale is about 60-70nm over a radius of about 20mm.

The next step is to compare this to COMSOL models of thermal lensing for heat sources of different sizes. This is to determine if this data matches a physical model.

Other possible explanations:

So far, I can only come up with one possible other interpretation. If there is excessive 1064nm light leaking onto the HWS, and the HWS doesn't filter it out enough with the bandpass filter (or this isn't in place), this might cause a systematic error in the HWS measurement. We can test to see if we're getting excess contamination of 1064nm light by leaving the HWS code running and turning off the SLED. The HWS code will record images on the HWS camera and when the IFO lock is lost or reacquired, we'll be able to see if there is excess 1064nm light on the CCD in the same position as the apparent thermal lens.

TITLE: 03/15 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 69Mpc
OUTGOING OPERATOR: Ed
CURRENT ENVIRONMENT:
    Wind: 28mph Gusts, 22mph 5min avg
    Primary useism: 0.07 μm/s
    Secondary useism: 0.23 μm/s

Winds are starting to pick up above 20mph.  And we recovering from a recent 5.4 earthquake in Alaska.
QUICK SUMMARY:

Ed was returning H1 to OBSERVING as I walked in (due to an AK EQ lockloss).  While transitioning, PI Mode#28 immediately & quickly rung up within 2min after we locked---luckily Ed was on it and he was able to adjust the phase to turn it around.

Just finished off going through the Shift Check Sheet.

TITLE: 03/15 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 0Mpc
INCOMING OPERATOR: Corey
SHIFT SUMMARY:
LOG:
15:!5 Karen and Christrina to Mid stations. Chris Soike to EX Chiller yard

16:06 Chris back from X and heading to Y.

16:55 Vacuum alarm EX_INSTAIR_PT599_PRESS_PSIG. There was  an earlier one as well for EY PT499 " ". This is probably due to Chris visiting chiller yards at each end.

17:33 Chris back 

EQ seen at: 
USGS: Listed as occurring at 19:43UTC
Seis BLRMS:  ~22:41utc (peaked at 0.4um/s for 0.03-0.1Hz)
Terramon:  Not sure when this posted, but it was at/before arrival time of 3:30utc
Tidal signals start seeing around 22:37utc
Magnitude: 5.4
Location: Semisopochnoi Island, Alaska
Start time: 3:30utc
Lock Status: Lockloss

18:28 Lockloss - Unknown

18:29 Richard out to TCS to check on Interlock

18:31 Richard back

18:40 Trouble getting Green Xarm back. PDH VCO error - Reset

19:26 NLN 

There are two diffs in SDF regarding CO2 LASER power/setpoint. Typical SDF wanting accuracy wanting e-15 resolution. Jason was contacted and gave the OK to accept the diffs and move to Observing.

19:32 Intention Bit: Undisturbed

- No extraordinary features were found in the bullseye signals at HF/VHF frequencies.

[Summary]

During the commissioning call in the past Friday, there was a suggestion to check the HF/VHF (~MHz region) behavior of the bullseye sensor in order to make sure that the sensor is detecting what it should detect. In response to it, I have measured high frequency part of the signals coming out from the bullseye segments using an RF analyzer (an HP 4395A). I didn't find extraordinary features. I am concluding that the HF/VHF contents are not an issue.

[Some details]

The measurement was done by inserting a 9-pin Dsub breakout board right in front of the whitening board (34154) during the maintenance period yesterday. This measurement was performed after Peter and Jason had finished their flow sensor task (34811). The PSL laser was running in a nominal condition. The IMC was locked with a low power (~2 W). The interferometer was kept unlocked.

Each segment was read out before they go into the whitening board. I hooked up an HP 4395A to the breakout board using a pair of clips and a BNC cable. Unfortunately, this cheap setup was so good that it picked up lots of RF lines. Nonetheless, I didn't see an outrageous line or suspicious feature in the bullseye signals. Most of the lines are as small as -60 dBm and many are less than that except for the one at 160 MHz which I think is a pick up from the measurement cable (as high as -50 dBm). See the attached for the spectrum. I also attach the raw data just in case.

Since all four segments showed almost identical spectrum, I saved the data only for the center segment. For comparison, I also saved the background spectrum with the clips left open. Note that the background spectrum wasn't stationary. After the measurement, I removed the breakout board and completely cleaned up the measurement setup.

Starting CP3 fill. LLCV enabled. LLCV set to manual control. LLCV set to 50% open. Fill completed in 1903 seconds. LLCV set back to 14.0% open.
Starting CP4 fill. LLCV enabled. LLCV set to manual control. LLCV set to 70% open. Fill completed in 1416 seconds. TC A did not register fill. LLCV set back to 42.0% open.

WP6522

During the maintenance period yesterday, I have measured the spectra of IMC WFS DCs with and without the IMC locked. The purpose of this measurement was to cross-check the calibration factor of 1/3 which previously estimated by Daniel (31631, Nov 2016).

A conclusion:

I agree with Daniel that the IMC WFS DC signals should be scaled by a factor of 1/3 when the IMC is locked.

[Some plots]

• The 1st attachment: raw spectra of the IMC WFS DCs
  • (orange) when IMC was unlocked with the MC2 significantly misaligned. Pin = 2 W. (It had to be low power in order not to saturate the ADCs.)
  • (red) when IMC was locked. Pin = 20 W. The main interferometer was left unlocked.
• The 2nd attachment: calibrated spectra of the IMC WFS DCs.
  • (blue) when unlocked.
  • (red) when locked.
  • Also, I have included an extra factor of sqrt( 8 / pi) to get all the spectra calibrated in the unit of fractional amplitude defined as |E_{10}/ E_{00}| or |E_{01} / E_{00}|.

A side note: depending on whether the IMC is locked or not, the spectral shapes vary. This is not so surprising because when the IMC is locked, the reflection port must be dominated by non-00 modes. So the signals should contain relatively large amount of cross terms from various HOMs. So for the reason, I don't have a good explanation why they have to be a factor of 1/3. Even so, it is interesting to see some peaks come and go.

Around 10:30 A M local time while inspecting the arm roads for tumbleweeds, John and I found a GSA vehicle stuck ~ 500 meters south of the Y End station and ~50 meters east of the access road. 
I have tracked the vehicle by license plate # to the fleet manager and she is contacting the manager that the vehicle is assigned to. I told her that in the future, anyone entering the site should, 1. Enter by the gate and not the desert and 2. Notify the control room when on site.
I also asked that the vehicle be removed tomorrow during our maintenance period.

Sheila, Jenne, Mark, Richard, Fil, Daniel

We made some progress on installing a prototype of the bullseye detector that Mark has been building in the PSL today. 

• Jenne and I went into the PSL and realized that the location I ha orignally thought of for the diode wouldn't work.  After dicussing it with Jason we deicded to move aside the beam profiler in the DBB HPO path and put the diode there.  There was about 0.65 mW of power in this path.  Jenne added a steering mirror (Y1) and a diverging lens (PLCC-25.4-103.0-UV-1064).  To install the diode we had to remove the rail that was on the table, we placed it on the portable cart on the oposite side of the enclosure. 
• We used a temporary adapter cable that Mark made that allows us to power the diode from the power strips under the table and get the signals out onto a DB9.  We used a breakout board to display the segments on a scope while we were in the enclousre.  Based on watching the signals while we steered the beam around, we think that the segments are arranged like this:
  • pin1 pin6 (seg 1) side of the diode closer to the anteroom
  • pin 2 pin 7 (seg 2) center
  • pin 3 pin 8 (seg 3) side of diode closer to HAM1
  • pin 4 pin 9 (seg4) bottom of diode
• We decided to use the unused half of the MC2 trans QPD whitening chassis for this diode.  Fil made an adapter cable that we could use to get the MC2 signals from the 25 pin Dsub from the transimpendance amplifier and the bullseye signals off the 9pin Dsub that comes out of the PSL into the whiteing chassis. (The 9 pin  cable reaches, but next time someone is in the PSL we could uncoil a little more from under the table). 
• The whitening chassis already had BIO, but there was no beckhoff code for the spare hardware.  Daneil added this, and named the whitening PSL-SPARE_QPD.  Dave did a DAQ restart for this change. 

We will hopefully get the whitened signals into the ADC channels that are already set aside and connected to AS_D in the ASC model tomorow.