TITLE: 03/16 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 68Mpc
INCOMING OPERATOR: Corey
SHIFT SUMMARY: Remained locked entire shift. TCS ITMY CO2 guardian took us out of observing multiple times at the beginning of the shift (accepted SDF differences attached). Bubba ran the fire pumps and I ran a2l when LLO lost lock.
LOG:

16:04 - 16:31 UTC: TCS ITMY CO2 guardian periodically taking us out of observing.
16:37 UTC LLO down. Bubba running fire pumps. Out of observing.
16:41 UTC running a2l.
16:46 UTC Bubba done running fire pumps. a2l done.
16:47 UTC Back to observing.
17:03 UTC GRB. LLO down.
18:02 UTC Betsy and Vern to both mid stations.
18:12 UTC Karen to optics lab
18:48 UTC Karen out of optics lab
19:33 UTC Cheryl to optics lab
19:47 UTC Elisabeth has car parked by H2 enclosure to move cables from enclosure to car and then mid Y.
20:00 UTC Elisabeth to mid Y
20:19 UTC Bubba to mid X to drop off wire
20:27 UTC Jeff B. driving to receiving, opening outside rollup door, putting ladder inside.
20:29 UTC Chandra to mid Y to check on thermocouples in discharge lines
20:35 UTC Jeff B. done
20:36 UTC Elisabeth back from mid Y
20:45 UTC Chandra back
21:29 UTC Gave Carlos remote access to check whatsup
21:52 UTC Betsy and Hugh to mid X
22:09 UTC Marc and Elisabeth to mid Y
22:24 UTC Cheryl done in optics lab
22:33 UTC Marc and Elisabeth back

Attempting to get the best tilt subtracted ground motion for sensor correction to the ISI has a seismometer piggy backing on the BRS Platform.  However, seismometer difficulties lead to testing other STS2s.  Still, our 'extra' STSs were not doing as well as we would like.  So, we pulled our one spare T240 from storage and ran it on the floor nearby. It was then moved into the BRS enclosure replacing the STS there but low frequencies were noisier than when on the floor.  On Tuesday, the Legs of the Table bolted to the BRS platform, on which the T240 sits, were insulated with 3/4" closed cell foam.

Krishna has looked and reports a factor of 3 improvement in the ASD and the coherence with the BRS is better.  Here attached is before and after spectra comparing the ground seismometer X & Y with the T240 (ADC channels).  The bottom plot has references from 0600utc 13 March before the Tuesday maintenance insulation addition.  The upper plot with current traces are from 1140utc on 15 March (Cool! I did not know DDT would display the T0 of the reference traces, I guess as long as you have no current measurement traces displayed.  19 years and still something to learn!)  We haven't had a low wind time since Maintenance basically so the comparison is not ideal.

Even with the larger ground motion, the Y axis of the now insulated T240 is quieter than before everywhere below 100mHz and closer to the well insulated ISI_STS nearby.  The X axis is noisier but matches the GND STS down to 20mHz, much better than before.  The winds have been about South 50degrees West (hitting the SW crane corner and that may rile up the X axis much more than the Y direction.  Since this temperature sensitivity was apparently a large part of our low frequency noise problem, we'll look at other items in the BRS enclosure and the enclosure itself for thermal improvements.

TITLE: 03/16 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 67Mpc
OUTGOING OPERATOR: Jim
CURRENT ENVIRONMENT:
    Wind: 10mph Gusts, 6mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.17 μm/s 
QUICK SUMMARY:

All of mid X and some corner station FMCS channels are not being seen from CDS.

TITLE: 03/16 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 65Mpc
INCOMING OPERATOR: Cheryl
SHIFT SUMMARY:
LOG:
Another quiet night. 

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

All four turbine flow sensors for heads 1-4 were replaced with new ones.  The signals from
all four sensors look okay but the one from head 3 is the noisiest.  Some air bubbles were
seen in the flow sensors but seemingly have worked their way out of the sensors by the time
the oscillator lid was put back.

    Going by the froth in the crystal chiller spout, we might still have some air bubbles
in the system.

    A large metal, copper coloured chip came out of the head 1 flow sensor.  The chip was
approximately 2 mm x 2 mm.

    The vortex flow sensors for the power meter and front end laser were re-attached and
released in Beckhoff - they were previously force written.  If problems come up again, we
can force write them again.

    The bypass valve is fully open.



Jason / Peter