Posted below are the dust trends for the past week, during the vets of End-X and End-Y. Plots are as expected. There are large numbers of high counts in the VEAs (monitor VEA1), which are consistent with work activities in the VEAs. The counts within the cleanrooms over the chambers show decent isolation of these spaces from the clouds of particles found in the VEA in general. 

   The large spikes within the cleanrooms (monitor VEA2)seen on 6/17 at End-Y and on 6/18 at End-X are the doors being installed. The flat line from VEA2 at End-Y starting on the 18th is the dust monitor being powered down.     

LHO got two STS2s returned from Stanford a few days ago and they are in the BG area.  One is installed as ITMY or STS2-B; the other is on temporary cabling going into HAM2 or STS2-A.  The attached ASD shows that the Y axis on unit A has excess noise below 3 hertz.  The noise is much less on the X & Z. It might be reasonable that the tilt condition is different between the BG location for Units A & B and the HAM5 location for Unit C so I'm not confident saying anything about the differences at low frequencies between A/B and C.  But A and B are within a couple meters of each other and we should expect the tilts for A & B to be very similar.  This further suggests the HAM2 unit has issues.  I should move unit A to its final location by HAM2 and its dedicated cabling but we've been down this swap fest route before.

The attachment data is from Sunday ~5am local

Laser Status: 
SysStat is good
Front End power is 33.1W (should be around 30 W); 29.1W @ Power Monitor PD
FRONTEND WATCH is GREEN
HPO WATCH is RED

PMC:
It has been locked 2 day, 21 hr 15 minutes (should be days/weeks)
Reflected power is 2.2 Watts  and PowerSum = 25.7 Watts.
(Reflected Power should be <= 10% of PowerSum)

FSS:
It has been locked for 2 d  21h and 29 min (should be days/weeks)
TPD[V] = 1.49V (min 0.9V)

ISS:
The diffracted power is around 7.2% (should be 5-9%)
Last saturation event was 2d 18 h and 5 m ago (should be days/weeks)

NOTES: ISS diffracted power was up to ~9% this morning. I've adjusted the refsignal from -2.12 to -2.14 to yield ~ 7.5%

We are currently LASER SAFE in the corner and the ends. PSL is shuttered, CO2 LASERs are OFF. End station Viewports and tables are closed and locked. Not sure about the on/off statues of the ALS.

Code Freeze has been deemed LIFTED

Basic LASER safety training for SURF and STAR students in LSB.

Corey replacing all handles on ISC I/O tables.

SEI - Jim working on blend filters

SUS - No ESDs until interlocks are re-installed; Kissel needs o determine which TFs still need to be run; HAM6 black glass has been cleaned - Heintze talked about how much of it will be installed in terms of the potential hampering of suspension wires.

VAC - https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=19252; https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=19255. EY = 2.12e-06; EX 2.45e-06.

FAC - Beam Tube cleaning ongoing; Ken hanging tubing in bt enclosure for ion pump.

CDS - modifying end station Beckhoff; CHanging out HV power supply scheme for PSL from LVEA rack mounts to CER supplies. 

Scott L. Ed P.

6/18/15
Cleaned 39.8 meters of tube ending at HNW-4-082. Test results posted on this A-Log. Remove and begin re-hanging lights in next section north.

6/19/15
Completed hanging lights, start vacuum of support tubes and spraying of heavily soiled floor areas with water/bleach solution. Cleaned 20.8 meters of tube.

Calum & Kate

Finished unwrapping and inspecting all 26 panels of black glass. 100% of the parts made it in one piece and all of the coatings look good. This is great news! The panels are dusty, smudgy, and streaky; and will need to be cleaned (this was expected). The plan is to use a methanol rinse followed by drag wipping. 24/26 pieces of glass were rinsed 2x, so we're about halfway through the cleaning effort. Currently using 3 large cleanroom tables, but we'll need at least one more for prep work.

Two points of note for LLO:

1) The following parts were packaged between 2 sheets of float glass:

D1500054-101 & 102

D1500055-101 & 102

It was a good idea to protect the oddly shaped parts, but care should be taken when opening them because a couple pieces of the float (packaging) glass had chips and cracks and these were spread around the wrapping. Again these did their job and protected the black glass (which was in good shape) just a heads up.

2)  Some of the parts are double packed in the bubble wrap. Again caution when opening.

Turning the chamber over to next group. Report to follow.

OMC Black Glass Shroud

9:35am: We arrived at the LSB after checking in at the control room to receive the OMC Black Glass. We had it shipped overnight from vendor with Fedex. It is due before 12pm.

12:04pm: Black Glass arrived.

5:30pm: Left LVEA after unpacking the black glass and transporting it to the cleanroom by HAM6. We got about 20% of the glass unwrapped and inspected. (We started with the most critical items.) More to follow. We will complete unpacking and inspection in the morning. So far so good in terms of the quality of the machining in the black glass and the coating.

One point. Before we entered the LSB we could hear an alarm. On entry the alarm panel by the receiving entrance was flashing fault "Batt. Charging". I pressed the "ACK" button to stop the alarm. It still says "Status: fault "Batt. Charging".

Particle count in cleanroom (4:52 pm): - Humidity 37%. Temp 68 deg F.  0.3um 10 / 1.0 um 10 / 2.0 10. The rest were zero. (Kate, Calum and Robert in cleanroom.)

Particle count in cleanroom (5:58 pm): - Humidity 34%. Temp 71 deg F.  0.3um 10 / 0.5 um 10. The rest were zero. (Kate and Calum in cleanroom.)

Calum Torrie and Kate Gushwa.

End stations on turbos backed by scrolls -> QDP80s shut down

Data extracted for the three week period of ER7 (since the timing system would nominally be running steadily the entire time). The histograms show:

- Tight grouping of the minute trends in the data; min and max values for each minute end up in discrete bands. 
- The Time Code Generators show nearly identical histograms for their mean minute trends.
- The mean minute trends of the GPS clock are much more tightly grouped with a width of roughly 20ns; with minimum and maximum offsets included, the width roughly doubles.

Issues:

- There was a single second during which the MSR Time Code Generator was off from the timing system by approximately 0.4 seconds. The issue self-rectified before the start of the next second. Second-trend data was not available through dataview (or at least I couldn't get any out of it). This did not happen in the EY and EX time code generators. It did not happen again in the MSR time code generator. The anomaly happened at GPS time 1117315540.

I've attached histograms as well as screenshots of data taken from Grace.

Kyle, Gerardo 

Removed 1st generation ESD pressure gauges from BSC9 and BSC10 and installed 4.5" blanks in their place -> Installed 1.5" metal angle valve and 2nd generation ESD pressure gauges on the domes of BSC5 and BSC6 -> Started rough pumping of X-end and Y-end (NOTE. dew point of "blow down" air measured < -3.5 C and < -5.5 C for X-end and Y-end respectively.  This is much wetter than normal.  I had found the purge air valve closed at the X-end today.  It was probably closed to aid door installation yesterday but not re-opened(?).  Purge-air can be throttled back in some cases but should never be closed off.  Y-end explained in earlier log entry)


Kyle 

Finished assembly of aLIGO RGA and coupled to 2.5" metal angle valve at new location on BSC5 -> Valved-out pumping for tonight -> will resume tomorrow and expect to be on the turbos before I leave tomorrow.

Summary: A seismometer was buried 40 m from EY to take advantage of strong attenuation of the tilt signal relative to the acceleration signal from distant sources. Seismometers located outside the buildings may be useful in reducing problems associated with tilt.

Our buildings are tilted by wind. Our seismometers do not discriminate between this tilt and acceleration (like a pendulum), so wind-induced tilt produces spurious control signals that can make it difficult to lock and maintain lock. A tilt sensor can be used to discriminate between tilt and acceleration, but we may also be able to discriminate between the two by taking advantage of source differences in the band below 0.5 Hz, where tilt generates the largest spurious acceleration signals. The tilt in this band is mainly generated locally by the wind pressure against the walls, while the acceleration signal is mainly generated by ocean waves and other distant sources.

While the seismometers are in the far field for most low frequency accelerations, they are in the near field for building-generated tilt (wavelengths at 0.1 Hz are about 50 km). To take advantage of the rapid attenuation with distance in the near-field, I buried an STS-2 seismometer in a meter deep hole I dug 40 m from EY (Figure 1).  Figures 2 and 3 show a comparison of the buried seismometer to the SEI seismometer on the ground inside the EY station. During the low wind period the spectra look virtually identical below 0.5 Hz and the coherence is high because the sources are mostly distant and the wavelengths are large. During the high wind period, the buried seismometer doesn’t change that much (there is some change in the microseismic peak because high/low wind were about 24 hours apart), but the building seismometer shows a huge signal from tilt.  The coherence in windy conditions is low because the tilt is highly attenuated 40 m from the building. Figure 4 shows spectra for higher wind, 15-35 MPH.

Of course the external seismometer would not detect real building accelerations due to the wind. But if the unwanted tilt signal dominates over the wanted wind acceleration signal, a seismometer outside the building may be useful, and I think that this is the case below about 0.5 Hz.

I note that I first tried this in the beam tube enclosure tens of meters from EY, but found that the wind tilts the beam tube enclosure almost as much as the building (but not coherently), supporting a hypothesis that aspect ratio is the important variable. Also, Jeff points out that, if we insulate the buried seismometer well (and I did not) we might even be able to do better than the building seismometers with their current insulation during even low-wind periods. Figure 5 is like Figure 2 except that the signal from the stage 1 Trilliums is included.

[sus crew]

Following the in chamber work from today at end-Y we took quick TFs on the quad and the transmon. They look ok.

Since the pump won't happen before tomorrow I started matlab tfs for all DOF.

The measurement will be running for few hours. 

ISI was locked by Jim in the morning.

Before doing anything, EY alignment slider [PIT, YAW] = [142.0, -75.1], TMSY = [116.6, -20.0], EY OPLEV=[-39, -15]-ish.

Transitioned to laser hazard, moved EY such that the green return beam hits the center of the relf PD: EY [PIT, YAW]=[207.4, -75.1]

- Krytox on beam diverter in situ: Good.

Everything went well as per yesterday.

- QPD strain relief: Good-ish.

Unlike TMSX, it turns out that all QPDs were already equipped with a make-shift strain relief using stainless steel cable clamps, the same clamps used for fixing the cables on the TMS ISC table, but the cables were without kapton tubes. We decided to install the right strain relief anyway.

In the end, we were able to install the right ones on three out of four QPDs. As for the remaining one (Green QPDB), we weren't able to install it as the 1/4-20 Allen key to attach the PEEK strain relief to the QPD base would have interfered with the YAW knob of one of the QPD sled mirror holders (M102 in D1201458).  The stainless steel strain relief was left as is.

After this work, we checked if QPDs still work and they did (used green beam for the green QPDs and a flashlight for IR QPDs).

- TMS balancing: Good.

After the work, we checked the balace of the TMS table with the green light injected to the chamber. The vertical alignment was found to be already good and therefore we did not make any mechanical adjustment. Similarly, the horizontal was also good and giving an extra digital bias of +13 urad (resulting in -7.0 urad in OPTICALIGN_OFFSET) made the return beam well-centered on ALS-REFL_PD. So the balance is good.

After everything was done: EY slider [PIT, YAW] = [142.0, -75.1] (back to the original), TMSY = [116.6, -7.0], EY OPLEV=[-24, -31]-ish.

Seems like EY moves around by 15urad-ish both in  PIT and YAW, so TMS alignment could be only as good as 15urad-ish.

I've taken a look at guardian state information from the last week, with the goal of getting an idea of what we can do to improve our duty cycle. The main messages is that we spent 63% of our time in the nominal low noise state, 13% in the down state, (mostly because the DOWN state was requested), and 8.7% of the week trying to lock DRMI. 

Details

I have not taken into account if the intent bit was set or not during this time, I'm only considering the guardian state.  These are based on 7 days of data, starting at 19:24:48 UTC on June3rd.  The first pie chart shows the percentage of the time during the week the guardian was in a certain state.  For legibility states that took up less than 1% of the week are unlabeled, some of the labels are slightly in the wrong position but you can figure out where they should be if you care. The first two charts show the percentage of the time during the week we were in a particular state, the second chart shows only the unlocked time. 

DOWN as the requested state

We were requesting DOWN for 12.13% of the week, or 20.4 hours.  Down could be the requested state because operators were doing initial alignment, we were in the middle of maintainece (4 hours ), or it was too windy for locking.  Although I haven't done any careful study, I would guess that most of this time was spent on inital alingment.

There are probably three ways to reduce the time spent on initial alignment:

• reducing the number of times that we do initial alignment.  We don't really know how often we need to be doing this, and we might be able to do some offloading in full lock before powering up and see if that gives us an alignment that is good for lock acquisition.
• There are a few improvements to the ALIGN_IFO guardian that might help a little. 
• Last, as the operators get more experience with the alignment procedure it should become faster.

Bounce and roll mode damping

We spent 5.3% of the week waiting in states between lock DRMI and LSC FF, when the state was already the requested state.  Most of this was after RF DARM, and is probably because people were trying to damp bounce and roll or waiting for them to damp.  A more careful study of how well we can tolerate these modes being rung up will tell us it is really necessary to wait, and better automation using the monitors can probably help us damp them more efficiently. 

Locking DRMI

we spent 8.7% of the week locking DRMI, 14.6 hours.  During this time we made 109 attempts to lock it, (10 of these ended in ALS locklosses), and the median time per lock attempt was 5.4 minutes.  From the histogram of time for DRMI locking attempts(3rd attachment), you can see that the mean locking time is increased by 6 attempts that took more than a half hour, presumably either because DRMI was not well aligned or because the wind was high. It is probably worth checking if these were really due to wind or something else.  This histogram includes unsuccessful as well as successful attempts.  

Probably the most effective way to reduce the time we spend locking DRMI would be to prevent locklosses later in the lock acquisition sequence, which we have had many of this week.

Locklosses

A more careful study of locklosses during ER7 needs to be done. The last plot attached here shows from which guardian state we lost lock, they are fairly well distributed throughout the lock acquisition process. The locklosses from states after DRMI has locked are more costly to us, while locklosses from the state "locking arms green" don't cost us much time and are expect as the optics swing after a lockloss. 

Sudarshan, Kiwamu, Darkhan,

Abstract

According to the PCALY line at 540.7 Hz, the DARM cavity pole frequency dropped by roughly 7 Hz from the 17 W configuration to the 23 W (alog 18923). The frequency remained constant after the power increment to 23 W. This certainly impacts on the GDS and CAL-CS calibration by 2 % or so above 350 Hz.

Method

Today we've extracted CAL-DELTAL data from ER7 (June 3 - June 8) to track cavity pole frequency shift in this period. The portion of data that can be used are only then DARM had stable lock, so for our calculation we've used a filtered data taking only data at GPS_TIME when guardian flag was > 501.

From an FFT at a single frequency it is possible to obtain DARM gain and the cavity pole frequency from the phase of the DARM line at a particular frequency at which the drive phase is known or not changing. Since the phase of the resultant FFT does not depend on the optical gain but the cavity pole, looking at the phase essentially gives us information about the cavity pole (see for example alog 18436). However we do not know the phase offset due to time-delay and perhaps for some uncompensated filter. We've decided to focus on cavity pole frequency fluctuations (Delta f_p), rather than trying to find actual cavity pole. In our calculations we have assumed that the change in phase come entirely from cavity pole frequency fluctuations.

The phase of the DARM optical plant can be written as

phi = arctan(- f / f_p),

where          f is the Pcal line frequency;

                     f_p - the cavity pole frequency.

Since this equation does not include any dependence on optical gain, the technique we use, according to our knowledge, the measured value of phi does not get disturbed by the change of the optical gain. Introducing a first order perturbation in f_p, one can linearize the above equation to the following:

               f_p^2 + f^2
(Delta f_p) = ------------- (Delta phi)
                    f

An advantage of using this linearized form is that we don't have to do an absolute calibation of the cavity pole frequency since it focues on fluctuations rather than the absolute values.

Results

Using f_p = 355 Hz, the frequency of the cavity pole measured at the particular time (see alog 18420), and f = 540.7 Hz (Pcal EY line freq.), we can write Delta f_p as

Delta f_p = 773.78 * (Delta phi)

Delta f_p trend based on ER7 data is given in the attached plot: "Delta phi" (in degrees) in the upper subplot and "Delta f_p" (in Hz) in the lower subplot.

Judging by overall trend in Delta f_p we can say that the cavity pole frequency dropped to about 7 Hz after June 6, 3:00 UTC, this correspond to a time when PSL power was changed from 17 W to 23 W (see lho alog 18923, [WP] 5252)

Delta phi also show fast fluctuations of about +/-3 degrees, and right now we do not know the reason that causes this "fuzzyness" of the measured phase.

Filtered channel data was saved into:

aligocalibration/trunk/Runs/ER7/H1/Measurements/PCAL_TRENDS/H1-calib_1117324816-1117670416_501above.txt (@ r737)

Scripts and results were saved into:

aligocalibration/trunk/Runs/ER7/H1/Scripts/PCAL_TRENDS (@ r736)