I took spectra of the PSL before and after the IMC lock last night. I used the value of H1:IMC-REFL_DC_OUT shown in the attached plot to select times when the IMC was locked and unlocked. I assume that a low level in REFL indicates that the IMC is locked. I also made a PSL ODC plot for this period of time. The FSS loopstate bit in the PSL ODC goes bad at the time that the value of REFL goes high. I have attached four spectra for the PDA: two taken during the lock, which look similar to the spectra I took yesterday with the forest of high frequency lines, and two after the lock which look qualitatively quite different. The unlocked spectra bad as expected, probably due to the unlocked IMC putting junk into the PSL. However, the forest of lines is still there in the PSL spectrum when the IMC is locked. I will follow this up with Jan to understand what is going on.

GPS = 1043654615

Common gain = 20 db, 1st boost on.

[Kiwamu, Cheryl, Giacomo]

Today, after we completed the power budget, we left the IMC locked and went to lunch. later on, we cound the IMC unlocked and almost impossible to lock, with any sort of higher order modes flashing and the control signals going a bit crazy.

A look at the last couple of hours showed that shortly after we locked the IMC, the mode matching had a glitch and then began to drift rapidly, bringing the DC_REFL power from about 75% to about 60% in 5 min, after which the lock was lost (see attached figure)

After verifying that both suspension and ISIs did not show any anomaly tha could explain the drift, we realized tha Kiwamu had been working in the PSL enlcosure around that time, and in particular installing a bracket on the PSL periscope. He reported that no particular accident accurred, and he did not vibrate or kick the periscope.

Kiwamu went back to the PSL and did a wonderful job in manually adjusting the top mirror mount, bringing the visibility back to about 87%. The operation required very tiny corrections to the mount, confirmng that nothing macroscopic happened during Kiwamu's previous work in the PSL (although ti was enough to make the IMC unlockable). The lock went back to be as easy as it used to be...

It is not clear if the added bracket weight caused the periscope to flex, or if the vibrations of working at the periscope caused the mount to move. In any case, it is clear that the IMC alignment is extrmely sensitive to any work perfomed around the PSL periscope... it is good to keep that in mind!

[Cheryl, Giacomo]

Today we were finally able to route the parking beam through its intended baffle and viewport. With this result in hand, we gave a first quick try at a power budget.

The short version of the story is that at the parking viewport we measured about  60% of the power that reaches MC1, or 86% fo the power coupled into the IMC (due to a rather sloppy alignment).

The beam was measured at the following locations (power in mW, IMC locked unless otherwise specified):

* The IMC REFL with the IMC locked is estimated from the scaling of the REFL PD signal between the locked and unlocked status. At the time of the measurement the alignment was not great and the visibility was about 70%.

Due to lack of time, we did not measure the beam power inside the PSL.

When compared to the power effectively coupled into the IMC (the difference between IMC_REFL locked and unlocked), the power at the parking beam is 86%. For comparison, during the last power budget at LLO, a value of 90% was found.

Also, looking with an IR viewer into the chamber from one of the side viewport, we can see a bright beam on the adaptive optic dummy in front of IM4. It is not clear if it is a ghost beam, but probably not given its brightness. Tomorrow we will try to tune the alignment and see if and how much power we recover in the parking beam.

Attached are plots of dust counts > .3 microns and > .5 microns in particles per cubic foot requested from 5 PM Jan. 29 to 5 PM Jan. 30. Also attached are plots of the modes to show when they were running/acquiring data. Dust monitor 10 in the H1 PSL enclosure is still indicating a calibration failure.

The data was taken from h1nds1.
720 seconds worth of data was unavailable on this server
1440.0 minutes of trend displayed

The bracket, which will hold the upper periscope mirror for the ALS system, was installed this afternoon. The attached picture shows the actual bracket installed on the structure with 8-32 screws.



During the installation, one of the threaded holes on the periscope structure (shown as A in the attached picture) was accidentally damaged and hence the screw won't be really tighten any more. The cause of the damage was that --- a lower screw (shown as A in pic) and another lower screw (shown as B) were orthogonally crossing each other in the structure. At first the B screw had been inserted and then the A screw was being tightened. Then I realized that they were interfering with one another, but it was too late. I unscrewed the A screw. However during the removal of the A screw the thread of the hole was mechanically damaged due to the fact that the screw had been bended slightly. The screw can be still in, but it can not be really tight any more. The B screw was removed without serious damage on the threaded hole, though the screw had a clear mark of the A screw. This was then replaced by a new one without a problem. The same situation was found in the upper screws and the issue was avoided by using shorter screws (8-32-3/8"). Currently the A screw is in, but loose. I will remove it tomorrow or later as it doesn't do anything good but it moves around and creates some vibration.

I consulted with Robert about this issue. A main worry was the mechanical stability of the bracket with one screw missing because it may wobble the bracket too much, resulting in unacceptable amount of phase noise in the ALS light (and perhaps even in the PSL main light). The total number of the screws are currently 11 (12 if including the broken one) --- seven of them are on the plane where the B screw is, and the rest of four are on the side where the A screw is. Note that all of the four screws are not shown in the picture. At this point we think that it (hopefully) will not be a matter as we still have so many screws in. We'll see how it goes.

Betsy W. and Arnaud P.

We took B&K hammer measurements on the QUAD installed on BSC1. The configuration during the measurement was BSC1 locked  QUAD unlocked and Vibration Absorbers ON.
The position of the accelerometer and the direction of axis were chosen from LLO measurements, cf picture attached to post 6022.
As for LLO, the hammer trigger threshold was set to 10N.

Two configurations of measurement have been recorded. For each of them, the 3 directions (X Y and Z) were saved from the accelerometer :
-excitation (hammer hit) along the X axis
-excitation (hammer hit) along the Y axis

The TF plots generated by Pulse Labshop have been directly exported to excel then pdf (enclosed). Each figure is showing phase (plot above) and magnitude (plot below) 

Comparing the results to the ones from LLO  (cf post 6022), the only particular thing to mention is the anti-resonnance at 25Hz for the two measurements. 
Otherwise, for the X impact-X response (first pdf, blue curve, 2nd plot), as for LLO we find peaks at 75Hz, 125Hz and 150Hz.
For the Y impact-X response (second pdf, blue curve,2nd plot), as for LLO we find a peak at 75Hz and an anti-resonnance at around 125Hz.

A bit of investigation will be needed before validating that step. 




 
 

(Betsy, Arnaud, some Travis, some Jim, some IAS)

In BSC1 today we:

1) Locked down the ITMy pitch adjustment screws.

2) IAS verified alignment of ITMy (see his alog).

3) Took B&K Hammer measurements with ISI unlocked (see Arnaud's alog).

4) Locked ISI.

5) Locked all ITMy EQ stop nuts.

6) Took B&K Hammer measurements with ISI locked such that we could compare with the LLO ITM data (see Arnaud's alog)

7) Tweeked Top BOSEMs to account for buoyancy.

8) Took particulate samples from surfaces.

9) Wiped sampled surfaces and flooring, pulling towards door.

10) Set 3 witness plates and 2 1" optic flat samples.

11) Took pictures.

12) Confirmed damping of ITMy.

13) Applied First Contact to ITMy-HR

14) Removed the particle counter from the chamber - midday.

A final round of TFs should be taken, and we should confirm that we have the correct B&K data.

I will need to remove the FC on Friday, but as far as SUS is concerned, I see no reason the spool replacement work shouldn't proceed.  I'll need door entrance to the chamber on Friday.

Apollo -> Removed bolts from BSC10's dome and doors.  Rai's hydrocarbon RGA assembly was also removed

Mick and I removed one of the HEPI vertical actuators from the North side of BSC8.  Loosened the other three actuators hardware on the North side ready for removal. 

Complementary filters are used on the HAM-ISI, to blend the signals coming from both the CPSs (Capacitive Position Sensors) and the GS13s (Innertial Sensors). A new set of those Blend Filters was recently created  at LLO, for the ISI involved in the IMC commissioning: HAM2 and HAM3. These filters are more sophisticated than the ones we used in the past. The goal of the update is to maximize the use of the GS13s in low frequency, while still limiting the differential motion injected into the mode cleaner by the ISIs. Those filters are now installed on LHO's HAM2 and HAM3 ISIs, and they were tested today.

Spectra were taken on the cavity length control signals under two configurations (Fig. 1): 
1) ISIs Damped
2) ISIs Damped + Isolation loops Level 2 (UGF=25Hz) applied to the output of the new blend filters mentionned above.
Thanks to the recent progress, and help, of Giacomo and Kiwamu, these plots are calibrated. 

(Fig.2): The motion of the ISIs, along the cavity length(X-axis), was monitored during both phases of the test. Transfer functions were calculated. Amplitude and Phase are respectively close to 1dB and 0deg, on most of the frequency range of the analysis. This is an indication of low differiencial motion injection by the ISIs. Improvements could be made below 100mHz, where the phase goes towards 180deg (opposite motion of the ISIs). However the frequency resolution is not very high there and new measurements should be made for observatins to be more reliable.

(Fig.3): Ground motion was monitored in the LVEA with a STS2 seismometer throughout this test. No relevant shift could be noticed at the input of the seismic isolation chain (ground). This last observation tends to confirm that the changes seen on the IMC legth control signal do not come from changes in the spectral content of the ground motion, but from improvements of the blend filters.

Note: The gain for the IMC lock servo was set to 10dB during this test.
 

The cdswiki web server was not accessible for a period this morning due to its local time drifting too much. We are in the process of configuring NTP via puppet to ensure this does not happen again.

The CBC data quality group have been looking at the noise coming out of the PSL to practice detector characterization for aLIGO. We noticed that there is a significant change in the nature of the PSL spectrum between Jan 29 and Jan 30, 2013, possibly correlated to the PSL reboot. I have attached plots of spectrum of H1:PSL-ISS_PDA_OUT_DQ to show this.

The first plot (viewer-0.png) shows the PSL spectrum from a good time on Jan 29. I have also attached the status of the PSL online detchar channel (ODC) for the same time period (viewer-1.png). The ODC state is all green, indicating that the PSL is functioning correctly and both the ISS and FSS are locked. This spectrum looks good.

However, the PSL spectrum from this morning (Jan 30) appears to have a strong line at 60 Hz with a harmonic at 120 Hz, a new line at 300 Hz, a forest of lines above 500 Hz, and a large bump at 650 Hz (viewer-2.png). I looked at the ODC data to pick 60 seconds where the PSL is locked to make the spectrum (viewer-3.png). The PSL appears to be going in and out of lock much more today. 

I tried picking a time this morning when the PSL was in a good state for a longer period of time. I have attached the PSL ODC plot for 40 mins from 0800 PST (viewer-5.png) which shows that there appears to be a good stretch of data at 0828 PST. The PSD for this time (viewer-4.png) does not have the large bump at 650 Hz, but the other lines are still there.

Is this a known issue with the PSL?

Mark B. and Arnaud P.

Starting TFs with Matlab on ITMy.