For the record, here are the weights of the glass optic, compared to the weight of the dummy we used to tune the suspension:

BS optic = 14,251g

Dummy mass = 14,180g

So, the optic hangs a bit lower in the structure than the metal dummy mass - Travis confirms this with the position error of the top BOSEMs.  We will correct this if IAS measures that we need to.

Also, FYI - a BS shipping cake tin weighs = 22,538g

Fogot to post this Wednesday.  These are the pitch/yaw numbers after Travis locked the quad pitch adjustor set screws Wednesday morning.

• Pitch: 5.0 µrad up
  • Target: 12.5 µrad up
  • Error: 7.5 µrad down
  • Tolerance: ±160.0 µrad
• Yaw: 72 µrad CCW
  • Target: 0.0 µrad
  • Error: 72 µrad CCW
  • Tolerance: ±160 µrad

All BSC8 HEPI actuators have been removed.  These may be used for BSC3 after replacing the left(NW,SE) return vertical flexible pressure lines from 30" to 41".

Attempting undamped TFs on IM1 using new script. Commissioning switch should go on and off automatically.

- Giacomo, Cheryl

Alignment of the IMC, and IM3 and IM4, increased IFO REFL from 106mW earlier this week to 147mW today, giving 90% power coupled into the IMC.  In our first measurement, the IMC alignment had drifted away from optimum, and the the IFO REFL beam was clipped on the baffle in front of IM4.

Power budget: 

• 2:58am:  6.0mag earthquake near Alaska.
• 9:09am:  Arnaud starting ITMy (BSC1) SUS Transfer Functions (at 9:09am till 11?)
• Rodruck/Apollo craning/fit checking Photon Calibrator periscopes (10-12)
• 10:30am:  Filiberto running cable around HAM3 around 10:30
• Hugh checking out issues with BSC1 HEPI Sensors
• SUS gave ok, so tomorrow (Fri), Spool & BSC1 door can be installed
• FMCS alarms:  EY Temperature (temperature heading over 75deg [from 69deg]) & MX Air Handler

The sensors used by HEPI-ITMY look functional. The attached plot shows the spectra of the L4Cs and the STS-2 (ground instrument).
STS-2 signals from HEPI-BSCs are broad-casted to the other chambers via a STS-2 distribution chassis (D0900351).
STS-2 signals seen by HEPI-HAM2 et HEPI-ITMY are identical (cf spectra).

Please see LLO aLOG 6041 for details.

Took a (last) set of TF on the ITMY. DTT xml files can be found here :

/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ITMY/SAGM0/Data/2013-01-31_1000_H1SUSITMY_M0_*_WhiteNoise.xml
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ITMY/SAGR0/Data/2013-01-31_1000_H1SUSITMY_R0_*_WhiteNoise.xml

The plots are consistents with models and last measurements, cf pdf enclosed

[Robert, Giacomo]

In the past few week we have alwayis notice a ~1 h period variation in the IMC-REFL power during IMC locks. We suspected that it has something to do with the temperature, but only this morning Robert forced me to take 5 minutes and look into it. There is a clear correlation between PSL room temperature and IMC-REFL power (i.e. alignment into the IMC) at and below about 1 mHz (no surprise).

Attached are data taken during an IMC lock at UTC 2013-01-25 04:30:00 (GPS = 1043123416)

- time series of the IMC REFL power (H1:IMC-REFL_DC_OUT_DQ) and the four temperature sensors in the PSL room (H1:PSL-ENV_LASERRM_[ACN/ACS/TBLN/TBLS]_TEMP_DEGC)

- transfer function and correlation between each of the temperature channels and IMC-REFL

TBLS (not surprising as the periscope is right there) and ACN (not sure where this sensor is...) show the biggest corelation with the IMC_REFL power.

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.

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. 




 
 

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?