Good data starts at 07/07/2013, 03:57:00 UTC

H1:ASC-Y_TR_A_NSUM_OUT_DQ should hover around 250cts, which is half of the full 500cts.

Here is an RMS plot in today's (aligned...) configuration, intentionally cut off at 50Hz.
(The high frequency stuff is about the same)

(Daniel, Stefan)

Based on yesterday's mode scan we identified where the 00 mode should be (tiny peak, with transverse modes spaced at 17890Hz to the right).

We did a dither alignment, first green (moving TMSY, ITMX and ETMX), then locked on the now identified 00-mode (moving PR2 and IM4).
That gave us 500 cts in the transmission quad sum (up from 250 counts).

Attached is the mode scan after the alignment.

(Daniel, Stefan)

First we realized that the 10x higher fluctuations we obserbed on Wednesday were entirely due to alignment. So we tweaked up what we thought was the carrier, and indeed reproduced the ~8Hz RMS performance.

At this stage we rand a mode scan (attached, plots 1 sand 2). The two attached plots are from two adjacent locks - they differ by 1/2 FSR, as expected.
For the 2nd one, the modes sit at

H1:ALS-C_COMM_VCO_TUNEOFS = [-4.744, -3.242, -1.882, -1.638, -0.380,  0.877,  2.187,  3.557,  3.837,  5.348]  V
Frequency offset           =[-62075, -44240, -26212, -22842, -05055,  12770,  30803,  48585,  52070,  69855] Hz

The transverse mode spacing 8945Hz ( 17890 Hz on the VCO)
The odd this is that the frequencies make most if the 10 mode is the biggest.

We also redid the transmon camera and LSC diode, taking out the ND filter which distorted the view. While the new image is not distorted, we still don't get a nice modal picture. Not sure why.

Yesterday we found a rather large contamination in the corner ALS COMM signal. There is highly non-stationary line around 24.5 MHz. Suspecting this maight be the green RF sidebands that are leaking through, we went to EY to look for their exact location. Measuring the transfer function from the FIBR servo to the PDH error signal, we were unable to identify the sidebands. Next, we took a close look at the notch feature which marks the first FSR. It is located at FSR = 37.4658 kHz with an uncertainty of 0.1Hz. The 3 dB points (down from the flat part) are at 37.426 kHz and 37.506 kHz, 80 Hz wide.

The cavity length then becomes FSR / 2 / c = 4000.88 m.

The RF frequency is f_M = 24.515730 MHz. Dividing by the FSR we get
f_M / FSR = 654.350, or in other words the sidebands ar expected at 0.35* FSR =  13.113 kHz +/- 0.065 kHz.

Looking again at the full sweep and zooming in near 13.1kHz we indeed see a tiny feature in the phase plot around 13.188 kHz. It moves to 12.868 kHz when the RF sidebanda frequency is lowered by 300 Hz.

The only other features in the sweep which are clearly identifyable are at 17.739 kHz and 19.731 kHz symmetrically around half the FSR. These are most likely the second order modes. Dividing 17.739 kHz by 2 we get a corresponding mode spacing of 8.87 kHz. For OAT the mode spacing was measured at 8.92 kHz with a different ITM at a different position.

(Stefan Daniel)

We moved the additional frequency difference divider to the common VCO. This required an increase of the PLL gain from 5 to 20. The unity gain was measured to be around 40 kHz. This also means that the gain for the common mode feedback increased by 10. We adjusted by lowering the gain of the SR560 from 10 to 1.

We took the opportunity to set all VCOs to a nominal frequency. The nominal frequency of the PSL/IMC VCO and the fiber AOM driver is 79'200'000 Hz. All ALS VCOs (EX/EY, COMM, DIFF) are set to a nominal frequency of 78'920'000 Hz.
 

The lasers in the end stations can be locked up or down by changing the sign of the phase frequency discriminator.

Due to cooling issues with the MSR, we have left the double doors between the MSR and the hallway opened for this weekend. We have set up a fan which blows the hot air at the rear of the racks out into the hallway. Please do not close the doors of move/obstruct the fan.

I have a script running which emails the MSR room temperature to CDS staff hourly, we will monitor the room over the four day weekend. We have contingency plans set up if we experience any further AC problems.

   The TMS-X suspension is mounted on the Bosch frame at End-X and the dummy mass table is suspended. The table is hanging almost level with no adjustments. The Upper Mass blades look to be in their correct position. The Upper Mass is still in stops, so we won't get a good read on how things are really hanging until the Upper Mass is leveled and suspended. This will be one of the first agenda items for next week.

  No real issues were encountered during the installation of the Upper Structure or with suspending the dummy mass table. The dummy table may be a bit low, but we will not know until we take some measurements.

  The Genie is parked under the dummy mass table as a safety stop during the long weekend. 

After pleny troubleshooting of minor electronics issues, we finally got to the point where we could check out the newly-installed sesnors of HAM6-ISI.

Sensors look fine. We can shoot for installation next week. Spectra are attached.

Note: One of the preamps of the HAM5-ISI ADE boxes (H3) needs fixing. It was used while HAM6's ADE was getting fixed. Symptom was a gain of 1/2 on the spectra of H3

Alignment tweaking on RefCav (Rodruck)

Investigating Dust Monitors at EY (Patrick).  EY Dust Monitor-2 is exhibiting odd behavior.  The 0.3um readings are several 100,000 counts (while 0.5 is zero). 

PCal work in H2psl (Colin, Pablo)

Truck came by to pick up barrel from Flammable Storage Bunker.

TMS Suspension work at EX (Andres, Jeff B)

TMS Telescope work at EX (Keita)

HAM6:  GS13 cards swapped, cps interface investigations continue

SURF Student (Emily) will mount accelerometers on Southern doors of HAMs 4&5.