I will be working on the IMC characterization as a part of the 10 W prep. During the period, the IMC probably will drop its lock several times.
Green team-
The arm cavity is finally locking stably, thanks to the work of Sebastian, Hugh, Jeff and company to reduce our pitch fluctuations. Now we have about 5% fluctuations in the transmitted power that comes from pitch fluctuations, much better than the 50% we had this morning, and the cavity has been locked at least for 10s of minutes. The slow feedback is now on, controlled by the autolocker.
We get a max transmission of about 740 counts on ALS-C_COMM_LF, while the single shot beam stayed at 45 counts, which means that the on resonance/single shot resonance is 16.1, so we are getting 74% of the power that we would expect and probably have 26% of our power in higher order modes ( improved from 45% this morning). This may have been due to Alexa and I moving the EOM in our effort to reduce the RF AM. Maybe it is worth tweaking the EOM alingment when the cavity is locked to see if this is the sourcce of our mode mismatch.
I will leave the cavity locking with the autolocker on, until the red team wants to misaling it.
The X arm cavity stayed locked with green only for over 6 hours last night. Attached is a histogram of H1:ALS-C_COMM_LF_OUTPUT calibrated in uW arriving on ISCT1.
I updated the iscmodeling tools on the workstations in the control room by checking out them from MIT's cvs server. Jim secretly installed the cvs command only on opsws4 for me. So if one wants to update them in some future, he or she should run the cvs command on opsws4.
(Alexa, Sheila)
We began by misaligning ITMX. At which point our starting RF AM signal was -47dBm at 24.41MHz. We inserted a PBS before the EOM to ensure that we had optimized s-pol into the EOM. Then we adjustd the EOM stage such that the RF AM signal dropped to -60dBm. The Imon signal then had an RF AM offset of 2mV, with a peak-to-peak of 4mV at 500Hz (in comparison to alog 9434). The Qmon signal had an RF AM offset of 1mV with a peak-to-peak of 3mV.
We then examined the noise out of Imon with the cavity misaligned, and only saw a factor of 2 decrease at 100Hz compared to the previous measurement (alog 9436). This reduction could have also come from the improved modulation depth we achieved today. There is still too much noise...
Occasional unexpected CP1 level fluctuations previously shown to be the result of the filling of the portable LN2 dewars. Attached is the latest example. Only noteworthy when fluctuations reach alarm levels (~1/2 the time)
The h1dmt0 and h1dmt1 computers are in the process of being upgraded to Ubuntu 12.04. This will take a couple of hours.
The upgrade process has finished. John Z. will need to update the DMT software on both computers to finish the job.
Hugh, Sebastien
Position loops (UUG 5Hz) have been installed on HEPI-ITMX.
The design of those loops can be find in the SVN at:
/ligo/svncommon/SeiSVN/seismic/HEPI/H1/ITMX/Scripts/Control_Scripts/Version_5/GET_H1_ITMX_Controller.m
The function GET_H1_ITMX_Controller stores the zpk filters into a structure called FILTER_OUTPUT. This structure is used by the HEPI scripts steps 6&7 to generate the plots and saved the filters into the good format.
Sebastian and I looked at trends back during the day to set the Target positions for HEPI. We left the Pringle modes out of the loop for a while because they were generating large drives to the actuators. After a couple hours we saw the trends of the pringles not going anywhere fast so we set those targets and engaged those loops.
When I looked at longer term trends to make this log I see that the HEPI Location values were zero until Hugo and I worked on the position loops on the 16th and the input matrices were populated. The trends look very flat/stable until ~8pm 21 Jan. The ISC crew reports suddenly experiencing a sudden misalignment. They traced it to ITMx HEPI. Some confusion about whether or not they attempted to engage the uncommissioned HEPI loops but the point is, HEPI moved and stayed. They realigned the SUS and continued. So HEPI will stay here.
Attached is the current Cart_Bias for the Target positions. If you see the HP or VP numbers far from the Targets, know that these are AC coupled.
Done.
From ~ 2:00 - 2:10 PM
Done
Done
For WP 4409
Work done, VEA transitioned back to laser SAFE.
[Jeff K, Stefan B, + detchar] The bitmask defining the summary bit for the Input Mode Cleaner state-vector (ODC) has been trimmed to respond to only those bits recording the ASC WFS switch (bit 1), and the relative power indicators (bits 11 and 12). In this mode glitches in the WFS alignment will be recorded by the relevant bits 2-9 but won't affect the summary bit, and a low-power mode will still result in summary=GOOD. This was tested first at LLO and logged here. This hasn't been set in the safe.snap, but will be monitored and coordinated over the next few days.
We confirmed that when the WFS alignment (mainly DOF2 Pitch and DOF1 Yaw) strays outside of the thresholds set, it does not have a noticeable affect on the calibrated length of the cavity. Attached are ASDs for both LHO and LLO of IMC_X_DQ. Plotted are two nominal times (red/blue lines) when everything is aligned (all the ODC bits are green) and two times (yellow/green) when the WFS are reporting poor alignment (the y-axis is not in counts/rtHz but the units of the channel - m/rtHz (?)). There is no noticeable difference between the four traces on a given plot. For the time being, we feel ok in removing the WFS alignments from the summary bit (as reported) however we plan to do long term studies of what the thresholds for each DOF should be and maybe then they can be re-added to the summary bit. Question for whoever can answer this - why is LHO so featureless (compared to LLO) and why are the scales (y-axis) so different between sites? Thanks
We are done. We excited the IMC many times during the period.