Hannah, Stefan

We quickly looked at the pretty dramatic 5Mpc (10%) range drop that occurred at 10:07 UTC on 2015/06/05.

Attached are DARM spectra for 09:30 UTC (good reference, black) and 10:07 UTC (bad reference, red).
We did loo for coherence with MICH_OUT and SRCL_OUT at both good and bad times, but none showed any significant coherence in the 40Hz to 150Hz frequency band. Neither do ISS_PDA or ISS_PDB.

I restarted daqd on h1broadcast0 at 13:01 PDT. Very soon afterwards all the DMT monitors started running again and we now have Sensemon and SeisBLRMS plots updating again in the control room.

H1 was locked and in science mode during the DMT outage.

In the spirit of full disclosure, I'm setting the HIGH alarm level on the H1:CAL-INJ_EXTTRIG_ALERT_TIME EPICS channel (hosted by the front end model h1calcs) to see if I can use the EPICS alarm handler to audibly alert the operator of a GRB. I'm also setting the HSV alarm severity.

Some LHO DMT monitors are not running. John and Maddie have been emailed about the problem. There is no CAL SENSEMON or SEIS BLRMS data at the moment from H1.

• 12+ hour lock last night
• Apollo is cleaning the beam tube
• Mich damp tuning helped stability last night
• jitter tuning improved range last night
• Vacuum, resuming installation of aluminum strips on the beam tube
• Mike, LSC Fellows have arrived
• LSC Fellows are: Stefan, Hang, Leo, Hannah, and Ellie

The improvement of 3 or 4 in peak height and a few Mpc seems to have held for at least a few hours, so I attach before and after spectra. Two hours was not much time for this tuning considering that settling time was several minutes. When possible, I would like to try, for example, adjusting some of the other degrees of freedom (we adjusted only 1 of 3).

We are testing a new CDS overview screen for ER7 called H1CDS_SCIRUN_STATE_WORD_CUSTOM.adl. It is identical to the non-scirun except the EXC bits should all be GREEN all the time. This means that when any excitation other than h1calcs is engaged the bit turns RED, and if the h1calcs exication were to be removed that will also turn RED (the assumption is that CW excitations are always running).

This is more along the philosophy of green means nominal. Of course the control room is free to run whichever display is preferred.

A couple ISIs, HAMs 5 & 6, and HEPI ETMX, have accumulated some saturations on inertial sensors but these were not at the time of lock loss.

Checking the offload drive to HEPI at the ETMs showed that we still had ~100,000 nm before hitting the ETMi_ISCINF_LONG 250000 limit.  Also, the cartesian positions of HEPI still seemed to be comfortably moving as directed.

model restarts logged for Thu 04/Jun/2015
2015_06_04 18:26 h1fw1*

* = unexpected restart

The MICH feedforward path into DARM has been retuned, since Gabriele recently found a nontrivial amount of coupling from 50 to 200 Hz.

First, the MICH → DARM and MICHFF → DARM paths were measured according to the prescription given here. Then the ratio of these TFs was vectfitted and loaded into FM4 of LSC-MICHFF. This is meant to stand in place of FM5, which is the old frequency-dependent compensation filter. The necessary feedforward gain has been absorbed into FM4, so the filter module gain should now be 1. These changes have been written into the LSC_FF state in the Guardian.

Details

The attachment shows the performance of the new retuning compared to the old retuning. At the start of this exercise, I had already changed the FM gain of the "old" retuning from 0.038 (in the Guardian) to 0.045, as this removed a lot of the coherence near 100 Hz.

Also, I had previously widened the violin stopband in BS M2 L, but had not propagated this change to the analogous filter in LSC-MICHFF. This is now fixed. Also note that if any change is made to the invBS compensation filter in BS M3 L, this change must be propagated to LSC-MICHFF as well.

I did not have time to implement SRCL feedforward. I suspect it would be a quick job, and could be done parasitically with other tweaking activities.

I injected pitch (270 Hz) and yaw (280 Hz) lines with the PSL piezo mirror and then tried to minimize them in DARM by adjusting values of the offsets of DOF2P and DOF1Y of the IMC WFS.  It was a bit tricky because of ten-minute alignment time scales. But we reduced the injected pitch peak height by a factor of 2, and the yaw by 5 (we cared most about yaw because the PSL jitter peaks are mainly in yaw).  The inspiral range increased by a few Mpc and the jitter peaks seemed down by a factor of a few, but I will wait until tomorrow to put in spectra in order to be sure that the improvement is stable. DOF2P was changed from 135.9 to 350 and DOF1Y from 47.5 to 200. I think we could do better with another 2 hours.

Robert, Kiwamu, Evan

Kiwamu, Elli

We are interested in whether we can see any changes in the spot size/location on the ITMs due to thermal drift during full lock.  We have decreased the exposure on the ITMY SPOOL and ITMX SPOOL cameras from 100000microseconds to 1000microseconds.  (These cameras are not used any interferometer systems)  We will take images with these cameras.  at 5 minute intervals for the next 24 hours.

Dan, Travis

Tonight during our long lock we measured the decay time constant of the ITMX bounce mode.  At 10:10 UTC we set the intent bit to "I solemnly swear I am up to no good" and flipped the sign on the ITMX_M0_DARM_DAMP_V filter bank and let the bounce mode ring up until it was about 3e-14 m/rt[Hz] in the DARM spectrum.  Then, we zeroed the damping gain and let the mode slowly decay over the next few hours.

We measured the mode's Q by fitting the decay curve in two different datasets.  The first dataset is the 16Hz-sampled output of Sheila's new RMS monitors; the ITMX bandpass filter is a 4th-order butterworth with corner frequencies of 9.83 and 9.87Hz (the mode frequency is 9.848Hz, +/- 0.001 Hz).  This data was lowpassed at 1Hz and fit with an exponential curve.

For the second dataset I followed Koji's demodulation recipe from the OMC 'beacon' measurement.  I collected 20 seconds of DELTAL_EXTERNAL_DQ data, every 200 seconds; bandpassed at 9 and 12Hz, demodulated at 9.484Hz, and lowpassed at 2Hz; and collected the median value of the sum of the squares of the demod products.  Some data were neglected on the edges of the 20-sec segment to avoid filter transients.  These every-200-sec datapoints were fit with an exponential curve.

Results attached; the two methods give different results for Q:

RMS channel: 594,000

Demodulated DARM_ERR: 402,000

I fiddled with the data collection parameters and filtering parameters for both fits, but the results were robust.  When varying parameters for each method the results for Q were repeatable within +/- 2,000, this gives some sense of the lower limit on uncertainty of the measurement.  (The discrepancy between the two methods gives a sense of the upper limit...)  Given a choice between the two I think I trust the RMS channel more, the demod path has more moving parts and there could be a subtlety in the filtering that I am overlooking.  The code is attached.

Something is not healthy on SR2 suspension.

Recently we noticed that some DAC on SR2 suspension saturated intermittently at a rate of roughlu once per 10 minutes or so. At the begginig we thought this was due to some ISC feedback saturating some DACs when we lock the interferometer. However, it turned out that it saturates even when no ISC feedback is sent.

The attached is a one-hour trend of all the saturation motniors of the SR2 top stage actuators from the period when SR2 was aligned and damped without any ISC feedback signals yesterday. As seen in the plot, the RT and LF DACs saturated mutiple times. The LF saturated more frequently than the RF actuator. Looking at the suspension screen, Betsy and I found that the longitudinal dampig showed higher signal level at its output than every one else. It is on the order of 100 counts at the output. Betsy is currently checking the longitudinal damping loop by running a transfer function measurement.