Wanting to eliminate CP3 as the source of the leak that appeared on 12/27/2015, I applied still more Vacseal to the area of the previously stopped leak which had been stopped months ago (see various aLOG entries) the difference is that this time a stayed away from the "cut/gouge" area that I had attributed as being the site of the leak but, instead, applied it only in the area where the spool roll seam weld interfaced with the stiffening ring stitch weld (also in the gap beneath the stiffener) -> WAHLAH! 

see attached pressure response

J. Kissel

Continuing on schedule(-ish, see LHO aLOG 24802), we've moved the PCALX line from 1501.3 [Hz] to 1001.3 [Hz]. I'll collect all of these times, amplitudes, and frequencies once we're done, but I'll post a mini-alog every time we change it to explain the drops to commissioning mode. Through the magical powers of awesome, Rick somehow picked a frequency that perfectly avoided the an-harmonic, 1st harmonic of the QUAD's violin modes. Nice work!

This change means the 1.5 [kHz] line was in place from 21:02:11 UTC to 22:38:27 UTC (padded by a 30 second ramp time on either side)

We've now resumed observation intent, and it appears we might be done with RF45 noise for the day (crossing fingers).

~1315 - 1355 hrs. local 

LN2 observed at GN2 exhaust after only 4 minutes -> Considering the exact procedure was followed as was during the previous manual over fill (2 days ago) and that then it had taken 29 1/2 minutes for LN2 to be observed at the GN2 exhaust, this demonstrates that opening the LLCV bypass valve 1/2 turn ccw is insufficient -> As such, from now on we should use 1+ full turn ccw (exhaust check valve bypass assumed to always be opened before LLCV bypass is opened) -> Today's data supports the choice of using 15% open for the LLCV, which was based upon the historical average needed to maintain the proper pump level- meaning that the pump level decays only slowly over the course of days if reliant only on the filling that occurs via the 15% open LLCV 

Next scheduled manual over fill of CP3 will be Monday, Jan. 11th before 4:00 pm

J. Kissel

Continuing on schedule(-ish, see LHO aLOG 24802), we've moved the PCALX line from 2001.3 [Hz] to 1501.3 [Hz]. I'll collect all of these times, amplitudes, and frequencies once we're done, but I'll post a mini-alog every time we change it to explain the drops to commissioning mode.

This change means the 2 [kHz] line was in place from 18:29:45 UTC to 21:02:11 UTC (padded by a 30 second ramp time.)

Also note there has been terrible sub-1[kHz] noise through out that ~1.5 hour period, but it has remained at low frequency, so I don't suspect that it will impact the estimate of the transfer function at these super-1[kHz] excitation frequencies.

Mid-SHIFT SUMMARY: Well, 4 hours ago everything was looking rather ok. Then RF45 glitching started to pound on the range. Jeff K came in and, with the guidance of Rick S., we went out of Observing and turned off P-Cal X to “listen” for a few minutes. Then we changed the frequency of the lines, to no avail. We then changed the EOM RF45 offset around a bit and then set it back to nominal. For a short while, the noise settled away and we got our range back. ≈ 15 minutes ago, the noise has returned and our range has gone wacky again. More news at 4:00PM PST….

We are using the Xend Pcal to drive the ETM with single-frequency excitations at high frequencies.

J. Kissel, E. Merilh,

Though we know it *should* have no effect, and there has been no conclusive evidence that it does, while out of intent to change the PCALX line, we moved the set point of the EOM 45 MHz control servo (H1:LSC-MOD_RF45_AM_RFSET) breifly down to 22.4, then up to 23.4, and then back down to its nominal value of 23.2. As usual, it's unclear whether this has done anything. We're now back into observation mode, with the intent bit set. Though the hefty bit of large features has gone away, there remains a bit of broad-band bnoise from 30 to 200 [Hz], and an harmonic streak of glitches in the OMICRON triggers.

J. Kissel, R. Savage, E. Merilh

While the IFO is screeching with RF45 noise, we've removed the intent bit and changed the 2501.3 [Hz] to 2001.3 [Hz]. In between, to exhonerate the PCALX from the excess noise and gltiching, we left all X-End lines OFF for 5 minutes between 18:26:10 and 18:30:15 UTC. No change in IFO noise characteristics -- still terrible.

The new line is at amplitude 35000 [ct] in the PCAL X oscillator (H1:CAL-PCALX_PCALOSC1_OSC_SINGAIN), and has been on since 18:30:15 UTC (with ramp of 30 secs prior). Attached is the SDF screen shot before we accepted the new values.

J. Kissel

I've come in to Ed mentioning that we've had intermittent RF45 glitching (see LHO aLOG 24789, LHO aLOG 24797), and there are concerns that the new PCAL lines are the source of the problem. I don't think this can be true. Here's why:

(1) The PCAL system is in no way related to the control servo for the 45 [MHz] modulation depth.
(2) The 2.5 [kHz] line (and 4 [kHz] line) had been on for ~6 hours before the first evidence for excess glitch rate / noise from RF45.
(3) The noise/glitchiness from the 45 [MHz] servo is taking on the "classic" behavior of intermittency (~15 minutes from Patrick, on and off for Ed).
(4) The amplitude of the PCAL line (with a ~0.1 [Hz] BW ASD) is just barely above the noise floor, much lower than any other sharp feature (i.e. the violin modes) above 1 [kHz], so I don't think it's a case of these new lines, say, saturating the OMC DCPDs (which is known to cause elevated noise / gltiching, etc.)
(5) The region surrounding these lines is feature free, so it's not a case of these new lines interacting with violin modes and ringing *them* up.

However, in order to get this "high" an amplitude, we are having to drive the Xend PCAL near the limit of it's range. It's not out of the realm of possibility that the PCAL's optical follower servo (OFS) is glitchy / non-linear near the edge of it range. However, again, because both the 4 and 2.5 [kHz] lines had been running for hours before any excess noise or glitchiness had shown up, I don't think this is the case either.

It seems to me that there is a visible amount of noise happening in PRCL and MICH Live between 7Hz and 30Hz. This seems to be a constant state as there is no "breathing" to this condition, at this point. I'll keep watching.

TITLE: Jan 9 DAY Shift 16:00-00:00UTC (08:00-14:00 PDT), all times posted in UTC

STATE Of H1: Observing

OUTGOING OPERATOR: Patrick

QUICK SUMMARY: IFO and environment look to be ok. µSei is at 90th%ile.

TITLE: 01/09 [OWL Shift]: 08:00-16:00 UTC (00:00-08:00 PDT), all times posted in UTC

STATE Of H1: Observing @ ~ 77 MPc.
SHIFT SUMMARY: Remained locked entire shift. Took out of observing briefly to change the end X PCAL frequency as requested by Rick. Possible RF45 noise for ~ 15 minutes. A couple of large SUS ETMY saturation glitches.
INCOMING OPERATOR: Ed

The noise reported earlier in log 24789 looks like another case of RF 45 problems that were not picked up by the monitor.

The first attachment is a spectrogram of DARM showing the burst of noise then a moving comb of lines. We've seen the RF 45 trouble manifest this way before - see log 23269.  Looking carefully at the monitor channel (second plot), one of the lines does appear there, though the burst of noise does not. POP_A_9Q does a good job of witnessing the problem (third plot).

Per Rick's request I changed the end X PCAL frequency from 4001.3 to 2501.3. I went out of observing from 12:01:46 - 12:08:13 UTC to do this. I accepted the SDF difference from doing this (see attached). I followed his instructions:

On the Cal/PcalX/Excitation MEDM screen

    Take ifo out of observing mode
    Set Sin Ampl to 0.00, hit return (this should ramp down to zero amplitude, hopefully)
    Set frequency to 2501.3 Hz, hit return
    Set Sin Ampl to 40000.0, hit return
    Accept changes in the SDF system
    Set ifo back into observing mode

Nutsinee had a tough time on OWL shift with H1 behaving badly until approx. 15:10 UTC, when it mysteriously improved. But the bad behavior returned around 17:00 UTC for about 30 minutes and I spent some time investigating its cause during this interval. Microseism was not too bad and wind was calm. There was no indication of excess noise on H1:LSC-MOD_RF45_AM_CTRL_OUT_DQ or coherence of that channel with DARM. Looking at a spectrogram of H1:CAL-DELTAL_EXTERNAL_DQ one can see broadband bursts across the bucket turning on and off suddenly (1-s resolution), with durations verying from a few seconds to about 30-40 seconds. Sometimes these were accompanied by loud bursts in the 10-20 Hz region, other times not. I looked for burstiness in other chnnels that was correlated with this. 

There was nothing well correlated in seismometers or microphones (either on the floor or in e-bays) or OPLEVs.  There were strong similarities on ASC-MICH_P and _Y, weaker on DHARD_P and Y, nothing on DSOFT_P and _Y, nothing on CSOFT, very weak similarities on CHARD and SRC2 P and Y. I am not familiar enough with the LSC/ASC couplings to know if this is just leakage of the length fluctuations onto ASC channels or if alignment is causing the problem. I looked at IMC_F an _L, MC2 TRANS which showed no indication that the cause came into the IFO on the light from the IMC. I tried looking at PRC ASC signals but they looked crazy in frequency with no time dependence (??). However SUS-PRM_M3_NOISEMON has large burst in the 10-30 Hz region on all OSEMS. HVETO finds these good for veto channels.

Travis was not finding anything bumping against its limits.

At 19:42:12 we lost lock. This coincides with the arrival of the maximum ground shaking in the 0.03-0.1 Hz from an EQ in Afghanistan, although the 1-3 Hz region showed sharp elevated shaking several minutes earlier. We are having a hard time getting back to locking.