[Sheila, Jenne]

While looking at our locklosses today, Sheila noticed that we are using up way more DAC range than is appropriate for the SRM while we are locked using the 3f signals.  Looking at a spectrum, it's all high frequency sensor noise. 

I lowered the frequency of the cutoff from 300 Hz to 200 Hz.  This eats 4 deg of phase at the 40 Hz UGF, so should be plenty fine according to an old OLG measurement Sheila found.   We could / should improve this even more, but (a) it's better than it was before, (b) this is only really a problem while we're on our noisy 3f sensor, and (c) we don't want to get too much more crazy without taking a fresh loop measurement, which we don't want to spend commissioning time on right now.

Attached is a set of spectra showing the old SRM output (blue) and the new (red).  Don't mind the bounce mode in the red spectrum - damping wasn't on yet during this measurement.

Today, H1 was primarily in the hands of commissioners working on high power.  At the end of the shift, H1 was passed over to the SEI team so they could do BRS work (mainly because H1 was starting to break lock quite a bit); this happened as the wind gusts were approaching 40mph.

Guardian was updated (Violin & Bounce mode damping separated).  I tried restarting nuc4 to show the updated ISC_LOCK Guardian, but had trouble with bringing it back up (the TV stayed OFF).

Day's Activities

• 8:01:  Magnetometer check in Elec Bay at EX.  Will not venture near BRS. (Robert)
• 8:51:  Jon Hanks in H2 Elec Room most of day
• 8:16 - 9:13:  Started Initial Alignment (then had meetings & other things come up)
  • SRM appeared to take longer (due to Rotation Stage being slowed to 10%?)
  • Want to get to DC READOUT for Jenne's power up attempts
  • NOTES:  
    • At Engage Soft Loops, watch POP90 (green) & keep it low by tweaking SRM (Jenne)
    • If environment is noisy, we're having ALS locklosses, ALS powers are all over (as well as other ifo signals), stay at LOCKING ARMS GREEN for a minute or so to let the WFS kick in.  (Sheila)
• 9:43-10:07 CP3 overfill (Kyle)
• 9:50 Jenne taking H1 for high power work.
• 10:44-10:49:  Kyle into LVEA to pick up equipment.
• 10:58:  Investigating facility related lines in the CER (Bubba)
• 11:00 &11:30Incursions into CER (Richard)
• 1:20pm Chris S dropping off an earth auger at EX (for Wind Barrier prototype).

0945 - 1000 hrs local -> To and from Y-mid 

Opened check-valve bypass valve, opened LLCV bypass valve 1/2 turn -> LN2 at exhaust after 1 minute 10 seconds -> Returned valves to as found 

Next manual overfill to be Wednesday, June 15th.

Group Status:

• SEI:  Time in MICH, so can work on DRMI configs.  Just monitoring BRS data.
• SUS:  -
• Facilities:  Wind Fence at EX construction begins
• VAC:  Encourage adjustment of Piranis (John).  
• PEM:  Digging a hole at some time
• PSL:  DBB work tomorrow
• CDS:  Testing of common mode summing board (Ed)

Maintenance:

• CDS:  Binary for PRM rms (looking at cable) Filberto, EY PUM (pull chasis), Safety system stuff, CDS work stations reboot at 6am, resync atomic clock.
• SEI:  top level manager for guardian (TJ)
• IOT2L Beam Dumps (beam and MC unlocked)
• Guage on top of HAM1---so make sure we coordinate this with IOT2L work!!
• Fire Dept testing bell in front room

Outreach:

respit from outreach visits.  School group on Fri.  

Krishna, Michael

We took a look at the noise of BRSX with damping forced on and off now that the new damper is installed. For context, the previous damper injected lots of broadband noise which made the BRS unusable during damping. The first plot in the attachment shows that with the new damper we get comparable tilt subtraction whether the damping is on or off. The second plot is a more broadband view of the BRS noise and shows that the damping rings up the torsional mode (~3 Hz) and some other higher frequency modes but doesn't change the broadband noise. The wind picked up right when we forced the damping on so there's an overall increase in low frequency motion.

After taking the measurements with the damping forced on (~1 hr), we found that the BRS had started drifting rapidly which decreased the ability to subtract tilt. This is due to the heat generated by the stepper motor that drives the turntable. In normal operating conditions, the damper shouldn't ever need to run for this long and thus shouldn't create such a large of a drift.

The take away from this is that the BRSX sensor correction need not be turned off if damping does trigger. The tilt subtraction might not be very effective shortly after damping but it should still be useable.

Michael, Krishna, Jim, Hugh

Here's a brief look at the performance of the BRSY sensor correction during Wednesday's ~20-40 mph winds. We were using 250 mHz blends and Warn_SC_2 sensor correction filters for Y axis (the beam axis). The interferometer was able to lock well as noted in 27658.

The first plot in the attached pdf shows an ASD of the ground seismometer Y, the BRS rX, the tilt-subtracted seismometer Y and the ST1 seismometer Y signals. The tilt-subtraction worked well and kept ST1-Y motion small even as isolation was provided above 0.1 Hz from the sensor correction filter. Note that ST1 still sees the ground tilt and the seismometer output is contaminated by tilt, hence the effect of the isolation is not clear in the ST1 Y channel but we expect it to be there. Ideally one would like to measure the tilt going into ST1 from the ground and cancel that (rX sensor correction), but as Robert showed in his alog a few weeks ago, ground tilt varies significantly on the LVEA floor and one would need multiple angle sensors to map it well or one (good) angle sensor on Stage 1.

The second plot shows the coherence between the ground seismometer Y and BRSY rX and that between the tilt-subtracted Y and BRSY rX. The high coherence in the first is good, but the high coherence in the second indicates that the tilt-subtraction is not optimal yet and improvements of ~2 could be had at low frequencies.

The third plot shows has the same lines from the first, along with the buried seismometer Y for comparison. One can see that the tilt-subtraction is more effective and is also more useful above 0.1 Hz.

The fourth plot has two additional lines - ST1 CPS and it's RMS. The RMS motion was kept below 1 micron but had an odd bump at 8 mHz. Jim and I tried to add a notch to the sensor correction at 8 mHz but were unsuccessful in suppressing it well.

This morning I modified the high pass filters for the tilt-subtracted seismometer channels as shown in the second attachment. The new (red) filters suppress signals below ~20 mHz with some gain-peaking at 40 mHz (which is acceptable) and decent phase above ~60 mHz. These seem to work well and keep the CPS signals small. They are installed at both ETMX and ETMY. The third attachment shows the sensor correction with this new filter . The wind-speeds were only ~10 mph but the CPS signal is smaller and doesn't show the ~8 mHz peak.

Will comment this entry when leaving

We are still losing lock more than 50% of the time once we start to increase the power into the interferometer. I slowed down the rotation stage to 10% of its normal speed. In this way I was able to make it to 10 W once. On the second try, the interferometer lost lock right after a gain step in the summing node board. The behavior of the CARM error signal does not seem any different from past successful power increases, so it is not clear to me what could be wrong with the summing node board.

In order to make it easier to engage the soft loops, I made the 20 dB boosts come on only when the soft loop error signals are less than 0.01 ct.

I also turned down all the hard loop gains by 6 dB and re-engaged the bounce mode notches in the suspension PUM drives, because the bounce modes were becoming unmanageable.

TITLE: 06/11 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Commissioning
INCOMING OPERATOR: None
SHIFT SUMMARY:  We have had good locking all night, getting to INCREASE_POWER for the first time in a long time.  It has been a bit windy, but just under the threshold for locking. 
LOG:
Locking, commissioning, locking, commissioning . . .  Mostly keeping Evan company.

As noted in alog 27683, turning on the 10dB gains in the M0 Lock filter banks for increased offloading speed was killing the lock. We saw that again today.  I turned on all the filters by hand, and it seems that it's the ETMY Y that is the problem - all others are fine.  Sheila pointed out that ETMY has filters for Y2Y and P2P in the M0 drivealign banks, but no other quads do.  We turned off the invY2Y filter, and we were able to run the EngageSoftLoops state.  We didn't turn off the invP2P, but we probably should so that all the quads are the same.

Bounce damping setting was changed for IY and EX so they damp at all. Don't know why the old settings don't work.

For EX I just flipped the sign.

For IY, I rotated the phase by 210 degrees in effect and increased the gain significantly. Gain increase might be unnecessary but I leave it like that because it seems to work faster.

ISC_Lock was changed but not loaded.

ETMX Mode3: FM1, FM2, FM4,  +10 gain (BP, -60deg, 100dB) seems to have worked quite well. No need to turn on a damping for 505.707 (which should be checked again with 0.0001 BW to see if it's really exists). 505.707 should be watched while damping 505.710 just in case.

The new violin mode table is being uplated slowly. The modes with Damp Setting column filled out are the one that's been sucessfully damped by the filter settings indicated in the table.