TJ, Nutsinee, Aidan

(I wrote a whole aLOG but Safari crashed and I lost it all - so this will be short).

Yesterday we:

• Replaced the HWS enclosure panel with wider apertures and attached the beam tubes to the flanges
• Removed the lexan covers from the viewports and covered the slots with the mating semi-circular pieces
• Aligned the HWS SLED beam to the center of the upper periscope mirrors.
• Using an IR viewer and counting turns on the upper periscope mirrors, we aligned the HWS SLED beams to the center of the in-vacuum lenses visible just inside the viewports
• Replaced the OLD HWS SLED (QSDM-840-5)
  • Old SLED: #07.14.265 (Max current: 153mA)
  • New SLED: #07.14.266 (Max current allowed: 195mA)
  • We retained the hardware current limit at 110mA. 

PT120B looking normal.

TITLE: 05/12 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

Pump down of vertex continues.
Aidan, Nutsinee and TJ working on HWS table. Removed panel to enlarge beam apertures.
Robert and Pep working at end Y. Lost connection to weather stations and dust monitors as part of their work.
Apollo working on FMCS upgrade at end Y.
Betsy running transfer functions on ITMX.
LVEA is laser hazard.

LOG:

15:21 UTC Betsy running transfer functions on ITMX
15:50 UTC Betsy, Calum and Nicole to mid Y then mid X
15:57 UTC TJ transitioning LVEA to laser HAZARD
16:05 UTC TJ done
16:07 UTC TJ and Aidan to HWS table
16:11 UTC Christina to mid X
16:18 UTC Gerardo taking viewport equipment to LVEA
16:25 UTC Nutsinee to HWS table
17:03 UTC Aidan, TJ and Nutsinee back. Brought HWS table panel out to have Bubba enlarge the beam apertures.
17:43 UTC Richard to LVEA to check functioning of Beckhoff laser safety interlock on table
17:47 UTC Richard back
18:25 UTC Jeff B. opening rollup door between cleaning area and receiving
18:30 UTC TJ to squeezer bay
18:37 UTC TJ back
18:38 UTC Jeff B. done
19:23 UTC Pep and Robert working at end Y, turned wifi on
20:11 UTC Chandra to LVEA to check on annulus
20:20 UTC Jeff B. to cleaning area
21:12 UTC Bubba to LVEA to turn off cleanrooms
21:23 UTC Jeff B. done
21:30 UTC TJ to cleaning area
21:36 UTC Mike and guest to LVEA
21:37 UTC Nutsinee working with TJ in cleaning area
21:42 UTC Aidan to cleaning area to work with TJ and Nutsinee
22:03 UTC Mike and guest out of LVEA
22:04 UTC Robert and Pep to end Y
22:51 UTC Robert and Pep back
22:57 UTC Nutsinee back

Peter F. and Kiwamu,

Related logs: 36106 and its comments

We looked into several (randomly chosen) lock loss examples to study how much the spot position can typically move on the test masses immediately after lockloss.

Summary:

• The arm powers decay in ~1 sec to get to 10% of the max powers.
• The test mass can get a kick vertically by 5 urad (corresponding to a spot position change of ~120 mm on the test masses) within 1 sec
• On the other hand, the horizontal kicks seem consistently smaller than the vertical ones by a factor of a few.

Locklosses:

We randomly picked the following lock losses:

• Apr 04 2017 13:02:26 UTC (Pin = 30 W)

• May 05 2017 23:48:06 UTC (Pin = 30 W)

• Dec 08 2016 06:09:25 UTC (Pin = 30 W)

• Nov 12 2015 18:11:16 UTC (Pin = 22 W)

• Jul 27 2016 08:15:22 UTC (Pin = 50 W)

See the attached pdf for the actual oplev signals and arm power signals for those times.

Angle motion to spot position:

Because of the negative g-factor design in aLIGO, the effective lever arm for the light in the arms is amplified by 1/(1 - gi * ge) = 5.8 for the spot positions where gi and ge are the g-factors for ITM and ETM, respectively. Therefore the lever arm is L/(1-gi*ge) = 23.5 km. In order to bring a beam with 5 cm radius to the edge of a test mass (with 34 cm diameter), the beam spot must move by 340 mm /2 - 50 mm = 120 mm. To produce such a large excursion in the spot position on an optic, one of or both test masses needs to tilt roughly by 120 mm / 23.5 km = 5 urad.

Some observations:

Usually ETMY PIT experiences the fastest change in the first 1 second after lockloss. It can easily reach 5 urad within 1 sec. Other pitch signals also showed a similar behavior in that they move relatively fast and typically reach 3-4 urad within 1 sec. All the pitch motions tend to go negative for some reason.

In contrast, the yaw motions didn't move as much as pitch motions. They typically jump by less than 1 urad at the beginning and later drift by a few urad relatively slowly.

Although we are still pumping down the corner vertex volume, TFs of the ITMX suspension show good signs of healthiness (no rubbing).  I think Gerardo mentioned being in the e-6 Torr range.  I cannot get the matlab auto TF script to work (with absolutely no time to troubleshoot this week) so I've just taken regular DTT looks with templates.  V, P, L all look good, Y main peaks are all in a good place - but not sure why the offset in the overall DC level - we've seen this before, again, no time to hunt and troubleshoot.  Haven't finished all of them.  

- Robert and Pep working at end Y
- Aidan, TJ and Nutsinee working on HWS table
- Pumpdown of vertex continues

Starting CP3 fill. LLCV enabled. LLCV set to manual control. LLCV set to 50% open. Fill completed in 473 seconds. TC B did not register fill. LLCV set back to 20.0% open.
Starting CP4 fill. LLCV enabled. LLCV set to manual control. LLCV set to 70% open. Fill completed in 208 seconds. TC A did not register fill. LLCV set back to 45.0% open.

• Current vertex pressure is 1.0e-5 Torr at BSC2 (2.8e-6 Torr at turbo)
• Vertex turbo is being backed by scroll pump
• QDP80 turned OFF - back filled with room air
• Opened leaky GV on IP1 (IP OFF) after verifying pump side pressure (e-3 Torr range)
• Leak checked X-beam manifold some more this morning - checked all flanges/viewports/camera housings on reducer flange near GV7. Then sprayed He in bag for about 15 minutes before running out of He. Left leak checker running for about 2 hours after that with no detected He signal
• Leak checked the two conflats on HAM2 that were removed during vent - no leaks
• X-beam manifold turbo station is OFF (not de-energized yet though)
• Monitoring GV4 annulus which is being pumped by aux turbo cart (pumping away excess He from leak checking)
• Aux carts on HAM4 and BSC3 doors are decoupled

WARNING:  don't turn on high voltage until pressure reads e-6 Torr range on PT-120B gauge

We noticed the other day that the HWS table beam apertures don't line up very well with the persiscope optics. After we got the viewport covers off today, I could see that the periscopes are lined up with the in-vacuum lenses. The actual problem is that the table is about 2" to the left of the design position because of an interference with the electronics rack. 

We decided the simplest solution is to just widen the apertures. So we've removed the panel and Bubba has it in the carpentry shop right now. We're going to widen the holes to match the inner diameter of the beam tube adapters.

I have reconnected the cold deck duct in the MSR room to help with the cooling until I can figure out what is wrong with the #3 Mitsubishi that serves that room. 
The temperature should start going down in that room, Carlos and I are monitoring this closely. 

Modified Software interlock to allow the Cold Cathode gauge to be turned on due to problems with pirani gauge.  This is the older style of two gauges  A being the pirani and b being the cold cathode. Patrick forced the Value of COLD_CATHODE_HIGH_LIMIT_TORR to 1 on LVEA LY vacuum control computer.  This allowed the Cold cathode to turn on.  This will be in place until we vent and can replace the guage.

Of the four diode boxes for the high power oscillator, diode box 1 is the one that has exhibited the greatest
degradation in output power.  A look at the individual pump diodes for that box shows that only diode 1 is the
one that shows the largest decay.

WP 6635
FRS 8091

This morning the 24MHz RF oscillator source for EY showed a timing error. Chassis was powered cycled and timing error cleared. RF output levels for unit are within spec. Richard did noticed the readback signals for this unit were incorrect. Unit is currently in the EE lab for troubleshooting.

S1000581

• At 6:40 pm local time the vertex pressure read 180 Torr at turbo station and 280 Torr at PT120B pirani gauge (which needs to be replaced - see below).
• Kyle and I leak checked x-beam manifold. There were several conflat flanges marked "untested." We also tested valves with rough vacuum adjacent volumes by removing the KF cap (we labeled these newly vented volumes as "up to air"), tested viewport with newly installed Pcal camera housing, turbo station, IP6, GV 4, 7. Kyle sprayed a significant amount of He on GV7 and about 30 minutes later we detected helium at the leak checker. It started out as a very small signal - mid -11 range and then fell, but then crept up a little higher, fell, crept, fell, crept until about 1e-10 Torr-L/s and then eventually fell back down to background of 1e-11 Torr-L/s. So then we bagged GV7 nipple with ameristat and sprayed He and waited 30 minutes before spraying all the other ports that may have caused the signal (because we were not careful to wait between sprays during the first go-around). No detection. We re-sprayed all other ports but could not re-create the leak.  Tomorrow we will wrap the nipple with mylar and refill our depleted He bottles to fully saturate the bellows nipple. I sprayed too much He at GV4 bonnet so now its annulus IP is off scale. We may need to connect an aux cart to help it out. Left the main turbo valved out for the night and will resume leak checking tomorrow.
• Tested IP6 using the new Gamma power supply by plugging in just one cable at a time to read out individual pump current. Each channel read about 260 uA and together they read 511 mA, so one half of the IP is not worse than the other. It may be that the old power supply was going bad. The pressure is trending down with IP6 valved in (we had it valved out all afternoon during leak checking).
• BSC3 & HAM4 door annuli are still on aux turbo carts

Stuff that needs to be replaced or fixed:

• HAM4 annulus IP does not indicate red on MEDM screen when it's OFF (FRS 8088)
• PT120B pirani gauge needs to be replaced. It's potentiometer bottoms out at 935 Torr at atmospheric pressure so we don't trust its readings (FRS 8089)
• IP1 gate valve leaks (FRS 8090)

Damping completed and flanges back on. No hitches. Three viton corks are in, preliminary laser vibrometry looks good. More later.

Gerardo, Vinny, Robert