- 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.

Scroll pump can't keep up with load yet, so the QDP80 will remain as the turbo's roughing pump tonight. Pressure set point is 0.65 Torr. Safety valve will close upon pressure breach or pump failure. Cooling fan is blowing on turbo.

Vertex pressure is 0.05 Torr.

Leaving site now.

[Kyle, Chandra]

Leak checked GV7 this evening by bagging GV nipple with mylar and inflating with helium at constant flow for 30 minutes. Oxygen sensor was used to verify air displacement. The leak checker detected a leak that crept up to 3.8 x 10^-9 Torr-L/s after several minutes, but then decreased while the bag was still saturated with He. Then we opened the valve and slowly soft closed again (all while maintaining He flow). During the stroke the He signal in leak detector continued to drop. We may have been detecting He from migration. We depleted an entire (small) bottle. 

While HAM4 was open, I took a photo looking towards HAM5. I couldn’t quite reach safely down into the middle of the SR3 – BS path, so the attached photo was taken from just above that path. The photo shows a strong retro-reflection from the HAM6 septum. The septum is at a fairly small angle from the beam spots on the BS and SR2, is nearly normal to the beam, and is not vibration isolated like the other reflectors in HAM5. I think we want to include a baffle in our upgrade plans that keeps the septum from being visible from the BS or SR2.

[Kyle, Gerardo, Chandra]

After 20 hrs of rough pumping over two days, we transitioned to turbo pump (0.6 Torr). Before we leave tonight we will transition from QDP80 backing to scroll backing and decide if we need turbo water cooling. Tomorrow we'll turn QDP80 off and leak check HAM2 conflats.

Pressure currently at 0.4 Torr.

The Swiss Cheese Baffle, MCA1, has been identified as the worst scattering coupling site at LHO (https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=35735 ). The baffle’s Q was so high that even minor damping was expected to significantly reduce its velocity. In addition, the baffle was accessible through ports in the reduction flange between HAM2 and the input mode cleaner tube, so the vent plan was modified at a late date to include damping of this baffle.

Before damping, I mapped out the motion of the baffle using the laser vibrometer. I was able to shine the beam through the camera ports beside the baffle at 3:00 and 9:00 and measure the motion of the suspension ring and the edge of the baffles (either side of the proposed dampers).  I found that, at these locations, the baffle edge was, at 12 Hz, moving more than ten times as much as its support ring and about 1/3 as much as the center of the baffle. Measurements at multiple baffle locations suggested to me that the 12 Hz mode was a combination of a torsional mode around the shorter standoffs, a mode where the whole baffle moves back and forth in the beam direction within its suspension ring, and a bullet-like mode where the baffle moves somewhat more at the center. These measurements  increased confidence that the selected locations were likely to work.

After doors had been put back on the open chambers, increasing purge air pressure, we pulled blanks covering ports at 4:00 and 8:00 (as viewed from the HAM2 side), one at a time.  I reached in through the port at 4:00 and inserted a Viton HAM1 table spring (cork) between the baffle and the baffle support ring at about 3:00, viewable through the camera port (see Figure 1). At the port at 8:00, the baffle is closer than the support ring, so I reached up and through the hole in the baffle at 9:00 and inserted the cork from the HAM3 side.  I put a third cork as far away as I could reach from the 8:00 port in the 6:00 direction, reaching about 7:00. Since the baffle and support ring are too far apart at this location for the cork, I inserted the cork between the baffle and the wall of the beam tube. We monitored the effect of each insertion with the vibrometer. The total time during which either port was open was under 45 minutes.

Figure 2 shows before and after spectra from the vibrometer and an accelerometer on the beam tube. Both sets were taken in similar conditions at air pressure. After damping, the 12 Hz peak was reduced to the degree that it no longer appears in the spectra for ambient vibration levels. To observe the peak I had to bang on the beam tube (lower plot).  Other regions of the spectrum did not show new peaks. Of course the final evaluation will require time and DARM.

A simple damping scheme like this could be used on other off-table baffles: at least one of the Eye baffles is moving in the micron range.

Robert S., Calum T., Stephen A., Eddie S., Vinny R., Gerardo M.

HAM4 Annulus system was valved off at 23:45 utc, aux cart remains connected and running.

BSC3 Annulus system was valved off at 23:50 utc, aux cart remains connected and running.

If pressure maintains for both systems the vacuum aux hardware will be removed tomorrow.

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

WP 6624

Field cabling to the Hartmann Table (ISCHT4) are reconnected. Things to note:

1. HWS cameras and new digital camera are on external power supplies. Same configuration as before vent.
2. Hartmann Sensor Power Distribution D1002206 - S1201877. Replaced led for negative 18V on rear panel.
3. Signal and power cables for Polarization PD Whitening Field Box inside the enclosure do not have a feedthrough panel.

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

Gerardo, Vinny, Robert