Preparation of Xend for install work continued yesterday. The retrofit of the iLIGO cleanroom was completed. Gerardo check on the remaining OpLev Pylon near BSC9. 

John, Hugh, Bubba and I agreed on path toward installation of the SEI support tubes, bellows and table. Please see list below. 

1. Remove septum at HAM3/Inspect for identified leak/-Apollo-Cleanroom in place/Kyle worked on this yesterday
2. Test septum at HAM5/6-Kyle-Cleanroom in place
3. Move ion pump from HAM5 to HAM6-Kyle-Cleanroom in place/Kyle worked on this yesterday
4. Install all possible feedthroughs on BSC1/2/3 and HAM4/5/6; blank off as needed-Apollo-Appropriate purge needed/Hugh is working on this	
5. Install support tubes, support table and bellows per E980268 at HAM6-SEI/Apollo-Cleanroom in place
6. Pump down and leak check volume-Kyle/Gerardo/John-No cleanroom needed

Summary:

The beam was likely very close to the right edge of ETMY since Friday, and this was due to the fact that we were only using TMS angle for the input beam pointing. We fixed this problem by using QPD servo and started over from scratch.

Now we're back to the point where we see some interference, and the good news is that the demod signal is much bigger than before (1V pp). Also we're seeing some change in the reflected DC power due to interference, unlike yesterday.

We still seem to be getting ultra higher order modes all over the place, and we don't see anything on the camera, so we need to refine alignment tomorrow.

The ETM and ITM are wobbling too much at about 1Hz, though. Due to this, the reflected beam seems to be clipped by either the Faraday aperture or the PDH diode aperture, and as a result the DC level of the PDH diode is changing by 30 to 50% constantly. This is not an interference effect (it changes even if you misalign ITM).

Also today the CM board A was not working at all. No output, fast and slow, regardless of the Beckhoff setting.

Alignment details:

When we started playing around with the alignment today, the demod output was the biggest when some light blob was hitting the right cage  bar of ETMY.  We tried many things but we always got back to this position. The likely cause of this is the fact that we only used TMS for initial pointing.

Since we initially only used the TMS angle to point the injection to the center of ITMY without using the PZTs on the ALS table, and since we needed to rotate the TMS so much, actually the ALS beam was falling off of one of the green QPDs. This means that there was a very high chance that the beam is not going through the center of the TMS primary.

Elli and I finished the QPD servo (a servo that uses PZT-driven steering mirrors so the beam from the ALS table is centered on two in-vac QPDs on the TMS) quickly so we didn't have to worry about QPDs. See Elli's alog entry.

After this, of course the pointing of TMS changed, so we started over by first aligning the TMS (with QPD servo on) to the center of the ITMY using baffle diodes, then aligning ITMY to the center of the ETMY using cage bars, then aligning ETMY to center the second beam on ITMY using baffle diodes.

Now we're getting much larger demod signal than before, and we can see that something is going on in the DC level (that is different from the clipping). And we don't see any light blob on the cage bars, so we know that the thing is not close to the edge any more. That's as far as we got today.

PSL is currently in low power mode, with the HPO off and only the frontend running. After tweaking alignment into the PMC the transmitted power is about 10W. PMC, ISS, and FSS are locked. If IO needs high power we will turn the HPO back on, but for now we will run with the frontend only.

IO has installed their own power control stage if they need less than 10W.

DBB plots are attached, taken after transition. For the 35W beam.

EricA & HughR
We managed 1 corner before our crane moving window closed.  7 to go (BSC7 & 4)

(corey, greg, jim)

The granite table is now clear of the HAMISI#7 Optics Table.  This table was installed with minimal fanfare and no issues.  It has been torqued down. 

(The springs were pulled down, Flexures installed, the Springs are now pulling up on the Flexures, Pull-Down hardware is still in places [it will be removed once we have the Optics Table torqued down])

Both the inner and outer annulus O-rings which are integral to the HAM3-BSC2 septum itself (BSC2 side) were shown to leak previously.  These leaks were re-checked following the most recent venting of the input MC volume and found to have been unchanged by the change in load across the septum.  This 2nd test was not documented and some doubt as to whether or not the bellows tie-rods had been relaxed prior to this 2nd test arose as they were discovered to be in tension when Apollo began to remove this septum plate for inspection yesterday -> So, today I rechecked the outer O-ring and demonstrated that it still leaks and can confirm that the bellows tie-rods are now loose.  As such, the septum will need to be removed for inspection/repair.

Current status as the Y END pressure continues to come down.

As reported before, PD1/2/3/4 on the ITMY baffle correspond to H2:PEM-CS_CHAN_30/29/28/27 and the MEDM screen didn't make any sense because of this.

The real issue should be some cabling somewhere (in-vac or out-of-vac), but instead of a proper fix I changed the medm screen.

PD1/2/3/4 still correspond to CHAN_30/29/28/27, but now MEDM  shows correct number at correct location.

Attached are plots of dust counts > .5 microns.

We're still aligning the arm, it's difficult because we cannot see the beam at all at this stage on the mirror.

Anyway, the beam goes to the ITM, and then to the ETM, then to the ITM and comes back to the ETM. We're seeing some signal from the demod board, which goes zero when the ITM is misaligned. So this is the real interference signal!

Unfortunately it's not like the arm is flashing or anything, I suspect that our alignment is off mainly in yaw because I can tilt the ETM in yaw and see the beam on both righ and left side of the ETM at about the same height. 

Tomorrow we'll look at the interference pattern in the reflection from the arm, DC level of the reflection, and the demod signal amplitude to help our alignment effort. We'll also optimize the demod phase from Beckhoff world.

Kyle, Mark L. (Apollo)

- Installation of IO components on H1 laser table started today.  Currently laser beam is dumped and we get no video signal, also some MEDM screens are red, for more information see work permit #3303.
- Apollo, work around HAM03 area to remove septum plate.
- Cable tray removal from around BSC02 area, Filiberto.

(corey, greg, jim)

HAM7ISI Springs have been installed, pulled-down, and Spring Safety hardware is in place.  Did a first run through on the Optics Table to pull out any broken/loose tangs.  The Optics Table can be installed tomorrow.  At this point, I was able to note quite a few serial numbers (s/n) while they were easily viewable.  Here are some of them:

Springs

(where the Tip is associated with each Corner;  i.e. a Spring which is bolted down to a Spring Post of Corner-3 actually has its Tip in the Corner-1 area)

• 1:  030
• 2: 041
• 3:  045

Spring Posts

• 1:  031
• 2:  017
• 3:  032

Flexures

• 1:  041
• 2:  046
• 3:  040

Stage0:  014

Stage1:  010

Optics Table:  009

The common mode board for the ALS cavity locking, S/N S1102637, has been modified to account for the fact that the green cavity pole is expected to be around 600Hz for the one arm mirrors we have (up from 200 Hz). The common compensation is now a 40Hz/600Hz pole/zero pair. We also modified the first boost filter, so it can be engaged. It is a 100Hz/1kHz pole/zero pair. In detail:
C121 -> 220u (from 33n)
R69 -> 18.0k (from 120k)
C118 -> 1u (from 100n)
R77 -> 165 (from 82)
We left R70 at 1.2k which reduces the HF gain by 7%.

Daniel, Keita, Rana, Aidan, Dale, Dick

Using the ITMY baffle PDs, we were able to get the green beam from EY to ITMY today! The aLIGO beam tubes are able to transmit light.

We spent hours today trying out various ideas about how the beam might be missing, but in the end we found it by moving the EY Transmon Suspension.

The MEDM screen for the TMS had a range of +/- 15000 cts. In fact, the TMS has an 18-bit DAC and so its full range is +/- 2^17 = +/- 131072 cts.

With the current ALS table alignment, the TMS biases which give the maximum voltage on each baffle PD channel are:

				chan name

				P

				Y

				CS_CHAN_27

				-10000

				+2900

				CS_CHAN_28

				-69000

				+1200

				CS_CHAN_29

				-48000

				+1000

				CS_CHAN_30

				-46700

				+17800

We used these numbers to "triangulate". Then we used the ITMY spool cam to further center the beam on the ITM. It is not at all visible on the ITM surface, but can barely be seen on the gate valve behind the ITM as well as a little glint on the edge of the hole in the baffle where the cavity axis is. Our random search pattern initially just gave flashes of ~50 cts, so the new digital filters helped after all. Eventually, the signal on each PD can separately be made to saturate at 32768 cts as we align the beam onto it.

The final TMS settings for "good alignment" to the ITM are P = -16000 and Y = +9250.  Correction: there were some digital offsets in the 'test' filter bank. After zeroing those out, the new numbers are P = -42800 & Y = +59200.

Vincent has turned on the ETMY HEPI with low frequency boosts (although no integrators yet) so the pointing should be more immune to the HEPI hydraulic pressure fluctuations. Still need to fix up the ITMY HEPI. There's some seismic measurements going on overnight, but we can next align the ITMY to get the beam back to EY and then lock the green laser to the arm.