While Keita Cheryl and I were trying to see 00 flashed from the mode cleaner yesterday afternoon/evening, I ripped the door cover on the west side of HAM2.  It is a small rip (about an inch long) right by the clip on the north side of the door.  Since everyone had gone home and we didn't know where to find new door covers, we just covered back up when we left.  

Attached are plots of dust counts requested from 5 PM April 18 to 5 PM April 19.

Both HAM2 and HAM3 ISIs were locked this morning for alignment work. It was a good occasion to take look at the time series of the ISIs' Capacitive Position Sensors, and make sure that the locked/unlocked shifts were within requirements.

Maximum shift observed < 800cts*.The locked/unlocked shifts are within requirements**. Results are attached.

*:Calibration: 32768cts/mm

**: Acceptance Criteria (E1000309-v13, p28)
 Absolute values of the difference between the unlocked and the locked table must be below 1600 cts

April 10th between midnigth and 1am (UTC) (cf dataviewer trend attached)

M1 PRM Pitch offset  = 2000
M1 PRM Yaw offset   = 50

M3 pitch = 2000
M3 Yaw  = 115

Today with the same offsets (cf medm screen attached)

M3 Pitch = 1164
M3 Yaw   = -199

PRM spectra is plotted on the pdf attached for 3 different dates, with 3 different alignment offsets.

*in blue April 15th with Pitch and Yaw set to zero

*in green today (April 19th) at noon with Pitch=2000 and Yaw=50

*in red, today (April 19th) at 5pm with Pitch=3900 and Yaw=350

Except the noise floor that is higher for the last one (red), all curves match (in terms of resonnances), showing that PRM is/looks fully suspended (transfer function would be the only way to be sure, but spectra is already a very good indicator).

the conclusion is that even with large offsets in Pitch (taking more than 90% of the DAC range) PRM doesn't seem to touch any EQ.

PS : as the picture shows, when the ADC reads a DC signal greater than 10,000 counts (red number), the IOP watchdog trips (eg when a large offset is applied), meaning you'll have to bypass it if you need to keep the offsets on.

Alarms: Dust Monitor, IOP Watchdogs, CDS Front end
Laser Hazard

08:06 Washington Crane on site for crane inspection
Pablo and Michael working in H2 Laser enclosure for PCAL
08:36 Transition to Laser Safe
10:30 Sno Valley on site to work on chillers
Japanese National Broadcasting film crew on site being escorted by Fred Raab
Crane inspection in LVEA and at End X
Aaron & Filiberto working at End Y
11:15 and 11:40 Dale escort two high school tours of control room
13:08 Washington Crane on site for crane inspection
13:20 Kyle pumping at End Y
14:00 Cheryl transition to Laser hazard
14:25 Alarm on air handlers at Mid Y, Kyle to check out.   

The H1 DMT computers were moved within the equipment rack in the MSR to make room for additional CDS hardware.  The DMT system has now been powered up and is available for use.

X1boot was powered down for a disk clone, which was successful.  It has been powered up again and is available for use.

Modified Trillium 240 Interface chassis at END Y to D1000749-v3. Resistors R30, R33, R37, and R38 were replaced with 20KOhm (Modification stops U7B from saturating).

Serial Numbers of Units:
S1103178
S1103179
S1103176

Expect to start pump down of Y-end today after Dr. appt. 

I aligned the IMC to a marginal state but good enough to see centering behind MC3, and through the FI, and to get a REFL beam to HAM1.  The alignment is bad enough that the 0-0 mode is scarce so power is low most of the time.

I spent a great deal of time on soft covers, both when they were all closed, and then again when I needed to have one open.  When I had one soft cover open, it was necessary to redo all the doors and have all 4 doors on HAM2/3 open, to ensure that the fabric wasn't rubbing the ISI (which was floating).  

This situation came about because Hugo thought I was worried about the ISI locked vs unlocked position, which I'm not.  I am worried about there ISI locked after the vent, then payload change on the tables vs refloated and rebalanced position.  Somehow Hugo thought I was saying I needed to work on the tables while they are floating, and I thought he said he couldn't lock them for my work because he would have to redo all of his transfer functions.  We have got to get this kind of thing straight so here is my part, in bold letters:

*** ISI in HAM2/3 - LOCKED (no payload changes) VS UNLOCKED (no payload changes) CHANGES THE POSITION OF THE TABLES VERY LITTLE ***

Given the troubles I had with the IMC alignment tonight
*** ISI LOCKED, THEN PAYLOAD CHANGE VS REFLOATED AND REBALLANCED, AFTER A PAYLOAD CHANGE, SEEMS TO BE A PROBLEM ***

From my observations in chamber, clearly something happened somewhere in HAM2 or HAM3, or both.  PSL pointing seems OK in HAM2, but beam is low at MC2, so that's a possible issue too.  PRM needed max. drive in pitch to get REFL through the baffle just before beam goes to HAM1, which could indicate a problem with PRM, or that the PRM is just responding to a change in the HAM2 ISI.

Status:
- beam on PSL wall seems OK - evaluating the picture will give me more info 
- MC2 changed in pitch by 500 urad in pitch to get IMC to flash, though IMC clearly needs more alignment
- PRM is maxed out in pitch to get REFL through the baffle to HAM1
- beam is low at MC2
- beam height at MC3 EQ stop baffle is good when driving MC2 with the 500 urad pitch bias
- beam is going through FI chain to PRM and back to REFL

I read an alog from a few days ago, which suggests the HAM2 ISI rotated and shifted and tilted from it's locked position.  I think the numbers in the alog are in counts.  I'll look into it tomorrow (later today).

HAM3 may have also seen some big change when floated and rebalanced.

PSL beam on the PSL wall was roughly in the same position - I have a picture, and will compare more closely tomorrow. 

Beam at MC2 is low by about 4mm, which means an angle change of 250 urad coming from HAM2, which could be a change in the input beam or tilt of HAM2.

After the IMC was flashing, although still not well aligned, the beam was going through the FI and REFL was returning from PRM and making it into HAM1.  Sheila and I did see that PRM did not return to a consistent position when driving it around it's max. pitch, which means it's hitting an EQ stop.  This needs to be looked at after I understand what happened to HAM2 and HAM3.

Conclusion:
I was hoping to sign off on the IMC and HAM2 alignment, but there are multiple issues with the current state of the IMC/PRM/REFL beam.  Some sort of beam does make it through the IMC and FI and back to HAM1, even if it's ugly and clipped (Keita's alog), so we could just close up and deal with the alignment issues under vacuum.  I find it easier to diagnose these issues at air, and would suggest we might want to have the ISIs in HAM2 and HAM3 locked and flash the IMC again, after I've had some time to look at trends.

Keita, Sheila, Kiwamu

 We installed a high power beam dump in HAM1 this afternoon.
Then we attempted to align the interferometer REFL beam path in HAM1 to let it go through a viewport, but we gave up doing it this time.
We will try to align the REFL beam next time in near future when the IMC flashes.


Installation of high power beam dump:
 Since Cheryl recovered the alignment of the IMC this afternoon and made it flashing, we were able to see the interferometer REFL beam which is downstream of the IMC. The first thing we did was re-positioning of the first steering mirror such that the REFL beam lands on the center of the mirror. The second thing was the installation of the high power beam dump in the REFL path. By design most of the REFL beam is supposed to be dumped at this high power beam dump using a high-reflective BS. After the dump was placed and dog-clamped the beam splitter was aligned such that the reflected beam hits the center of the beam dump.

Alignment of the REFL path to viewport:
 We attempted to align the REFL path. The beam after the high-reflective BS is the one which is supposed to get out of HAM1 through a viewport to ISCT1. As the beam goes through the high-reflective BS the beam became weak and basically the beam power was too low to work with. First of all the sensor card wasn't useful any more due to the too low power. Alternatively we tried to see the beam from the outside using an IR viewer but it was quite hard to tell if we were really seeing the beam because the beam spot was a bit too far away (~ 2 m) to look from the outside and also simply too weak. So we gave up this time. If we can bring an IR viewer in the chamber, this might help us to see the spot. In any case we will come up with some alternative strategies for this issue. Another thing which prevented us from a smooth work was the PRM watchdog as described below.

PRM watchdog kept tripping :
 PRM wasn't in a great condition in the sense that it kept tripping every 2 minutes or so. Because the interferometer REFL beam relies on the alignment of PRM, we had to stop working and wait for it many times. After we carefully kept watching the MEDM screens, eventually we got a hypothesis --- due to a big bias applied on the top mass in pitch, enabling the control slowly brings the PRM alignment to a point where the OSEM readout hits the ADC watchdog threshold of 10,000 counts. Actually the pitch bias had been increased this evening by Cheryl and Sheila to get the beam retro-reflected and it is at the edge of the MEDM slider range.
 Another thing I would have to mention here is that I accidentally leaned on the HAM2 ISI when I was checking the beam around. This tripped the watchdogs of all the suspended optics on the HAM1 table at once. After we recovered all of them we found PRM behaving in that way.

RFEL beam seems clipped :
 Keita claimed that the beam looked clipped at its bottom and slightly its side. This was found after the PRM watchdog mambo jumbo. It is unclear what happened.
 

Went in to BSC6 while Apollo crews are hanging the door.

There were following things left in the chamber, and all of them were removed:

• In-chamber boots.
• A sock for SUS.
• TM protection plate for SUS cage (packed and bagged by Apollo).
• Metal step for in-chamber work.

I didn't see 1" witness mirror on the floor but I don't know if it's supposed to be there (it was not on Jody's check list either). Witness plates were there and of course they were left in.

One thing to note: Things are dirty. I was able to see lots of dust particulates on the witness plates on the floor as well as TMS mirrors (see pictures). ETM was better, but I was able to see some glints when I used a flash light.

I wiped the floor, about 1sqft in front of ETMY and maybe 2sqft right under TMS using Vectra wipes with alcohol, but it was not clear if I was removing dust so I stopped and told Apollo people to close the door. The wipes I used to wipe the floor was saved but I don't intend to do anything with it.

Anyway, as far as I'm concerned, BSC6 is ready to be pumped down.

Full pictures are available at resourcespace:

https://ligoimages.mit.edu/index.php?url=https%3A//ligoimages.mit.edu/pages/search.php%3Fsearch%3D%2521collection1307

Attached are plots of dust counts > .3 microns and > .5 microns in particles per cubic foot requested from 5 PM Apil 17 to 5 PM April 18. Also attached are plots of the modes to show when they were running/acquiring data.

Data was taken from h1nds1.
T0=13-04-18-00-00-00; Length=86400 (s)
1260 seconds worth of data was unavailable on this server
1440.0 minutes of trend displayed

I closed it -> How long had this been open?

The two steering mirror assemblies, D1101851, are installed in BSC2. They went in fairly smoothly. One hitch is where the support bracket attaches to the chamber's lower bracket; the weld from the lower bracket to the chamber wall kept the two surfaces from mounting flush.

The two mirrors are NOT installed yet. They oxidized during their bake and I am still working on figuring out if anything should be done about that. The mirrors shed a little, but it seems as though they are not shedding anywhere near the level that the chamber itself is.

We set up Viton Pads under HAM3-ISI balancing masses. The size of those pads is the same as the size of LLO's. However we set those pads under 1/2 the mass LLO uses, in order to rise the corner frequency of the mass+Viton stack.

Comparison before/after is attached.

The Viton Pads improve the 310Hz peak in V efficiently, by a factor > 5 without any drawback to it. Results are satisfying enough for now. We may try other configurations next time the chamber is open.

Looking at PR2 transfer functions ran yesterday night, an extra resonnance appears at 2.8 Hz for M1 pitch to pitch transfer function when comparing it to the model and phase 3a testing transfer functions ran on december 2012.

Betsy and Travis are investigating to find its source.