The pumpdown started at 4 PM (2300 UTC). At 10 PM, we (Jenne, Jan, and I) opened up the RV1 valve to full open. That's the second inflection point in the plot.
Atm 2 is showing the butterfly valve that closes down down the orifice at higher pressure to slow down the pumping speed.
See elog entry #2573
We swapped the PMC s/n 2677 for s/n lho006.
The table below summarizes the power levels before and after the PMC swap.
- The power into the PMC (1.67 W) was measured with Scietech bolometer before the first steering PMC mirror. The leakage through the steering mirrors was measured with Ophir power meter to be 12+8 mW. There is also a lens between the mirrors which was not measured.
- The power through the PMC was measured after the doubler pick off (105 mW), steering mirror (4 mW), and lens (not measured).
- The estimated reflection from four lens surfaces is 1-2% hence 1% uncertainty in the losses in the table.
- The beams into the PMC and on REFL PD were realigned. The beams downstream of the PMC are blocked as we did not realigned the PMC and doubler paths.
- The trans PD ND filters were removed. The VDC=1.28 V now.
- The NPRO current is 2.102 A
Atm 1 old
IFO pressure was 2.3 mTorr this morning,
The Maglev's foreline valve V4 was closed so P2 rose to 4 Torr. The Maglev was running fine with V1 open.
This is a good example for V1 to be closed by interlock, because at 4 Torr foreline pressure the compression ratio for hydrocarbones goes down.
V4 was closed by interlock when TP2 lost it's drypump. The drypump's AC plug was lose.
To DO: set up interlock to close V1 if P2 exceeds 1 Torr
We added C1:Vac-CC1_pressure to the alarm handler, with the minor alarm at 5e-6 torr and the major alarm at 1e-5 torr.
The folding crane was fixed and tested this morning by the NNN rigging company. Pictures will be posted by Steve in the morning.
Afterwards, the ITM-east door was installed, jam-nuts checked. No high voltage was on for the in-vac PZTs.
The annulus spaces were roughed down to 350mTorr by Roughing Pump RP1. For this operation, we removed the low flow valve from the RP1 line.
After the spaces came down to ~400 mTorr, we closed their individual valves.
Warning: The VABSSC1 and VABSSC0 valves are incorrect and misleadingly drawn on the Vacuum overview screen.
Our idea is to have a much slower pumpdown this time than the last time when we had a hurricane kick up the dust. Looks like it worked, but next time we should do only 1/2 turn.
The 1 Ton yellow crane support beam jammed up at Friday morning, June 25.
The 40m vertex crane has a folding I-beam support to reach targeted areas. The rotating I-beam is 8 ft long. The folding extension arm gives you another 4 ft.
The 12 ft full reach can be achieved by a straightening of the 4 ft piece. There is a spring loaded latch on the top of the I-beam that locks down when the two I-beams align.
This lock joins the two beams into one rigid support beam for the jib trolley to travel. The position of this latch is visible when standing below, albeit not very well.
To be safe it is essential that this latch is locked down fully before a load is put on the crane.
We were preparing to pump down the 40m vacuum system on Friday morning. The straight alignment of the 8 and 4 ft piece made us believe that
the support beams were locked. In reality, the latch was not locked down. The jib trolley was driven to the end of the 12 ft I-beam. The 200 lbs ITM-east door was lifted
when the 4 ft section folded 50 degrees around the pivot point. This load of door + jib-trolley + 4 ft I-beam made the support beam sag about 6 inches
The door was removed from the jib hoist with the blue Genie-lift. The sagging was reduced to ~3".
The Genie-lift platform was raised to support the sagging crane jib-trolley. The lab was closed off to ensure safety and experts were called in for consultation. It was decided to bring in professional riggers.
Halbert Brothers, Inc. rigging contractor came to the lab Tuesday morning to fix the crane. The job was to unload the I-beam with safety support below. They did a very good job.
The static deformation of I-beams sprung back to normal position. There are some deformation of the I-beam ~2 mm where the beams were jammed under load.
It is not clear if this is a new deformation or if the crane sections have always been mis-aligned by a couple of mm.
The crane was tested with 450 lbs load at 12 ft horizontal travel position. The folding of I-beams were repeatedly tested for safe operation. Its a 1 ton crane, but we tested it with 450 lbs because that's what we had on hand.
We're working on the safety upgrade of this lift to prevent similar accident from happening.
Atm 1) load testing 2007
Atm 2) jammed-sagging under ~400 lbs, horizontal
Atm.3) jammed-folded 50 degrees, vertical
Atm.4) static deformation of I-beams
Atm.5) unloading in progress with the help of two A-frames
Atm.6) it is unloaded
Atm.7-8) load testing
Atm.9) latch locked down for safe operation
Atm.9) zoom in of the crane sections misalignment
Healthy BS oplev
We did the following:
1, closed V1, VM1, annuloses: VASE, VASV, VABS, VAEV, VAEE and VA6
2, stop rotation of Maglev-TP1, waited to decellerate and turned off power to it
3, closed V4, stoped rotation of TP2, waited to decellerate and turned power off
4, opened VM3 to RGA that is still running
I will come in tomorrow 9-10am to restart pumping.
The San Gabriel mountain has been on fire for 6 days. 144,000 acres of beautiful hillsides burned down and it's still burning. Where the fires are.
The 40m lab particle counts are more effected by next door building-gardening activity than the fire itself.
This 100 days plot shows that.
I repeated the BS oplev spectrum today and I do not understand why it does look different. I did it as Kiwamu describes it in entry#4948 The oplev servo was left ON!
It is working today! Finally I repeated the BS spectra, that we did with Kiwamu last week
The optical levers were centered during these measurements without the reference of locked cavities. They have no reference value now.
SRM sus need some help. ITMX is showing pitch/yaw modes of the pendulum .....OSEM damping is weak?
1.5 days of happy psl-ioo with litle bumps in C1:PSL-126MOPA_HTEMP