Decoupled Vertex MTP from isolation valve (10" gate valve).  Will replace gate valve tomorrow.

Summary. The crystal cooling circuit increases the PSL table motion an order of magnitude around 80-90 Hz and in some other bands. Mitigation schemes are discussed.


We measured vibrations on the PSL table shortly after the laser and auxiliary cooling systems were running. The accelerometer and data acquisition system were huddle tested against the LVEA seismometer and the accelerometer was mounted about a meter –X of the crystal box on the PSL table. 

Figure 1a and b show that the full cooling system increased table motion by an order of magnitude in some bands. 

We made several tests to see if a particular part of the system was the biggest problem. This turned out to be the case: when the crystal cooling circuit was bypassed or shut down it was difficult to distinguish the cooling-on and cooling-off spectra even though the blue auxiliary system and all parts of the red system, including the 30W laser system, were running except for the crystal cooling circuit. The culprit crystal cooling circuit is identified in the photo of Figure 2. Figure 3 shows that the excess noise disappears when the crystal circuit is bypassed but all other circuits are running. 

With regard to mitigation, Figure 4 shows that the vibration can be reduced by a factor of 2 by reducing cooling water circulation from 18 liters/minute to 15. However, this reduction may effect the performance of the laser. If a pressure-variation reduction system (pulse filters and hydropneumatic accumulators), such as were installed for the TCS laser cooling system, were installed near the input and output of the crystal cooling circuit, we might reduce vibrations from the purposefully generated turbulence in the crystal circuit. We might also have some success with structural damping: Figure 1a and b show that a sharp peak at about 83 Hz is evident in Y (the short axis of the table) and Z but not X. This would be expected for a rod-like resonator aligned along the X-axis. Candidates include the cable tray that supports the crystal cooling hose and the top stiffening bar of the crystal enclosure, both visible in Figure 2. 

Robert Schofield, Lutz Winkelmann

As of this late last week and this weekend, we have removed the lower structure of the QUAD and set it in the SUS cleanroom.  Alastair has pulled (and profiled) on the order of 10+ fibers, and another batch of storage containers is about ready.

We held a brief meeting this morning to make sure everyone was "on the same page" since this chamber is slightly different than the BSCs that we have already cleaned: there are four tubes attached to BSC4. There was some discussion about the number, type, and location of barriers. As agreed at the meeting, work started with the barriers in all but the north nozzle which is attached by a short spool to HAM9. Working without a barrier at the HAM9 spool preserves access to the chamber cleanroom and precludes any confined space related safety issues. The trade-off is that one extra person is required to be a runner. 

Once brushing started, work went quite smoothly. The guys worked with one drill all day (#21) which was possible because John has given us permission to run a drill until it dies. The collar and upper sections were completed by lunch time. The mid-section and two nozzles were finished by the end of the day. 

Attached are plots of dust counts > .5 microns.

Kyle, Gerardo 

Helium baseline value 3 x 10-10 torr*L/sec at start of testing and 6 x 10-10 torr*L/sec at completion of testing (~3hours).  Large known leaking feed-through shielded via 4 layers of ultra tape.  Helium flow > 1 bubble per second when submerged.  

YBM to be vented on Monday and leaking feed-through flange will be replaced then.  

• Feedthru work in progress at BSC6
• Ongoing H2 PSL installation
• ICC at BSC4
• L1 OMC installation slated for Monday

I added a branch to the vacuum line for the H2 PSL over to ISCT4. I attached it to a model 227B dust monitor there with its internal pump removed. It should be running now at location 1 in the LVEA.

Gray, Warner

We weighed the two main components of the BSC storage container today. The lid weighs ~650 lbs, the base weighs ~2500 lbs for a total of ~3150 lbs. This does not include the 2 base mounting plates (which weigh ~50 lbs a piece, they are currently with clean and bake) or the pile of lid fasteners.

Three weeks ago the PSL team started to install the H2 laser and its stabilization. In summary the 35W front end laser and the 200W high power oscilator (HPL)are running. The HPL is injection locked. The diagnostic breadboard (DBB) is installed and functionable (final calibration still pending). The 35W front end is aligned to the DBB and first modescans and noise measurements were taken. The full PSL DAQ system was tested via a loop back test (inputs connected to outputs at field module location). The four PSL real time models are running.

Some more details:
We have installed the 35W and the 200W laser on the table in the laser area enclosure (LAE), the laser pump diodes in the laser diode room (LDR), the chillers in the chiller room, run pump light fibers between the LDR and LAE. In addition we installed all the PSL electronics in the PSL racks in the LVEA. The CDS system (front end, AA/AI filters) are installed temporarily in a rack in the LVEA (they need to move eventually to the H2 electronics room). All cables are run between the CDS system and the PSL rack, and between the racks and the LAE. Many of the PSL optical components (including PMC, reference cavity, DBB) are on the table. The laser computer control (Beckhoff) was installed and tested. The laser interlock system was tested and the test protocol signed by PSL subsystem lead and LHO laser safety officer. The 35W laser was realigned and tested. The pumplight fibers were tested and the slopes of the four laser diode boxes were taken. After that the fibers were connected to the HPL and the laser resonator, pumplight injection and 4f optics were aligned. (See a different lab book entry for the HPL performance). All optical spares were transfered into the ante room of the LAE. After several alignment itterations the HPL showed a similar good performance as it did in Hannover and the injection locking was initiated. The system locked at the first try and optimization of the combined 35W/HPL system is ongoing.
We installed all required DAQ cables between the field modules and the AA/AI filters. This is a temporal installation on the AA/AI filter side and a final installation on the PSL rack side. We did not connect all the spare cables. This should be done during the final installation (when the CDS rack moves to the H2 electronic room). To test the CDS DAQ chain we run a loop back test (model and scripts were developed by Ryan DeRosa). This send out a 100Hz signal via the DACs, AI filters and cables to the field modules. From here the signal is send via a second cable back to an AA filter, digitized with an AD card and the in-phase and quadrature signals are calculated. We found one broken cable (PMC module AI channel 10) which was fixed.
All software required for the automatic DBB measurements was installed and first DBB measurements were take. The final calibration of the DBB is in progress.

It was found that the sus monitoring systems did not have channel 31 on ADC0 reserved for timing/duotone inputs. After some discussion it was determined that all IO chassis should have the same timing input signals, including all monitoring systems.

The SUS ETM (D1001725-v8) and BS/ITM/FM (D1002741-v4) wiring diagrams were updated to accommodate these signals. This also required updates to the h2susauxb478 and h2susauxb6 models, which were corrected and committed. However, while working on h2susauxb478 I found that there were some discrepancies in the input channel mappings. The wiring seems to be missing mappings for the following channels:

BS Left Slow I (rms)
    BS Left Fast I
    BS Left Volt Mon
    BS Side Slow I (rms)
    BS Side Fast I
    BS Side Volt Mon

The model that was committed is therefore incomplete, and will need to be updated once the wiring diagram has been fixed. NOTICE: neither model was rebuilt or installed.

Kyle, Gerardo

Found gross leak at electrical feedthrough ( > 1 x 10-3 torr*L/sec, can't measure directly as it is off of the usuable scale on the leak detector!) on the middle 12"/4.5" flange cluster on the south side of BSC8 -> Covered with tape and the YBM pressure fell off a factor of 10 and then assumed a nominal slope -> Bench tested a proposed replacement part and it was OK -> We may perform a round of sensitive testing tomorrow with the gross leak taped off and vent on Monday to replace the bad part.

Not to preempt Kyle's news but FYI.

ICS Part  SRI Hermetics 960140-1

Hermeticity "Certified" with SRI Certificate of Conformance # COC-04562

After installing 3 new T240 last week on ISI-BSC6, we faced off a centering issue on one of them after bolting the seismometer to stage 1. This morning, we unbolted the malfunctioning T240 and gently moved it. We put it back in place without attaching it to stage 1. This time, the centering process worked successfully. We measured powerspectra in the X-Y-Z directions. These spectra are in good agreements with the reference powerspectra.
We bolted the POD to stage 1 and re-measured powerspectra. The spectra still look good. However, this seismometer will be replaced as a precaution in the coming days.

The work today concentrated in BSC-4: bellows nozzles were vacuumed out, C-3 support tube covers were installed and secured, and dust barriers were installed. There was a short delay while we looked for a missing Viton rim that attaches to the aLIGO dust barriers. In the end, we punted and used a clean iLIGO dust barrier that was slightly too small with some extra Viton attached. 

Measured pump currents for different output power levels at the individual fiberbundle tip for the high power oscillator of the PSL.

The output power was measured with a thermopile 300 W external OEM Ophir power meter.

The H2SUSFMY M2 OSEMS were adjusted such that the flags were out of the LED beam path for an open light offset measurement could be taken. These measurements were performed earlier but with different results. The previous open-light cts were much lower than those measured today. The OSEMs were backed off the flags until the ADC cts levelled off.  Three of the OSEMs had open light counts above ~25000 cts with the "LR" OSEM only at ~22000 cts.  The OSEMs were then aligned such that the flags were occulting about half of the beam path.  The attached image is a snapshot of the new alignment.  The 'H2:SUS-FMY_M2_OSEMINF_*_OUT_DQ' now read around zero.

The same 'tdsavg' command was used to gather the average ADC cts over a 30-second time span. The signs of these values were flipped, and the values halved.  These are the new offsets in the 'H2:SUS-FMY_M2_OSEMINF_*_OFFSET' values.  The gains calculated by normalizing these results to 30000cts.

The new offsets are:
'H2:SUS-FMY_M2_OSEMINF_UL_OFFSET' = -12936 cts
'H2:SUS-FMY_M2_OSEMINF_LL_OFFSET' = -12827 cts
'H2:SUS-FMY_M2_OSEMINF_UR_OFFSET' = -12819 cts
'H2:SUS-FMY_M2_OSEMINF_LR_OFFSET' = -11181 cts

New gains:
'H2:SUS-FMY_M2_OSEMINF_UL_GAIN' = 1.16
'H2:SUS-FMY_M2_OSEMINF_LL_GAIN' = 1.169
'H2:SUS-FMY_M2_OSEMINF_UR_GAIN' = 1.17
'H2:SUS-FMY_M2_OSEMINF_LR_GAIN' = 1.342

Previous offsets:
'H2:SUS-FMY_M2_OSEMINF_UL_OFFSET' = -3697 cts
'H2:SUS-FMY_M2_OSEMINF_LL_OFFSET' = -12915 cts
'H2:SUS-FMY_M2_OSEMINF_UR_OFFSET' = -8545 cts
'H2:SUS-FMY_M2_OSEMINF_LR_OFFSET' = -11282 cts

Previous gains:
'H2:SUS-FMY_M2_OSEMINF_UL_GAIN' = 4.056
'H2:SUS-FMY_M2_OSEMINF_LL_GAIN' = 1.161
'H2:SUS-FMY_M2_OSEMINF_UR_GAIN' = 1.755
'H2:SUS-FMY_M2_OSEMINF_LR_GAIN' = 1.329

Had various impediments in getting leak testing equipment ready but finally got a working setup -> Noise too high to actually do any sensitive measurements at this time but I went ahead and sprayed some helium as a proof of concept dry run -> The one and only flange I tested turned out to be a 3 x 10-7 torr*L/sec leak!!!  Its going to be a long day tomorrow!!

J. O'Dell, J. Garcia

Continuing with the diagonalization of the FMY M1 OSEMs, mechanical adjustments to the FMY top mass (M1) were made to further decouple the "F1" and "SD" OSEMs from the Yaw DoF.  The same sine wave excitation at 1.4Hz was injected to the "H2:SUS-FMY_M1_TEST_Y_EXC" channel with a 100ct amplitude. The expected contributions to the "Yaw" transfer function should be the "F2" and "F3" OSEMs with desired isolation of the other OSEMs ("F1", "RT","LF", "SD") at ~30dB or less.

Initial measurements indicated the "F1" OSEM to be ~10dB isolated from Yaw, with the other OSEMs at ~30dB isolation. Our reasoning was the "F2" and "F3" OSEMs were not in line with the center-of-mass of M1, causing a slight Pitch that would manifest itself in the "F1" OSEM response.  To lower the COM of M1, a 300g mass was added to the top of M1.  The OSEMs were then realigned to center the flags and the first pdf is the same measurement with this configuration.  The "F1" response is roughly ~20dB lower than "F2" and "F3" and the "SD" response about ~17dB lower.

"fmy_osem_diag_yaw_add_mass_300g_f1align_111005.pdf"

This promising result encouraged us to add more mass to lower the COM further.  A 100g mass was then added to M1. At this time, it was noticed the flag of the M2 LL OSEM was twisted and possibly rubbing against the OSEM photodiode sensor and/or LED source.  The M2 LL OSEM housing was removed, and the subsequent measurement is displayed on the second pdf.  The "F1" isolation is now at ~25dB and the "SD" OSEM now at ~29dB.  

pdf #2 - "fmy_osem_diag_yaw_add_topmass_400g_f1alignm2llosemoff_111005.pdf"

The flag for the M2 LR OSEM was noticed to be twisted as well, and it's OSEM housing was removed.  The current configuration of the FMY is the M2 LL and LR OSEM housings are removed, there is now 400g added mass to the M1, and the M1 LF and RT flags are out of range of their respective OSEM beam paths due to the added mass.