Weekly Report for Week Ending August 16, 2001

The LIGO Executive Committee Agenda for Monday  August 20, 2001 will be:

 (Meeting time: 10:30 am Pacific Time)

Open meeting 10:30 - 11:30

1. Announcements
2. LSC Issues (Weiss)
3. Comments on Weekly Report
4. WBS 1 LIGO I Construction (Lindquist)
• Field Change Orders/Contingency Liens/Change Requests
5. WBS 2 LIGO Lab Operations
• Administration (Lindquist)
• Sites (Raab, Coles, Shoemaker, Sanders)
• Detector (Whitcomb, Coyne)
• Campus Research Facilities (Weinstein (40 Meter), Libbrecht (TNI), Zucker(LASTI))
• Data Analysis and Computing (Lazzarini)
6. WBS 3 and 4  Advanced R&D and LIGO II (Sanders)

Special Items:  MINORITY UNDERGRAD OUTREACH, LSC MEETING REPRISE

Special Announcements:

Weekly Report Highlights
 

LSC Issues (Weiss)

no report

LIGO I Construction/LIGO Laboratory Administration (Lindquist)

WBS 1.2 LIGO Operations--Administration

The list of current actions revised to reflect the status of open actions assigned through August 2, 2001 may be found at ACTION LIST.

From: Ed Chargois <chargois_e@ligo.caltech.edu>

• Nothing significant to report.

>From: Linda Turner - turner@ligo.caltech.edu>

Web pages for the DCC give simple how-to's for document numbering, easy access to the latest on-line documents, and search capabilities for the DCC database. Take a look. . .

ACCOMPLISHMENTS

• No report this week.  Linda is at Hanford for the LSC Meeting.

ACTIVITY

• most of my efforts for this period were geared toward handling/processing/printing/transferring of LSC documents from the LSC Meeting at Hanford.
• some progress was made on auditing of PSI drawings.

Press here to access the DOCUMENT CONTROL CENTER WEB PAGE.

From: Esther Cunningham <esther@ligo.caltech.edu>

Press here for ACCOUNTS PAYABLE HISTORY DATA.

From: "Brambila, Ruth" <Ruth.Brambila@caltech.edu>

• Completed new change orders on subcontracts to CSIRO, and Waveprecision (General Optics).  Awaiting acknowledgements of receipt of change orders.
• Added funds and extended performance periods through September 30, 2002 on blanket purchase orders to Newark Electronics, Pasadena Eye Medical, and Red Wing.
• Completed closing PO's through March 2001.  Prior to March 2001, there are only 11 purchase orders which remain open.  There were a few with nominal dollar amount encumbrances which have been submitted to Dorothy for a decision whether those funds should be released and the PO's closed or whether they should stay open for more activity.
• Payment requests submitted for goods and services which normally would be issued under a purchase order, the payment requests are now being processed and issued under a purchase order.
• The new subcontract to E.G.O. is still pending.

• Submitted Cost Transfers for costs charged to roll-up task instead of correct sub-task.
• Updated Visitor Program report for new visitors per information provided by Donna.
• Sent Finance a schedule of funding realignments required for R&D program.
• Prepared a revised calculation of projected underspend for Operations based on increased spending in July.
• Reviewed R&D report prepared by Cindy.
• Prepared comparison schedule of FTE's budgeted vs employees charged to Operations as of July.
• Sent out inquiries to managers re encumbrances in old Operations accounts to determine whether they need to be closed or transferred to the new accounts.

From: irena@ligo.caltech.edu (Irena Petrac)

• No report this week.  Attending LSC Meeting in Hanford.

• The installation of the laser safety system continues at Livingston with the cable pulling nearly complete.  There are still a number of action items remaining to be completed at Hanford before their system can be installed.

SUPPORT (Wood)

• Attended a training session on how to enter data for the Annual Salary increases.  It is a web-based application and much in line with how ORACLE wants it done.
• Had an on-going battle with the library over getting after hours access to Millikan.  Turns out, it was all a question of checking out books.  Yes, it is possible for LIGO contract employees to get into Millikan after hours.  This is quite distinct from getting into Millikan and checking out books---after hours.  If this makes no sense to you, it didn’t to me, either.
• Made a request for a pre-award PTA to be set up for Gary’s Management School account.  We’ll probably get it sometime next week.

Advanced LIGO (Frey)

Progress Period from 08.10 to 08.16

Accomplishments:

• Weekly Advanced LIGO Project Controls meeting not held this week due to schedule conflicts, LSC, and vacations.
• Advanced LIGO MRE Proposal (Highest Priority)
• Continuing the development of the Cost Estimate.
• Continue to pursue all other sub system schedules.
• Updated web site with latest schedule for meetings.
• The following is a summary of status by sub system:
1. COC - Work on action items per second review continues.
2. PSL - Work on action items per second review continues.  Next step is for Peter King to complete BOE and for management to scrub / determine funding sources.  Next meeting date has not been scheduled.
3. AOS - Finished revisions to the schedule, cost sheets and items.  Action items for others are still outstanding.  Second review is scheduled for August 20th at 1pm at LSCR.
4. IO - Continue work on cost sheet and cost item changes.  Second Review is scheduled for Friday August 24th at 9:35am at LSCR.
5. SUS - Continuation of second review is scheduled for Friday September 7th at 9am.  Work on action items per second review continues.
6. SEI - Efforts continue on action items.  Next review date has yet to be scheduled.
7. All other subsystems have yet to be scheduled for their first review.  These dates are pending per direction from Gary Sanders and Dennis Coyne.
• Continue to update the TNI Schedule and incorporate any changes.
• Nothing new to report.
• Continue to update the LASTI Schedule and incorporate any changes.
• Nothing new to report.
• Project Plan for the 40-Meter Lab Upgrade continues.
• Nothing new to report.
• Continue to test the Cost Book Tool.
• Continue to work with BK executing current action items.
• Finished work on BOE table and Detailed Task table.  Running tests on reports using AOS data.
• Mapping and formatting of OPS cost data for input on hold pending additional changes to budget data per NSF re-submit.
• Development of the Advanced LIGO Project Controls Guidebook continues.
• Project Web Site for posting schedule and progress related data continues to be updated with the latest and greatest.
• See http://www.ligo.caltech.edu/~tfrey/index.html

• Next weekly Advanced LIGO Project Controls meeting scheduled for Monday, August 20th at 1pm at Large SCR.  Focus of the meeting will be the AOS Second MRE Cost and Schedule Review.
• Advanced LIGO MRE Proposal (Highest Priority Task)
• Highest priority is the development of the Cost Estimate.
• Will continue to pursue all other sub system schedules.
• PSL - Continue to input data per comments from Dennis Coyne in preparation for next meeting TBD.
• Prepare for AOS second MRE review - cost reports and schedules.
• Finish input of changes to the IO cost sheets and schedule per comments of review meeting.
• Continue inputting changes to SUS and prepare for next meeting scheduled for September 7th.
• Continue inputting changes to SEI and prepare for next meeting TBD.
• Will follow up with Garilynn B. regarding status of COC cost and schedule.
• Will import cost data and complete schedule integration.
• Will Continue to update the TNI Schedule and incorporate any changes.
• Will update the plan with progress as of 08.17.01 and  post to site by the 21st.
• Will Continue to update the LASTI Schedule and incorporate any changes.
• Will update the plan with progress as of 08.17.01 and  post to site by the 21st.
• Will continue updating the 40 meter schedule and incorporate any changes.
• Will update the plan with progress as of 08.17.01 and  post to site by the 21st.
• Cost Book Tool development continues.  (Highest Priority Task)
• Will continue ops cost data input.
• Will continue to work with BK importing data and executing action items.
• Will continue the development of the Advanced LIGO Project Web Site.

Will continue the development of the Advanced LIGO Project Controls Guide Book.

WBS 1.4.1.2   Project Controls (LIGO Construction)

Gary and I met with the NSF on Wednesday, August 8, 2001.

• We should proceed with a request for a no-cost extension.  One letter will be sufficient, but should identify MRE and Operating funds separately.
• The NSF wants a separate budget form for each of the five years of the proposed Operations.  I will need a five year proposal from MIT to support this (at least the approved budget forms).  This proposal, to be submitted via FastLane, will have to be provided to the NSF before they can act on our request for FY 2002 funds.
• No formal response to the DCAA Audit Report is required.  A memo to OSR is the proposed course of action.

The following Change Requests have been submitted.  CR-010007 is new, submitted this week by Stan Whitcomb for reploishing and recoating the beamsplitter optic.
 

Press for the latest Contingency Needs Projection.

From: Kris Duncan <kris@ligo.caltech.edu>

• Continued working on the July 2001 monthly CSSR.  Calculating earned value for the Detector and LDAS groups.
• Continued with construction contract/work package close out.

• I have gathered all the information for the monthly reports on the Construction and Advanced R&D accounts for July 2001 and put them on the network. Since the Advanced R&D report has been put into a new format, I will no longer send out the details at a later date. Everything is put on the network at the same time.  Bookmarks have been setup to help you navigate.
• Florence Kaufman and I have decided to put all the reports into one place (for your convenience)...so they can be found at:


http://docuserv.ligo.caltech.edu/~fireport
 

• I received the MIT invoice for the month of July, 2001. As soon as I receive the TWONK Report (cost allocation) from MIT I will submit the data for payment.
• I attended a class on Discoverer and found it to be very informative.
• I continue to review the open encumbrances on the Construction and Advanced R&D accounts to see if the requested removals have been made. I will continue to review these accounts weekly until all encumbrances have been removed.  (Remember, I can only get these errors corrected if the Task Managers point them out to me).

From: Ed Jasnow <jasnow@ligo.caltech.edu>

• Ed Jasnow met in Livingston with the president of Brunt Construction, Michael Ragusa, to discuss progress on the Livingston Staging Building.  The building is approximately two months behind schedule.  The contractor indicated that he would finish by the contract completion schedule, which is now February 14, 2002, as a result of the addition of the elevator for the handicapped.  The progress of the contractor will be checked again in three months, which is halfway to the completion point.
• The final draft of the Invitation for Bid for the Hanford OSB East Building has been submitted by NTD Architects.  This IFB is being reviewed by Ed Jasnow and Otto Matherny.  It is scheduled to go to print on August 21, and be released on August 24.

Quality/Safety (Tyler)

No report this week.
 

LIGO Hanford Observatory (LHO) Operations (Raab)

no report

LIGO Livingston Observatory (LLO) Operations (Coles)

The cryo pumps at the vertex were regenerated this week and the RGA's are being prepped in anticipation of opening the gate valves down the arms for a quick "peek" while Stan is at LLO next week.

We have gotten a price from LSU for the router for our second T1 line. They should be out here next Tuesday to install a temporary router, which they will loan us until ours arrives.

Most of the SURF students have completed their summer projects and gave their final presentations to the LLO staff during the last week. Many of the staff are away this week on vacation, at the LSC meeting, or at professional training classes. A fuller report will be sent next week.

Detector/Technical Support (Whitcomb, Coyne)

See also the daily electronic logs for the installation and commissioning activities:
Hanford Detector Log
Livingston Detector Log

1.1 LHO INSTALLATION & COMMISSIONING

2km Commissioning

The master (Matt) remeasured the gain coefficients and normalizations for the lock acquisition code, and this seemed to give good performance: lock acuisition in about one minute typically, lock durations of ~ one hour, recycling build-up typically in the 15-20 range.  We didn't see any of the periods of poor locking (as observed during E5), but we didn't have as much time trying to lock as we had during E5 either.  Matt used the full interferometer (State 4) to remeasure the gain coefficients for the lock acquisition code; this is supposed to give the same values as the ones measured in states 2 and 3, and amazingly enough, it did!

4km Commissioning

The MC high frequency actuator is the VCO in the PSL system, so we began to carefully address the PSL system since it is tied to the MC system. A few things were noticed:
  i.  the PSL bandwidth was limited to ~300kHz instead of the designed 1 MHz;
  ii. the PSL error/control system was also breathing around 10kHz.

Measurements of the PSL electronics (alone) showed that the PC path was eating phase by 40 deg at 100kHz. An improvement in bandwidth for both PSL and MC systems could be achieved if this delay is decreased.

Furthermore, the breathing observed in the error/control signals for both the MC and PSL systems, also showed up in the 1/(1+OL) PSL measurements. If the 1/(1+OL) measurement is non-stationary, then the gain of the system is non-stationary. The symptoms seem to indicate that the crossover between the FAST and PC path changes over time, causing, at times, the system to go instable. When the control is instable, that's when you observe the rising broad peak in the error/control signals in the MC/PSL systems. Since in the 1/(1+OL) measurementthe UGF never changes despite this non-stationary behavior, then something non-stationary is happening in the FAST path of the PSL.

Once the PSL/MC situation was assesed, we proceeded in aligning the transmitted MC beam to the 4k PRM. At the moment, we have found the reflected beam off of RM, the reflected beam off of ITMX and ITMY, and we began observing Michelson fringes.
 

Suspension Tuning

1.2LLO INSTALLATION & COMMISSIONING

New MC Servo

PSL

2.0 OtherEngineering and Scientific Activities

2.1 Design/Analysis/Fab

Core Optics

Optical modeling

Suspension Design

IOO PERISCOPE

PSL

40 m PSL: The optical spectrum analyzer arrived, along with the 29 MHz Pockels cell used for locking the modecleaner.

Lee Cardenas

• PMC mode matching continue on.
• New NPRO S/N 259 received from Lightwave.   It will be tested soon
• (13) more super polished substrate received from Mindrum Precision Inc.
• The new pump unit and the RGA unit for the baking has been brought back from 40m. Lab.

• 80 MHz VCOs -- GEO/LHO spare: tested
• FS Servos -- GEO/LHO spare; tested
• PMC servo (LHO Spare) recently damaged @ the 40m. being repaired
• Frequency Reference Boards: GEO/LHO spare: in test
• RFPDs: GEO/LHOspare being built

Intensity Stabilization

• Schematics for the EPICS/Interface ISS servo are nearing completion. A design review is scheduled for Friday.

LSC

• Helped clarify some PSL related tests in the 40 meter lab
• Flavio continues to work on the timing system, the more he looks the more bizarre things get.
• Mohana has begun the fabrication of additional MC servo cards and is writing test procedures for this servo.

CDS/DAQ/ASC/LSC/Digital Suspensions

• Code for LVEA processors is ready.
• Completing end station software, which also requires modifications to the ASC software.  Test points are in the code; now adding excitation. Should be ready by Friday.
• Upgrade will require update of DAQS configuration file to include these ~340 additional excitation/test point channels.

• Parts have been shipped (though we may be short a few working pentek modules, but we can work around this for now.  Next shipment of pentek odules is due in three weeks.)
• Working on code additions to support DSC end station GDS (as noted above).

4) Assemble the 4k suspension data collection unit.
Since a whitening board to interface between coil driver monitors and DAQS was never specified, we would need to assemble a fair number of generic DAQ interface modules to connect the coil signals.  I have to check on how many we have available.

5) Run mid station DAQS with GDS arbitary waveform generator code to drive ICS115 DAC outputs:
Having some difficulties getting this to run in our test setup.  Appears though all communications to DAC are correct, but get no output voltages.  Lori will continue to work on solving the problems with this.
 

40 Meter Interferometer (Weinstein)

• PSL (Abbott R., Abbott, B., King, Ugolini, Vass):
• While taking a transfer function measurement of the PMC servo, we discovered that the large 62.6 kHz oscillation previously thought to be a resonance of the mirror PZT was actually a harmonic of an enormous 31.3 kHz resonance of unknown origin. Rich and Ben Abbott fashioned a simple notch filter tuned to this frequency with spectacular results. We now see 80 dB of gain at 10 Hz with a unity gain frequency of 3 kHz, and the PMC remained locked overnight for the first time.
• With our PMC now locking more robustly, we have measured 85% visibility and 65% transmission in the cavity.
• With Peter's assistance, SURF student Andrea deMichele has recalibrated the in-loop frequency noise and found a much more reasonable result, though we still cross above the LIGO specification at about 100 Hz.
• After Ben added a couple of wires to the PMC servo board, we are now reading all fast channels into our DAQ.
• We have received our new Tropel and all of the optics necessary to test the long-term stability and drift of the laser (QPDs, steering mirrors, etc). Mike Smith will help us setup this experiment, and the measurement will begin on Friday.
• Please be advised that the 40m PSL is now *always on*. Safety glasses are required at all times in the clean room.
• Vacuum Envelope (Vass, Ugolini):
• Steve has determined that our total leak plus outgassing rate is 2*10^-4 torr L/second, within a factor of two of the rate measured before the installation of the mode cleaner envelope.
• Steve installed a nipple for our new RGA, and has been measuring it's cleanliness with our old RGA to see if it needs to be baked (probably not).
• Dennis has finished the IOC chamber gate valve cabling, and is still ferreting out a problem with the ion pump control code.
• Optical Layout (Mike Smith): Mike has updated his main integrated facility drawing, and is satisfied with the current position of the PSL table. He has also moved the pickoff optical tables at the EV and SV to match the location where they were installed last week. He is currently finalizing drawings and parts lists for the ISC tables.
• Suspension Controllers (Abbott B.) Ben has finished the drawings of the two suspension controller racks sited along the east arm. Next are the two end racks, followed by a reannotation of Jay's connection and cabling diagrams.
• Cabling (Larry Jones): Larry has relaxed the flexibility requirement on our cabling, and has contacted the braiding company to assemble three twisted-pair samples, one with the original 48-gauge wire, one with thicker wire/fewer strands, and one with the teflon Cooner wire used in the Mark II 40m. Larry has also finished preliminary drawings of the cable clamps and requested a quote from Molding Solutions.
• PEM: Now that the appropriate cables and connectors have arrived, we plan to install our weather station and two GPS antennae on the roof on Friday. SURF student Victor Tsai has completed the EPICS code and screens to readout the weather information. We are still unable to communicate with STACIS via our VME processor, and have contacted the manufacturer for assistance.
• DAQ: Two of the disks in our 500GB RAID array have failed in the last week. Rolf has taught us how to replace a bad disk and has ordered five more spares. Data taking has not been interrupted.
• SURF: Our students are finishing their papers, and arguing passionately over the exact distance between the LIGO sites.

Thermal Noise Interferometer (Libbrecht)

This week we encountered our first setback in noise reduction. After much
initial success reducing laser frequency noise by increasing the gain of
the mode cleaner, we implemented additional gain boosts at low frequencies
and saw the noise increase.  We are currently working on resolving this
problem.  Many thanks to Rick Karwoski and Sander Liu at CDS for loaning us
a VCO!

LASTI (Zucker)

LASTI (Harry, Mason, Mason, MacInnis, Miller, Mittleman, Ottaway,
Rollins, Shoemaker, Zucker):
 

This week we concentrated on preparing for the LASTI review at the
LSC meeting.  The baseline optical layout, interferometer parameter
choices and associated noise budget, PSL and
infrastructure progress, and near-term test plan options were among the
highlighted items.  Ken also showed a conceptual design for fitting
hydraulic seismic pre-isolators under the HAM13 stack. Overall
the review was very productive, and the committee provided useful guidance
through questions and comments. Presentation graphics will shortly
be available under LIGO-G010269-00; Peter Saulson, committee chair, will
assemble and submit a formal report in a week or so.
 

Meanwhile in the lab Myron and Fred continued preparing lab infrastructure
and parts for cleaning, bakeout, assembly and balancing
of SOS suspensions for the short
cavity test. We've tentatively arranged a visit from Betsy Weaver in
mid-September (after her honeymoon!) to train us in the SOS preparation
and balancing process.

Data Analysis and Computing (Lazzarini)

_______________
 

E2E MODELLING:
_______________
 

Mode Mismatch
-------------
(Biplab)
 (i) Checked that the effects of mode-mismatch simulated in full LIGO model
     including recycling summation cavity match well with analytical derivation.
 (ii) MIT's FFT: With help from Bill Kells sorted out several issues about FFT runs.
     Started running FFT code and comparing results with full LIGO e2e runs.
     Results of comparison at this initial stage are encouraging but I see need
     of more detailed understanding of how FFT code runs corresponding to a
     same-parameter run in e2e or vice versa in order to sort out differences.
 

CVS Archive
------------
(Ed Maros) Moved the CVS archive for the e2e work onto ldas-sw.
    Gave presentation on how to use the CVS archive in its new location.
 

Alfi
----
(Bruce) Continuing implementation of Alfi box and primitive file parser for Alfi5.
 

(Melody)
- Discussed Java coding conventions with Bruce. Currently modifying the
  existing code to comply with the conventions.
- Reorganizing the Java code packages. The code should be checked back in by
  COB Thursday.
 

Mechanical simulation work (from July upto last week)
-----------------------------------------------------
(Virginio) This is my report with just the main activities about the mechanical
 simulation. I apologize for including in a single weekly report the activity
 of the entire month of July (almost).
 

 - Three-dimensional LIGO I Suspension simulation is ready to be plugged into
 e2e. The simulation includes a realistic topology of the actuators and sensors
 also. Geometrical suspension asymmetries can be easily introduced. The cross
 check with an experimental spectrum using a set of OSEMs suspension has been
 successfully done with an agreement of about 2%. To obtain a better
 characterization of the suspension local controls, a set of new measurements
 needs to be done.
 

 - A simple way to introduce the Hytec models of the BSC stack is under study.
 At first look it seems necessary to introduce some new functionalities to MSE
 to allow the possibility to merge two separate state space representations.
 

 - Some tests have been done to introduce the suspension violin modes also.
 

Boston week:  (Assembly/Installation)
 

 Worked mainly with Calum Torrie, Norna Robertson and Rich Mittleman to assemble
 the second quadruple pendulum chain. Thanks the work I made during the weekend
 I was able to run some measurements to characterize one chain of the suspension.
 I worked essentially on the reacting chain because we didn't have any OSEM really
 aligned yet.
 

 - Mounted three LVDTs which allowed to measure the longitudinal transfer
 functions from the "new" mass to the "upper" mass and to the "middle" mass,
 using the upper most stage as mechanical compliance. The sensor parts were
 attached to the suspension masses by using a pretty good double sided scotch tape.
 

 - Mounted also another coil actuator (an old and bigger OSEM) between the two
 upper masses acting against the reacting chain but I was not able to make it
 work using the control box inputs (pin out incompatibilities).
 

Measurements:
 

 I took several sensors spectral densities hoping to be able to make some
 frequency mode characterization. I did not have time to do a more accurate
 system identification.
 

 I measure the t.f. which seems to be reasonably good.
 Those measurements are affected by a large cross coupling with all the DOF
 because the chain was not properly aligned yet and because of the
 orientation of the sensors and the actuators. The actuation was done using
 the control box longitudinal input.
 

Observations:
 

 The LVDTs seem to work fine and particularly good for t.f. measurement
 (good sensitivity and large dynamic range)
 

 It is clear that it is not easy to measure the t.f. using the OSEMs
 because of the small dynamic range of the sensor and because of the small
 clearance between the magnets and the coils. All the coils need to be
 quite well aligned to be able to shake enough the mass. This alignment
 doesn't seem to be critical for the damping of the suspension.
 

 I didn't have time to measure any t.f useful for the study of the performance
 of the active damping. The LVDT can probably be used to verify the efficiency
 of the damping for the lower stages.
 

 The most important result is that the results obtained show the possibility
 to measure the transfer function of the entire chain (4 stages) using the
 LVDTs as sensors.
 

Last week
 

 Worked with Giancarlo Cella to fix some library bugs. The following ones
 seem to be solved:
 

 - The phase lag going through the mechanical resonances is now properly
 computed when a viscous damping is plugged into the simulation.
 

 - The simulation bug on the violin modes of a wire under tension (without
 the flexural contribution) seems to be solved. The Library now works
 properly to compute the right frequency spectrum of a simple suspension made
 of a wire and a bob. This approximation works reasonably well (applicable)
 when the wire tension is high compared the flexural restoring force.
 Comparison with a real experimental data gives a good result less than 10%
 of discrepancy in the frequency spectrum. Next step which is under progress
 also is to check the violin mode simulation inside a more complex system.
 

 - Wrote a simple program to check the class which implements the flat Blade
 (a la Virgo) to finally have the description of all the main internal modes
 of the advance LIGO suspension.
 

LIGO II/Advanced R&D (Sanders)

From Mark Barton:
I also did more reverse-engineering of the Glasgow Matlab model of the Advanced LIGO reference design

From Rich Abbott
Worked on the specifications and implementation for the next generation capacitance position sensors with the vendor

Received the new voice coil actuators from LLO and have begun the process of characterization in order to best design or buy a driver.

From: GariLynn Billingsley <Billingsley_G@ligo.caltech.edu>
Bob Oreb of CSIRO visited Caltech on the 15th.  Bob reports that sub Angstrom measurements of the microroughness of polished sapphire have been obtained while experimenting with different polishing approaches.

From: HELENA ARMENDULA
Silicate bonding
Recent tests on silica/sapphire bonds show that, when
the bonded substrates are baked at 120 degrees C,
there is a considerable amount of stress on the silica
glass causing it to brake in most cases.
We investigated bonds that were baked shortly after
manufactured as well as 60 day old bonds with the same
results.
Strees is not observed on un-baked bonds.

For additional information about this report, contact sanders@ligo.caltech.edu