Weekly Report for Week Ending April 25, 2002

The LIGO Executive Committee Agenda for Monday  April 29, 2002 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:  Continue last week's CCB meeting

Special Announcements:

Starting with this  weekly report (4/24), reports of  commissioning work will be included in the Hanford and Livingston reports as appropriate.
 

Weekly Report Highlights
 

LSC Issues (Weiss)

no report

LIGO I Construction/LIGO Laboratory Administration (Lindquist)

LIGO Operations--Administration

The focus of the site teleconference held on Thursday, April 25, 2002 was Outreach.  Mark Coles and Fred Raab made presentations.

• Louisiana ranks near the bottom of the nation for scores on tests for basic skills and high in need for improved science education.
• Majority of LA high school physics teachers are not certified in physics.
• Having someone with formal education credentials may be helpful in future interactions with NSF/EHR.
• At Hanford, Gladstone High School program has been successful.  Efforts have included establishing a database of microseism activity and correlating it with ocean wave heights.
• Outreach track record during early operations praised.  Extremely successful REU program involving on the order of 20 students per year.

Do not seem to be able to get throught he front door at NSF for additional support.

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

• Assisted the Optical Engineer (G. Billingsley) with packing and shipping of two (2) Glass Optics for testing, serial numbers S150MA and S75M001, to Massachusetts Institute of Technology,  attn: P. Fritschel.  Receipt was confirmed.  Account Number P157753.
• Assisted the Detector Group (H.Armandula) with packing and shipping of nine (9) Optic Substrates, serial  numbers 8101, 8105, 8136, 814(?), 8166, 8172, 8214, 8220, and 8232 to MLD Technologies, Eugene, OR,  attn: D. Curry.  Receipt was confirmed.  Account Number P157746.
• Assisted the Seismic Isolation Group (L.Matone) with the shipment of a carton to dSpace Inc, Novi, MI,  attn: M. Moshree.  Account  Number P157718.
• Assisted the General Computing Group (L. Wallace) with palletizing and shipping of two (2) computers, SUN BLADE 1000/Keyboards, four (4) Color Flat Screen 18.1" Monitors, and four (4) Graphic Cards to Massachusetts Institute of Technology, attn: K. Bayer. Account Number P204324.
• Provided Disposition Instruction to Massachusetts Institute of Technology Property Office (John Erkkila) to dispose locally of five (5) pieces of Obsolete and Uneconomically repairable equipment: two (2) Sun Micro Computer, SNs 833E0210, 835E1245, one (1) SUN Controller no SN, one (1) SUN Tape Drive SN: 835E0106, and one (1) SUN Disk Storage SN: 835E0529.

>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

• Continued to work on the upcoming rollout of the new LIGO procedure and policy manual.
• Created small DCC "quick reference" cards for orientation of new staff.
• Continued to work with Ryan and Dave on the press kit being assembled.  Worked with Cleveland on scanning the many news clippings collected during the past three years.  The DCC numbers assigned to each still need to be imbedded on the document.

ACTIVITY

• Processed numerous electronic documents.
• In the process of scanning a 20+ page document (color transparency) to make it available for web posting.
• Progress continues on conversion of old charge account files to electronic form.

 

04/25/02	Packages	Faxes
In	40	35
Out	7	18

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

Press here for ACCOUNTS PAYABLE HISTORY DATA .

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

• Completed change order # 10 to Thomas Staffing, change order # 10 to Promec, and change order # 1 to Frequency Devices.  Working on Howden Buffalo and Siemens.

• Identified several purchases where incorrect Expenditure Types were used for part of the purchase thereby resulting in unwarranted Indirect Charges and requested that corrections be made.
• Prepared PTA Set-Up Form for new capital account for Fine Actuation System at Livingston.
• Modified monthly operations report to include new tasks for Fine Actuation System and the Control Rooms.
• Worked on reconciling items recorded as Equipment to Equipment Data Base.

 
• Financial reports can be found at: http://docuserv.ligo.caltech.edu/~fireport

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

• Nothing significant to report.

CONSTRUCTION:

Construction on the LLO Staging Building continues to creep towards the end.  A change order was issued for modifications to the men's room in accordance with the findings of the fire marshal.  This extends the contract end date to May 3, 2002.  Additionally, agreement was reached on the conduct of the test for the removal and replacement of the bridge between the new and existing buildings.

Siding for the LHO OSB East Building is scheduled to be delivered on April 29.  The contractor has been working around this late delivery, and is maintaining the contract schedule.

OPERATIONS:

An announcement was made concerning the orientation seminar for foreign nationals on the LIGO staff scheduled for Friday, May 3.  This seminar will be conducted by Ms. Marjory Gooding, Director of Caltech's International Scholars Office.  The Hanford and Livingston sites will be linked by video conference.

SUPPORT (Baldon, Torres, Lloyd, Tischler)

• Processed the paper work for twenty-eight (28) new/revised trips, and there are eighteen (18) trips in various stages of completion before ticketing can be done and paper work completed (mostly SURF 2002 students).
• Completed six (6) Expense Reports, and there are nineteen (19 reports yet to be done.
• Reconciled zero (0) P-Card items this week since it was month-end and no charges were posted as yet.
• Started working on the LIGO/REU/SURF Program with Dr. Libbrecht.  Thirty (30) students have responded to my initial inquiry for travel and twenty-nine(29) have been completed at this time, with eleven (11) still being worked on, and four (4) still not responding to my inquiries.
• Worked on the preparation and distribution of the Travel/Vacation Itinerary for April 22, 2002.  Performed normal recording and filing associated with Travel and Reimbursement.  Also performed miscellaneous duties as requested by various members of  the LIGO Project here at Caltech as well as from members of the staffs of each of the two (2) sites.
• I continue to do MIT's travel to the sites for installation activities and also to assist them wherever possible.

• Esther and I processed a little over 40  invoices for payment this reporting period. For the total number of incoming invoices received for this period see "Cost Schedule Control Systems" report by Esther Cunningham. Tracked and followed up on various invoice problems and reviewed and recorded payments processed by Esther the week of April 8.
• Processed the usual requisitions and change orders.
• Continue to monitor contract and blanket order encumbrance and notify task managers when supplements are needed.
• Jim continues with data entry in the LIGO database and helping out in the DCC.

• Formatted incoming report from Syracuse University, submitted it to the DCC.  Posted the report on the small web page for review along with the Syracuse research plan.  Scanned Attachment 1 from CRRI, submitted it to the DCC.
• Chased the delayed order for eye wear replacement shields from Lase-R Shield.  At least part of the order arrived, the other part to arrive next week.
• Over five days tracked a FedEx package (cold packaging required) from Anaheim to Pisa, Italy.  Product arrived in good condition.  Helped prepare a requisition for special materials.  Checking with vendor to ensure they received the order, then to get status on ship date.
• Updated site trips.  Placed several Pcard orders.  Stored office supplied obtained for the 2nd and 3rd floor of Bridge.
• Changes to LIGO roster this week: postdoc Osamu Miyakawa, and Ops Specialist at LLO, Katrina Carter.

• Shameless promotion of Cinco de Mayo celebration.
• Have most templates and will begin formatting a standard template for each one, consistent with one another
• Group photo scheduled
• Info gathering SURF/LIGO orientation, this in conjunction with GoF [refers to "gang of five," which is tasked with preparation of package for new employees; actually more than five people involved at this time -pel]
• Info gathering for press kit folder and brochure design.

Advanced LIGO (Frey)

Progress Period from 04.19 to 04.25

Accomplishments:

• Weekly Advanced LIGO Project Controls meeting was not held this week.  Next meeting date has not been scheduled.
• Commissioning Calendar:
• Met with and worked with ITS, and received an account to setup a calendar using the Corporate Time application.
• Also used the Calcium Calendar product to set up a calendar.
• You can view the differenced between the two products at http://www.ligo.caltech.edu/~tfrey/Calendars.htm
• Larry is in the process of procuring the Calcium product per comments received to date.
• Continued to work with Primavera regarding an outstanding technical issue and received a program patch that I am now using and testing.
• Advanced LIGO MRE Proposal (Highest Priority)
• Continuing the development of the Cost Estimate.
• Continue to pursue all other sub system schedules.  Continue to review all subsystem schedules and incorporating new target dates per DCC Doc. No. LIGO-M020121-A by Dennis Coyne.
• Updated web site with latest data.
• The following is a summary of status by sub system:
• COC - Work on action items per second review continues.  Next meeting date has not been scheduled.
• PSL - Finished inputting changes to the cost book and schedule.  Next meeting date has not been scheduled.
• AOS - Work on action items continues.  Inputting / reviewing data provided by David S.  Next meeting date has not been scheduled.
• IO -  Work on action items continues.  Next meeting date has not been scheduled.
• SUS - Working with SUS group to incorporate current comments.  Cannot get an updated schedule and we know for a fact that no progress has been achieved on the electronics front (10 Month Planned Cycle per Prototype).  Executing outstanding action items and preparing revised meeting minutes.
• SEI - Work on action items continues.  Next meeting date has not been scheduled.
• ISC - Continue to review data.
• 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.
• Cost Book Tool.
• ROSTER DATABASE:
• Continue work on my action items providing BK with needed data.
• Attended gang of 5 meeting this week.
• COST BOOK DATABASE:
• Nothing new to report.
• DCAA - Work continues on the incurred cost audit.
• Nothing new to report  (All Quiet on the Western Front).
• 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 to be scheduled.  Per Gary, we will be scheduling a meeting soon.
• Continue effort getting the web based calendar system up and running for the commissioning group.
• 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 - Will complete estimate and schedule changes.
• AOS - Continue inputting changes to and prepare for next meeting TBD. (New data from David to be input).
• IO - Continue inputting changes to and prepare for next meeting TBD.
• SUS - Continue inputting changes to and prepare for next meeting TBD.
• Will update the plan when data is made available.
• SEI - Continue inputting changes and prepare for next meeting TBD.
• COC - Work on action items by Garilynn continues.  Anticipate schedule changes prior to next meeting TBD.
• ISC - Finish review of data.  Input data and change WBS as requested.
• Will issue updated meeting minutes for every subsystem as action items from most recent review are completed.
• Will Continue to update the TNI Schedule and incorporate any changes.
• Will update the plan with progress as of 05.03.02 and  post to site by the 7th.
• Will Continue to update the LASTI Schedule and incorporate any changes.
• Will update the plan with progress as of 05.03.02 and  post to site by the 7th.
• Will continue updating the 40 meter schedule and incorporate any changes.
• Will update the plan with progress as of 05.03.02 and  post to site by the 7th.
• Roster Database
• Will continue to work with BK and executing action items.
Cost Book Tool development continues.  (Highest Priority Task)
• Mapping and formatting of OPS cost data for input will now continue with co-operative agreement approved.
• Will continue to work with BK executing action items.
• Will continue to provide support to PL for DCAA audit(s).
• Will continue the development of the Advanced LIGO Project Web Site.
• Will continue the development of the Advanced LIGO Project Controls Guide Book.

A draft of the quarterly progress report for the end of February has been distributed for comment.  Have received some comments.  Expecting additional comments early next week.

A LIGO Change Control Board was held on Manday, April 22, 2002.  The following change requests were approved:
 

The following additional change requests have been submitted:
 

We were unable to complete the discussions concerning CR-020006 during the time scheduled for the CCB meeting April 22.  Discussion will resume Monday, April 29, 2002.

Press for the latest Contingency Needs Projection.

From: Cindy Akutagawa <cindy@ligo.caltech.edu>

• Various personnel/payroll /HR related work.

Quality/Safety (Tyler)

• The Gang of Five plus 4 (GOF+4), has nearly completed their task of creating for LIGO, personnel processing checklists and a "LIGO Policies Manual" (LIGO-M020196).
• The GOF+4 effort will also provide a LIGO information web page to assist LIGO staff, students and visitors with a quick and easy method to learn about LIGO requirements, procedures, process travelers, templates, etc.
• The GOF+4 is planning to have the policy manual and web page "on-line" by mid May.
• The personnel processing checklists are already in use.

LIGO Hanford Observatory (LHO) and Interferometer Operations (Raab)

This week's submittal now accounts for commissioning activities at the lab.
We welcome this change, since there really is no other reason for having a
lab here, except for commissioning and science runs.Summary of Commissioning Activities at LIGO Hanford Observatory (compiled by F. Raab)
-------------------------------------------------------------------------------------
(see elog for details - if it's not in the elog, it didn't happen...)
 

This was a very frustrating week, with two sickly interferometers refusing to lock most of the time. By 4/25, we had gotten the 2k back to reasonable behavior but the 4k was in need of further nursing. Thanks to visitors Rolf Bork, David Shoemaker, Peter Fritschel, Greg Harry, David Ottoway and Bill Kells for all their help and guidance. John Zweizig and Steve Penn have arrived to help Daniel get DMT matters in hand.

Rolf and Dave Barker installed new LSC hardware and software on the 2k to cure a number of problems and add capability. An important new feature is the ability to add more filtering. This will help with noise investigations at high frequency, where we know we are dark-noise limited (and where we have seen hints of additional noise still remaining). Previously Daniel had shown that raising the light level improved the noise, but lowered the robustness of locking. The poor robustness was guessed to be due to insufficient gain to suppress rms length fluctuations in LSC, but we were out of knobs to turn. Now we have better ability to tailor the loops. Rolf also loaded new LSC and DSC software onto the 4k to improve dynamic range and test-point availability.

David Shoemaker worked on shaker/accelerometer measurements of relative motion between the tops of the support piers and the BSC and HAM vacuum chambers. The measured transfer functions will be used in support of pre-isolator work and a possible scheme to do feedforward suppression of stack peaks was discussed. The transfer functions looked workable for a digital servo controller.

Greg Harry, David Ottaway and Bill Butler pursued measurements of test-mass Qs for refining thermal noise models. This came at an excellent time since the interferometer locking was problematical on both machines. One crew could concentrate trying to debug locking one machine, while Q measurements - which require only a single Fabry-Perot to lock - could proceed simultaneously. At least someone could report progress at the daily commissioning meetings! The beam jitter out of the mode cleaner was also checked by Ottaway & co. and given a clean bill of health.

Peter Fritschel and Bill Kells worked with resident staff to solve the locking problems on both interferometers. Eventually, we obtained a consistent (and maybe even true) story to explain locking difficulties on the 2k; mostly electronics problems (blown stuff) in the ETMx coil driver. Before Rolf's software changes, it was the ETMx LR coil, afterwards a railed side OSEM. Upon getting these fixed, 2k was back to its old form.

We were less successful with the 4k interferometer, but it received a thorough check out. Overall the main symptom is that there are periods when it takes a long time (i.e. a good part of a day) to lock and other periods when lock occurs rather easily (within 5-10 minutes). Once locked, the interferometer apprears to hold rather well and a few several-hour locks were recorded when people were sleeping. Unfortunately, the program for the week, engaging dewhitening filters and working on the common mode servo, had a high probability of destroying lock again and again until the servos are well-tuned. Engagement of the 4k dewhitening filters typically caused a break of lock after a few seconds. It was felt that this might be due to the large frequency noise on the light in the absence of the common-mode servo, so we postponed further work on this to implement the common-mode servo. However the locking difficulties gave a dismal duty cycle for common-mode work so we eventually focused  on the locking difficulties. A problem noted early on, which probably hurt the common-mode work and might have been implicated in locking, was that the 4k was using an old rev' of the MC servo. We brought the system up to spec and then continued to work on locking. The change did not appear to help lock acquisition. The prime suspect of these investigations is now a range problem in actuation force available in the end stations. As noted by Peter, the 4k has 1/2 the range of the 2k, while its drive requirement is 1-2 times greater (the higher number corresponding to a frequency-noise limited regime). Peter has recommended, and we are preparing to implement, an extension of actuation force in end stations.

In other work, Doug Cook calibrated the optical levers and Peter and Fred developed independent (and agreeing!) calibrations of 4k OSEM channels, one based on Doug's optical lever calibrations and one based on Landry's interferometer calibration work. In the process it was noted that ratios of pendulum to 1st stack resonance peaks varied greatly from chamber to chamber. The BS, ITMs and MC mirrors had their damping gains reset to obtain uniform damping (Q of 10). Peter used the calibrated channels to check the position-to-angle  coupling for the 4k using the force/angle compensation filters. A coupling of 0.3 rad/m is typical and acceptable. Peter also made a calibrated measurement of angular fluctuations for the 4k ITMy. Work began on the 4k tidal common-mode servo, as Hugh Radkins began frequency response measurements of the PSL tidal actuator.

The week ended with yet another spontaneous alignment change in the 4k input optics (damn that MMT2!) and potential evidence for a parasitic interference path in the 4k interferometer was also under investigation. We also continue to accumulate anecdotal evidence that a small misalignment of the 4k mirrors can aid lock acquisition.

Other News
----------

Construction work continues on the new building at a rapid clip, but the lack of any siding delivery is making Otto nervous. Delivery is scheduled for early the week of April 29, but we'll believe it when we see it.

There was a problem with housing SURF students this summer, created when PNNL notified us that they would not be able to accomodate our more than one month old request for rooms for the students. Jill has moved very quickly to secure an alternate source of housing, while also keeping an apartment open for commissioning visitors. Good work, Jill!

LIGO Livingston Observatory (LLO) and Interferometer Operations (Coles)

Interferometer Commissioning:  The barrier of 2 x 10^-15 m/sqrt(Hz) at 100Hz was crossed this week. The concurrence of improved (but not final) operation of the common mode servo, the ability to engage all the de-whitening filters and reduction in the f > 80 Hz noise from the angular damping servo of the recycling mirror has improved the performance in the 100 to 300 Hz band. The remaining noise correlates with frequency fluctuations. The noise from the motions of the recycling mirror is not yet understood. It is a factor of 100 larger than had been expected by naive reasoning.Several possibilities that had been suggested as source of the noise in the 100 Hz region were rejected. The possibility that the noise at 100 Hz is due to sidelobes from the windowing of the data prior to Fourier transformation was eliminated as also was the possibility that the noise was due to non-Gaussian transients in the data.

Software has been developed, usable in the control room, to make time domain studies of the signals. A histograms of bandpass limited signals can now be made of many of the interferometer and PEM signals. A user friendly program is being tested to make time-frequency vs amplitude plots of the data. The laser glitches seen during E7 are being analysed with these new programs. A problem with glitching in the PSL PMC feedback was traced to a faulty 5V regulator and fixed. Glitching behaviour was monitored in the laser intensity, but no cause of the glitching has yet been found.

The anti-symmetric wavefront sensor has been incorporated in a closed loop and with the tidal servo together has held the recycled interferometer at maximum power for several hours. The symmetric wavefront sensor has developed useful signals.

CDS: Setup scripts to log CDS access activity on london for both ssh and to web pages. Created epics database and medm screen for testing and noise hunting xycom 220 boards. Ashfaq Khan visiting LLO this week. Gave him a tour of LLO and talked to him about the CDS system. Working on getting the a test-stand setup for the Penteks. Testing a code I wrote to run the penteks and log data. Downloaded and modified Tidal servo medm screens and databases from Hanford. Scripts for the Mode Cleaner Mixer Offset servo was written and installed. (Chethan)

LDAS: Helping Ed Daw to add new features to his slope DSO by the May 6-9 bursts group meeting. Getting up to speed in writing search codes for LDAS. (Igor)

Laser Safety: Working closely with the installer to correct the logical bugs that are coming to light as we proof test the system. Tomorrow Gerry and I will host an all-hands meeting to explain the full system operation and answer people's questions. Viewgraphs being prepared and will be placed in the DCC.

External Pre-Isolator: Received the full drawing package from Stanford, and am beginning to learn the solids modeling software in which it was created. (Jonathan Kern)
 

Detector/Technical Support (Whitcomb, Coyne)

40 Meter Interferometer (Weinstein)

• Suspension Controller front end software (Jay Heefner, Rolf Bork, Alex Ivanov, etc):
• Jay reports that the newly re-written SUS FE software for the H4K input crate is running and under test at Wilson House (using VME equipment on loan from the 40m). As soon as it is certified (next week?), minor mods will be made to make it work at the 40m.
• One challenge is that at H4K, there are some 2180 filters required, each up to 8th order, and operating at 2048 Hz; the Pentium is barely up to the task. At the 40m, we don't have suspended MMT or steering mirrors, so the Pentium should be able to manage our 8 vertex-area suspensions with time to spare.
• The 40m input mode cleaner will have digital alignment control, which does not yet exist at the sites. Jay believes that suitable modifications to the core optics ASC software should be straightforward for the 40m MC.
• Suspension Controllers & other CDS (Ben Abbott):
• The 1X2 rack has been moved to 1Y3 1/2 (1Y10), and Tom from the electric shop is running power to it. It will be used for ISC (read-in of sensing photodiodes).
• The ISS DC photodiode pcb file has gone to the boardhouse and should be here by Monday.
• Bob has finished wiring the power to 1Y2 (input mode cleaner length and alignment control), and I will test that, and start on the internal wiring tomorrow, with Bob.
• I have made 5 eurocard slot testers which will be enough to test all of the different types of eurocard wiring quickly and acurately.
• I have to mail back yet another failed IBM RAID disk. All failed disks have come from the first batch; most of these first batch disks have failed. A database will be maintained, to see if any of the replacement disks are also failing.
• Dennis and Ben continue to populate the suspension controller front end rack (1Y5) and input mode cleaner control rack (1Y2) with equipment as it becomes available; the job is approaching completion.
• Jay and Ben will assemble a Test Plan document to fully test the EPICS controls for 1Y5 and 1Y2.
• Optical Layout (Smith):
• Mike has delivered the latest drawings and spreadsheets detailing every part that goes into the optical sensing paths for the IO Diagnostics, IMC_R and IMC_T. Almost all the parts are in hand, and the remainder are on order, and due in the next week or 2. Now he's off getting married, honeymooning in France, and visiting VIRGO. Back in 6 weeks. Have a good time, Mike!
• We will begin assembling the optical sensing paths for the IO Diagnostics, IMC_R and IMC_T as soon as the optical table enclosures are available (next week).
• Mike had taken out the quad photodiodes from the IMC_R and IMC_T sensing path drawings; when he gats back he'll put them back in.
• Mike designed a special mount for a small (8mm) lens needed for one optical path, and plans on designing a more rigid mount for the QPDs.
• Optics (Billingsley, Armandula):
• Helena has inspected our BS01, BS02, PRM01, PRM02, PRM03, SRM01, SRM02 optics which have been recently been received from polishing at CSIRO. SRM01 has a very small scratch (3 mm long x 0.3 mm thick) within the central 10mm area.
• Helena is checking radius of curvature.
• Helena is revising with REO the coating quote.
• Suspensions (Romie): Bartie Rivera from LHO is sending a box with the last alum. and stainless baked parts for the 40m test mass suspensions. They should be delivered to Receiving tomorrow. They are addressed to Steve, so Receiving shall probably call for delivery information. The travelers are not in the box; he'll send them to me.
• Facilities and vacuum envelope (Vass):
• Larry reports that the optical table enclosure for the AP table is in the shop and should be ready next week. Small beam tubes from the vacuum chamber to the AP table, thence to the PSL table, thence to the SP table, are in the works and also should be ready soon.
• The 8" adjustable bellows on our 13 meter mode cleaner beam tube has one or more bent rods. Larry is not sure how this could have happened. He is having the shop make stiffener sleeves to put on the rods.
• Camera mounts are in the shop and should be ready in 2 weeks.
• Dennis is diagnosing problems with our STACIS system and the readout of the STACIS controllers.
• The Caltech AC guys tell us that they will deliver an estimate for the work required to improving the AC in our new control room, by May 6.
• Steve is replacing our two turbopumps with new ones that work with dry scroll forepumps. He's also replacing our old CC gauges with new ones.
• South Annex Bake Ovens (Taylor, Cardenas):
• All the bake ovens # D, E, (large oven) B and C (small ovens) and are up and ready to be used. The new large bake oven # F is not ready yet.
• Bake oven # E was used to bake the optical port flanges last weekend, and this weekend the BK7 optical port windows themselves will be baked. Thanks to Helena for showing Bob Taylor how to clean and prepare the optical port windows.

Dynamic Light Control in-vacuum mirror mounts are being prepared for baking.

Sander Liu:
Anti-Alias Filter Chassis - Delivered three LEMO version units to 40M this week

Thermal Noise Interferometer (Libbrecht)

 This week we made substantial gains in the sensitivity of the North Arm
 Cavity. Careful inspection of several of the components in each arm
 cavity servo revealed that the North Arm Cavity's photodetector was not
 tuned to 14.75MHz, but rather to 24.9MHz. With the help of Ben Abbot at
 CDS, we replaced the NAC photodetector with one tuned to the correct
 frequency, and we observed the equivalent NAC length noise come down by
 about a factor of three in our region of interest.

 This brings us closer to achieving our goal of comparable sensitivities
 in both arms, but we are not there yet. The noise in NAC is still
 approximately a factor of 3 greater than SAC's, and it does not display
 a clear f^-0.5 spectrum in any region, as does SAC. (See figure below.)

 We are currently continuing our noise hunt in the North Arm Cavity, and
 we are building a second set of notch filters so that we can lock both
 arms simultaneously.

LASTI (Zucker)

no report

Data Analysis and Computing (Lazzarini)

Simulation and Modeling (Bhawal)
E2E Physics meeting
------------------------
We discussed the relative importance and ways of inclusion of various noise sources
and their coupling mechanisms in LIGO I model keeping the forthcoming Science runs
in mind. These noises and coupling mechanisms are summarized below in Matt's report
(additions/suggestions are welcome)

LIGO I simulation system
--------------------------
(Matt)
Characterized/debugged optics and LSC sensing chain for SimLIGO.
Gathered LHO4k optical parameters into E2E format.  Made preliminary
list of noise sources and couplings to be addressed in simulation

---- Noise Sources
Seismic -> 1, 4d
Frequency -> 4
Digital Electronics -> 6
Analog Electronics -> 5, 7
Shot -> 5a
Thermal -> 3
Intensity -> 4

---- Couplings Mechanisms
1) Stack -> 2a
2) Pendulum -> 3
   a) suspension point
   b) actuators
   c) wire resonances
   d) test mass internal modes
3) Mirror Position -> 4
4) IFO
   a) simple optical asymmetries (R, T, L, ROC)
   b) non-horizontal geometry (wedge angles, earth's curvature)
   c) phase maps
   d) scattering
5) Sensing Chain -> 6
   a) photo-detector
   b) whitening filters
   c) anti-aliasing
6) Digital System -> 7
   a) ADC
   b) digital TF
   c) DAC
7) Actuation Chain -> 2b
   a) anti-imaging
   b) dewhitening
   c) coil drivers

LSC time delay
-------------------
(Hiro, Luca, Matt)
Luca compared the LSC electronics response with a matlab model to find that the
amplitude is consistent, but an extra phase of 70 micro seconds had to be added
ad hoc way to make the model match with the data.

Discussion with Stan and analysis using e2e explained this delay. 40 micro seconds
delay comes from the delay needed by digital electronics, and 30 micro seconds delay
comes from the digitization. The second delay comes in in the following way when ADC
and DAC are used. When an analog signal of sin( omega * t ) comes in, the output is
not a smooth function, but is like staircase, from T to T+tau (digitization time
step), the output value is sin(omega*T), from T+tau to T+2 tau, output is
sin(omega*(T+tau)), etc. So, when the analog output after DAC is analyzed, the
component with frequency omega is like sim(omega*(t+tau/2)). This way, a digital
electronics running with a time step of tau introduces a delay of tau/2.
30 micro seconds = 1/16k/2.

The recycling cavity
---------------------
(Biplab, Hiro) Studied effects of mismatch (both as-built and that due to thermal
lensing) on resonant beam in recycling cavity which is degenerate and marginally
unstable and validated different types of e2e runs.

Code development and maintenance
---------------------------------
(Hiro) Several important improvements and bug fixing are done and committed to CVS
to study the LSC time delay and to support the upcoming simLIGO package.

Alfi
------
(Melody)
- Fixed some problem reports for alfi5.

LIGO Data Analysis System

Software Systems (Anderson for Blackburn)

    The LDAS software team has been busy preparing and testing
the first Beta release of the LDAS software (0.2.0). If all goes well
the this release will take place on April 29 or shortly thereafter.
All Laboratory LDAS systems are currently running a pre-release
version to help with the testing and certification process.

    Extensive testing of the new diskcacheAPI has identified several
stability and scalability issues when run on the large filesystems at the
Observatories. To date, all known issues have been resolved.

    This release will also support the handling of Proc Frames
for the first time, for example, the pre-processed Frequency Spectra
generated and stored by the pulsar search code (SFT), and the creation
of reduced data set frames. The writing and reading of Proc Frames
is the last hurdle for this release but significant progress
has been made this week.

    Another major improvement for this release is the patching
of gcc run-time library bugs that has reduced the number of LDAS
software crashes by more than an order of magnitude.

Lazzarini:
In addition, we have discovered some issues with frames being written. Lat and long
coordinates were discovered to be reveresed by people using this information for the stochastic search.
There is also a question of whether angular measures will be in radians or degrees. Sorting out this last issue
requires interaction and feedback from Virgo.

Hardware Systems (Anderson)
(Dan Kozak)

* Continued HPSS migration from Redwoods/3590s to 9940s, HPSS user
  directory reconfiguration (moving towards no data in user home
  directories) and account maintainence (mostly retiring accounts).

* Still working to get StorageTek to make good on replacing the Ultra 10.

* Did some investigative work on the Fibre Channel switch software
  "upgrade" that failed to install.  I'm waiting for word from Sun, but I
  currently think we are already running the most current version (and
  therefore no further action will be necessary on this).

* LIGO SAN testbed:

    SAM-QFS working, migrating data to (last week) and from tape
    (this week).  SAM has successfully written data to multiple
    tapes (i.e.  it is communicating with the STK silo).  Worked to
    familarize myself with all the administrative and configuration
    options available and have been copying LIGO E7 data from HPSS
    to the testbed to use for testing purposes.

(Al Wilson)

* Testing and configuration of the new Datacon for the CIT system.
* Troubleshooting of cfdef ver 5 with Linux systems.
* Care and feeding of the cfdef definitions files.

(Stuart Anderson)

* Helped with stress testing the new diskcacheAPI and managing the
  pre-release cycle for the next LDAS release.

Livingston
----------
(Igor Yakushin)

* Helping Ed Daw to add new features to his slope DSO by the May 6-9
  bursts group meeting. Getting up to speed in writing search codes for
  LDAS.

Hanford
-------
(Greg Mendell)

* Assisted with the pre-release of the new version LDAS.

* Sent out a reminder to LDAS system administrators to restart ssh
  agents on admin boxes running the script that does backups and to clean
  up public keys as needed.

Data Analysis Activities (Lazzarini)
Mendell:
1) Assisted in testing the new prerelease of LDAS.

2) Generated test SFTs on the ldas-dev system for testing the reading of
data from the frame proc structure.

3) Currently assisting with further debugging of the reading and writing
proc data.

General Computing (Wallace)
MIT:
(Keith)
-Rebuilt a couple of machines that had been compromised.
-Working on a new backup procedure.

Livingston:
(Shannon)
-Rebuilt a couple of PC's.
-Setup a new workstation.
-Fixed a couple of computers for users.
-Benchmarking some tools for monitoring PC's.
-Working on the PIX setup and configuration.

Hanford:
(Christine)
- Rebuilt a PC that had been infected with the W32klez virus.
- Worked with Dell Technical support to get a new graphics card for a
brand new PC.  Installed the graphics card, but the PC still had
problems.  Reinstalled Win2k, ran Dell utilities and reinstalled
monitor and graphics card drivers.  PC appears to be working better now.
- This weekend I will be installing a 2810 to provide fast ethernet into
some of the offices.
- Started an inventory of software on site and disposed of some old
software and documentation.
 

CIT:
(Mike)
Reloaded two PC's, in the 40M, that included Win2000, General Computing Software
and additional software that was requested by Allen and made ghost images of
these computers.
-Added additional software to two more PC's and updated Anti Virus Software
and ghost images.
-Performed a complete rebuild on one laptop for loaner pool and cleaned up two
additional laptops plus added a few more software packages. I still need
ghost images of these machines then they will be ready to be put back into
the loaner pool.
-Worked on installing video capture card that should have loaded with no
problem but unfortunately this did not go well. I have to do some research
on this it looks like I need to down load current drives or I might have
some bad hardware.
-Started rebuilding Pherkab on a new server this well be loaded with
2000 server which will update the current OS that is NT4.0. I have a lot of
testing to do before I make this change but hope to have this up by next
week sometime.
-Onsite User Support included; printer, hardware, and software problems and
additional
hardware to some of our users computers.
-Looking onto a whole lot of virus issues so far it looks like we only had
one user that was infected by this round of viruses. This means that our
users are doing a great job on checking the virus definition file dates and
if their software is out of date they are updating right away, which also
verifies that their virus software is working correctly. When Norton is
picking up these viruses' users are deleting these unknown messages with
attachments and are contacting me, which is great. When I get the current
updates, I continue to send out notices for virus updates or known viruses
that have been getting past around.

(Veronica)
- LIGO website: most of the time is spent working on the LIGO Policies and
Procedures online manual. Met with Linda regarding documents to be
included. Attended a Gof5 meeting on the subject.
Working on the Press Kit website.
Posted various updates to the LIGO website (Fellowships, Undergraduate
projects, Elba program, MOUs).
Getting familiar with the VRVS setup for an upcoming LIGO seminar; a
general opinion is that the webcam broadcast should become a permanent
feature of the LIGO (and possibly CaJAGWR) seminars.
- CaJAGWR: Made several arrangements (rooms for the Executive Committee
meeting and a lecture hall for the May talks). Compressed and posted the
video of the last week's talk by Seiji Kawamura. Sent the transparencies
to DCC to be converted to pdf. John Armstrong will be taking my place as a
cameraman while I am in Italy; prepared a howto write-up for him.

(Lisa)
- E-mail vacation messaging is now working. Through a couple days of testing and
rebuilds of the sendmail and vacation programs the final solution is a perl
version of vacation with the present version of sendmail. Working on a procedure
to have more testing performed before the next upgrade to sendmail.
- Started working on fixing the mime attachments in mailman archives.
- Working on some cgi scripts to improve the inventory system.
- Setup ancha (blade 1000) with Larry.

(Larry)
-Worked with Ed and Mike on getting SUN equipment sent to MIT.
-Worked with Lisa on getting a SUN box setup for Rolf to use.
-Attended the security audit review. The document being generated from the audit
will be put in the DCC. Most of the problems concerning the PC's have been taken
care and the other issues are being worked on, mainly password aging and
documentation.
-Spent some time getting and distributing information concerning the WAN
connection for Hanford. NoaNet is trying to schedule a meeting with everyone
involved and Albert is working the Internet2 connection issue. So far things are
still looking good for that connection.
-Worked a number of purchases. One thing that has been lacking in a number of
purchases is a notation indicating that certain parts are to be installed into
another part or system. The additional price in some cases makes the purchase
fall under the equipment catagory and not under supplies. Working on a memo to
get this information out to those in GC that work with purchases.
-Resolved a interesting problem with a network switch having problems. One of
the new edge switches from Foundry had problems but those problems coincided
with a edge switch problem on campus and a PC configuration causing problems on
a local subnet. We are keeping an eye on things since we could not determine if
these events triggered each other or they just happened around the same time.
-Working on new builds for the sand box units and the remote control room setup.
-We've had a lot of virus hits and spam-mail but so far nothing that has caused
any real problems. Most people have been good about keeping their virus-scan up
to date and not opening suspect files.
-Dealt with a couple of VRVS setups. More people are finding a use for the tool.

Lazzarini:

LIGO had been undergoing a computer security audit by Caltech Adminisitration IT audit services (not part of ITS).
We worked with the technician performing the audit over a period of about two months. He checked PCs and Unix systems for
both General Computing and LDAS systems (Caltech only), We received a report debriefing this week. A written report will also be issued.

Generally, things were found to be in good order, except for a few (unsurprising to us) points:
    -    documentation is in need of updating; general concern that if our current staff were to "disappear", the knowledge of administration duties is not sufficiently diffused to be taken up seamlessly by others;
    -    the PCs represent a weakness -- our NT servers that had been set up (not by Wallace or his staff) were improperly configured with regard to security measures;
    -     the ability for individuals to (re)configure their LIGO PCs after they have been configured by Wallace and his staff represents a serious potential for security breeches and/or configuration errors.
        -    One egregious case recently, e.g., was a PC that was reconfigured and which inadvertently tried ottake over DNS services for LIGO - apparently part of the cause of problems we had earlier this week.
 

LIGO II/Advanced R&D (Sanders)

From: Helena Armandula <ahelena@ligo.caltech.edu>
Advanced LIGO Coatings

The "Q" substrates being coated with Ta2O5/SiO2 at MLD were ruined when the rotator failed during the coating run. Also lost were nine 1" dia. substrates being coated to evaluate absorption.
 

From: ctorrie <ctorrie@ligo.caltech.edu>
Advanced Suspensions

Janeen and I are working on preparing the drawings for the mode cleaner in advance of an internal drawing meeting on the 29th.
Larry Jones has looked over about half of the drawings in advance of the meeting and has discussed required changes to the drawings and ideas for some upgrades to parts. We hope to have looked over and discussed all of the drawings by tomorrow and I will include the changes ahead of Mondays meeting.
I have been continuing my weekly class in the workshop and have made several visits to discuss some prototype parts we are getting made.
Norna, Janeen and I met with Ricardo De Salvo and Virginio to discuss some design aspects based on their experiments. We also met with Ric Paniagua to discuss the prototype blades that are being made on campus.
Norna and I have been working in the lab testing some more blades. Norna has also been helping me recommend a modification to the upgrade on the Quad that we proposed last month. This is as a result of the blades not behaving exactly as we had theoretically calculated. This modification has been transferred to Rich at MIT.

From: Peter King <pking@ligo.caltech.edu>
Pre-stabilized Laser (PSL)
==========================

2.2 Advanced LIGO
    Shally Seraf reported that he obtained 20 W from the combined 10-W
laser and recently obtained amplifier.  20 W is the output power that
Stanford had stated would be enough for their 100-W demonstration.

From: Janeen Hazel Romie <romie_j@ligo.caltech.edu>

AdLIGO Suspensions
Preparing for our Mode Cleaner suspension drawing review on the 29th
 

Date: Tue, 23 Apr 2002 10:31:04 -0700
From: Riccardo DeSalvo <desalvo@ligo.caltech.edu>

Resuming the weekly and the weekly meeting after a two months hiatus
during which the group mainly focussed in studying LIGO seismic remedial
options (reported by Dennis Coyne).

LIGO I remedial studies:

The LIGO I remedial effort (mainly Virginio, Szabi, Luca, Alessandro and
Riccardo) produced 4 reports and several drawings:
* Report  T020038-01-R on Active internal damping (AID) option
(constructive drawings in D020212-00-R) and
* Reports T020039-00, T020052-00, T020055-00 on the implementation of
SAS external mini-towers on each pier. The intent is
1. to passively pre-isolate the LIGO stacks starting at a frequency
below 100 mHz with the potential to passively provide all, and more, of
the required remedial isolation,
2. to inertially damp the stack resonant frequencies (since the mass of
the external structure and the down tube are comparable and since with a
soft suspension the suspension stiffness does not short the signal to
ground, the resonances moving the downpipe will show up as recoil on the
external structure with roughly 1 to 1 amplitude)
3. to provide a soft platform for additional (external) active
isolation.

The first (AID) option was developed to the point of starting
construction of the LASTI prototype and is being mothballed because the
effectiveness of the piezoelectric pre-isolation seems to make this
option superfluous.

The second option has also been fully designed, but more analysis is
required to verify its performance.  Scaled, component-level, prototype
tests have been performed. This option is practically ready for system
prototype construction, if it should be needed.  In the event that the
baseline approach is not ready, or if we determine that we need
isolation at higher frequencies (higher frequency stack modes,
suppression of the suspension bounce mode), then this external SAS
approach could be implemented.

Mainline activities:
 

In this period Hareem kept the glassy metal line alive while Akiteru
continued the 3m commissioning and Alessandro supervised the Ultrasound
milling machine commissioning and his development of Newtonian motion
vertical accelerometers.
 

People:
 

One month ago Hareem has been accepted as a graduate student at Caltech
and has tentatively accepted to make a PhD thesis in SAS on low thermal
noise glassy metal mirror suspension developments.
Two weeks ago Michael Hall, undergraduate from Drexel, joined us for a
six month stage in SAS.
Also two weeks ago Kelin Wang, postdoc, joined us for a 6 month
appointment, initially hired for the AID program, now working also on
glassy metal development.
This week Youichi Aso, graduate student from Tokyo University, has
joined us for w three period exploratory period, hopefully remaining
with SAS for his PhD work.
 

Last weeks activities:
 

Hareem, Michael, Kelin
Testing the cryostat after repairs from Quantum Design.  For weeks an
intermittent leak fooled us and produced erratic data.  Quantum Design
replaced both the sample chamber and the cryo pump.
 

Advancing the glassy metal production
For general understanding sake, the production of glassy metal foils
undergoes the following five steps all of which have to be optimised for
the required alloy.
1. The different components of the alloy are mixed in 5 to 10 g batches
in the mini arc melter to produce beads of sufficiently precise
percentual composition.
2. The 5-10 g bead is remelted in the miniarc melter and suched in flat
molds to produce 1 x 4 x 20 mm ribbons.
3. The ribbons are sheared to produce 100 mg samples.
4. The 100 mg samples are re-melted in the miniarc melter to produce
mini beads.
5. The mini beads are levitated in the spiral RF coil of an induction
melter and then dropped between the jaws of the splat cooler.  At this
stage the alloy is cooled into a 30 to 50 micron thick disk.
 

Produced MoRuB and MoRuBSi samples and reshaped them into ribbons (steps
1 and 2)
MoRuBSiAlP samples (step 1) have been produced.
The ribbon mold has too wide (1 mm) entrance gap for this new alloy and
the melt enters it before the suction starts.  A new mold has been
machined (0.6 mm gap) and tested to have too little gap to allow
suctionin the mold.   Tests will be done by building an intermediate gap
(0.8 mm) mold.
 

The induction melter and splat cooler was repaired (splat jaws coils
arching suppressed with additional isolation).  Tests were done
splatting Aluminium and Nickel samples.  Started tests with Mo
mini-beads.  Broken and run out of injection crucibles, will get more
next week.  Also ordered new spiral coils of various lift gain.
 

Tests on brazes.
Au71Sn29 does not wet well glassy metals.
Au7.6Sn28.3Ti1 being tested, bad results recorded on glasmet because of
surface oxidation, will repeat test with poly-MoRuB and CuBe, also will
test commercial AgSnTi brazes.
 

Aso
Starting studying low frequency and low thermal noise suspension
geometries
 

Alessandro
Preparing kapton coating tests for UHV use in AID.  The glue this time
safely arrived in Pisa (yesterday) and the samples from Lee Cardenas are
on its way.  LVDT coils will also be wound and mothballed.
Accelerometers will be finished and mothballed.
The Ultra Sound milling machine is nearing completion and will be
delivered mid May.
 

Akiteru
Just aligned the 3 m FP interferometer, first lock soon!!  His report:
“After struggling few weeks, we saw the 3m cavity resonance for the
first
time this evening. The transmitted light is still squeezed, but further
fine
tuning should correct it.
Now both the mirrors are aligned by using local optical levers and
feedback
to the mirror actuators. We will try to lock the cavity with this
configuration, and we will switch the alignment control to the upper
stages,
the suspension platform and the IP, after establishing the length
control
servo.
Anyway, it was not very comfortable tilting the mirror by moving counter
 

weights and twisting the wires, and for the 300 m cavity, this method is
 

quite hopeless. So we need to implement remote DC alignment control for
the
final version of SAS for TAMA. This may be done with the coil magnets on
the
suspension platform, but I guess mechanical tuning
[a la Virgo with micropositioned counterweights, R.D.S.]
is more preferable.  Akiteru”
 

Publications:
“article in press-final proofs” of the LVDT and constant force actuator
papers received from NIM
 

From: Benno Willke <bfw@mpq.mpg.de>

Status report: University of Florida
                Guido Mueller and Rupal Amin
Re: RTP PM prototype (X-cut)

Testing of a full 180 MHz PM prototype is in
progress. Observed modulation index is about 0.2 corresponding to 66V
across a 4x4x15mm crystal.
Current problems are dominated by the practical difficulties (such as
transformer burnouts and heat sinking for electrical compenents).

In terms of thermal lensing, we took beam profiles with and without the
modulator in the beamline. At nearly 40 Watts, we observed little to no
change in the high power laser's mode.

We will be measuring birefringence and changes to the beam geometry in
further detail.
 

***********************************************************************
LZH status report:

1. wave front sensor:

Our new diploma student Philipp Huke has started his work at LZH in the
beginning of april. Currently he is evaluating our new Shack-Hartmann
sensor and found some minor problems. The manufacturer's specifications
and the user's manual supplied didn't fit exactly to the unit that was
delivered to us. A second problem observed in our test setup is a strong
fluctuation of the reconstructed wave front (general slope changes by
more than one wavelength in quiet environment). This even happens when
we use the NPRO as probe laser and seems to be related to the sensor
head. By producing x and y cuts in the two dimensional CCD array we
observed single pixels changing their signal by a factor of two from one
picture to another. Since it seems to be always to be the same pixels
changing their value, we exclude things like dust in the laser path or
similar things. Since it happens for three different HeNe lasers and
even the NPRO, we don't believe that this phenomenon is due to the laser
source.

2. 25 watt oscillator

Martina has started to evaluate the scalability of the GEO 600 type
slave oscillator to 25 W of power. The idea is to use diffusion bonded
rods (3 mm by 8 mm with undoped region 2 mm long) and increase the pump
power. Martina observed that starting from a low pump power and noting
the laser output, increasing the pump power and than returning to the
lowe value, she couldn't reach the same output power at that low pump
intensity. Last week the laser shut down immediately and examination of
the crystal showed, that the undoped end cap just fell of the crystal.
It seems that it was not bonded well to the crystal and that there was a
small gap between the doped and undoped parts, that changed its size
when the crystal temperature changed. The modelling showed that we have
been below the safety limit by a factor of 3 to 4 with the pump power
employed (taking the lower 130 MPa value for the fracture limit from the
literature) and that the maximum  for mechanical stress is far away from
the bonding region. We are lucky that we have a few spare crystals, so
that the experiments can continue without delay. The general strategy by
Martina is first to optimize a V (standing wave) resonator, representing
one half of the GEO 600 type bow-tie ring resonator and then add the
second crystal and go for the ring cavity.

3. modelling

The modelling concentrated on completing the data set for the
temperature and stress distribution and didn't bring any new fundamental
results. At the moment the development of the 25 W is supported by some
modelling efforts.
Additionally, a little modelling is done concerning our higher doped
rods pumped from both ends.

4. pump optics

René is working on the pump optics for the high power stage. At the
moments he tries to find out the optimum length for the homogenizing
quartz rod. Alternatively there is the idea to employ GRIN lenses at the
ends of the fibres. We hope to get samples from a manufacturer to find
out if they can stand the power density.

5. 100 W stage

While trying the two rod head, we found out that our HR 808/HT 1064
combination "is not AR 1064 enough". One end of our rods has been tilted
by one degree and the reflected light from that end seems to produce
some problems in connection with sealings of our laser heads. The
destruction of one rod reported on the LSC meating seems to be related
to this effect. Therefore we have only one of these rods at LZH and two
are out for polishing the tilt away.
We also have higher doped rods that can be pumped from both ends and are
used in the moment, because they don't have the AR/HR combination on one
end but are AR 808 and AR 1064 coated on both ends (but they also have
the tilt on one end).
With one rod and no compensation Maik has reached about 35 W, but the
systems is very sensitive to alignment (partly because pump light is not
homogenious enough.)
Currently Maik is trying to set up a single rod head in connection with
birefringence compensation by a Faraday rotator.
 
 

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