_____________

Kent Blackburn for the Grid R&D Team:

GRID APPLICATION DEVELOPMENT

• Britta attended the Condor Week Workshop in Madison hosted by the Condor developers each year this week.
• Working with ISI developers of Pegasus to implement a test suite for a mini binary inspiral workflow that can be run on a schedule to test out both the OSG and the LDG for compatibility and issues for LIGO workflows. This would allow quicker recognition of changes that impact LIGO workflows on these two grids.
• Held a teleconference with Globus developers and OSG Users.
• Group to discuss how LIGO and others are using WS-GRAM for job submission. CMS users reported issues with job deletion and job throughput. LIGO reported its results with running Einstein@Home on the OSG via the WS-Gram interface. A follow up meeting is scheduled for early next week, involving the German DGrid developers that are responsible for the job submission mechanism for running Einstein@Home on the DGrid and the OSG.

OPEN SCIENCE GRID INTEGRATION AND VALIDATION TESTBED

• Britta is testing out LIGO applications on the pre-release.
• OSG software stack currently installed on ITB sites.

GRID COMPUTING MANAGEMENT

• Organized and held kick-off meeting of of the subcommittee of the OSG Council for "At-Large" VO members of the OSG (VOs that do not have representation on the OSG Council). Meeting generated several well received ideas on how to define and accomplish a suitable form of representation.
• Posted Grid Administrator job opening on SPIRES to attempt to draw in more resumes.

_____________

Diego Fazi:

• Compared results from SPA injection runs as obtained with LAL/LALAPPS from 02/06/2008 and with the branch used by Drew from 07/01/2007.
• Re-analyzed results from the S5 1-month injection runs for both PTF and SPA using a different clusterization.
• Calculated the theoretical SNR threshold for PTF (6.4) that corresponds to a threshold of 5.5 for SPA.

_____________

Amber Stuver:

LIGO Research

• Continued working on event follow-up investigation involving the detection delay between detectors and the event SNR ratio between them.  I have been generalizing the investigation to use 3+ detectors and the best application of this is very different than just considering 2 detectors (I have two well defined positions on the sky for 3 detectors so the range of acceptable SNR ratios is much smaller and can be so small that I am concerned that the error in the SNR is greater than the what is determined from the two locations; how do I handle polarized waves now?).  In the process, I have also been considering using this investigation for the GW astronomy inverse problem.  So, I have been taking some reading detours into the use of multilateration for GPS satellites since this directly applies to the inverse problem (and to finding source sky locations with 3+ IFOs).  I expect to be able to further develop this follow-up module to reconstruct the h+ and hx waveforms (al a Gürsel and Tinto [Phys. Rev. D, 40, (1989) 3884]).  A friend of mine used the maximum entropy method to do a reconstruction for core collapse supernovae.  I am thinking about contacting them to discuss their methods.
• I keep fairly updated documentation on this follow-up module here.
• This currently does not have my work on 3+ detectors since nothing on that is finalized (except for finding the two sky locations).  This will eventually be written up as a technical note and, after I have actual application performance results, I would like to publish this

SEC Work

• Went on a school visit to Livonia High School with Kathy Holt.  I presented the concept of space-time and gravitational waves to 6 classes (~120 students).  For demonstration and illustration purposes, we brought a free standing gravity blanket (taught spandex gravity well).  This got a wonderful reception especially with the discussion of black holes and the 'speed limit' concept of the speed of light.  I was taken aback by how very different these classes were from my educational experience.  These were classes of 8th graders that had some students who were 16 (my sister is 16 and a high school sophomore)!  Regardless, I believe this was a fulfilling experience for the students judging on their engagement and excitement.
• Gave control room tours to ~180 students.

_____________

Joseph Betzwieser:

• Preparing for a full h(t) review.

_____________

Pinkesh Patel:

• Made a matlab script to check on certain heterodyning issues that have cropped up in resampling. Things all look normal and as expected. So mystery losses are still a mystery.
• Preparing for a presentation to the pulsar group, proposing a globular cluster search.
• We fixed H2!! Somehow. Although we arent sure what it was. I also did some free swing measurements and found that some resonances have shifted. Investigating it further.

_____________

Drew Keppel:

• Separating the times in the S5 1Yr  Low Mass CBC analysis so that vetoing one ifos changes those times from, for example, triple times to double times

_____________

Anand Sengupta:

• High mass search started on the 2nd year last month data.
• e-thinca paper has finally made it to the arXiv [http://arxiv.org/abs/0804.4816].
• Exploring the maths of fast convolution methods. Reading relevant papers and tutorials on this subject.

_____________

Igor Yakushin:

• Working to satisfy LIGO-GEO S4 paper review team:
  • there was discrepancy between two independent calculations of incoherent WaveBurst + CorrPower pipeline - resolved
  • there was a discrepancy in livetime between coherent and incoherent pipelines - resolved
• Working to apply the final DQ and vetoes to S5 first year coherent WaveBurst triggers.

Laboratory Computing (Anderson)

LDAS Software Systems (Maros)

• Started porting unit tests to Version 7 of the frame specification. This revealed several problems with the library which were corrected. Also used a memory analysis tool to ensure proper memory management.
• The TCL exec call has been replaced with a proc with now emits a log entry when it is invoked. This allows for the diagnosis of places where the code can be optimized by their elimination.
• The movement of rmJobFiles from the managerAPI to cntmonAPI is now complete. Several other corrections to the cntlmonAPI were done.
• System testing was done using version 1.9.276 of LDAS. Two of the system tests had unexpected results. The first was the metadata test which hung during execution. The lsync test could not initially find the file lsync.rsc. When the test was rerun the next day, it completed as expected. The "All User Command" tests via tcl sockets are working properly.
• The directory /archive has been added back to the mount point list. Initially the job rate decreased as the cache was being rebuilt. After it completed, the rate returned back to 1600 jobs per hour. A problem report (P$#3261) has been created as a query for S5 frames did not yield any entries.
• Week long running of ldas on ldas-test is being done with version 1.9.280 of LDAS. The previous week long run only had the usual errors of "no such symbol" from the datacondAPI.

LDAS System Administration (Anderson)

Caltech

(Phil Ehrens)

• Cluster node321 has powered off spontaneously twice in the last week. The logs show no indication of the cause.
• A fan began to fail in node157 causing a number of correctable disk errors. After replacing the fan no further disk failures were noted.
• Node323 is reporting multiple MCE errors each day associated with CPU 2. I will replace the memory modules associated with this CPU. This action was indicated last week, but was not taken due to confusion caused by the excessively long time this node requires to POST.
• Liebert #1 (Red) in Synchrotoron 215A is in a constant state of alarm due to humidity underrun. Facilities is arranging for a service call from Liebert to deal with this recurrent issue.
• Had phone meeting with David Reitze regarding MOU review software requirements for the 2008-2009 cycle.
• Discussed Attachment Z requirements for MOU review with Tom Nash.
• Installed CentOS 5.1 on node500 (spare cluster node) and began to configure and to create kickstart environment suitable for upgrading the cluster from Fedora Core 4 to CentOS 5.1.
• Discussed management of the CIT iLog installation with Bruce Sears, and assumed maintenance of CIT iLog config.
• Various certificate and other user related duties.

MIT

(Fred Donovan)

• A couple of disk replacements; some more work on monitoring scrips.

General Computing (Wallace)

MIT

(Fred)

• Installing new os for KM.
• Some troubleshooting MW XP desktop.
• Built cernlib.
• Some ilog work (web interface).
• Deactivating old equipment in nw17 (and office).

Livingston

(Dwayne)

• Corrected the remote connection problems with the PQNode system.
• Main gate, guard shack communication problems in kantech system turned out to be a loose EPROM on controller board.
• Auditorium audio problems were reported, but upon investigation all worked properly.
• Rebuilt NATALIA as a CentOS 5 install, ldap client on new network.
• Added some documentation to the LLO GC Wiki.
• Started using pca on more Solaris 10 installs, but experiencing problems booting one of them... to investigate today.
• Assisted a user with some scanner problems.
• Upgraded a user's MacBook to Leopard.
• Assisted a user with some ImageMagick questions.
• Created a GC account for a user.
• Helped a user with some email filtering.
• Other usual/unusual user support requests.
• Cleared spam trap.

Hanford

(Larry)

• Continuing work on mail services.
• Some documenting of different servers.
• Tracking down a machine running webservices.
• Modification of a couple of user environments.
• Tracking of SUN orders.
• Backup of home accounts.

(Mike)

• Continued work on DHCP and Mail servers.
• Other misc. user support for a few users.

Caltech

(Christian)

• Albert Lazzarini - Created new Windows XP parallels image.
• Jay Marx - Extracted a portion of Einstein DVD for Jay to use on a PowerPoint presentation.
• Lee Cardena - Email is not working. Lee’s Eudora was pointing to old acrux email server.
• Riccardo Desalvo - Battery charger for laptop is not charging. Called Mac support and replaced charger.
• Surplus old monitors and cpus this week.
• Minor tweaks on the unit in the display case.
• Other misc.: Continued onsite software/phone support.

(Mike)

• More work on a 40meter server. Upgraded memory, and continued installing additional software packages. I have now turned this server over to 40m.
• Installed a UPS on W/B 3rd Floor network closet.
• Compacted database for DCC. I also updated all windows updates on Antares and Pherkab.
• Did some shuffling around of computer equipment, setting up a cubicle for a new user on W/B 3rd floor.
• Additional testing on EVO with Larry and Christian. Using multiple USB Microphone’s on Mac/Windows computers. The windows side of the house seems okay on most of the microphones we tested. Unfortunately the testing on the Mac side is not as successful. It seems like out of all the microphones we tested the PHOENIX AUDIO SOLO USB Microphone works the best with a MAC.
• Worked on a few printers. One had some error messages that had to be resolved, before swapping out supplies.
• Ran end of month backups on NT servers.
• Other user support and misc. sysadmin tasks.

(Veronica)

• LSC:  Installed a new navigation link at the old homepage; ongoing work on the new one.  Updates of the database of technical papers, other web updates.
• LIGO:  Researching a replacement videocamera; narrowed it down to three models, an order to be placed next week.  Ongoing work on a mashup for a travel webpage.  Other web updates /user support.
• CaJAGWR:  Web updates /user support.

(Larry)

• Worked on a number of procurements. The Dell equipment has arrived and has been delivered. The SUN equipment should ship next week.
• Reworked some of the home account backup schema in getting things ready to move that process over to the new tape robot system.
• Spent time working on multiple air-conditioning issues. Another unit went out in one of the computer rooms. The belt had pretty much disintegrated, once replaced the room quickly cooled back down. The unit in room 18 had the new motor installed and is now working at full capacity.
• Worked on a new server for the 40M. Still some tweaking to do but it is now at the 40M and being worked on at that location.
• Setup a few new user accounts.
• A lot of testing on different h/w items with the EVO system. Just about all of the equipment has worked with the PC's without much of a problem. Still working out issues to get setups that will work consistently on the MAC side of the house.
• Some work towards setting up some of the new servers/server replacements. This will be on going for the next few months. Regular user assistance.

(Melody)

• New DCC: Getting familiar with the current DCC and how the current requirements are satisfied by it.  Working on prioritizing the requirements. Briefly looked at the docdb code.

Advanced LIGO and Supporting R&D (Shoemaker)

Advanced LIGO Systems

Systems Science

From: Peter Fritschel <pf@ligo.mit.edu>

• Formulated responses to the PDR committee questions, and held first review meeting Wednesday.
• Matt Evans' re-formulation of coating thermo-optic noise is now complete, and he's now working on writing it up into a paper. The bottom line is that thermo- optic noise was previously over-estimated, and is now estimated to be insignificant compared to coating brownian noise.

Systems Engineering

From: Dennis Coyne <coyne@ligo.caltech.edu>

Operations Activities

• Reviews - Supporting or conducting the following reviews simultaneously, all at various stages of completion:
  • HEPI FRR: review to be scheduled in May
  • IO FDR & Long-Lead PRR: Committee met to review team answers to questions. Next committee meeting date TBD
  • E/ITM Glass FDR/PRR: All review data available. Committee meeting date TBD
  • E/ITM Mechanics FDR/FRR: Held first committee meeting to collect questions
  • FMP PDR & (limited) Fab readiness review: preparing for a review in May
  • SYS PDR: Held first meeting with the review committee. Next meeting to address additional questions in 3 weeks
  where FDR = Final design review, PDR = preliminary, FRR = fabrication, PRR = procurement, and the other acronyms are standard LIGO subsystem terms. For a list of reviews, see the main AdL wiki page <http://lhocds.ligo-wa.caltech.edu:8000/advligo>

AdL Project-Funded Activities

• Technical Review Board (TRB):
  • A report on the TRB's recommendation to switch from the baseline marginally stable recycling cavities to stable recycling cavities is being prepared.
• Vacuum Review Board (VRB):
  • VRB to has declared 303 and 303 Se stainless steel no longer acceptable. The LIGO UHV approved materials list, E960050, which allows all 300 series stainless steel, will be revised (the impact on eLIGO is being assessed). Drawings for AdL will be revised accordingly.
  • Issued a request to the VRB to consider a proposed limit for high vapor pressure elements in alloys to be used in the LIGO UHV: LIGO-L080045-00, "Limits to high vapor pressure elements in alloys for LIGO UHV components". Could permit some more metallic alloys in vacuum.
  • Issued a request to the VRB to advise on the proposed welding quality specification in the E010613, "Generic Requirements for Detector Subsystems": LIGO-L080046-00, "Weld Quality Requirements for UHV Weldments".
• Change Control:
  • Pending Change Control (CR) request for the Change Control Board (CCB) for the scope transfers between subsystems and the costs changes associated with the TRB's recommendation to adopting stable recycling cavities.
• Configuration Control:
  • Approved DCN E060262-02 for B-OSEM production drawings
  • Approved DCNs E080179-00 and E080169-00 for RM (HAM Large Triple Suspension) and OMC Suspension maraging steel cantilevered blade springs
  • Approved DCN E080182-00 for release of an RGA specification for qualifying the cleanliness of BSC chamber suspension structures
• Design:
  • Realized that the work to accommodate all horizontal wedge angles in the optomechanical layout, in the last several months, violated the ICD agreement with SUS for vertical wedges. The current significant horizontal wedge angle for the ITM (1.3 deg) would require re-design for the SUS quad. The difficulty and extent of this re-design is being evaluated. In the meantime AOS/SYS is exploring an alternative layout based on very small wedge angles (~0.1 deg). Initial work looks encouraging
  • Tech memo on vacuum equipment layout considerations and vacuum equipment layout drawings pending.
  • Issued answers to the initial set of questions from the Systems PDR review committee (see the AdL wiki).
• Interfaces:
  • Issued RODA M080057-00, Minimum spacing between FM and ITM
  • See the RODA status page <http://www.ligo.caltech.edu/%7Ecoyne/AL/ project_management/RODA/RODA_status.htm> and the Interface Control page <http://www.ligo.caltech.edu/%7Ecoyne/AL/Systems%20Site/ICD.html>.

Modeling and Simulation

From: Hiroaki Yamamoto hiro@ligo.caltech.edu

H2 WFS and TCS (Hirose Eiichi, Osamu, Hiro)

• Eiichi of Syracuse Univ visited Caltech to model H2 in order to understand the input power dependence of the WFS of H2.
• Eiichi wants to use simulation tools to analyze the observed behavior to make a more stable ASC with TCS for H2.
• For example, the change of the SB mode structure due to the ITM thermal lensing, possible imbalanced between X and Y arms, could possibly explain the input power dependence, and simulation tools are most useful to get semi quantitative predictions.
• Eiichi has written a matlab code based on the modal model formulation done by Daniel and Nergis. Hiro worked with Eiichi to debug the code and fixed some appropriate formulas used in the code.
• FINESSE is a more general purpose frequency domain model. Osamu set up FINESSE to simulate H1 and H2, based on the code to simulate TAMA. The setup can use different values for refractive indexes of ITMX and ITMY to mimic different levels of thermal lensing effect. The basic setup is done and Osamu is validating the code by comparing with old WFS notes.
• Eiichi will use these codes to analysis the H2 data so that H2 can operate stably at higher input power. This will be a valuable exercise for more complicated ASC/TCS in advLIGO.

Static IFO Simulation (Hiro)

• Hiro is developing a matlab code which will do the same modeling as Yi Pan - for the validation of the FFT code and to understand the difference between FFT and lower order modal model.

Mechanical Simulation for Advanced LIGO (Sany and SLU team)

• Continued the e2e modeling of the AdvLIGO Input Mode Cleaner (IMC) taking into account the PSL frequency noise incident to the IMC. Made some progress in redesigning the IMC’s control servo filters. The newly designed frequency control servo filter has 70 dB higher gain at 100 Hz than the previous filter. (We had designed the previous filter without taking into account the PSL’s frequency noise.) This modification resulted in an order of magnitude improvement in the frequency noise on the IMC’s transmitted light in the frequency range above the crossover frequency (60 Hz). However, the MC transmitted light’s frequency noise below 0.3 Hz has been found a factor of two higher than the previous case. More analysis is being made.

Facilities Modifications and Preparations

From: John Worden <worden_j@ligo-wa.caltech.edu>

• Continued preparations for review. We are investigating our cleaning and baking capability. One consideration is to move towards dishwashers and aqueous cleaning fluids for the simple metal parts - this might allow more capability at the sites without the hassle and danger of solvents like acetone and methanol.

Prestabilized Laser

From: Peter King <pking@ligo.caltech.edu>

Operations

• I have been delving into the literature to find data about the eye damage threshold.  This relates to setting a basis for the laser incident reporting threshold level.  Most of the data found so far is for pulsed laser systems, typically found in military applications.

Project

• The data acquisition and controls hardware for the tests at the AEI are all together (thanks to Gary and Todd).  Rod has generated the loan agreement and other documentation related to shipping the stuff out of the country.

Interferometer Sensing and Control

From: Peter Fritschel <pf@ligo.mit.edu>

Development

• We got an update from the ANU group on their 'digital interferometry' experiment and the thinking on how this could be applied to AL arm stabilization. A tech  note and viewgraphs can be found in the AL wiki.

Control and Data Systems

From: Rolf Bork rolf@ligo.caltech.edu

ELigo

• Work continues on OMC hardware shutter.
• Alex is testing DAQ configuration with data concentrator at 40m lab.
• It is presently running in parallel with their standard Framebuilder.

AdvLigo R&D

• Continuing to work on CDS code generator documentation. Draft copy should be ready late next week.
• AdvLigo PSL controls shipped out to AEI today. I will be at AEI May 5 thru May 22 for installation and test.
• Several of us are busy testing the latest CDS code generator software. In the process, found a TP bug (added 5usec on every 1Hz boundary) and fixed.
• Daniel, et al, working on next version of timing slave prototype. Jay has also had discussions with Szabi on how to interface into the CDS I/O chassis.

AdvLigo Project

• Jay and Gary have started a parts list and fabrication for site Quad Sus test stands.

Seismic Isolation

From: Ken Mason kmason@ligo.mit.edu

SEI Activities and Progress at LHO

• Jeff Kissel and Brian O'Reilly.are assisting with the assembly and testing this week. The position sensors were assembled and installed (minus a few vented washers).  Currently working on hooking up their electronics.
• Four conflats have been installed (have one more, but it needs to be cleaned).  Crossbeams have been installed.

BSC ISI Installation and Test

• One of the small actuators (pre-AdL-design) has a bad cable and has been working intermittently. The break appears to be in the potted area which is difficult to repair. PSI has sent us a spare bobbin. If it is usable, we will clean it and insert it into the existing magnet assembly.

HAM SEI Documentation and Design/ HAM Gullwing Design

• Optimizing design of tube weldment for aLIGO HAM crossbeam redesign. Developing designs for retrofitting HEPI for the new crossbeams.

SEI Project Activities

• Spoke with three suppliers interested in supplying actuators for advanced LIGO HEPI. We are writing a statement of work to include the fabrication, assembly, and testing.

Suspensions

From Janeen Romie and Norna Robertson

(romie_j@ligo-la.caltech.edu, nroberts@ligo.caltech.edu)

Operations Work

HAM Suspensions for Advanced & Enhanced LIGO

• Received final verdict and are awaiting precise specification from the Vacuum Review Board on stainless alloys allowed in the vacuum system. Currently, the LHO OMC fabrication effort includes some verboten 303 parts. However the good news from the campus machine shops is that only 3 parts have been made using 303 and that those parts can be redone and still meet the original schedule. Additional cost of $750.
• The 303 parts in the LLO OMC will stay put until an appropriate time to switch them out.
• We note there is a test procedure which could in principle be used if necessary to determine if material is 303 or 304, but before one could use this, research would need to be done to qualify a process to clean the test chemicals from the parts.
• Drawings are being created for many recycling mirror suspension parts. Drawing check is ongoing. Again, we are awaiting a precise specification for allowable stainless alloys.

BSC Suspensions for Advanced LIGO

• ETM/ITM fabrication readiness review for mechanical elements of quad suspension is ongoing. There was a meeting this week with all reviewers and RAL folks. There will be another one next week, although RAL will continue responding to reviewers' comments in the meantime.
• The DCNs for the Birmingham OSEMs have been signed and they are ready to place orders. Two remaining open issues being investigated are:
  • possible replacement of macor with alumina for sleeving to get better thermal conductivity and potentially lower noise
  • possible replacement for phosphor-bronze spring clip
    The next batch of noise prototype B-OSEMs are expected to ship next week

Project-Funded Activities

• Sub-system facilities requirements for Advanced LIGO storage, cleaning, baking, sub-assembly and assembly work is being collected and converted to architectural drawings for the sites. This is in preparation for a Facilities Modifications Review. The HEPI Fabrication Readiness Review is ongoing with participation from SUS as reviewers.
  

Core Optics

From: GariLynn Billingsley <Billingsley_G@ligo.caltech.edu>

Project

• One of our fused silica vendors has requested an extension of the RFQ due date to May 9th, 2008.
• All vendors have been notified of the extension.
• A review committee has been suggested, recruitment has commenced.

Development

• Cheryl Vorvick has provided images of ETMY after it came out of the bake oven, and re-hung on it's wire, ready for installation.  Unfortunately it is covered in dust.
  http://ilog.ligo-wa.caltech.edu/ilog/pub/ilog.cgi?group=detector&date_to_view= 04/24/2008&anchor_to_scroll_to=2008:04:24:15:30:55-Vorvick. Studies to determine the source and changes in procedures underway.
• John Worden has offered to find space in a Hanford mid station for the tooling used in coating iLIGO optics (Thank You!!).  The vendor is consolidating and needs the space.
• We have received a sample phase map from Tinsley, and should now be able to compare similarly processed PSDs.

Auxiliary Optics

From Mike Smith <smith@ligo.caltech.edu>

ADLIGO

Work under Project Budget

• IFO Layout - Mike made a conceptual layout of a new configuration that essentially eliminates the wedges on the ITM (still keeping 0.08 deg) and the BS (still keeping 0.04 deg). Eliminating the ITM wedge may be necessary to simplify the quadruple suspension design. The 0.04 deg wedge on the BS causes the main output beam and the prompt reflection from the BS AR surface from the ITM direction (ITM PO beam) to exactly coincide at the surface of the SRM3. The ITM PO beam then separates cleanly from the main beam in the vicinity of SRM2 and can be steered to the ISC output bench and to the Hartmann ITMx input. The ghost beams from the ITM and BS that head toward the recycling cavities will be captured by "scraping" beam dumps that surround the main beam near the PRM3, PRM2, PRM, SRM2, and SRM mirrors. The ghost beams that head toward the arm will pass into the arm and subsequently hit the arm tube baffles inside the beam tube--Peter F. pointed out that these ghost beams are several orders of magnitude smaller than the scattered light down the arms from the ITM and ETM, and should not cause excessive noise. An additional benefit from this new layout is the elimination of the suspended ITMx PO telescope. 
  
  Luke will suspend his work on updating the optical layout in Solid Works until the baseline optical concept is finalized.

Work under Operations Budget

• SLC - Dennis will ask Mark Barton to investigate the effect on the OSEM noise of having the Arm Cavity Baffle, which will be made of low carbon steel, close to the ITM and ETM quadruple suspension. He also advised AOS that 303 stainless steel is no longer a vacuum compatible material.

ELIGO

Work under Operations Budget

• SLC - Ken has completed the final design layout for the manifold baffle. Luke is in the process of revising the HAM5 baffle.

Input Optics

From: David tanner@phys.ufl.edu

Development

Input Optics for Adv LIGO

• Updated documentation for procurement readiness review meeting (all)
• Updated schedule progress.
• Work on optical layout for IO is stopped, pending the next big change. (Luke and David)
• Submitted RFQ to ATFilms for two low loss, high laser damage threshold thin film polarizers.  (Rodica)

Advanced LIGO Mode Matching

• We tested a prototype DKDP ring heater (RH) and the results are very encouraging, indicating that an astigmatic corrective element can indeed be formed by unsymmetrical heating of DKDP. The currently used RH is not optimal. We are working on a vacuum compatible RH. The original design expects that RH be used to compensate 10% of the the thermal lensing from TGG crystals. In the current experiment, we were able to compensate more than 30% of the expected thermal lensing in TGG at AdLIGO power levels. (Muzammil)

Advanced LIGO Modulators

• We continue to work on AdvLIGO modulators and MZ scheme. (Volker)
• We are working on finite element calculations for the Adv.LIGO FI magnet. (Volker)

Input Optics for eLIGO

• I've been studying control theory and making sure I understand PDH locking. I'm also preparing to do a mini-study of angular instability in the mode cleaner as a function of power. Hopefully by the end of the week we'll be able to measure the new mode-mismatch into the arms and interferometer. (Kate)
• We continue to work on the eLIGO modulators for LHO and LLO. (Volker)

---

For additional information about this report, contact Albert Lazzarini