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  • LIGO Hanford Observatory News
    recipes use higher temperatures but what do you use for an oven when your cake is longer than a mile Basically we made the tube itself into an oven We wrapped its four foot diameter in fiberglass insulation about ten inches thick See Figure 1 at left Then we ran 1 850 amperes of current down its length The stainless steel tube effectively acted as its own heating element Designing and staging this effort took more than a year of hard effort by Bill Althouse Al Lazzarini Rai Weiss Mark Lubinski Mark Guenther and Kerry Stiff At the same time helping staff the field operation round the clock were Sid Bevans Larry Garelts Ron Houtrow Tim Neasham and Tom Russel Special portable power sources needed to be acquired Many were graciously loaned to us by those kindly folks at the Fermi National Accelerator Laboratory in Illinois and promptly wired up About one megawatt of electricity was drawn through a series of transformers to provide the large DC currents through the Beam Tube as well as AC power for the pumps and instrumentation along the tube A flatbed truck See Figure 2 below left was used as a platform for each 1 2 megawatt power supply along with its associated transformer and heat exchanger to make the system portable Special copper cables Figure 3 below right with a total cross section of 2 4 square inches of copper carried current back from the tube Their ends were carefully trimmed in length to balance currents in the various loops Next turbopumps at each end of the tube pumped non condensable gases like hydrogen while eight cryopumps were spaced out along the tube to pump condensable molecules Roughly 400 thermocouples monitored temperatures along the Beam Tube and a data acquisition system was set up to monitor the entire bakeout system Residual gas molecules in the tube were monitored by a mass spectrometer throughout the bake Metal bellows spaced every 130 feet took up the thermal expansion from the bake and special gauges were used to verify that the mechanical strains on the tube agreed with our structural modeling In late August we started slowly raising the tube temperature and we cooled down again in October By the end it had taken a bit more than 30 days to get all the bugs out of the baking process this first time around When Rai Weiss surveyed the vacuum data and declared that the bakeout goals had been met and the tube was leak free we figured this bake was ready for the record books and started moving equipment for the next bake due to start in mid November Now if only we could figure out how Aunt Tillie gets that texture in her fruitcake Enthusiasm Abounds As Hanford Hosts Latest NSF Review Contributed by Phil Lindquist The normally scheduled semi annual review of the LIGO Construction Project was conducted by a panel of experts on behalf of the National Science Foundation NSF on October

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9811news/9811han.html (2015-06-02)
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  • LIGO Livingston Observatory News
    the services needed Additionally we are preparing the various labs for use once Detector installation begins early next year installing cable trays ordering furniture cabinets de ionized water system electrical test equipment and the like We are also setting up additional office spaces for visitors in anticipation that many guests and participants in gravitational wave research will visit us to join in the installation and commissioning activities New Student Employee at the LIGO Livingston Observatory Contributed by Mark Coles Slade Maurer joined our staff last week here at the LIGO Livingston Observatory Slade 21 is a senior at Southeastern Louisiana University SLU which is located in Hammond about 15 miles to the east of Livingston SLU is primarily an undergraduate institution with an enrollment of 15 000 Slade is majoring in computer science with a scientific concentration and he is minoring in math At SLU Slade has been maintaining the UNIX and LINUX systems He has been working with Prof Dan McCarthy a plasma physicist on the optimization of software which models non linear features of the magnetic field in a Tokamak reactor Slade has restructured the software and distributed it to run on a PC network of 22 Pentium TM boxes over a 100 megabit ethernet network He is currently applying to graduate schools to continue his studies in computer science His interests in this field include parallel distributed processing neural networks and problems in large scale data analysis At the LIGO Livingston Observatory Slade is assisting LIGO s systems administrator Larry Wallace with the support of the computer network Among Slade s hobbies are travelling sailing and enjoying sushi and other ethnic foods He has a Snark which he sails on Lake Pontchartrain Born in Maine Slade grew up in California New Jersey and Louisiana We welcome him

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9811news/9811liv.html (2015-06-02)
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  • LIGO Caltech News
    about 2000 nm The phase shifting is accomplished by piezoelectric transducers which push uniformly on the reference flat mount such that the cavity length between the reference and test piece changes by about two waves The custom software supplied with the WYKO combines the data from these snapshots and produces a map of the cavity shown here at right The variations seen in this plot are the combination of the test piece the reference flat and the air in between We are currently working to separate out the reference flat so that it may be subtracted from subsequent measurements of LIGO optics The Core Optics Components have been polished to better than 0 8 nanometers rms deviation from a perfect surface In larger terms that compares to slicing the earth at it s equator and grading the cut so that the standard deviation is only one inch from a perfectly flat plane These optics are very smooth They were measured at the polisher CSIRO Commonwealth Scientific and Industrial Research Organisation of Australia and some were measured at the National Institute of Standards and Technology We owe many thanks to both of these institutions for there excellent work and also for providing guidance in the art of metrology as we attempt something never done before to measure an optic coated at 1 064nm to within one nanometer rms Forty Meter Achieves Recycled Configuration Contributed by Bill Kells After the 40 meter interferometer was reconfigured for recycling in the Summer and Fall of 1997 first resonant servo locking was then achieved that December See our February 1998 newsletter for an earlier related article The successful operation closely followed the design and hardware modifications to the 40 meter facility implemented by Jennifer Logan as a post doctoral project in LIGO During 1998 under

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9811news/9811cit.html (2015-06-02)
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  • LIGO MIT News
    three HAMs or Horizontal Access Modules which are general purpose chambers allowing access through large openings next to the optics This equipment is configured in an L shape of 15 m length with a mid station in one arm to allow modulation frequency sidebands to fit comfortably The vacuum system had been just recently completed as was our new lab and the time for the transport and installation of the one to the other was now upon us A complete photographic slideshow awaits you below but hold on We re not finished with the set up yet The system which we have christened LASTI for LIGO Advanced System Test Interferometer will be used to develop and test components for future interferometers to be installed at the LIGO Observatories Because the physical interfaces are identical to those at the Observatories we can test isolation and suspension components as they will be installed at the Observatories and this is in fact our principal target for this installation The LIGO Scientific Collaboration Suspension Working Group is gearing this installation for the critical system tests and high sensitivity characterization of the next generation of isolation and suspension systems Of course we will consider any other way this test interferometer can help make LIGO work now or in the future And now for the fun part photos of the installation The only entrance to our new high bay that we could even come close to using was within one inch of the size of the incoming chambers and that was only after the main ports were taken off the chamber sides The rigging devised to bring in the components was imaginative and involved tipping and twisting the components with all possibilities tried in 3 D CAD first of course and then transfer from crane to

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9811news/9811mit.html (2015-06-02)
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  • LIGO Hanford Observatory News
    This background is the sound of atoms at work the steady rustling of the vibrating atoms in the mirrors the sound of violins generated as the suspension fibers recoil from their own vibrating atoms and the occasional fiberquakes due to sudden realignments of microscopic crystal boundaries in the suspension fibers Effectively the goal of the seismic isolation is to build the practical realization of an inertial frame an idealized concept since the days of Isaac Newton LIGO s seismic isolation was designed by scientists and engineers at LIGO and at HYTEC Inc in Los Alamos New Mexico Manufactured component by component in factories across the US and tested in labs here at the LIGO Hanford Observatory and at HYTEC the seismic isolation follows a basic stack design that has been used in test interferometers at Caltech and MIT The basic idea is to stack up strong stiff lightweight structural members interleaved with soft compliant shock absorbing springs all built to the very exacting standards of ultra high vacuum hardware It s also big as you can judge from the two photos here In Figure 1 at left Corey Gray stands outside a HAM chamber with some of the blue and steel colored structural members showing And in Figure 2 at right Rick Savage Haisheng Rong and again Corey the Men In White can be seen installing an optical table into the same HAM chamber While Caltech and Hanford team members assembled the stacks other groups have also been racing to get ready for the optics installation in January The University of Florida scientists teamed with LIGO scientists and engineers have been hard at work getting the mirrors and mirror suspension hardware ready for the New Year Team PSL Pre Stabilized Laser has busily prepared the injection source a 10W precision

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9812news/9812han.html (2015-06-02)
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  • LIGO Livingston Observatory News
    and commissioned All of the vacuum equipment has been installed and by year end it too should be completely commissioned Hensel Phelps Construction Company recently provided us with some very nice aerial photos of the Livingston Observatory taken by Aero Data Corporation of Baton Rouge Louisiana I thought you might enjoy seeing them Happy Holidays from the LIGO Livingston Observatory Staff This first picture at right shows the entire LIGO Livingston Observatory It was taken at an altitude of 14 500 feet using a Zeiss RMK TOP 15 survey camera These next views were taken at an altitude of 1200 feet using a LINHOF Aero Technika 4 x5 format film camera These two shots are of the corner station Next at left a view from the west arm looking east toward the corner station And then at right a view along the south arm of the interferometer LIGO Participates In Educational Outreach Day Contributed by Mark Coles The LIGO Livingston Observatory was a participant in the educational outreach day at the American Physical Society s Plasma Science Expo held November 19 in New Orleans LIGO staff members participating were Mark Coles Jonathan Kern and Bonnie Wascom Among the twenty seven

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9812news/9812liv.html (2015-06-02)
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  • LIGO Caltech News
    the photo at right is quite invulnerable to this noisy environment immune even to a 4 0 earthquake And most importantly we are achieving good results Small Contaminants Big Problems Optical contamination of the Core Optics by material outgassing particularly hydrocarbons is a serious issue for LIGO Because of the large optical circulating power we use even small contaminations can cause dramatically large optical absorption and scatter decreasing the sensitivity of the LIGO interferometer by a reduction in circulating power Further optical absorption deforms the curvature of the Core Optics and even induces a thermal lensing effect resulting in an overall performance degradation of the LIGO interferometer To avoid this LIGO has set a strict loss requirement of 10 ppm yr in scatter loss and one ppm yr in absorption loss The purpose of contamination studies is to make sure that any non optical materials LIGO plans to use do not induce losses exceeding the LIGO loss requirement We have three high finesse 30000 contamination test cavities qualified previously in vacuum under a continuous light illumination at 1064 nm with a power level comparable to that in LIGO Ringdown measuring total cavity loss and mode spacing measuring cavity absorption loss

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9812news/9812cit.html (2015-06-02)
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  • LIGO MIT News
    telescopic instrument for measuring the angle of a reflective surface Using precision adjustment fixtures the suspended optic is rotated in its cradle within the vacuum chamber until the autocollimator readout indicates it s hanging true to the nearest arcsecond The theodolite then also indicates the axial and lateral position of the mirror which must be accurate within millimeters In late November Ken Mason Myron McInnes and Matt Smith of MIT participated with Caltech and Hanford personnel in a highly successful alignment dry run in a test mass chamber at the Hanford site Figure 1 at left shows them measuring the orientation of the test mass mockup used for this experiment the aluminum disk in the background with four holes in it using the modified theodolite autocollimator visible in the foreground which was designed integrated and tested at MIT before being shipped to Hanford Once in operation LIGO must achieve and maintain alignment about three thousand times better than this to attain its target sensitivity and must also stabilize the mirror separation to better than a thousandth of an angstrom i e a ten billionth of a millimeter The sensing part determining whether the interferometer is on resonance and if its alignment is optimized in real time is handled by highly specialized length and alignment sensing photodetectors with a supporting cast of protection shutters power splitters beam handling telescopes filters and diagnostic sensors These components are integrated into ISC tables which are installed near the LIGO vacuum envelope near the four viewports which serve up the interferometer s main and auxiliary output beams Figure 2 at left shows Rana Adkikari first year grad student and Peter Fritschel research physicist putting the finishing touches on IOT7 the first of these ISC tables shortly before packing it in its padded crate for shipment

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9812news/9812mit.html (2015-06-02)
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