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  • LIGO Livingston Observatory News
    the partial pressure of hydrogen To help achieve this the beam tube steel is baked and cleaned to prevent any contamination of its inner surface Any accidental rupture of the vacuum venting in unfiltered air within the beam tube would be catastrophic The concrete enclosures therefore were designed to protect the beam tube from hunter s stray bullets or other accidental mishaps that could jeopardize the interferometer The enterprising people at Concrete Products of Washington saw an additional use for these protective enclosures About 40 additional enclosures were fabricated and buried to make a wine cellar for a commercial winery located in the Columbia River Basin wine country The first results of this use are now available Look for Terrablanca Merlot 1997 at a wine merchant near you There is an arch on the label Coastal Bridge Co the concrete enclosure fabricator in Louisiana has also fabricated an additional 12 enclosures which are available for purchase So far they have not been contacted by any Louisiana vineyards Even the beam tube itself seen in Figure 2 at right has found additional uses Chicago Bridge and Iron Co which fabricated and installed the entire beam tube fabricated one additional short test

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9805news/9805liv.html (2015-06-02)
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  • LIGO Caltech News
    be modified to allow statically linked binaries from DEC Unix to run on the LINUX system A second vendor Alta Technology offered to provide LIGO with static versions of this needed FFTW benchmark program using both floating point precision and double precision complex FFTs The results are shown in Figure 3 below right Gauging the results we see that for both the Sun and the Alpha peak performance for the FFTW occurs for very small data size order 32 complex data points The most likely reason for this is the number of data registers in the CPUs A sharp fall off begins at above 1024 data points tailing off at about 16384 sample points where the Alpha is delivering about 250 MFLOPS of FFT performance This is short of the earlier design estimates Those estimates suggested that working with million point FFTs would be optimal if the performance was flat in the region between 128K and 2048K samples The FFTs could be shortened to roughly 256K samples without modifying the underlying convolution algorithm and its performance for the optimal filtering techniques This is driven by the time the binary inspiral waveforms are in the interferometers most sensitive frequency band a 1 2 1 2 solar mass binary will be in initial LIGO s band for 70 seconds and by the significance of higher frequency structure in the waveforms to the detection process In this specific area the Alpha is delivering the best performance but only at the level of about 150 MFLOPS for FFTs down by a factor of 5 from peak performance The added cache size on the Alpha workstation helps maintain the large sample size performance to twice that of the Sun with its 2MB cache Clearly the larger cache is needed for mega point FFTs The Alpha workstation was also performance tested by the end to end group It gave the best showing of any computer tested by a factor of between two to three This demonstrates the tremendous numerical performance afforded by the Alpha CPU to a broad scope of problems The end to end model is not dominated by FFTs However there was a clear downside to using the Alpha workstation at least with the Redhat LINUX 5 0 operating system The Alpha port of LINUX was both incomplete many system header files were missing and unstable in its behavior and ability to compile system level code Redhat LINUX 5 1 is available and will soon be installed on the Alpha workstation It is hoped that this new version will fix many of the software problems encountered when using the Alpha Greater optimization of the GNU C compiler for this platform would also be extremely beneficial Microway has already dropped this unit s price by 25 percent A 633 MHz unit is now available and a 700 MHz system delivering over twice the integer and floating point performance has been announced for delivery the third quarter of 1998 The other Alpha vendor Alta Technology is

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9805news/9805cit.html (2015-06-02)
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  • LIGO MIT News
    at NATO in Brussels He was director of international affairs at the foundation from 1991 until last year when he resumed work as physics division director His photographs including Cibachrome work were shown here at the Corcoran Gallery of Art where he had one man shows and at the Troyer Fitzpatrick Lassman Gallery Dr Bardon was a native of Paris and a graduate of the Sorbonne He moved to New York in the 1950s and later received a doctorate in physics from Columbia University where he did research in high energy physics He published papers in that field His honors included the NSF Meritorious and Distinguished Service medals and two Presidential Awards He was a fellow of the American Association for the Advancement of Science and the American Physical Society Survivors include his wife Renate Bardon of McLean three sons Oliver Bardon of Boston Adrian Bardon of Amherst Mass and Roland Bardon of McLean a brother and a sister A Remembrance by Rainer Weiss All of us who interacted with Marcel have our own special recollections of him I remember him best from the earliest days of the LIGO project when it was still only a concept It is clear that Rich Isaacson had captured Marcel s imagination with gravitation as a subject of physics and not merely as a branch of mathematics Marcel had a strong conviction that a healthy physics program needed two components First solid work in established fields with ample scope for change in our present understanding of nature And secondly an element of risk taking that could cause a revolution in physics should it prove successful After a study of a long baseline gravitational wave interferometer system was proposed to the NSF and approved by peer review I met with Marcel who was supportive and

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9805news/9805mit.html (2015-06-02)
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  • LIGO Hanford Observatory News
    Suina and Lee Cardenas was putting the laser and its supporting optics and electronics through the final test phase at Caltech Just after Labor Day a bon voyage party was held at the Pasadena campus as the laser was shipped out and the Pre Stabilized Laser team headed off to Hanford The new laser is an all solid state device specially developed for LIGO by Lightwave Electronics It provides 10 Watts of output light in the near infrared 1 06 microns wavelength from a Nd YAG crystal that is pumped by several AlGaAs diode lasers The high power output crystal actually works as a power amplifier boosting the light injected from a smaller high precision Nd YAG laser This configuration is referred to as a MOPA or master oscillator power amplifier configuration The Caltech laser team has tamed the raw output of this laser using a variety of optical and electronics components to achieve remarkable levels of stability The end product of this effort is the pre stabilized laser or PSL Over the time scales that are crucial for gravitational wave detection of order 1 to 10 milliseconds the PSL intensity is stable to six significant figures and the PSL frequency is stable to 14 significant figures The partially assembled PSL can be seen in Figure 2 at right taken on September 14 The Lightwave laser is the optics package to the right at the far end of the enclosure Various PSL components can be seen in the foreground The principal frequency defining component a small Fabry Perot cavity encapsulated in a thermally stabilized vacuum chamber was not yet installed in the enclosure The laser was turned on later in the week that the photo in Figure 2 was taken The light from the Pre Stabilized Laser gets handed off to the Input Optics team from the University of Florida who will inject the beam into the vacuum system where their vibration isolated optics can further filter and stabilize the light For more on this see the next article below The HAM Has Landed During all this laser installation activity the Input Optics team was busy in the LHO Vacuum Assembly lab doing final construction of their optical assemblies But that story is slated for another day The HAM Has Landed Contributed by Fred Raab On Thursday July 23 I went out into the corner station to admire the completed First Article of the vibration isolation system for the HAM chambers HAM refers to a Horizontal Access Module a type of vacuum chamber which holds the input and output optics that inject laser light into the main LIGO interferometer and also receives output light from the interferometer As I viewed it the HAM optical table appeared to float steadily above its isolation system But a slight jarring of the system revealed that the apparently stiff layers of springs and steel wobbled like a bowl of jello LIGO interferometers require laser light that is highly purified compared to the light emitted

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/98678news/98678han.html (2015-06-02)
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  • LIGO Livingston Observatory News
    first in the X Arm End Station by mid May and then in the Y Arm End Station a few weeks later June saw the completion of Vacuum Equipment installation in the corner station pictured in Figure 3 at right and the installation of GNB 44 48 Gate Valves on the Y Arm Also during June a significant milestone was reached with the completion of CBI site installation of the Beam Tube with all field welds and helium leak testing completed Zero leaks were confirmed with a project total of 800 tube sections helium leak tested at the fabrication shops and 808 field girth seams leak tested in the field a testament to CBI s welding quality and pre testing visual inspections Towards the end of June direct Global Positioning Satellite GPS measurements were taken through the enclosure on five of the X Arm control supports the results indicating that no re adjustments were necessary Busy Summer By mid July all Vacuum Equipment had been aligned and installed and grouting work was set to begin Towards the end of the month the first accumulation reports came in and the results were most encouraging CBI completed the second global calibration on the X Arm on July 30 with monitoring by Residual Gas Analyzers on both modules The air signature reading on that arm was subsequently accepted In August CBI began pump down of the Y Arm The rough pumping was completed the turbo pumps were then connected to the Beam Tube and started Process System International PSI performed electrical and pressure testing in the X Arm End Station By mid month all Vacuum Equipment was installed aligned and grouted PSI meanwhile was anticipating the start of vacuum system pump down and helium leak testing In celebration of their hard work and

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/98678news/98678liv.html (2015-06-02)
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  • LIGO Caltech News
    mounted spring The vertical component of the force transmitted by the link is modulated by the changing link angles decreasing near the chosen working point by almost exactly the amount of the increase of the recall force of the stiff cantilever spring The result is that as increasing load drags down the load disk the recall force stays almost constant and the spring acts as an extremely soft one Simulations And Experimental Tests The GAS concept has been simulated and tested at Caltech The experimental setup built after the simulation is shown in Figures 2 3 and 4 below The contraption is built in Unistrut TM each blade is clamped between two disk brakes that allow the tuning of its inclination The counter inclined link is made with steel wire looped around a nail stuck in the tip of the blade Figure 2 below left shows the experimenters with their experimental setup Virginio Sannibale left Riccardo DeSalvo and Sandro Bertolini right Absent is Giancarlo Cella The Unistrut TM device is intended not as a real filter but purely to check the GAS principle Figure 3 next in line exhibits details of the experimental setup Note the big wrench in the upper right corner of the photo which is used to tune the blade s tilt when the disk brakes are released Note also one of the radial distance tuning screws top left acting on the disk brake base Figure 4 last in line is a side view of a blade Compare with the simulated shape of Figure 1 Some Results Despite the crudeness of the system this prototype completely validated the simulated model In Figure 5 at right the comparison between predicted and measured results is made Figure 5 The Vertical Resonant Frequency versus payload disk height for different radial positioning of the blades The left graph is simulated data and the right one is measured data The three measured data curves correspond to a progressive advancement of the blades by xx and xy mm Some Findings A resonant frequency minimum of 250 mHz with a load of 150 Kg 330lb could be achieved The frequency minima with GAS are several times wider than in a corresponding MAS case Additionally a much lower thermal sensitivity is calculated The mass and the perturbations of the magnets are eliminated The Tuning Mechanism The GAS strength can be simply tuned by changing the radial distance between the blade s base and the link point on the load disk by means of the horizontal set screws behind the support of each disk brake visible in Figure 2 The effect of this tuning is well visible in Figure 6 at left In a real filter the vertical resonant frequency would be factory pre set A dimensional tolerance of 0 5 mm is required to set the filter at 250 mHz Prototype Limitations And Future Developments The achievement of lower vertical resonant frequencies was impeded in the prototype by the slip and stick friction of the

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/98678news/98678cit.html (2015-06-02)
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  • LIGO MIT News
    language lab nervous frog research ROTC the model train club the central machine shop and our group all happily coexisting But in the coming months the building will be demolished to make room for a new computer science building to be designed by Frank Geary Meanwhile our new building NW17 at 175 Albany Street in Cambridge actually resembles Building 20 in its basic construction It was built early this century to house part of a large bread factory As Figure 2 at right reveals it s a three floor wooden frame building but with an attractive brick facing and nicely rebuilt interior Our group occupies all of the basement where our lab is located and parts of the upper two floors for our offices and public spaces The overall floor space is similar to what we had in Building 20 but the similarities end there The offices are air conditioned carpeted and hardwired for data Some though are a bit oddly shaped and feel a little prison like see Figure 3 at left We have a meeting room and kitchen and a space actually designed for our administrative support The lab space was laid out from scratch for our needs Overpressured HEPA filtered air feeds all the labs All the surfaces are fresh and clean so we can keep the spaces about as dust free as our procedures allow The high bay shown in Figure 4 at right is an especially important and wonderful part of the new lab It is planned to accommodate the new MIT Test Interferometer consisting of a LIGO Beam Splitter Chamber three Horizontal Access Module chambers and connecting tubes to form a 15m L shaped system As mentioned in earlier LIGO Newsletters this system will allow full scale suspension and isolation tests for advanced LIGO

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/98678news/98678mit.html (2015-06-02)
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  • LIGO The Editor's Page
    with a new look new and improved content and a renewed commitment to you our loyal readers to publish a new issue each and every month Hah Soon our humble little gazette will be as common on the breakfast tables of the world as artificially sweetened chocolate frosted jelly filled starch products If I seem a little giddy this month it s only because editing this issue of the newsletter has had an intoxicating effect on me You ll see what I mean as you read on High spirits and playfulness are rampant this edition Whackiness Zaniness and Kookookery too are much in evidence One way to tell is by the number of exclamation points strewn throughout the articles This issue has more exclamations than a Three Stooges film All my writers this month are shouting laughing hitching up their skirts and kilts and dancing on the tables all apparently bursting to apprise you of recent LIGO news Check out for starters Fred Raab s account of the Beam Tube bakeout at Hanford Notice how the headline First Module A Hot Success is fairly barked out at you And that same exuberant tone watutses through his whole story The man plainly needs tranquilizers Then zip over to Garilynn Billingsley s tale of the LIGO work going on at Caltech s Metrology lab The story barges in the door with a single shouted word Earthquake and the pace never relents But for the absolute zenith in sheer stuttering inarticulate excitement tip toe over to Gerry Stapfer s report on Livingston Louisiana s recent atypical weather I mean it s an article about weather right How interesting can that be The weather is what you talk about when you can t think of anything else to say But Gerry is so volcanic

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9811news/9811ep.html (2015-06-02)
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