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  • Page Two of LIGO Scientific Collaboration News
    Benno Willke was the coordinator and graciously hosted all the attendees ensuring that everyone had what they needed especially their email Above LSC meeting sessions underway inside the University of Hannover Below the atrium lobby registration desk and food trays In addition to the crowded slate of sessions three evening tours were available to see the GEO 600 site and the interferometer Close to two dozen people loaded on the bus each evening for the 20 minute ride to the observatory On the second evening of the conference everyone ate together as is the custom this time enjoying a delicious buffet of German and international favorites at the Maritim Grand Hotel The Maritim Grand Hotel In and around Hannover there were opportunities to enjoy the many sights and sounds of Germany A short walk from the University was the Wilhelm Busch Museum with its lush and serene surroundings The Wilhelm Busch Museum A bit further along were the breathtaking Herrenhausen Gardens where magnificent flowers fountains and sculpture dazzled the eye And just across the street was the inviting Berggarten The Herrenhausen Gardens and the Berggarten Located within the Berggarten sprawl is the Rain Forest House providing a replica environment of

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0312news/0312one2.html (2015-06-02)
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  • An E7 Special Report
    interferometer at the LIGO Livingston Observatory LLO was operated in a recombined but not recycled configuration While we have demonstrated the operation of the LLO interferometer in a power recycled configuration we are able to operate for longer time periods in the non recycled mode Seismic noise is significantly higher at Livingston than at Hanford and use of the non recycled mode reduces seismic sensitivity In addition a newly installed active compensation system was used to filter the large microseism present at LLO see our Winter 2001 LIGO newsletter for details At Hanford the two kilometer long interferometer was operated in a power recycled configuration while the site s second instrument the four kilometer long interferometer was operated in a recombined but not recycled configuration A new system to compensate for the tidal distortion of the earth s crust by the sun and moon was used to allow for extended continuous locking of the instruments Large levels of vibration were present at Hanford each weekday from approximately 7 00 am to 3 30 pm due to a building construction approximately 700 feet from the corner station Our machines were unavailable during these periods as expected There were also some high wind conditions and when wind speeds exceeded 25 30 miles per hour we were able to observe effects in our data The four kilometer interferometer used the new digital suspension controllers that will eventually be retrofitted into the other interferometers Microseism compensation for the Hanford interferometers was not yet available Figure 3 below shows the calibrated strain sensitivity of the three LIGO interferometers at the time of the E7 run Commissioning continues on all the interferometers and further improvements in noise performance are already observed The response of each interferometer was calibrated three separate times during the engineering run by injecting sine waves into the mirror actuators while sweeping the frequency Data Acquistion The data acquisition system continuously sampled data on 6544 channels from the two interferometers at Hanford and 1348 channels from the interferometer at Livingston Although a gravitational wave signal will be seen on a single channel many other channels are needed to supply information on the operation of interferometer components as well as its physical environment Each channel was sampled at a rate between 16 Hz and 16 kHz depending on the frequency range of interest for the given channel The resulting data rate was 4 7 MB s at Hanford and 2 7 MB s at Livingston The acquired data were stored on local disk caches of 8 5 TB at Hanford and 4 8 TB at Livingston and were made available for online data analysis The data were also copied to tape for archiving at the Caltech Center for Advanced Computing Research Data Monitoring Monitoring programs ran continuously to assist the operators and scientists in keeping tabs on the current interferometer status and to record state transitions and noise transients for use in later analysis Monitors run during the E7 included a summary of seismic

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0202news/0202spr.html (2015-06-02)
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  • LIGO Livingston Observatory News
    overview talks on the status of LIGO an update on LISA and a programmatic view from inside the NSF of gravitational wave related activities Typical Louisiana cuisine as seen below was the focus of that evening s activity featuring crawfish catfish pistolettes boudin and bread pudding We thank Leger s Catering of Baton Rouge for their excellent service during the meeting We would also like to thank Dennis Woltering and WWL TV New Orleans for their media coverage of this important event LLO Enjoys Visit from Professor Israel Quiros Contributed by Mark Coles Professor Israel Quiros of the Las Villas Central University in Santa Clara Cuba visited LIGO on March 27 to give a talk on Quintessence and Gravitational Waves One of the most exciting recent discoveries in cosmology is the existence of dark energy or quintessence This newly discovered feature is the source of about two thirds of the energy density of the universe A promising candidate responsible for this is a dynamical scalar field slowly rolling down its potential Prof Quiros addressed some recent models of the universe that include quintessence and considered its possibility to describe gravitational waves as signatures of the early universe Quiros s research mainly involves alternative theories of gravity Kaluza Klein gravity and branes and astrophysics dark energy quintessence models His graduate education was at Moscow State University 1983 1990 as a nuclear theorist but since 1995 he has worked in field theory He taught nuclear physics at the Institute for Nuclear Science and Technology in Havana and since 1993 he has been at Las Villas Central University in Santa Clara Cuba Professor Quiros gave a most interesting talk and toured the LIGO facility His visit was also an opportunity for us to learn about the scientific research environment in Cuba Professor Carl Brans of Loyola University of New Orleans was responsible for arranging the visit of Prof Quiros to LIGO Prof Brans s name is familiar to many as the author along with Robert Dicke of an alternative formulation of general relativity in which the gravitational constant is a function of some scalar field This scalar tensor theory of gravitation was the focus of Carl s graduate work under Dicke at Princeton LIGO s own Prof Rai Weiss was a post doctoral researcher in Dicke s group during these years Above Professors Rai Weiss and Carl Brans discuss the fine points of relativity Professor Quiros s visit to LIGO accompanied by Carl Brans was an opportunity for a reunion after many years In the photo above Rai Weiss at left and Carl Brans right are seen discoursing on the well known relativistic phenomenon that causes each of them as observed within their own reference frame to remain remarkably young while observing that the other person has aged considerably Third Annual Tree planting in Livingston Contributed by Mark Coles For a third consecutive year the LIGO Livingston Observatory LLO has participated in a reforestation program sponsored by the Louisiana Department of Forestry This

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0203news/0203liv.html (2015-06-02)
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  • LIGO MIT News
    interferometer data of significant sensitivity The LDAS MIT configuration is comprised of 16 PC s each with 1 1GHz AMD Athlon processor and 1GB RAM This clustered configuration of PC s running linux is often referred to as a beowulf cluster The system also includes a number of multi processor PC s serving as master and data conditioning nodes in the cluster as well as two quad processor SUN TM units that act as the frame data and database servers In its current configuration the LDAS MIT system offers a bit over 1TB of disk storage while it is equipped with a stand alone AIT 2 tape unit Here is a recent picture of the MIT cluster celebrating its ninth month Figure 1 LDAS beowulf cluster at MIT LDAS s primary role is to run astrophysical searches i e the algorithms optimized to look for specific astrophysical signatures in the gravitational wave channel of the interferometers At the same time and outside the LDAS cluster another SUN TM unit a Blade 1000 is used for performing analyses of the enviromental auxiliary and gravitational wave channels for diagnostic detector characterization and veto purposes This is the Data Monitoring Tool DMT software environment that may read frame data from as well as write database entries to the LDAS side Burst Search at LDAS MIT The Bursts Working Group of the LIGO Scientific Collaboration has undertaken the task of implementing the end to end Bursts analysis pipeline The group s main challenge is to prepare a pipeline able to detect an unmodeled possibly very weak signal to distinguish it from detector noise and to interpret the result in an astrophysically meaningful way There are several pieces that make up this challenge some highlights of which may be itemized in the following Data are brought in from the sites to the local LDAS cluster Bursts algorithms are then executed on the LDAS system for the identification of possible candidate events The algorithms currently implemented in LDAS are based on simple time domain filters Arnaud et al Daw or time frequency analysis starting with Fourier transforms of the time domain detector data Anderson et al Sylvestre Events are identified whenever the total power of the data in a frequency band of interest exceeds by some statistical significance the noise power or by looking in a more detailed way at the clustering of loud events in the time frequency plane Figure 2 A time frequency plane obtained from stacked up periodograms of the gravitation wave channel from the Hanford 2K detector during E7 Two clusters of loud events in this plane are identified with the two thin black rectangular boxes lying vertically at left and right in the figure Several line features horizontal stripes can be seen with most of them identified as harmonics of the 60Hz power lines This is the time frequency cluster method developed by Sylvestre Once identified the events time frequency features time stamp duration central frequency bandwidth as well as their

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0203news/0203mit.html (2015-06-02)
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  • LIGO Caltech News
    s my responsibility to make sure all these presentations are available on the web as soon as possible once the meeting has adjourned With over 150 presentations given during this past LSC the size and scope of these vital get togethers in ever increasing and so is the task of preparing each speaker s presentation for net access by all collaborators The first day or two of the conference is probably the easiest for me as the submittal of presentations is at first merely a trickle But each day the rate grows in intensity The trickle becomes a flow then a rush And I find that as the presentations elapse and the conference comes to a close what had been a steady stream now swells into a massive deluge After all the laptops have been closed the buffet tables cleared the coffee urns drained of their dregs and the last participant is on the plane back home I m surrounded by an ocean of overhead presentations all waiting to be posted urgently That s when my real work on the LSC begins the behind the scenes work the grunt work the dreaded Paper Work And that s when I shift

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0203news/0203cit.html (2015-06-02)
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  • LIGO Hanford Observatory News
    to Update Gladstone s LIGO Software Running a LIGO Earth Tide Calculator at Gladstone Processing LIGO Microseism Data in MS Excel Processing Microseism Differences Opening the Oyster and Finding the PERL Modeling the GHS Microseism Software using MATLAB Twenty Years of Wave Heights and Wind Speeds from Pacific Ocean Buoys Examining the Magnetic Field of the Earth in Southeastern Washington Writing Graphical Interfaces for Command Line Programs Composing an Improved Web Site for GHS Science Research Keeping the Wheels on the Bus the Life of a Project Administrator At left Topics of POWERPOINT presentations given by students on their projects top right integrated science students present methodology of a study of ocean wave activity over the last twenty years using buoy measurements found on the NOAA web site above live video projection allows community members to view interference fringes from a Michelson interferometer students built But how do you make the science and engineering of something like LIGO more than a virtual experience Mr Ingram developed a solution to a key problem for establishing broad participation by students back at the high school He realized that the three students who interned at LIGO each summer had developed hands on contact with instrumentation that grounded their ability to understand the data produced by this equipment They could provide some of this grounding to their student colleagues on research teams back at the school But how could that hands on feel be communicated to more students Ingram s solution was to devote a fraction of the student work to building demo instrumentation for the school so that everyone could get a chance to play It was a brilliant move because students could now get their hands onto equipment without any of the risks that might be involved with research grade instrumentation Still the intellectual environment of a research lab is worlds away from the school environment and we also wanted to immerse students into an authentic atmosphere So each year students spend a day visiting the LIGO Hanford Observatory to meet with scientists and engineers to get to know them and each year I make a couple of visits to Gladstone We also made a very important purchase for the classroom a phone with a good speaker that allows me to meet with students in their classroom every third week to discuss their research projects Using the web students can show me their work as we chat on the phone and plan how to solve problems they encounter We can quickly call in high powered technical expertise as needed with an e mail or a phone call So what has been the scientific output of the students Well when we started LIGO one of our requirements was to design actuation systems that would reduce the effect of the microseism on LIGO s interferometers The microseism is a shuddering ground motion with a period of eight seconds that corresponds to the largest ground velocity experienced in a quiet location like the Hanford site

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0205news/0205han.html (2015-06-02)
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  • LIGO Livingston Observatory News
    of the interferometer is expected to improve even further Figure 2 Late night commissioning activities at LLO The interferometer is seen here locked in a power recycled state This is indicated by the bright spots on the end test mass mirrors visible in the upper two quadrants of the left side projection display An intensity stabilization servo was also added to the pre stabilized laser control system by Flavio Nocera Peter King and Rich Abbott This system will result in a more stable laser power input to the interferometer This consistency of the laser power means that the circulating power in the mode cleaner is also more constant thus reducing the radiation pressure noise on the apparatus Otherwise variations in the radiation pressure causes the length of the mode cleaner to change This produces frequency noise as the laser attempts to vary the wavelength of the laser light to keep the mode cleaner in resonance This is the inner loop servo which stabilizes the intensity delivered to the mode cleaner A second outer loop servo which closes the loop around the output intensity of the mode cleaner will be implemented after S1 and this should result in yet further improvements The wave front sensor and its associated servo control loops on the anti symmetric port were brought into full operation by Gabriela Gonzalez of Louisiana State University LSU This sensor tracks the relative angular alignment of the interferometer with respect to its Fabry Perot arms It produces a servo control signal which is used to maintain the angular alignment of the anti symmetric port output the gravity wave signal at frequencies up to around 0 5 Hz An important finding has been that the alignment servo using this wave front sensor keeps the AS I signal which is not controlled directly by any servo bounded so that the saturation does not occur in the RF amplifiers as the light power is increased By precisely aligning the output beams of the interferometer at the output port the carrier contrast defect is reduced In simpler terms it stays dark because the output beams from each arm are held in a fixed relative alignment at the maximum destructive interference point This allows the laser power to be substantially increased resulting in a reduction in the interferometer noise at high frequency Figure 3 Composite photo of the layout of ISCT4 The various beam paths are indicated by red lines Wave Front Sensor 1 is visible in the upper right hand corner Another key improvement underway is the implementation of a piezo electric actuator system PEPI to minimize the disturbance on the interferometer due to ground motion exciting resonant modes in our vibration isolation stacks The new system being implemented by Joe Giaime of LSU Rana Adhikari and LSU graduate and soon to be Caltech graduate student Dan Busby is an enhancement to an early system Giaime and Adhikari implemented prior to the seventh Engineering Run E7 The new system uses a sophisticated digital control

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0205news/0205liv.html (2015-06-02)
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  • LIGO Caltech News
    as well as contributing to the program Thanks are also due to Gary Sanders and Ric DeSalvo for their work on the organization and program and to Veronica Kondrashov for constructing and maintaining the local conference web pages and for gathering and posting the conference talks The goal of the conference was to discuss the physics coverage that might be achieved considering that in the near future there will be interferometers both on Earth and in space as well as an array of resonant detectors all of whose sensitivity will improve thanks to the many ongoing research and development programs These goals were certainly met and then some starting with a stage setting talk by Giazotto followed by presentations from Tinto and Benacquista on Sources and by Arnaud and Cagnoli on the Angular Coverage and Optimal Configurations of Terrestrial and Space Based Detectors Talks by Kawamura and Vecchio discussed filling in the gap between terrestrial and space based detectors A series of talks described the status of present detectors of all varieties as well as results and lessons learned from the operation of these detectors These discussions included the results of the Japanese TAMA 300 LISM coincidence observations and data analysis presented by Sato Tagoshi and R Takahashi and Marka s presentation on the LIGO E7 run Stimulating sessions on Network Analysis and Data Exchange Organized by Mours and on Progress in Computing Simulation and Data Analysis organized by Lazzarini and Ricci marked the midpoint Following these sessions Saulson presented an interim summary entitled What have we learned so far Details about the work on all future detectors currently under study invoking the latest technologies and aspirations were presented by their advocates These were followed by several days worth of very technical talks on Lowering the Sensitivity Floor ranging from

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0205news/0205cit.html (2015-06-02)
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