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  • This Just In: Four Kilometer Cavity Lock at Livingston
    Livingston was locked in the TEoo mode for periods of about a quarter of an hour There were large amplitude fluctuations in the transmitted beam correlated with cavity optic axis pitch instabilities The lock is not robust as there is

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0101news/0101ep.html (2015-06-02)
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  • LIGO Hanford Observatory News
    the locking performance was not the result of one change but rather the sum of a large number of incremental changes many worked out in the months prior to the final push The servos which damp the angular modes of the suspended optics were switched from local sensors to optical levers The light levels on photodetectors had to be optimized to give large enough signals but not to saturate The time delays between the light and the electrical signals had to be tuned to give the correct phase shifts to modulation signals Electronic servo gains had to be adjusted dynamically as the interferometer came into resonance to compensate for the factor of several hundred higher light levels The sensors which hold the interferometer in optimal alignment after lock is obtained had to be tuned up and brought into operation The signals that are used by the control servos had to be understood over a wide range of configurations Each of these steps might require hours sometimes days of careful experimentation to pinpoint a problem then the added time needed for hardware and software changes to implement a fix and then still more hours of testing and understanding of the system after changes are made Not to mention of course a few dead ends to meander down LIGO Discovers Moon and Sun Contributed by Fred Raab and Hugh Radkins LIGO detected its first astronomical objects last November during a week long engineering run at the LIGO Hanford Observatory Okay so maybe the Moon and Sun were pretty well known already And no we did not detect the spacetime curvature from these objects directly with our laser beams And no it won t pay the bills But as a Tri Cities Astronomy Club member pointed out It s like the first dollar bill taken in by a new business Frame the data and hang it on the wall The first week long data record from the Hanford 2 km interferometer clearly showed the Earth Tide the stretching and shrinking of Earth s crust under the gravitational forces from the Moon and the Sun Roughly twice a day the surface of the Earth s crust rises and falls a few centimeters This motion is not easily detectable by LIGO which measures the distances along its horizontal arms as perpendicular to vertical as they can be on a roundish planet But as the Earth s crust bulges upward it also stretches horizontally Think about drawing a picture of LIGO s arms on top of an inflated balloon and then squeezing the sides of the balloon As the LIGO Observatory drawing rises and falls it also stretches and shrinks Note that each piece of the drawing stays fixed on the surface of the balloon as it stretches That tidal stretching of the Earth s crust causes the 2 km distance between the midstations and the corner station of the observatory to change by tenths of a millimeter a huge distance on the scale of LIGO

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0101news/0101han.html (2015-06-02)
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  • LIGO Livingston Observatory News
    end mirror The optic can be seen in the center of the picture It is dimly illuminated by the light sources within the position actuators the OSEM s along its periphery The laser beam is the bright spot centered in the top half of the image It has been deliberately steered onto the ETM telescope support tube so as to be easily seen Then at right is an image of ITMx the input mirror of the Fabry Perot cavity along the X arm The camera view is looking in the direction of the input laser beam The input optic can be seen in the bottom half of the picture dimly illuminated by the positioning actuators The return beam reflected from the end mirror is the bright spot centered in the top half of the image where it has been deliberately projected onto the optic s support structure just above and to the left of the optic The vertical object to the right of ITMx is the beam splitter suspension structure All in all it was a great way to start the New Year LIGO Educates INTECH Teachers Contributed by Guest Author Monica Ballay of Denham Springs High School During the week of November 13 17 2000 twenty one teachers from Livingston Parish schools participated in an INTECH training program INTECH instructs teachers on ways to incorporate technology in the classroom using a variety of methods As part of the training the teachers were involved in a field trip to the LIGO facility in Livingston Louisiana Their purpose was to study gravity and understand how it shapes the universe The LIGO facility in Livingston is the largest ground based science observatory in the U S and is one of a duo of such installations the other is located in Hanford Washington Funding for this gravity wave search comes strictly from grants provided by the National Science Foundation and is conducted in partnership with Caltech and MIT One of the goals of LIGO is to be a resource center for educators students parents and the community Dr Mark Coles head of the LIGO Livingston Observatory says that a science museum is in the future construction plans There is also a grant that will permit funding of a twenty inch telescope which will be accessible to the public over the web offering the ability to take pictures of stars and solar activity Also in the plans for the future is a 175 seat auditorium to house large groups for touring LIGO is currently conducting tours for small groups and you can access that information from any of their websites Livingston Hanford Caltech or MIT There are many activities for small group involvement Groups can experience first hand what many have come from around the world to see Several scientific models are on display for examining and hands on manipulation Also available is an observation deck so you can see the unique layout of the observatory Groups can also paint murals on the outside

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0101news/0101liv.html (2015-06-02)
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  • LIGO Caltech News
    Pennsylvania State University the University of Texas at Brownsville the Australian National University in Canberra and the LIGO Laboratory Data and Computing Group at Caltech Now approximately six months later we have successfully completed our second MDC This one was specifically targeted at validation of the parallel optimal Wiener filtering algorithms that constitute the basis of the search strategy for chirp signals embedded in the interferometer noise This latest activity involved researchers from the University of Wisconsin at Milwaukee UWM and the Data and Computing Group at Caltech This latest MDC proved that the data analysis software system consisting of C data management and parallel processing code based on the Message Passing Interface MPI standard written at Caltech could be successfully integrated with a set of C libraries as dynamically loaded shared objects developed principally at UWM The MDC was the culmination of over half a year of intense collaboration among approximately a dozen people The main component of the challenge was to demonstrate that the pipeline analysis design we developed could be run around the clock to process up to 1 000 different waveforms templates per node representing various mass pairs for chirp signals The datastream used in the analysis was produced with a simulation program so that its statistical properties could be precisely controlled and known a priori Representative waveforms were then embedded in this data stream so as to test the signal search code The equivalent to over three days of data were processed using just nine nodes of our cluster of PCs This analysis required performing several million Fast Fourier Transforms FFTs each of order half a million data points The code has not yet been optimized and factors of four improvement are expected to be possible in the C libraries To learn more about the LDAS system being developed at Caltech follow this link There you will find interesting links to the joint software projects involving LDAS and the LSC which are at the core of these Mock Data Challenges follow the link to LDAS LSC Software Development in the bulleted list To read about the actual trials and tribulations of the January MDC you can find interesting electronic log book entries here Follow the read only instructions to access the Mock Data Challenge Group Log link near the bottom of the page to review the diaries for January 11th through January 19th 2001 Finally here are a few candid shots to enjoy taken at the end of our MDC End to End E2E Simulation Helps LIGO Scientists Achieve and Characterize Lock Acqusition of the Hanford 2 km Interferometer Contributed by Hiro Yamamoto A software package has been under development over the past four years to assist us in modeling the LIGO interferometer hardware This is a time domain model written in C with GUI front end and it can simulate a wide variety of optical configurations Scientists can use this software to generate a time series of data that can be compared to the

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0101news/0101cit.html (2015-06-02)
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  • LIGO Hanford Observatory News
    shipping containers for the ride to the Hanford Observatory Once arrived the process of cleaning outfitting and suspending the mirrors begins Special fixturing is used to attach magnets for suspension actuators and guides for the suspension wires The mirrors are balanced on a loop of wire 1 100th of an inch thick to a specified angle with an accuracy of a few minutes of arc After gluing the suspension guides the mirrors are vacuum baked and certified pure by residual gas analysis A final wet cleaning is then followed by insertion into the vacuum prepped suspension cage Even in the clean air of our optics lab where dust levels are typically kept below 1 particle cup of air an occasional particle will land on a mirror In the photo at right above optics engineer Doug Cook does a last touch up dry cleaning before the optic leaves the lab using a blast of carbon dioxide snow to remove particles followed by an ionization treatment to neutralize static charge on the mirror and keep particles off the surface The mirror module is quickly wrapped for transport to the vacuum chamber area Above The photo at left shows the mirror module at its final destination vacuum chamber BSC1 Engineers Mark Lubinski left and Doug Cook are sliding the mirror module along a Teflon Highway which lessens the friction allowing for a smoother ride The structure is placed onto temporary fixturing which allows us to position it precisely under the optics table getting the translational rotational and axial coordinates just right Once the module is secured to the optics table the mirror is released from its safety stops and then precision aligned by adjusting a series of permanent magnets to achieve the final pitch and yaw angles Engineer Hugh Radkins shown in the

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0102news/0102han.html (2015-06-02)
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  • LIGO Livingston Observatory News
    within the cavity Two brief stretches are visible in the figure where the light level falls to a low level indicating that the cavity is out of lock These are apparent at the left and right sides of the figure The red and green traces indicate the maximum and minimum values of the transmitted light and the gray trace is the average level We are now trying to understand the fluctuations between the minimum and maximum values observed during lock We repeated this procedure on the Y arm Using the experience gained locking the X arm we were able to lock the Y arm almost immediately once we put light in the cavity This involved an extra optic because the light reflected off the beam splitter before entering the Fabry Perot cavity We are now using the data obtained from locking the cavities to investigate the sources of noise in the laser the environmental and seismic noise and the controls which align the interferometer mirrors and condition the light Our next step is to recombine the two beams to form a Michelson interferometer with Fabry Perot arms Stay tuned for further developments Scouts Do Good Deed for LIGO Contributed by Mark Coles Last January 27 the Livingston Parish Cub Scout Pack 80 and Boy Scout Troop 156 planted 1000 cypress seedlings on the grounds of the LIGO Livingston Observatory Approximately 40 boys and their parents arrived at 7 am on a drizzly Saturday morning to plant the trees and by about 10 30 am all 1000 were planted This is the second year in a row that the observatory has had cypress seedlings planted and the second time that Scout Troop 156 has planted them Louisiana state makes the seedlings available through the state sponsored cypress re forestation program Each year the program distributes over 300 000 cypress seedlings statewide to be planted as part of re forestation and erosion control projects Since cypress roots spread out along the surface of the earth and love to get their feet wet they are excellent for erosion control Control of the soil motion along the borrow pits paralleling the 2 5 mile long arms of the interferometer is of particular concern for us so we found this partnering with the state forestry department and the local Boy Scout and Cub Scout organizations to be wonderfully advantageous for everyone The trees were planted along the west arm the X arm of the interferometer starting at the mid station and working out in either direction In about 15 years this area should be beautiful We plan to continue this program in the future creating a legacy for LIGO which should be a wonderful resource in the years to come After a 2 5 mile hike back to the observatory corner station the boys and their parents enjoyed hot dogs on the grill chips and sodas They ll all be back for an evening tour of LIGO later this spring Construction Starts Up Again in

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0102news/0102liv.html (2015-06-02)
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  • LIGO Caltech News
    saw no stakes When I asked the surveyor where the stakes were we realized that all of the stakes had been knocked out So I asked him if he really staked out this area or was he bluffing He insisted that someone must have knocked out the stakes I wondered who would be crazy enough to knock out stakes in the middle of the woods After restaking lo and behold some were again knocked out Who could it be Later in the week while with the surveyor we saw a cow charging a stake Apparently it was the orange color of the flag on the stakes that was ticking off the cows They were the culprits Needless to say no more red or orange flags were used at the Livingston site Over the past twelve years what s the funniest story or memory you have from LIGO Well as part of my default position one time I was called into Bill Althouse s office in the presence of Rai Weiss and I learned that in order to remove water vapor pressure in the beam tube the tube would have to be baked So I asked what has this to do with me Their answer was my assignment go and find the cheapest way to insulate the beam tube Returning to my office I called the Owen s Corning Research Lab in Houston Texas at the end of their day Of course I told the man about the project and what we were trying to find etc I then told them I was looking to insulate a tube and in the cheapest way When I told him it was a tube 16 kilometers long and 4 feet in diameter I suddenly had his attention He rapidly asked me several questions What s inside the tube Velocity of materials flowing in the tube Temperature Etc I said Wait a minute there s nothing inside What do you mean nothing Absolutely nothing empty He called a few guys into his office and said Hey come listen to this guy He wants to insulate a 16 kilometer tube full of nothing and doesn t know how much it s going to cost him One of the guys in his office asked What s this project all about I don t know some kind of fu fu government project Sounds like they want to catch gravity waves and look for a black hole And from then on it just got more and more hilarious you see these guys didn t realize they hadn t muted the call I could hear the whole exchange He later called back and apologized for making nasty comments I said that I was paid to do this and it was indeed a serious project The man at Corning felt so sorry for me that he came to Los Angeles and helped me cost out the insulations for the beam tube I m almost afraid to ask but what about your

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0102news/0102cit.html (2015-06-02)
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  • LIGO MIT News
    research work has centered around the physics of MACRO the Monopole Astrophysics and Cosmic Ray Observatory located in the Gran Sasso Laboratories in Italy He has searched for magnetic monopoles nuclearites as well as for neutrinos of potentially astrophysical origin or decaying from cosmic ray interaction products in the atmosphere Besides learning more about how the instrument works Erik s interests in LIGO are centered in data analyses that will look for gravitational radiation during bursting episodes in the universe or as a stochastic background Gregg Harry has joined the MIT LIGO group to work on the LIGO Advanced System Test Interferometer LASTI and to continue work on thermal noise Gregg has been in this field for some time having done his PhD research with Ho Jung Paik at Maryland and having just finished a postdoc with Peter Saulson at Syracuse he started with a undergrad degree from Caltech He has interests in the astrophysics of gravitational radiation experience with acoustic GW detectors and has a specific interest and expertise in thermal noise Among other things Gregg will perform experiments to study the mechanical losses in coatings on mirrors and help put LASTI together Keith Bayer joins us to help

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0102news/0102mit.html (2015-06-02)
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