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  • LIGO MIT News
    that looks to be a very effective way to quiet down the seismic noise troubling us It has a variety of virtues it is designed to address the low frequency end of the spectrum from 0 1 to 10 Hz and will cut down not only on the stuff that bothers us at a few Hz but will also make the lower frequency demands on the suspension actuators smaller it can be installed in LIGO now without any significant disruption to the already installed interferometer it can stay in place through the shift from initial LIGO to Advanced LIGO so is an investment in the future and it is already well developed Once we identified the difficulty with the seismic noise we put development of the pre isolator on the proverbial front burner with the objective of getting it installed as quickly as possible The development of the concept and a realization using a hydraulic actuator has come from our collaborators at Stanford Take a look at this Work on Hydraulics document for greater detail We are also pursuing a design with electromagnetic actuators at MIT We are now at the point of putting together some of the prototypes for a test we will perform of the LASTI installation at MIT Some photos below show where we are To briefly describe the design the LIGO Seismic Isolation is supported upon four blue piers even though they have come out as gray in the left side illustration above In the initial LIGO design scissors jacks and translation tables allow some adjustment of the quasi static position of the seismic isolation and optics attached to it On the end test masses there is also a fine actuator designed for slow corrections tidal microseismic along the optical path These are currently being extended to use at higher frequencies as a quick and remarkably successful means to reduce the excess noise The pre isolator design calls for removal of the scissors jack translation table and some other hardware between the top of the blue piers and the actual structure of the seismic isolation shown in the middle illustration above and its replacement with the new pre isolator one at each of the four corners This pre isolator has to support the very significant weight of the seismic isolation system so some very substantial springs are needed to off load this weight The two photos below show prototype springs In the left side image you can see that the spring has clockwise and counterclockwise segments to eliminate torques upon extension A very nice clean alternative design which we ll use from here onward is shown in the image at right This machined spring is easier to make reliably and is very pretty to boot The mechanical design of the structure from Ken Mason at MIT along with the rest of the Seismic team uses two springs at a 60 degree angle to achieve its purpose as shown in the next photo below Ken admits this

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0207news/0207mit.html (2015-06-02)
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  • LIGO Livingston Observatory News
    Tina Perez an undergraduate student at the University of Texas Brownsville Texas Left Edrick Preddie an undergraduate student at Southern University Baton Rouge Louisiana Right William Quarles an undergraduate student at James Madison University Harrisonburg Virginia Left Andrew Weber an undergraduate at the University of Maryland College Park Maryland Right Mark Sauerwein a graduate student at LSU Baton Rouge Louisiana Left Jennifer Tu an undergraduate at MIT Cambridge Massachusetts Right Eric Villarino an undergraduate at University of Texas Brownsville Texas The students are housed at Southeastern Louisiana University We are very grateful to the administration for making the Southeastern Oaks student housing complex available to our students for the fourth consecutive year This makes it possible for the students to live in a campus environment with access to gymnasium pool library and the social life available in and around a major college campus See this web page by Robert Johnston a student participant from UT Brownsville for a nice commentary on housing the surrounding environment and description of the work environment from a student perspective Not far from LLO there are many fascinating places to visit Above a scene during a tour of Honey Island swamp While each of the students has the opportunity for one on one interaction with a mentor we have also organized an extensive series of summer lectures covering the physics of LIGO astrophysical sources of gravity waves and technical topics associated with the design commissioning and operation of LIGO This year we have also scheduled two field trips in association with these lectures to the 2 GeV synchrotron light source at LSU which is used to characterize the impurities in sapphire test samples that may be used to form the optics of an upgraded LIGO interferometer and to the ALLEGRO resonant bar gravity wave detector

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0207news/0207liv.html (2015-06-02)
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  • LIGO Caltech News
    taking a sabbatical and now his dream has become reality Beginning in August Stan will enjoy the beauty of Australia as he works at the Australian National University while playing tourist in the land of Oz Before he left many of Stan s LIGO colleagues gathered in a farewell celebration at the Crown City Brewery in Pasadena to say so long and to wish Stan well Though gone for only

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0207news/0207cit.html (2015-06-02)
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  • An S1 Special Report
    to replace the optic into its original position and alignment At the same time we needed to analyze this newly discovered failure mode of the interferometer and take appropriate actions to ensure a similar accident would not occur again S1 would have to be postponed for approximately two months to complete repairs Making The Best of the Situation Delaying S1 was a huge disappointment There was no way to avoid the inconvenience to several scientists already on their way to the observatories But we could help minimize the impact to the commissioning program by scrambling to reschedule significant commissioning work on the remaining working interferometers At Hanford we decided to implement the common mode servo on H1 the 4 km interferometer The common mode servo is the last and most crucial of the control systems that reduce the laser frequency noise Without a working common mode servo the H1 interferometer would not have the scientific reach of H2 or L1 the 4 km interferometer at Livingston both of which had working common mode servos We expected that H1 would not be scientifically important for S1 but that the run would test reliability of H1 as we had done for the other interferometers during earlier engineering runs With a two month delay of S1 it looked possible that we could get the common mode servo working on H1 allowing it to have a similar scientific reach to the other interferometers Well it all worked out Repairs were completed to H2 Preliminary modifications to hardware and software were put in place to prevent similar accidents in the future We were able to get the common mode servo working on H1 Unfortunately we did not have much time to tune the interferometers for operating stability In fact delivering working machines for the rescheduled run required an all nighter up to the start of the run But everything was working when the curtain came up on S1 at the LIGO Hanford Observatory at 8 00am PDT on August 23 S1 Performance at Hanford A key measure of performance for the interferometers is the fraction of time during the run that each machine was in science mode that is ready to observe a possible astrophysical event We call this fraction the duty cycle of the machine Ideally each machine would have a duty cycle of one hundred percent so it would always be available to make an uncompromised detection of an astrophysical event In the real world however the duty cycle is limited by events that cause the machine to lose lock by the time it takes the machine to lock again by the time needed to tune up alignments or other operating parameters that can drift during the run and by environmental conditions that make controlling the interferometers unlikely or impossible We were able to keep H1 in science mode for 58 percent of the S1 run and H2 was in science mode for 73 percent These are excellent results considering that we did

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0209news/0209s1r1.html (2015-06-02)
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  • LIGO Hanford Observatory News
    really challenge the students Students with more experience can then use such databases in their studies Fred holds a copy of Ocean Tides on the Northern Pacific Coast 1995 2001 surrounded by the students who produced it This year the students in Integrated Science have produced a study entitled Ocean Tides on the Northern Pacific Coast 1995 2001 It s the book I am holding in the photo above taken with the students who produced it Earth tides stretch the planet s crust due to gravity from the sun and moon and LIGO could not work unless we removed the effect of these distortions In 1999 a Caltech freshmen Eric Morganson analyzed the problem for us during his summer internship at the observatory Incidentally that was also the first year of our partnership with Gladstone High School Eric wrote a program that we use today to remove the huge effects of the earth tide from our interferometers Basically we command actuators in our end and mid stations to move the vibration isolation systems and mirrors according to Eric s program so that the mirrors will stay a constant distance from the mirrors in the corner station This procedure is good enough to remove 80 to 90 percent of the tidal effects from our interferometers whether or not they are in lock and we use feedback to tune out the remainder when the interferometers are in lock Back in 1999 we made the decision not to include the well known ocean tides in Eric s tide model as a compromise to keep things simple and just good enough Now we are becoming interested in including the effect of ocean tides which cause a depression of the earth s crust and also a gravitational tug coming from the coast The new student database created by downloading data from tidal monitoring stations and using a program for tabulating trending and plotting the data will become a reference database for improving this system Physics students at work In Physics class I spent time roaming between different student projects In the photo at left above students are investigating properties of masses and springs and trying to capture acceleration data on a laptop computer If successful we will feature their work in an exhibit at the observatory that demonstrates how vibration isolation works I also helped other students seen at right above understand the basic principles of FM radio transmission and reception so they can build a computer simulation of this process which has similarities to LIGO fringe detection techniques Above A handheld spectroscope allows Chemistry students easy viewing of the atomic spectra of mercury atoms The topic of Chemistry class was how spectroscopy the study of how different colors of light interact with atoms and molecules is used to understand the properties of matter I brought along a small plastic spectroscope developed for Project Astro to let students view atomic spectra from the mercury atoms in the fluorescent lamps in the classroom as seen in

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0212news/0212han.html (2015-06-02)
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  • LIGO Livingston Observatory News
    optimal way to present the various data needed to maintain the interferometer in stable operation In the above picture video images of the light reflecting from various suspended optics appear on monitors in the upper right real time control signals generated by the interferometer appear in the large projected image on the right hand side of the front wall DMT displays of four interferometer figures of merit are projected on the left and a suite of additional control and data signals appear on the computer monitors in the foreground We were able to maintain the interferometer in stable operation during the run although not in high sensitivity mode enabling the common mode servo We also identified several valuable improvements and implemented some bug fixes in DMT software during the run The data was recorded and will be available on disk so that further improvements can be made prior to the next mini run scheduled for mid December at Hanford Above Patrick Sutton Penn State University evaluates the Rayleigh Monitor a data monitoring tool he developed which examines departures from Gaussianity of various parameters of the interferometer This brief M1 run gave us the opportunity to plan and evaluate a strategy that will be most helpful to us during the two month long Second Science Run S2 scheduled to begin in February 2003 Hurricanes Threatened LIGO Livingston Observatory Contributed by Gerry Stapfer A more alarming headline would have been if the Livingston Observatory had been actually damaged by the destructive events Happily the pair of hurricanes that swept through our region in mid autumn neatly bypassed us here at LLO The first one Isidore missed us to the east a week later the second Lili veered to the west Above Satellite view of Hurricane Isidore Hurricane Isidore approached the Louisiana coast as a Categor Four Hurricane Just before landfall it appeared to be heading on a path right over the LIGO site Fortunately for us it veered to the east and weakened to a Category Two Hurricane as it reached land Below Path of destruction There was significant damage to the west of Baton Rouge mostly from the wind Though we were lucky this time we did learn and have the chance to practice just what to do when an event such as an approaching hurricane threatens the observatory Fortunately we had a Hurricane Preparation Plan to guide us in the correct steps to shut down and secure the observatory The plan is structured into several sections such as General Computing Computers CDS LDAS Computers Lasers and Vacuum Equipment The rationale for shutting down the computers is to prevent possible damage in case of extended power failures or low voltage conditions The other area of concern was the vacuum system in particular the beam tubes which we isolated from the remaining vacuum equipment by closing the 48 inch diameter gate valves The Plan served as a checklist to assure that all of the vital portions of the observatory were protected The

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0212news/0212liv.html (2015-06-02)
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  • LIGO Caltech News
    education role as the first and often times last physics teacher for most students Recognition of these dedicated physics teachers and professionals has grown through several annual awards presented by the AAPT The first AAPT award established was the Oersted Medal given in recognition for notable contributions to the teaching of physics Its first recipient William S Franklin received the medal posthumously in 1936 A man bristling with energy in his lifetime Franklin had boasted that the teaching of physics was the greatest fun in the world Being chosen to give the annual Richtmyer Memorial Lecture is an honor that began in 1940 This lectureship is in memory of Floyd Richtmyer who had broadly influenced the development of physics in America Topics for the lecture are selected in which Richtmyer would have found interest were he still alive Given at the winter meeting it is presented to a large audience of members of the American Physical Society as well as the AAPT In 1952 the Distinguished Service Citations were initiated in recognition of physics teachers or other contributors to physics education By 1963 the Millikan Lecture Award was added at the yearly summer meetings Recognizing an individual for notable and creative contributions to the teaching of physics the first lecture awardee was Paul Klopsteg By 1966 a medal was designed to be awarded to each winning lecturer In 1990 another significant source of recognition in the field of physics was established by the AAPT The Paul Klopsteg Lectureship honors Klopsteg as a founder former AAPT President and long time active member of the organization The lecture is featured at the summer meeting and is given on a topic of current significance of general interest to a non specialist audience At the Summer 2002 AAPT meeting LIGO Director Barry Barish received the Paul Klopsteg Lectureship award and delivered the keynote speech entitled Catching the Waves with LIGO As a LIGO employee I heard about the event during a casual lunch break conversation Interested I sought an interview with Barish with the idea of reporting the story in the LIGO Newsletter Extremely reluctant to be spotlighted for the honor itself Barish finally conceded to the interview when tempted with the possibility of discussing physics education a subject about which he becomes avid and radiant During our talk Barish chatted animatedly about physics as a foundational science the challenge of introducing students to the subject in an appealing way that will seize their interest and imagination and about organizations like the AAPT which has done so much to promote the importance of physics instruction Asked to describe the honor of receiving the Klopsteg Lectureship Barish downplayed any personal merit for the award More important he said was the opportunity to speak before such a fantastic audience of interested teachers It was this attitude of deep appreciation for science and physics teachers that showcased Barry Barish s true passion inspiring students with the excitement of scientific research and discovery And while there are challenges

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0212news/0212cit.html (2015-06-02)
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  • Special Report on GWDAW
    Seated to the left of Barish is Albert Lazzarini of LIGO Next photo Nobuyuki Kanda and Barry Barish shake hands as Masa Katsu Fujimoto and Yoshihide Kozai smile their approval of the new understanding The initial effort will focus on joint analysis of a 9 plus hour segment of coincident data taken during LIGO s S1 and TAMA s DT7 runs in August September 2002 This data set constitutes a testbed for prototyping joint analysis approaches Plans are also being made to run simultaneously during the upcoming two month long LIGO S2 and TAMA DT8 runs in February April 2003 To promote close cooperation and exchange of information and ideas for this activity a small working group of five individuals each from the LSC and TAMA has been established The working group includes the following people Masaki Ando University of Tokyo Patrick Brady University of Wisconsin Milwaukee Sam Finn Pennsylvania State University Nobuyuki Kanda Osaka City University Erik Katsavounidis MIT Albert Lazzarini Caltech Hideyuki Tagoshi Osaka University Ryutaro Takahashi National Astronomical Observatory of Japan Daisuke Tatsumi National Astronomical Observatory of Japan Peter Saulson Syracuse University The initial searches to be conducted in collaboration will target unmodeled signals from bursts or

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/0212news/0212spr.html (2015-06-02)
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