ALLEGRO:status Dec 2004

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ALLEGROstatus Dec 2004

• Warren Johnson, Bill Hamilton, Peter Zhang,
  Andrew Weber, Damon Nettles, Jon Hanson,
• Mark Burgamy, Jordan Weaver
• Louisiana State University
• Ho Jung Paik, Vol Moody, Andrew Weber
• University of Maryland
• Siong Heng
• Glasgow

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ALLEGRO at LSU
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Unique Features

• Near an interferometer (LIGO Livingston
  Observatory)
• Able to rotate
• Very low rate of
• non-Gaussian
• noise.

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ALLEGRO schematic
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Goals of Observing Program

• Search for bursts, at higher sensitivity, in
  collaboration with IGEC and LIGO.
• Search for high frequency stochastic background,
  in collaboration with LIGO Livingston. (Antenna
  rotation allows a unique experiment chopping any
  stochastic signal. )
• (Inspiral sources included in bursts?)
• (CW searches no longer competitive?)

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Observing this year

• (Had trouble with cryogenics in 2002 and 2003.)
• Latest attempt at a fix was finished Dec 2003.
• Worked! Running continuously since Feb 13, 2004.
• Rotated to IGEC orientation (parallel to European
  bars) on May 5, 2004.
• So now have gt 200 days available for comparison
  with NAUTILUS, EXPLORER, and AURIGA.
• Duty factor gt95 and noise improved.

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Noise improved
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Excellent stability in 2004
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New reliable calibrator

• One plate of capacitor is tightly coupled to bar.
• Other plate is weakly coupled to the bar, so acts
  like a free mass.
• Both plates electrically isolated.

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Result

• We now have a reliable method of absolute
  calibration of the detector response.
• Have benefitted greatly from the strong
  collaboration with Loyola and LSC.
• Martin McHugh giving paper on calibration later
  at GWDAW.

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Next step burst analysis, in coincidence with
IGEC

• Need new burst filters, to make best use of the
  high bandwidth, and to remove the lines. Nearly
  finished.
• Since the 2 detectors of the Rome Group have also
  been operating for most of last 6 months
• We hope that IGEC can reconstitute itself,
  agree on a method of data analysis, and confirm
  or deny the ROG indications of GW bursts from
  the galactic disk.

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Stochastic Analysis

• Have used the S2 run data as a complete shakedown
  for all procedures. Have learned many lessons.
• The regular stochastic-ALLEGRO telecon has been a
  crucial, and successful, method to collaborate
  with the LSC.
• Loyola John Whelan and Martin McHugh
• WSU Sukanta Bose
• Glasgow Harry Ward
• Cardiff Joe Romano
• Status talk by Whelan later at GWDAW

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Wp9
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Wp11
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Wp15
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Underway construction and tests of new two-mode
Maryland transducer, with double SQUID
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End
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Exploded views showing components
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Progress of UM transducer construction

• Krishna Y. Venkateswara, M. Vol Moody, and Ho
  Jung Paik
• Department of Physics
• University of Maryland, College Park
• December, 2004

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Niobium mass assembly

• The diaphragms for m2 and m3 have been machined
  to 0.092 and 0.018, respectively
• At 300 K, the frequencies are measured to be f2
  880 Hz (with the rim mass extrapolated to the
  antenna mass) and f3 1007 Hz. At 4 K, f2 is
  expected to increase to 917 Hz.
• f3 is uncertain due to the stress from machining.
  After heat-treatment, the final mechanical
  tuning will be done by electropolishing.
• The frequencies and Qs will be measured as a
  function of ? before and after the
  electropolishing.

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Electrical circuit

• The Macor coil form and the Nb insert, which
  holds the coil form and the double SQUID, were
  machined.
• After winding a Nb sensing coil and mounting a Nb
  capacitor ring, and both were lapped flat.
• So far the Nb coil has been used as a capacitor
  plate to pick up the motion while the Nb ring was
  used to drive it.
• A single Quantum Design dc SQUID will be coupled
  to the sensing coil through a superconducting
  transformer.
• For future tests at 4 K, the motion will be
  sensed by the inductive transducer.

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Double SQUID tests

• Testing a copy of the double SQUID system put
  together by Venante and collaborators from AURIGA
  group.

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Plans

• Will test full-length wiring effect on SQUID
  noise
• Will test complete transducer (ready for drop-in
  replacement on ALLEGRO)
• ? Offload tests from Maryland?

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Plans

• Continue running to the end of LIGO S4 run.
• Warm-up and mount the NEW Maryland transducer, IF
  we can get it ready in time.