Annecy/Dec'04

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ALLEGRO:status 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 > 200 days available for comparison with

NAUTILUS, EXPLORER, and AURIGA. • Duty factor >95% 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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11Next 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

Annecy/Dec'04

20Niobium 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 Q’s will be measured as a function of before and after the electropolishing.

Annecy/Dec'04

21Electrical 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.