ALLEGRO Resonant Bar Detector

Introduction

The cryogenic resonant detector at LSU has been named ALLEGRO, for A Louisiana Low temperature Experiment and Gravitational wave Observatory. It is a cryogenic resonant mass detector with a superconducting inductive transducer and a SQUID amplifier. Until repairs began in January 1995, it had a calibrated strain noise of about 1e-21 per root Hz in two narrow bands near 900 Hz, which translates into an rms burst strain noise of 6e-19 and a noise temperature of 6 mK. We recorded data continuously for nearly three and a half years, beginning in June of 1991 and ending in January 1995. A search for coincidences with the EXPLORER detector of the University of Rome was made for the last 6 months of 1991 and for the two months around the time of supernova 1993J. No coincident events were found above 200 mK, but a new upper limit for gravitational wave flux was established.

Allegro was put back into operation in 1996 and has been taking data more or less continuously since that time. Its sensitivity is slightly less than it was in the 91-95 run but it is making up for that by its great stability and lack of non gaussian noise. A paper is being written in conjunction with the Auriga, Explorer, Nautilus and Niobe groups which will set a new, lower upper limit.

Data is currently being compromised by construction on the new gravity wave laboratory. Data collection during construction has been intermittent, and we have taken this time to implement some repairs and upgrades.

Of Further Interest

ALLEGRO Archive Pictures
Publications from the ALLEGRO project