## LSU Historical Dissertations and Theses

1997

Dissertation

#### Degree Name

Doctor of Philosophy (PhD)

#### Department

Physics and Astronomy

William O. Hamilton

#### Abstract

The Allegro gravitational wave detector has been operational from 1991-1994, and 1996-present. We present a detailed description of the detector and the data acquisition system. Two distinct types of data analysis are detailed. First, we describe the search for burst sources of gravitational radiation. These are impulse forces acting on the bar, presumably from the stellar collapse associated with supernovae. Construction of the optimal filter for burst signals is described, as well as its application to the data from the detector. The uncertainties introduced into timing and signal strength estimates due to stationary noise are measured, giving the windows for both quantities in coincidence searches. Second, we describe a very different type of analysis, the search for a continuous source of gravitational radiation from a rotating neutron star. Unlike the burst events which last on the order of a millisecond, this signal is expected to persist for the duration of the experiment. Since Allegro is sensitive at frequencies near 1 kHz, only neutron stars with spin periods near 2 ms are potential sources. Since there are no known sources of this type for Allegro, we directed the search towards the globular cluster 47 Tucanae. This was due to the large number of millisecond pulsars located there. No claim to have detected a CW signal is made, although a number of candidates are identified. The analysis puts a constraint of $3\times10\sp{-24}$ on the gravitational strain emitted from a pulsar in 47 Tucanae.

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