LIGO Document P1800114-v1

Experimental Search for Avalanches of Entangled Dislocations as a Source of Dissipation and Mechanical Noise

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Recent measurements using highly sensitive instruments have shown increased dissipation and the appearance of random low frequency noise in metal flexures. These effects have been attributed to avalanches of dislocations, a phenomenon supposedly controlled by self-organized criticality (SOC) statistics. This experiment is attempting to detect these subtle effects using a variation on the Kimball-Lovell 1927 rotating beam experiment that was used to measure the loss angle of materials above 1 Hz. A frequency range of 1 Hz and below was chosen to study the effects of dislocation entanglement. The loss angle of a high carbon steel (piano) wire has been measured with mili-radian precision and the feasibility of making future measurements of loss angle with μ-radian precision has been demonstrated at arbitrarily low rotation speeds. If dislocation avalanches are a source of the 1/f noise in these flexures (where f is the event frequency), it is expected that deviations will appear in the material loss angle, and we expect to see them with this experiment.
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Final Draft Submitted to the CSULA Graduate Studies office.

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