TEMPERATURE AND FREQUENCY-DEPENDENCE OF ANELASTICITY IN A NICKEL OSCILLATOR

The frequency dependence of the real and imaginary parts of a nickel oscillator's transfer function is described over 3 decades in frequency by the use of simple expressions. These expressions incorporate only the resonance frequency omega(0), the quality factor Q, and a characteristic exponent beta determined by a single measurement of creep. They are based on the ansatz phi(omega) = Q(-1)(omega/omega(0))(-beta), where phi is the imaginary part of the spring constant. Over a 100 K range of temperature T, the exponent beta similar or equal to 0.18 was constant even though Q(T) changed by a factor of 8. These expressions are potentially useful for accurately describing a mechanical oscillator whose transfer function must be modeled at frequencies far below omega(0). Examples include accelerometers based on a flexure element and suspensions for interferometric gravitational wave detectors.