Extending Vibrations Measurements by Mössbauer Effect

G. A. PASQUEVICH; A. VEIGA; P. MENDOZA ZÉLIS; N. MARTÍNEZ; M. B. FERNÁNDEZ VAN RAAP; F. H. SÁNCHEZ

Medellin

Conferencia; XIII Latin American Conference on the Applications of the Mössbauer Effect; 2012

Universidad de Antoquia

The measurement of the Mössbauer effect (of a system where both source and absorber are well known) in a synchronously way with a periodic perturbation, has inherent information of the system response to this perturbation. Although this approach was recently proposed to measure the local magnetic susceptibility by Mössbauer Effect, it has been used for a long time to measure small ear vibrations [1]. In this work we present an extension of the vibration experiments, by measuring them at different absorber-source relative velocities (using a Mössbauer-constant-velocity strategy [2]). To this end we have developed an electronic module that generates a programmable reference signal and counts events in counters (up to 1024) synchronously with the reference signal. A set of test experiments are performed using a 57Co in Rh source and a natural stainless-steel 25 μm foil absorber fixed to a piezoelectric plate. The frequency response of the piezoelectric plate in the 100 Hz - 10 kHz range is obtained. Velocity variation with amplitudes greater than 1 mm/s can be  measured acquiring at several source constant velocities (relative to laboratory) in a cyclic loop. This procedure increases the limit of the velocity amplitude, being the upper limit given by the quality of the constant velocity driver. Here we report the observation of harmonic motions of up to 20 mm/s peak to peak, extending the non-linearity limit suggested by Ruggero et. al. of 1 mm/s in [3]. [1] L. Robles et. al., J. Acoust. Soc. Am. 59, (1976) 926. [2] A. Veiga et al., Hyperfine Interactions, 167 (2006) 905. [3] M.A. Ruggero and N.C. Rich, Hearing Research, 51 (1991) 215.