Use of the Mössbauer effect to measure small vibrations

Abstract

A technique is described for the measurement of small vibrations (in the Å range at audio frequencies) of small bodies (in the mg range) using the Mössbauer effect. The movement of a Mössbauer source relative to an absorber produces variations in the counting rate in a detector behind the absorber. The registration of these variations in synchronism with the source movement provides information on the amplitude and phase of the source movement. The synchronous counter here consists of six scalers, and the circuitry which generates the signal driving the source (mechanically or acoustically) and which synchronously fans out the counts into the scalers is described in detail. The computer method of analyzing the results is also described. The special characteristics of the technique, aside from its sensitivity (proportional to frequency) and applicability to small systems, are the possibility of observation at a distance and through intervening objects and its insensitivity to brief gross movements. It is therefore particularly suitable for in vivo measurements on the mechanism of hearing. Applications and comparisons with other techniques are discussed.