Sensitivity, capacitance gauge

As a result of the narrow resonant band-width, the RF circuit is sensitive to relatively small changes in the capacitance of the ion trap assembly. One of the initial modifications that we made was to rotate the ring electrode and to re-route the RF lead to allow installation of the optic assembly (see Figure 9.7). A new lead was fabricated from 18 gauge copper magnet wire and connected to the ring electrode in its new orientation, resulting in an increase in capacitance of ca 0.25 pF. Subsequently,... 

Capacitance dilatometer methods are substantially more sensitive than the strain gauge technique (Slavin, 1972 Lacheisserie, 1975) but accurate low temperature calibration requires considerable care, as does the mounting of highly anisotropic materials (Tb and Dy) for rotation measurements (Keeler and Pearson, 1978). 

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