Results from electrostatic calibrations for measuring the Casimir force in the cylinder-plane geometry

TL;DR

This paper presents electrostatic calibration results for measuring the Casimir force in cylinder-plane geometry, highlighting anomalies and challenges in force measurement at small distances, with implications for thermal correction detection.

Contribution

It provides new insights into electrostatic anomalies and measurement challenges in cylinder-plane Casimir force experiments, comparing them with sphere-plane configurations.

Findings

Anomalous distance dependence of electrostatic force and potential.

Frequency shifts indicating non-Coulombian effects at small distances.

Milder potential dependence observed in parallel plane configuration.

Abstract

We report on measurements performed on an apparatus aimed to study the Casimir force in the cylinder-plane configuration. The electrostatic calibrations evidence anomalous behaviors in the dependence of the electrostatic force and the minimizing potential upon distance. We discuss analogies and differences of these anomalies with respect to those already observed in the sphere-plane configuration. At the smallest explored distances we observe frequency shifts of non-Coulombian nature preventing the measurement of the Casimir force in the same range. We also report on measurement performed in the parallel plane configuration, showing that the dependence on distance of the minimizing potential, if present at all, is milder than in the sphere-plane or cylinder-plane geometries. General considerations on the interplay between the distance-dependent minimizing potential and the precision of Casimir force measurements in the range relevant to detect the thermal corrections for all geometries are finally reported.