Measuring the dependence of weight on temperature in the low-temperature regime using a magnetic suspension balance

Abstract

A novel set-up was developed that allows us to cool samples close to liquid helium temperatures, measure their exact temperature and determine their weight in a buoyancy-free environment along a wide temperature range using a magnetic suspension balance. This allows for the first time to accurately determine the weight of both high-T-c (BSCCO and YBCO) and low-T-c (Nb) superconductors during their phase transition. Our data allow us to put limits on possible weight changes over temperature (alpha < 2 x 10(-8) K-1 for copper) as well as violations of the weak equivalence principle for superconductors while passing their critical temperature (eta < 2 x 10(-3)).