Characterizing Majorana Loss for Cold Atom Vacuum Standards

Cold atom vacuum standards (CAVSs) are the first primary standards and sensors for pressure in the ultra-high and extreme-high vacuum regimes. They measure the loss of magnetically trapped atoms to infer the collision rate due to residual gas in a vacuum chamber and, by extension, the pressure. However, magnetic traps are also susceptible to Majorana loss, non-adiabatic Landau-Zener transitions caused as atoms transit near the magnetic-field zero-point. Majorana loss is a trap-dependent loss and represents a potentially large systematic effect for a CAVS. We present comparisons between theory and experiments in quadrupole and Ioffe-Pritchard traps to better characterize the Majorana loss process. These results will help to improve the accuracy of a CAVS and will improve understanding of magnetic trapping.