Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

A search for Pauli-exclusion-principle-violating K_α electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8 × 10 ³⁰ s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8 × 10 ³⁰ s at 90% C.L. It is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of ⁷⁶Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.