Experimental test of charge conservation and the stability of the electron

A new experimental lower limit of 5.3 × ${10}^{21}$ years for the mean lifetime of the electron for decay into nonionizing particles is reported. A finite value for this lifetime would have implied a breakdown of the law of charge conservation. The experimental technique consists of a search for the internally-absorbed 11.1-keV x-ray and Auger-electron cascade which would follow the decay of a $K$-shell electron in a germanium atom in a high-resolution Ge(Li) detector.