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Mache (unit)

Mache (symbol ME from German Mache-Einheit, plural Maches) is an obsolete unit of volumic radioactivity named for the Austrian physicist Heinrich Mache.[1] It was defined as the quantity of radon (ignoring its daughter isotopes; in practice, mostly radon-222) per litre of air which ionises a sustained current of 0.001 esu (0.001 StatAmpere).

1 ME = 3.64 Eman = 3.64×10−10 Ci/L = 13.4545 Bq/L.


  1. ^ Riezler, Wolfgang (1950). Einführung in die Kernphysik (4 ed.). H. Hübener. p. 49. Retrieved 2009-09-25.