Mache (symbol ME from German Mache-Einheit, plural Maches) is a unit of volumic radioactivity named for the Austrian physicist

Heinrich Mache Heinrich Mache (27 April 1876 – 1 September 1954) was an Austrian physicist. He won the Haitinger Prize of the Austrian Academy of Sciences in 1915. Life Born in Prague, after his secondary school studies, Mache completed the first year of ...

. It was defined as the quantity of

radon Radon is a chemical element with the symbol Rn and atomic number 86. It is a radioactive, colourless, odourless, tasteless noble gas. It occurs naturally in minute quantities as an intermediate step in the normal radioactive decay chains through ...

(ignoring its daughter isotopes; in practice, mostly radon-222) per litre of air which

ionises Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule i ...

a sustained current of 0.001 esu (0.001

StatAmpere The statampere (statA) is the derived electromagnetic unit of electric current in the CGS-ESU (electrostatic cgs) and Gaussian systems of units. One statampere corresponds to / ampere ≈ in the SI system of units. The name ''statampere'' is ...

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

References

Units of radioactivity Obsolete units of measurement {{measurement-stub