Europium-155 in Debris from Nuclear Weapons

The lithium-drifted germanium detector enables determination of europium-155 on a routine basis in environmental samples contaminated with debris from nuclear weapons. From measurements of europium-155, cesium-144, and strontium-90 in air filters collected between 1961 and 1966, the yield of europium-155 from weapons was estimated at 1400 atoms per 10$^{6}$ fissions, which is close to the yield of europium-155 from fast fission of uranium-238.