title: Alpha radioactivity of the lunar surface at the landing sites of surveyors 5,6, and 7.
abstract: Evidence has been obtained for a radioactive deposit on the lunar surface at Mare Tranquillitatis with a total intensity of 0.09 +/- 0.03 alpha disintegration per second per square centimeter. The presence of polonium-210 in amounts that are close to equilibrium indicates a continuous turnover rate of lunar material at this site of less than 0.1 micrometer per year. The lack of such a deposit at two other lunar sites suggests lower local concentrations of uranium there.
authors.forename: A L
authors.initials: AL
authors.lastname: Turkevich
authors.forename: J H
authors.initials: JH
authors.lastname: Patterson
authors.forename: E J
authors.initials: EJ
authors.lastname: Franzgrote
authors.forename: K P
authors.initials: KP
authors.lastname: Sowinski
authors.forename: T E
authors.initials: TE
authors.lastname: Economou