  This paper describes a procedure for the validation of alpha-particle sources
(exempt unsealed sources) to be used in experimental setups with liquefied
gases at cryogenic temperatures (down to -196 C) and high vacuum. These setups
are of interest for the development and characterization of neutrino and dark
matter detectors based on liquid argon, among others. Due to the high purity
requirements, the sources have to withstand high vacuum and cryogenic
temperatures for extended periods. The validation procedure has been applied to
241Am sources produced by electrodeposition.
