title: Search for the radioactivity of 180mTa using an underground HPGe sandwich spectrometer.
abstract: The radioactivity of (180m)Ta has never been detected. The present attempt to detect it was carried out using a newly developed HPGe sandwich spectrometer installed 500m water equivalent underground in the HADES laboratory. The sample consisted of 6 discs of tantalum of natural isotopic composition with a total mass of 1500 g and a total mass for (180)Ta of 180 mg. The sample was measured for 68 days and the resulting lower bound for the half-life of (180m)Ta was 2.0 x 10(16)y, which is a factor of 2.8 higher than the previous highest value.
authors.affiliation: European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium. mikael.hult@ec.europa.eu
authors.forename: Mikael
authors.initials: M
authors.lastname: Hult
authors.forename: J S Elisabeth
authors.initials: JS
authors.lastname: Wieslander
authors.forename: Gerd
authors.initials: G
authors.lastname: Marissens
authors.forename: Joël
authors.initials: J
authors.lastname: Gasparro
authors.forename: Uwe
authors.initials: U
authors.lastname: Wätjen
authors.forename: Marcin
authors.initials: M
authors.lastname: Misiaszek
mesh_terms: D006207:Half-Life; D011851:Radioactivity; D013051:Spectrometry, Gamma / Q000379:methods*; D013635:Tantalum / Q000032:analysis*
chemical_list: D013635:Tantalum