title: Experiments and theory of ¹³⁸La radioactive decay.
abstract: We measured with unprecedented accuracy key features of the (138)La radioactive decays as β particle energy distribution from 0.5 keV to the end-point and ratios of electron capture probabilities PL/PK, PM/PK and PM/PL. This was achieved by making use of LaBr3:Ce and CeBr3 scintillator detectors. The advantage of the presented technique relies on the double role of LaBr3:Ce as source of (138)La and detector medium resulting in a relatively efficient counting statistics and unaltered β energy detection. The experimental results are compared to advanced computational techniques and significant deviation is found below 20 keV with the computational spectrum showing a 5% excess of β particle relative to the experimental spectrum at 10 keV.
authors.affiliation: AP, RST, FAME, Delft University of Technology, Mekelweg 15, 2629JB Delft, The Netherlands; Gonitec BV, Johannes Bildersstraat 60, 2596EJ Den Haag, The Netherlands. Electronic address: f.g.a.quarati@tudelft.nl.
authors.forename: F G A
authors.initials: FGA
authors.lastname: Quarati
authors.affiliation: AP, RST, FAME, Delft University of Technology, Mekelweg 15, 2629JB Delft, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Dorenbos
authors.affiliation: CEA, LIST, Laboratoire National Henri Becquerel, Bât. 602 PC111, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France.
authors.forename: X
authors.initials: X
authors.lastname: Mougeot
keywords: Electron capture probability ratios; Exchange effect; La-138; Q value; β spectrum