Abstract
Terbium-152, decaying by electron capture and beta+ emission to 152Gd with QEC = 3990(40) keV and T1/2 = 17.8784(95) h, shows promise in nuclear medicine. First-in-human trials have demonstrated its suitability for positron emission tomography (PET) imaging, with potential applications in personalised cancer treatments through its membership of the terbium theragnostic quartet. A source of 152Tb was produced at CERN-ISOLDE, using spallation of a tantalum target induced by a 1.4 GeV proton beam and mass separation with the ISOL method. The source was then shipped to ILL Grenoble for measurement. This paper details the electron-gamma spectroscopy of the decay using the PN1/LOHENGRIN setup, supporting the gamma-gamma spectroscopy of 152Tb sources produced in the same ISOLDE run. Preliminary measurements of the relative intensity of internal conversion electrons are presented, validating theoretical predictions of internal conversion coefficients for several transitions and confirming their assigned multipolarity. The final analysis will support the gamma-gamma spectroscopy in establishing a revised level scheme for the decay, leading to an updated beta strength function and a corresponding change in dosimetry calculations.