Investigation of Electron Capture in ¹⁷⁶Lu with a LYSO crystal scintillator

¹ Trento Institute for Fundamental Physics and Applications, INFN-TIFPA
² Physics Dep. University of Trento, Via Sommarive 14 I-38123 Trento, It.

^* e-mail: Francesco.nozzoli@unitn.it

Published online: 8 December 2023

Abstract

The nuclide ¹⁷⁶Lu is one of the few naturally occurring isotopes that are potentially unstable with respect to electron capture (EC). Although experimental evidence for ¹⁷⁶Lu EC decay is still missing, this isotope is instead well known to β⁻ decay into ¹⁷⁶Hf with an half-life of about 38 Gyr. Previous searches for the ¹⁷⁶Lu EC decay were performed by using a passive Lutetium source coupled with an HP-Ge spectrometer. Our approach uses a LYSO crystal both as Lutetium source and as an active detector and the obtained ¹⁷⁶Lu EC branching ratio limits are 7 × 10⁻⁴ and 4.4 × 10⁻⁴ for the capture of the 1s and 2s electron, respectively. Previously known limits for the EC in ¹⁷⁶Lu are improved by a factor 3 to 15 depending on the considered EC channel.