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

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.