Phys.Rev. C 108, 014327 (2023)

L.Hariasz, M.Stukel, P.C.F.Di Stefano, B.C.Rasco, K.P.Rykaczewski, N.T.Brewer, D.W.Stracener, Y.Liu, Z.Gai, C.Rouleau, J.Carter, J.Kostensalo, J.Suhonen, H.Davis, E.D.Lukosi, K.C.Goetz, R.K.Grzywacz, M.Mancuso, F.Petricca, A.Fijalkowska, M.Wolinska-Cichocka, J.Ninkovic, P.Lechner, R.B.Ickert, L.E.Morgan, P.R.Renne, I.Yavin, for the KDK Collaboration

Evidence for ground-state electron capture of ⁴⁰K

RADIOACTIVITY ⁴⁰K(EC); measured decay products, X-rays, Eγ, Iγ; deduced EC⁰/EC^* relative branching ratios to the ground state and excited state of ⁴⁰Ar, T_1/2, decay scheme. First experimental verification of a third-forbidden unique transition. Discussed the impact of found evidence of the ⁴⁰K decay to the ground-sate on the geochronology and nuclear theory. Comparison to theoretical estimations. Sensitive x-ray silicon drift detector (SDD) and Modular Total Absorption Spectrometer (MTAS).

doi: 10.1103/PhysRevC.108.014327