Emission probability ratios of Ni-Auger electrons: p(K-LX)/p(K-LL) and p(K-XY)/p(K-LL) following K-capture in the 64Cu decay mode

The K-X-ray spectra of nickel, resulting from K-electron capture during the decay of 64 Cu, were recorded using an Amptek SDD detector. The 64 Cu isotope was synthesized through a photonuclear reaction, 65 Cu(γ,n) 64 Cu, induced by bremsstrahlung radiation generated through the deceleration of 15 MeV electrons in the nuclear electric field and virtual photons interactions mediating electron-nucleus scattering. The study determined the K-X-ray intensity ratio, K-L vacancy probabilities, and Auger electron emission probability ratios for nickel, specifically p(K-LX)/p(K-LL) and p(K-XY)/p(K-LL). These findings are noteworthy, as radioisotopes emitting Auger electrons, akin to those emitting α and β particles, are gaining prominence in targeted radionuclide therapy, where accurate Auger electron emission probabilities post K-capture are critical for enhancing therapeutic outcomes. The experimental data were compared with theoretical predictions from Multi-Configuration Dirac-Hartree-Fock (MCDHF) calculations and prior literature. Discrepancies between experimental results and MCDHF estimates may arise from unaccounted electron correlation effects in the theoretical framework. • Kβ/Kα intensity ratio in Ni after 64 Cu K-capture measured as 0.1378 ± 0.0008. • Auger emission ratios p(K-LX)/p(K-LL) and p(K-XY)/p(K-LL) were experimentally determined. • Data agree with recent experiments. • Theoretical MCDF models underestimate Auger probabilities by 6–24%. • Results are relevant for Auger-based targeted radionuclide therapy and atomic physics.