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 ⁶⁴Cu, were recorded using an Amptek SDD detector. The ⁶⁴Cu isotope was synthesized through a photonuclear reaction, ⁶⁵Cu(γ,n)⁶⁴Cu, 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.