X-ray production with heavy post-accelerated radioactive-ion beams in the lead region of interest for Coulomb-excitation measurements

Characteristic K X-rays have been observed in Coulomb-excitation experiments with heavy radioactive-ion beams in the lead region (Z = 82), produced at the REX-ISOLDE facility, and were used to identify the decay of strongly converted transitions as well as monopole 0(2)(+) -> 0(1)(+) transitions. Different targets were used, and the X-rays were detected by the Miniball gamma-ray spectrometer surrounding the target position. A stable mercury isotope, as well as neutron-deficient mercury, lead, polonium, and radon isotopes were studied, and a detailed description of the analysis using the radioactive Hg-182,Hg-184,Hg-186,Hg-188 isotopes is presented. Apart from strongly converted transitions originating from the decay of excited states, the heavy-ion induced K-vacancy creation process has been identified as an extra source for K X-ray production. Isolating the atomic component of the observed K X-rays is essential for a correct analysis of the Coulomb-excitation experiment. Cross sections for the atomic reaction have been estimated and are compared to a theoretical approach.