Radiative electron capture at ultrarelativistic energies: 33-TeVPb82+ions

Cross sections for radiative electron capture (REC) by 33-TeV Pb{sup 82+} ions in Be and C targets have been extracted from an analysis of measurements of total electron capture by these ions in Be, C, Al, Cu, Sn, and Au targets. The REC cross sections in the Be and C targets, where REC is significant, were obtained by subtracting cross sections for electron capture from pair production (ECPP), the only other significant capture process at these energies. The ECPP contributions in Be and C were determined from extrapolations of measured cross sections in the heavier targets where the ECPP process dominates, with suitable accounting for slightly decreased screening effects for the light targets. We obtain an experimental K-REC cross section (0.010{+-}0.002b per electron per Pb K vacancy), which agrees with a calculation of REC made by applying detailed balance to the corresponding process of radiative recombination and using tabulated photoelectric effect cross sections. A comparison is also presented of the present experimental result with other heavy-ion measurements made at lower energies, and with nonrelativistic and relativistic calculations, which differ considerably in this energy regime. (c) 2000 The American Physical Society.