The capture of slow antiprotons in Kr and Xe

The capture of slow antiprotons (energies less than 1.0 au) by the noble gas atoms krypton and xenon is considered following the paper by Briggs [3]. The cross sections are calculated using the adiabatic 'hidden-crossing' theory in which the transient collision complex is treated as a diatomic molecule with the positively-charged atomic ion and antiproton as nuclei. Estimates of the percentage population of long-lived 'circular' states suggest that probability of primary capture of antiprotons into such states is negligible. The corresponding data for other noble gas atoms are also given for comparison. The capture cross section for Kr and Xe are two orders smaller than for He. (Author)