XENON RECOIL-ION CHARGE-DISTRIBUTIONS PRODUCED IN ELECTRON-CAPTURE AND LOSS COLLISIONS OF 8-MEV U-KR/

Recoil-ion charge distributions produced in single collisions of 8 MeV /u Kr13+ and Kr32+ projectiles with Xe atoms have been measured using time-of-flight spectroscopy. The post-collision charge states of the p rojectile ions were determined by magnetic dispersion onto a position sensitive microchannel plate detector. The recoil-ion distributions fo r ionization accompanied by electron loss from Kr13+ projectiles were bell-shaped with averages that ranged from 7.4 for 1-electron loss to 13.9 for 5-electron loss. The recoil-ion distributions for ionization accompanied by electron capture to Kr32+ projectiles were also bell-sh aped, but had much higher average charges that ranged from 20.4 for 1- electron capture to 28.5 for 4-electron capture. The large difference in the average charges produced in the two types of collisions is main ly attributable to charge magnification by Auger decay. A simple model quantitatively explains the variation of the capture-ionization charg e distribution width and average charge as a function of the number of captured electrons.