Associative ionization of uranium atoms and oxygen molecules

The absolute cross section for the reaction U+O2→UO2++e has been remeasured in an experiment where a beam of U atoms from a tungsten oven passes through O2 gas at low pressure, and ions formed by the reaction are collected at one of two condenser plates on either side of the beam. Uranium atom density was determined from the time-integrated uranium atom current, which was determined by terminating the beam in a plastic bag, the uranium mass contents of which were measured by neutron activation analysis. The finding is that the effective cross section for a beam-through-gas experiment is 4.01 ( +- 0.55) x 10-17 cm2, a factor of 2.39 higher than the value determined in an earlier experiment of Fite, Lo, and Irving, where the time-integrated uranium atom current was measured by condensing the uranium on a plate and alpha particle counting of the condensate