X-ray study of the deep inelastic reactions 1,160-MeV136Xe+Pb and136Xe+232Th

Abstract

The spectra of K x-rays emitted by the target-like reaction products in the deep inelastic collisions 1,160-MeV 136Xe+ Pb and 136Xe+ 232Th were investigated. Targetlike x-ray emission probabilities per projectile-like and per target-like product were determined and compared with theoretical predictions of atomic vacancy production in the higher-Z particle (lsa-vacancy production). It is shown that a large fraction of the x-rays is produced by internal conversion of 7-rays in the higher-Z reaction product. Measurement of target-like x-rays in coincidence with projectile-like and with targetlike reaction products allowed the determination of the average survival probability against fission and of the Z-distribution of the highly excited target-like nuclei as a function of the Q value (total kinetic energy loss). The observed average survival probabilities agree qualitatively with theoretical predictions of Wilcke et al. Nuclearreaction-time effects on the lsa-vacancy production in these collisions could not be demonstrated with any certainty.

PbK-shell ionization probability in high-energy Xe+Pb collisions

“…A second motivation is to determine atomic K-vacancy production at projectile energies exceeding the Coulomb barrier. Here, earlier work has shown that K-shell internal conversion of gamma rays can contribute significantly * Permanent address: Physics Department II, Fudan University, Shanghai, Peoples Republic of China to the observed K-vacancy production probability in the higher-Z partner [6,7]. In particular, for Xe bombardment of Pb at 8.5MeV/a.m.u.…”

“…Since the slightly inelastic part of the scattered Xe energy spectrum cannot be separated from the elastic part because of the finite resolution of the particle detector (~20 MeV at 1-GeV bombarding energy) [93, it is not possible to separate atomic and nuclear K-vacancy production in a straightforward way. K x-rays from Pb-like reaction products in coincidence with deep inelastic Xe-like particles are generated predominantly by internal conversion of gamma cascades, so there the separation of the atomic effect is even more difficult [6,7]. Even for slightly inelastically scattered particles many gamma-ray transitions occur in cascades of low multiplicity, so that most K x-rays due to nuclear internal conversion are accompanied by one or more (unconverted) gamma rays.…”