Charge and mass distributions in the reaction ofAr40ions withU238

Abstract

The reaction of 288 MeV ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ ions with thick ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ targets has been studied experimentally with nuclear chemistry techniques. The formation cross sections of 130 radioactive nuclides were measured. The data have been used to delineate charge and mass distributions. The mass distribution is interpreted as a superposition of several components: transfer products (quasielastic component, 400±120 mb), multinucleon transfer products (deep inelastic component, 100±50 mb) and products from complete fusion-fission (620±150 mb). In addition, there is evidence for sequential fission of heavy products formed in quasielastic and deep inelastic transfer reactions. In the first case a double-humped mass distribution (150±30 mb) with the characteristics of low-energy fission is observed. Apparently, the sequential fission after deep inelastic processes occurs at higher excitation energies. For the quasielastic component the mass to charge ratio is close to that of the projectile or target, whereas for the deep inelastic component and for the fusion-fission component the mass to charge ratios appear to be full equilibrated. Proton pickup reactions in the deep inelastic reactions of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ lead to a buildup of products up to at least $Z=26\mathrm{}$, indicating a continuous development from deep inelastic transfer to fusion-fission.