Mass and charge transfer in the heavy ion reactionsNi208andNi

Abstract

Target-like reaction products corresponding to the transfer of one or several nucleons have been measured as a function of the total kinetic energy loss in the reactions Pb+' Ni (1215 MeV) and Pb+ Ni (1107 MeV) with a focusing time-of-flight spectrometer which provided a unique mass and charge separation and good energy resolution. The analysis of the experimental data covered the range from elastic scattering to deep-inelastic collisions. In the quasielastic region, neutron transfer dominates. The transfer probabilities as a function of the distance of closest approach can be described by a semiclassical theory of tunneling. Quasielastic transfer from the Ni targets to the 0 Pb projectile is strongly inhibited by the reaction Q values. For the intermediate and deepinelastic collisions, the mean values and variances of the mass and charge distributions as a function of the dissipated energy, as well as the correlations between neutron and proton transport, are discussed in a statistical diffusion theory. The important influence of the static potential energy surface on nucleon transport in the deep-inelastic region is demonstrated. Deviations from the simple diffusion model, observed at small to medium energy losses, are discussed.

Inelastic scattering and nucleon transfer in the system232Th+206Pb near the Coulomb barrier

“…Similar anomalous slope constants were previously reported in [3,4,[32][33][34]. In [3,4] the measured slope was explained by a critical dependence on the angular momenta of the states excited in the transfer process, rather than intrinsic excitations of the collision partners.…”

“…The basic prediction for sub-Coulomb transfer reactions is therefore an exponential rise of the transfer probability with decreasing distance of closest approach. After an exponential dependence with the distance of closest approach had been established experimentally, the above relation, (2), was applied by several authors [2,30,[33][34][35] even to describe reactions at energies above the Coulomb barrier. In particular, it was used to determine the (intrinsic) excitation energy above the yrast line at which the nucleon transfer occurs.…”

“…If the neutron binding energies for forward and backward transfer are not too different, the effect is approximately accounted for by setting [31][32][33] Pex=Peff=P-PZ+P3-+ .... P/(1 +P), where the P" are the n th powers of P.…”

Nucleon transfer reactions to rotational states induced by206, 208Pb projectiles

“…Cross sections deduced for few-neutron transfer reactions i.g. turned out to be large and in the same order of magnitude than measured in somewhat lighter systems [13,17,[19][20][21]. In the two-neutron transfer channel leading to 23~ high spin states up to at least I= 12 are populated.…”

“…We use our data for an estimate of this energy, being aware of the fact that the procedure has been questioned [17]. From the fitted slope in Fig.…”