Multi-nucleon transfer in the interaction of 977 MeV and 1143 MeV $^{204}$Hg with $^{208}$Pb

TL;DR

This study measures multi-nucleon transfer yields in $^{204}$Hg + $^{208}$Pb collisions at two energies, revealing significant discrepancies with existing models and highlighting the need for improved theoretical descriptions.

Contribution

It provides new experimental data on MNT yields at specific energies and compares these results with current models, exposing their limitations in accurately predicting transfer products.

Findings

Measured MNT yields are similar at 977 and 1143 MeV but lower than at 1257 MeV.

Observed cross sections are much larger than model predictions for several isotopes.

Models incorrectly predict formation of N=126 shell nuclei not seen in experiments.

Abstract

A previous study of symmetric collisions of massive nuclei has shown that current models of multi-nucleon transfer (MNT) reactions do not adequately describe the transfer product yields. To gain further insight into this problem, we have measured the yields of MNT products in the interaction of 977 (E/A = 4.79 MeV) and 1143 MeV (E/A = 5.60 MeV) $^{204}$Hg with $^{208}$Pb. We find that the yield of multi-nucleon transfer products are similar in these two reactions and are substantially lower than those observed in the reaction of 1257 MeV (E/A = 6.16 MeV) $^{204}$Hg + $^{198}$Pt. We compare our measurements with the predictions of the GRAZING-F, di-nuclear systems (DNS) and improved quantum molecular dynamics (ImQMD) models. For the observed isotopes of the elements Au, Hg, Tl, Pb and Bi, the measured values of the MNT cross sections are orders of magnitude larger than the predicted values. Furthermore, the various models predict the formation of nuclides near the N=126 shell, which are not observed.