Production and $\beta$ half-lives of heavy neutron-rich nuclei approaching the r-process path at N=126
Abstract
Fragmentation reactions of relativistic 238U and 208 Pb projectiles have been used to investigate
the production of heavy neutron-rich nuclei approaching the r-process waiting point at A≈195.
The relativistic energies, together with the use of a high resolving-power magnetic spectrometer
were key conditions for the unambiguous identification of nuclei in the region of interest. Using
this technique we were able to identify 73 new heavy neutron-rich nuclei expanding considerably
the north-west frontier of the chart of nuclide. Moreover, we were able to determine the half
lives of 13 of those nuclide. The measured values are signific antly shorter than the predictions
used for r-process model calculations. The confirmation of these results for r-process nuclei at
A≈195 would indicate that the r-process at this point is faster than expected, leading to a larger
production of the heaviest nuclei.
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