$\beta -$decay properties of r-process nuclei in the region around $^{137}$Sb

Studies aimed to explore the $\beta $-decay properties of very neutron rich nuclei are very important, since $\beta $-decays processes are related to the location and height of the r-process peak abundances. To this end, an experiment has been performed at GSI (Darmstad) to determine the T$_{1/2 }$and P$_{n}$ values of nuclei in the region around $^{137}$Sb. Different exotic nuclei, including some important ``waiting points'' around the A=130 region were produced by fission of a 750 MeV/u $^{238}$U beam. The separated fragments were implanted into a stack of four double sided Silicon strip detectors, allowing a correlation between implantation and $\beta $-decays; $\beta $-delayed neutrons were measured with the Mainz 4$\pi $ neutron long counter. Results obtained from this experiment will be presented.