β-delayed Neutron Decay Studies of r-process Nuclei near ^137Sb

In order to understand r-process nucleosynthesis, it is necessary to know the β-decay half lives and neutron emission probabilities (P_n) of the neutron rich nuclei which lie along the r-process path. To this end an experiment was performed at GSI to measure the T_1/2 and P_n values of r-process nuclei around the waiting-point nucleus ^137Sb. The nuclei of interest were produced via the projectile fission of a 750 MeV/nucleon ^238U beam and identified using the FRS fragment separator. A stack of 4 double-sided silicon strip detectors were used to detect the implanted nuclei and subsequent β-decays. Neutrons emitted from β-delayed neutron decays were detected using the Mainz 4π neutron long counter. A set of approximately 10 r-process nuclei in the A=130 region, including the waiting-point nuclei ^136Sn and ^137Sb, were measured during the experiment. Preliminary results of the experiment will be discussed.