Beta decay properties in the doubly magic 78Ni region

78Ni is the only doubly magic nucleus known to exhibit both decay modes, the β-delayed gamma and β-delayed neutron emission. These properties of 78Ni and of nuclei around it, recently studied by BRIKEN collaboration, determine the content of the seed region for the further evolution of the r-process nucleosynthesis.

BRIKEN collaboration has commissioned and operates the world largest beta-delayed neutron detection system with nearly 150 3He tubes. 87% of 3He neutron detection volume and two Ge clovers were contributed from ORNL.  Different versions of the ion implantation-beta decay array have been used with BRIKEN, from highly pixelated AIDA array to WASABI Si-stack complemented by the YSO scintillator developed at the UTK [1].  Experiments including the study of 78Ni and profiting from high intensities of 238U primary beam at 345 MeV/u were performed at the BigRIPS fragment separator at RIKEN (Wako, Japan).

The status of data evaluation [2,3] and further plans to study 78Ni decay will be discussed.

1. Yokoyama et al., NIM A937, 2019, 93.

2. Rasco et al., NIM A911, 2018, 79.

3. Yokoyama et al., PR C100, 031302(R), 2019.