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β-decay studies of nuclei far-off the line of stability and neutron-rich side are crucial in understanding nuclear structure evolution, and provide inputs for r-process [Burdbidge et al., 1957] simulations. Half-lives, one- and two-neutron emission probabilities (P_{n, 2n}), and neutron energy spectra are the most critical observables, helpful in simulating r-process pathway. The region (26 ≤ Z ≤ 34) around doubly magic ⁷⁸Ni lies on the r-process pathway and provides a testing ground for the completeness of various physical models.

Focus here is on the experiment performed at RI-beam Factory at RIKEN Nishina Center, Japan to study the region by performing time-of-flight based spectroscopy for the delayed neutrons using detector array called VANDLE [W.A. Peters et al., 2016]. Direct measurement of energy spectra will provide information about the Gamow-Teller strength distributions. It will also directly verify the conclusions from the BRIKEN experiment [R. Yokoyama et al., submitted to Phys. Rev. Lett.] where evidence for dominating single neutron emission from 2n unbound states was observed in ^84-87Ga decays.