β-delayed neutron and γ-ray spectroscopy of 17C utilizing spin-polarized 17B

Excited states in C-17 were investigated through the measurement of beta-delayed neutrons and gamma rays emitted in the beta decay of B-17. In the measurement, three negative-parity states and two inconclusive states were identified in C-17 above the neutron threshold energy, and seven gamma lines were identified in a beta-delayed multiple neutron emission of the B-17 beta decay. From these transitions, the beta-decay scheme of B-17 was determined. In particular, a de-excitation 1766-keV gamma line from the first excited state of C-16 was observed in coincidence with the emitted beta-delayed neutrons, and this changes the previously reported beta-decay scheme of B-17 and level structure of C-17. In the present work, the beta-NMR technique is combined with the beta-delayed particle measurements using a fragmentation-induced spin-polarized B-17 beam. This new scheme allows us to determine the spin parity of beta-decay feeding excited states based on the difference in the discrete beta-decay asymmetry parameters, provided the states are connected through the Gamow-Teller transition. In this work, I-pi = 1/2(-), 3/2(-), and (5/2(-)) are assigned to the observed states at E-x = 2.71(2), 3.93(2), and 4.05(2) MeV in C-17, respectively. DOI: 10.1103/PhysRevC.87.034316