Spin-parity assignments in15C*by a new method:β-delayed spectroscopy for a spin-polarized nuc

Abstract

We propose a method of spin-parity assignments in decay spectroscopy. Its feasibility was tested for the ␤-delayed neutron decay of spin-polarized 15 B. The ␤-decay asymmetries were measured in coincidence with the delayed neutrons, and the AP values were evaluated for five allowed transitions leading to the excited states in 15 C (E x ϭ3.103, 4.220, 4.657, 5.866, and 6.426 MeV͒. The spin parities of the former three states were uniquely assigned as 1/2 Ϫ , 5/2 Ϫ , and 3/2 Ϫ , respectively. These assignments are consistent with the previous assignments. Because of insufficient statistics for the 5.866-MeV state (1/2 Ϫ), an incorrect assignment (3/2 Ϫ) could not be excluded within the 1 deviation. The spin-parity of the 6.417-MeV state is suggested to be 1/2 Ϫ. The peak analysis with detector response in the neutron time of flight spectra enabled precise determinations of the level energies and widths. The level widths were determined for the first time. The present method is also applicable for ␤-delayed proton, ␣, and ␥ decays, and it can be a powerful tool for spectroscopic studies of nuclei far from the stability.

β-delayed neutron andγ-ray spectroscopy of17C utilizing spin-polarizedUeno1, Miyatake2, Yamamoto3 et al. 2013Phys. Rev. CSelf Cite28160View full textAdd to dashboardCite

“…The accuracy of the analysis was evaluated using the 15 B β decay measured in the present work. It is known that in the 15 B β decay, the transition to E x = 3.10 MeV, which has the highest transition strength in the β decay, is followed by the E n = 1.76 MeV β-n emission [22,28]. Thus, a Kurie plot was also obtained for this transition using the same experimental apparatus.…”

“…Since P is common to all the transitions, the final state I π can be assigned such that A β becomes proportional to the experimentally determined A β P values when the initial state I π is known. For the first time, by using this new method, the I π values of the excited states in 15 C have been successfully assigned with the spin-polarized 15 B beam [28]. Further, by taking the advantage of highly spin-polarized Li and Na beams, the nuclear structures of 11 Be [29] and 28 Mg [30] have been studied through the spin-parity assignment of the excited states.…”

Evidence for Gamow-Teller Decay ofNi78Core from Beta-Delayed Neutron Emission Studies

“…In classical studies of β-delayed neutron emission in light nuclei individual neutron-emitting states can be observed (see, e.g., [31,32]). As indicated in the introduction, the neutron energy distribution of midmass nuclei studied using limited resolution devices does not correspond to individual resonances [7].…”

Development of a Reference Database for Beta-Delayed Neutron Emission

“…The decay of 17 N, a well-defined standard for neutronbranching ratio measurements (see Table I), can be used for energy-and detector-response calibrations in TOF experiments. The energy of the three main neutron lines are well-known from 3 He ion chamber measurements [93][94][95][96][97] and appear fully resolved in TOF measurements [81,98].…”