Speaker
Description
A study of unbound excited states in $^{17}$C through one-neutron knockout of $^{18}$C at the energy of 245 MeV/nucleon on a carbon target was performed using the SAMURAI spectrometer. Relative energy spectrum of unbound $^{17}$C was reconstructed from momentum vectors of $^{16}$C fragments and neutrons. The relative energy spectrum was characterized by six resonances at $E_{\rm rel}$ = 0.54, 0.81, 1.41, 1.92, 2.30, and 3.22 MeV. Three of them at $E_{\rm rel}$ = 0.54, 1.41, and 2.30 MeV were identified to be in coincidence with $^{16}$C(2$^+_1$), while others have no coincidence with that.
Orbital angular momenta of two resonances at $E_{\rm rel}$ = 1.92 and 3.22 MeV were determined as 1 by momentum distributions. The resonance at $E_{\rm rel}$ = 0.81 MeV, assigned as 5/2$^+_2$, was newly observed in the present work. With regard to the resonances having the coincidence with $^{16}$C(2$^+_1$), decay properties of candidate states were examined by branching ratio and shell-model calculations, and spin-parities of them were tentatively assigned. From the present study, it turned out that the YSOX shell-model interaction, involving tensor force for $p$-$sd$ cross-shell part, provides a good account of the observation. In the presentation, the results and detailed interpretation will be shown.
