Parity-transfer $({}^{16}\mathrm{O},{}^{16}\mathrm{F}(0^{-},g.s.))$ reaction as a selective probe of isovector $0^{-}$ states in nuclei

Abstract

We demonstrate that the parity-transfer $({}^{16}\mathrm{O},{}^{16}\mathrm{F}(0^{-},g.s.))$ reaction provides a selective probe of isovector $0^{-}$ excitations in nuclei. This reaction selectively populates unnatural-parity states through a $0^{+}\to 0^{-}$ transition in the projectile. The excitation-energy spectrum of ${}^{12}\mathrm{B}$ was reconstructed via the ${}^{12}\mathrm{C}({}^{16}\mathrm{O},{}^{16}\mathrm{F}(0^{-},g.s.))$ reaction at 247~MeV/u from the coincident detection of the ${}^{15}\mathrm{O}+p$ decay products of ${}^{16}\mathrm{F}$. The known $0^{-}$ state at $E_x=9.3\mathrm{MeV}$ was clearly observed with a strongly enhanced forward cross section, establishing the selectivity of the reaction. Structures observed at $E_x=6.6\pm 0.4$ and $14.8\pm 0.3\mathrm{MeV}$ exhibit forward-peaked angular distributions and are suggested to contain significant $0^{-}$ strength. These results demonstrate that the parity-transfer reaction provides a powerful probe of $0^{-}$ excitations and highlight its potential for systematic studies of spin-isospin modes, including pion-related dynamics, in nuclei.

Revised version. Submitted to PTEP