Extraction of the non-spin- and spin-transfer isovector responses via the $^{12}\mathrm{C}(^{10}\mathrm{Be},{}^{10}\mathrm{B}+γ)^{12}\mathrm{B}$ reaction
The isovector response in $^{12}$B was investigated via the $^{12}$C($^{10}\mathrm{Be}$,$^{10}\mathrm{B}$+$γ$)$^{12}$B$^\ast$ reaction at $100 A \, \mathrm{MeV}$. By utilizing the $γ$-decay properties of the 1.74 MeV $0^{+}$ and 0.718 MeV $1^{+}$ states in $^{10}\mathrm{B}$, the separate extraction of the non-spin-transfer ($ΔS=0$) and spin-transfer ($ΔS=1$) isovector responses up to an excitation energy of 50 MeV in $^{12}$B in a single measurement is demonstrated. The experimental setup employed the S800 spectrometer to detect and analyze the $^{10}\mathrm{B}$ ejectiles and the Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA) for obtaining the Doppler-reconstructed spectrum for $γ$-rays emitted in-flight by $^{10}\mathrm{B}$. A $^{12}$C foil was placed at the pivot point of the spectrograph. The $^{12}$B reaction product was not detected. Contributions from transitions associated with the transfer of different units of angular momentum in the non-spin- and spin-transfer responses were analyzed using a multipole decomposition analysis. The extracted non-spin-dipole ($ΔS=0$, $ΔL=1$) and spin-dipole ($ΔS=1$, $ΔL=1$) responses were found to be consistent with available data from other charge-exchange probes, validating the non-spin- and spin-transfer filters used. While statistical uncertainties and experimental resolutions were relatively large due to the modest intensity of the $^{10}\mathrm{Be}$ secondary beam, the results show that, with the much higher intensities that will be available at new rare-isotope beam facilities, the ($^{10}\mathrm{Be}$,$^{10}\mathrm{B}$+$γ$) reaction and its $ΔT_{z}=-1$ partner, the ($^{10}$C,$^{10}\mathrm{B}$+$γ$) reaction, are powerful tools for elucidating the isovector non-spin- and spin-transfer responses in nuclei.