Proton resonant states in ${}^{23}\mathrm{Al}$ have been investigated for the first time by the resonant elastic and inelastic scattering of ${}^{22}\mathrm{Mg}$$+p$ with a ${}^{22}\mathrm{Mg}$ beam at 4.38 MeV/nucleon bombarding a thick (CH${}_2$)${}_n$ target. The low-energy ${}^{22}\mathrm{Mg}$ beam was separated by the CNS radioactive ion beam separator (CRIB). The energy spectra of recoiled protons were measured at average scattering angles of ${\theta }_{\mathrm{lab}}\approx 4{}^{°},17{}^{°}$ and $23{}^{°}$. A new state has been observed at $E_x=3.00$ MeV with a spin-parity assignment of ($3/2^{+}$). In addition, resonant inelastic scattering has populated three more states at excitation energies of 3.14, 3.26, and 3.95 MeV, with proton decay to the first excited state in ${}^{22}\mathrm{Mg}$ being observed. The new state at 3.95 MeV has been assigned a spin-parity of $J^{\pi }=(7/2^{+})$. The resonant parameters were determined by an $R$-matrix analysis of the excitation functions with a SAMMY-M6-BETA code. The core-excited structure of ${}^{23}\mathrm{Al}$ is discussed within a shell-model picture. The stellar reaction rate of the ${}^{22}\mathrm{Mg}$($p,\gamma$)${}^{23}\mathrm{Al}$ reaction has been reevaluated, and the revised total reaction rate is about 40% greater than the previous result for temperatures beyond $T_9=0.3$.

• Received 15 May 2007

DOI:https://doi.org/10.1103/PhysRevC.76.055802