We have used the 43 MeV/nucleon primary tritium beam of the AGOR facility with an intensity of $4\times {10}^7$ pps and the BBS experimental setup to study the (t,${}^3\mathrm{He}$) reaction between $0^{°}$ and $5^{°}$ lab angles on ${}^{12}\mathrm{C}$, ${}^{48}\mathrm{Ca}$, and ${}^{58}\mathrm{Ni}$ targets. The standard ray-tracing procedure has allowed us to obtain excitation-energy spectra up to 30 MeV in six angular bins for each residual nucleus, with an average energy resolution of 350 keV. The reaction mechanism has been described in distorted-waves Born approximation (DWBA) using the DWBA98 code. In this approximation, the form factor is treated as a folding of an effective projectile-nucleon interaction with a transition density. The effective projectile-nucleon interaction has been adjusted to reproduce the $0^{°}$ cross section of the $1^{+}$ ground state of ${}^{12}\mathrm{B}$ populated in the ${}^{12}\mathrm{C}$($t$,${}^3\mathrm{He}$) reaction. We have employed random-phase approximation (RPA) wave functions of excited states to construct the form factor instead of the normal modes wave functions used earlier. This new DWBA+RPA analysis is used to compare calculated and experimental cross sections directly and to discuss the giant resonance excitations in ${}^{48}\mathrm{K}$ and ${}^{58}\mathrm{Co}$ nuclei.

• Received 14 January 2005

DOI:https://doi.org/10.1103/PhysRevC.73.014616