Mechanism of the heavy-ion charge exchange reactionC12(12C,12N)12B at 35 MeV/nucleon

The heavy-ion charge exchange reaction ${}_{}{}^{12}{}_{}{}^{}$C${(}^{12}$C,${}_{}{}^{12}{}_{}{}^{}$N${)}^{12}$ B has been studied at E${(}^{12}$C)=35 MeV/nucleon. Angular distributions in the range 3.7–12.1° (c.m.) have been measured for the $1^{+}$ (0.0 MeV), $2^{+}$ (0.95 MeV), $2^{\mathrm{-}}$ (1.67 MeV), and $4^{\mathrm{-}}$,$2^{\mathrm{-}}$ (4.5 MeV) states in ${}_{}{}^{12}{}_{}{}^{}$B. A broad peak at 7.8 MeV excitation was also observed. Microscopic one-step distorted-wave Born approximation calculations yield $V_{\sigma \tau }$ strengths ≥2 times those obtained in (p,n) reactions at similar energies per nucleon. Although this is significantly smaller than $V_{\sigma \tau }$ values obtained in other heavy-ion charge exchange studies, mostly carried out at energies less than 10 MeV/nucleon, it is concluded that the reaction mechanism is still dominated by sequential transfer (two-step) processes at 35 MeV/nucleon. A rough estimate indicates that one-step processes will dominate at bombarding energies above about 50 MeV/nucleon.