Resonance states in the $^{12}$C+$^{12}$C modified Morse potential

Abstract

The resonances in $^{12}$C+$^{12}$C system described earlier using long range Morse potential determined from resonance data itself, are reexamined in the light of the recent development of the two new methods for identification of resonances in the scattering theory, namely Imaginary Test Potential and Imaginary Phase-shift methods. The high lying resonances are found to be not genuine as pointed out by Kato and Abe, and as such are discarded. This discomfiture is due to the (i) shallow behavior of the Morse potential at the outer edge and (ii) inappropriate insertion of Coulomb tail used in that work. These two deficiencies are now removed in the present study by finding a modified Morse potential with steep rise in the outer edge, and joining smoothly to it a term approximating the Coulomb tail. Calculation of the resonances for this modified Morse potential using the above two methods of identification of resonances in our study, yields more than 25 states with angular momenta $0^{+}$ - $12^{+}$ in the relevant energy regions. This reaffirms the diatomic-like rotational and vibrational picture of the nuclear molecular resonances in $^{12}$C+$^{12}$C system proposed earlier, and shows close resemblance with the physics of diatomic molecules, a phenomenon belonging to altogether a different area. It is revealing that the similarity extends right upto the level of potential which is Morse type in both the cases. This study also reveals new features of heavy ion potential.