Study of the threshold anomaly effect in the reaction $$^{7}$$Li+$$^{208}$$Pb at energies around the Coulomb barrier
E. Vardaci, P. K. Rath, M. Mazzocco, A. Di Nitto, G. La Rana, C. Parascandolo, D. Pierroutsakou, M. Romoli, A. Boiano, A. Vanzanella, M. Cinausero, G. Prete, N. Gelli, F. Lucarelli, C. Mazzocchi, M. La Commara, L. Fortunato, A. Guglielmetti, F. Soramel, L. Stroe, C. Signorini
Abstract
Abstract The elastic scattering in the reaction $$^{7}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow/> <mml:mn>7</mml:mn> </mml:msup> </mml:math> Li+ $$^{208}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow/> <mml:mn>208</mml:mn> </mml:msup> </mml:math> Pb was investigated in the bombarding energy range from 25 to 39 MeV. The real and imaginary parts of the optical potential were analyzed by using a phenomenological potential. A dispersion relation analysis is presented in order to investigate the threshold anomaly effect. It is concluded that $$^{7}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow/> <mml:mn>7</mml:mn> </mml:msup> </mml:math> Li has an intermediate behavior between the tightly bound nuclei such as $$^{16}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow/> <mml:mn>16</mml:mn> </mml:msup> </mml:math> O and the loosely bound nuclei such as $$^{6}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow/> <mml:mn>6</mml:mn> </mml:msup> </mml:math> Li where the lack of the threshold anomaly is unambiguously observed. Reaction cross sections are also extracted from the elastic scattering data and its comparison with the ones of other systems has been performed to draw hints on the effect of the breakup channel.