Fusion of ⁴⁰Ca + ⁴⁰Ca, ⁴⁰Ca + ⁴⁸Ca and ⁴⁸Ca + ⁴⁸Ca

¹ Dipartimento di Fisica, Università di Padova, and INFN, Sezione di Padova, I-35131 Padova, Italy
² INFN, Laboratori Nazionali di Legnaro, I-35020 Legnaro ( Padova), Italy

^a e-mail: giovanna.montagnoli@pd.infn.it

Abstract

The recent experiment on fusion of ⁴⁰Ca + ⁴⁰Ca is described in some detail and the results are reported. A full excitation function has been measured from well above the Coulomb barrier, down to low energies where the cross section reduces to ≃20 µb. A comparison is done with the recently published data on fusion of ⁴⁰Ca + ⁴⁸Ca and of ⁴⁸Ca + ⁴⁸Ca. The trends are different, in particular as far as the logarithmic derivatives (slopes) are concerned, in the interesting energy region below the barrier. The slope for systems where ⁴⁰Ca is involved, show a characteristic behavior with a tendency to saturate in a limited energy range just below the main barrier. The slopes resume increasing at lower energies, possibly indicating the influence of nuclear structure (the strong octupole vibration of ⁴⁰Ca) at such low energies, together with the clear presence of the fusion hindrance phenomenon. The results of coupled-channels calculations are presented.