Near-barrier fusion of ^16,18O + ⁵⁰Cr: the role of positive Q-value two-neutron stripping channel

【摘要】 To study the coupling effect of the positive Q-value two-neutron stripping channel in the sub-barrier of ¹⁸O + ⁵⁰Cr, the fusion excitation functions were measured for the 16,¹⁸O + ⁵⁰Cr systems at energies near and below the Coulomb barriers by using the electrostatic deflector setup. ¹⁶O + ⁵⁰Cr was selected as a reference system. The coupling effect of the low-lying collective excitation states in sub-barrier fusion was considered based on coupledchannels calculations. For ¹⁸O + ⁵⁰Cr, the calculated fusion cross-sections of coupled channels, including the lowest 2 +vibrational states of the target nucleus and projectile, give subtle under-estimation for the experimental ones at energies below the Coulomb barrier. This means that there is limited room for the transfer effect in ¹⁸O + ⁵⁰Cr, compared to the widely accepted argument of positive Q-value 2n-transfer remarkably enhancing the sub-barrier fusion cross-sections. Analogous systems of neutron-rich ¹⁸O-induced fusion in existing literature show the same peculiarity that the positive Q-value two-neutron stripping channel has no remarkable influence on enhancing sub-barrier fusion cross-sections.更多还原

【Abstract】 To study the coupling effect of the positive Q-value two-neutron stripping channel in the sub-barrier of ¹⁸O + ⁵⁰Cr, the fusion excitation functions were measured for the 16,¹⁸O + ⁵⁰Cr systems at energies near and below the Coulomb barriers by using the electrostatic deflector setup. ¹⁶O + ⁵⁰Cr was selected as a reference system. The coupling effect of the low-lying collective excitation states in sub-barrier fusion was considered based on coupledchannels calculations. For ¹⁸O + ⁵⁰Cr, the calculated fusion cross-sections of coupled channels, including the lowest 2 +vibrational states of the target nucleus and projectile, give subtle under-estimation for the experimental ones at energies below the Coulomb barrier. This means that there is limited room for the transfer effect in ¹⁸O + ⁵⁰Cr, compared to the widely accepted argument of positive Q-value 2n-transfer remarkably enhancing the sub-barrier fusion cross-sections. Analogous systems of neutron-rich ¹⁸O-induced fusion in existing literature show the same peculiarity that the positive Q-value two-neutron stripping channel has no remarkable influence on enhancing sub-barrier fusion cross-sections.更多还原