Measurement of the ground state 2n pickup probability for ²⁸Si+⁶⁸Zn and its role in sub-barrier fusion enhancement

The ground state and excited state transfer yields for the 2-neutron pickup channel in the ²⁸Si+⁶⁸Zn system have been measured explicitly. The recoil mass separator at the Nuclear Science Centre, New Delhi was used for the measurement. A NaI(Tl) detector was used for detecting the de-excitation γ's from the transfer products. The kinematic coincidence technique was employed for the transfer measurement. Simplified coupled channels calculations show that out of all transfer channels the major contribution to the sub-barrier enhancement comes from the ground state 2 neutron pickup channel with a ground state Q-value of +1.83 MeV.