Evolution of single-particle strength in neutron-rich 71Cu

The strength functions of the πf5/2πf5/2, πp3/2πp3/2 and πf7/2πf7/2 orbitals in neutron-rich 71Cu were obtained in a 72Zn(d,3He)71Cu proton pick-up reaction in inverse kinematics using a radioactive beam of 72Zn at 38 MeV/u. A dedicated set-up was developed to overcome the experimental challenges posed by the low cross section of the reaction and the low energy of the outgoing 3He particles. The excitation-energy spectrum was reconstructed and spectroscopic factors were obtained after analysis of the angular distributions with the finite-range Distorted-Wave Born Approximation (DWBA). The results show that unlike for the πf5/2πf5/2 orbital and contrary to earlier interpretation, the πf7/2πf7/2 single-particle strength distribution is not appreciably affected by the addition of neutrons beyond N=40N=40.
The authors are thankful to the Ganil accelerator staff, informatics service and to the IPN design office. We are grateful for the grant of the Romanian National Authority for Scientific Research, CNCS - UEFISCDI, project number PN-II-ID-PCE-2011-3-048, to the grant FPA2010-22131-C02-01 from the Spanish government and to the OTKA contract No. K100835.