LABORATORI NAZIONALI DI LEGNARO
Nuclear magnetic moments are sensitive probes of the single particle properties of the nuclear wave function. The magnetic moment operator, with its explicit dependence on protons or neutrons involved in the configuration of the state and on their angular momenta, serves as a stringent test of the proposed main configuration of the nuclear state, as well as of other admixtures. It is, therefore, necessary to study nuclear magnetic moments of nuclei that lie close to nuclear shell closures or, in general, to any place on the nuclear chart where the valence nucleons start filling a higher lying orbital in the next major shell. A good example is provided by the N = 40 region around 68Ni on the neutron-rich side of the nuclear chart, where the positive parity ng9/2 orbital dives into the negative parity fp shell. It is a long standing issue whether N = 40 has to be considered as a new (sub)shell closure or whether the peculiar effects observed in the region can be traced back to the parity change between ng9/2 and the fp shell which prevents 1p1h states from contributing to the wave functions of positive parity states. As an essential part of my PhD degree at the Instituto de Estructura de la Materia, IEM-CSIC, we carried out an experiment at REX-ISOLDE in November 2011. The aim of the experiment was to measure the g factor of the first excited 2+ state in 72Zn, g(21+), using the Transient Field (TF) technique in combination with Coulomb excitation in inverse kinematics and two different thick multilayer targets. This technique has been successfully employed in the past in a large number of stable ion beam experiments [1]. However, only recently it was applied for the first time using low-energy radioactive ion beams at Oak Ridge [2,3]. Therefore, in this seminary it will be introduced the different aspects of the performed experiment. First we will present the newly constructed transient field reaction chamber adapted to the special needs of TF measurements with short-lived radioactive beams. Then we will report on the experimental details and the data analysis procedure with a special emphasis on the advantages of the employed setup in this respect. Finally, we will discuss the experimental result in the context of the systematics in this region of the chart of nuclides and compare it to a number of different large-scale shell model calculations and also some conclusions about the technique will be reported. [1] K.-H. Speidel et al., Prog. Part. Nucl. Phys. 49 (2002) 91. 2] N. Benczer-Koller et al., Phys. Lett. B 664 (2008) 241. 3] G. Kumbartzki et al, Phys. Rev. C 86 (2012) 034319.

DATA: 28-04-2014