ISOLDE Seminar

Nuclear moments, from ground states to short-lived excited states, using radioactive ion beams

by Georgi Georgiev (CSNSM)

26/1-22 (CERN)




Nuclear moments are among the most sensitive experimental observables towards the structure of the atomic nuclei. They allow probing the single-particle and collective nuclear properties as well as the fine interplay between them. The magnetic moments are in general considered as a fingerprint of the purity of the nuclear wave function while the quadrupole moments are the closest approach we can get to the shape of the nuclei. The interest towards the nuclear moments is especially vibrant in the regions of the nuclear chart where (sudden) modifications of the nuclear structure is expected. The large span of nuclear lifetimes, from seconds down to picoseconds, require the utilization of a variety of techniques. The nuclear moment studies of exotic nuclei, requiring the use of radioactive beams, is a challenging task, which requires some modifications of well-established stable-beam techniques.

Obtaining a spin-polarized ensemble of radioactive nuclei is a must for any beta-NMR measurement of ground-state nuclear moments. The beta-NMR setup has been brought to ISOLDE some years ago and the Tilted-Foils technique has been applied for the first polarization tests on 8Li in 2012. Following this success a proposal has been submitted and approved by the INTC to perform a measurement on 129In. The requirements of the Tilted-Foils technique and the beta-NMR setup will be presented. The plans for the upcoming experiment will be discussed as well.

Developments of the Time Dependent Recoil in Vacuum (TDRIV) technique for its application with Radioactive Ion Beams (RIB) have been performed recently at ALTO. The use of H-like charge state allowed obtaining high precision value for the gyromagnetic factor of the 2+ state in 24Mg [1]. The experimental results will be discussed in line with their impact on constraining the nuclear theories as well as on the applicability of the method at RIB facilities. This development allowed for submitting a proposal to the INTC for a RIB study of 28Mg. The peculiarities and the challenges of the forthcoming experiment will be presented.

[1] A. Kusoglu et al., Phys. Rev. Lett. 114, 062501 (2015)