Precision laser spectroscopy of Be isotopes and prospects for SLOWRI facility at RIKEN

Abstract

Development of a universal slow RI-beam facility based on rf-carpet ion guide technique is being progressing at RIKEN RI-beam factory. With a prototype setup, precision optical spectroscopy experiments were performed for beryllium isotopes. An additional capability of providing parasitic slow RI-beams from the projectile fragment separator BigRIPS is also discussed.

Atomic physics techniques for studying nuclear ground state properties, fundamental interactions and symmetries: status and perspectives

“…The ground state HFS of 7 Be + was measured by the group of Wada [29,30] at RIKEN. This work represents the very first laser spectroscopic measurement of the HFS of a radioactive ion produced at relativistic energies in a fragmentation facility.…”

“…The charge radii of beryllium isotopes including that of the one-neutron halo 11 Be were determined at RIKEN by the group of Wada [30,31] in a Paul trap and at ISOLDE by Nörtershäuser et al [32,33] with higher accuracy using collinear spectroscopy with fluorescence detection. For the first time with laser spectroscopy applied to short-lived nuclei, a frequency comb was used in the ISOLDE experiment in order to measure the resonance frequencies in collinear and anti-collinear geometry, thus eliminating uncertainties in the acceleration voltage of the mass separator.…”

“…The latter could be ions which have no electronic transitions suited for efficient excitation with available laser systems such as highly charged ions. Michiharu Wada [30] and Iain Moore discussed in their talks slowing-down of ions in a gas cell. Such devices exist now at all facilities where nuclear ground state properties are determined by atomic physics techniques.…”

“…The only exception is RIKEN where a gas catcher and an ion trap is used for laser spectroscopy of beryllium ions [29,30]. Projectile fragmentation has the advantage over the ISOL method that chemical properties of the produced radioactive species do not play a role (except a very minor one in the gas catcher filled with noble gas but also containing some impurities).…”

“…Therefore a set-up for collinear laser spectroscopy and beam polarization is planned at the in-flight fragmentation facilities NSCL, MSU [278] and at RIKEN. As discussed at the Poznan conference by Michiharu Wada [30] in his talk on laser spectroscopy of Be isotopes, the collinear spectroscopy set-up at RIKEN would be part of the low-energy ion beam facility SLOWRI. It is planned to use the beam of the 400 MeV/u superconducting cyclotron after fragmentation and separation in the projectile fragment separator BigRIPS.…”