Collinear laser spectroscopy of neutron-rich niobium

Hyperfine structure spectra and isotope shifts of the neutron-rich nuclei ⁹⁹Nb, ¹⁰¹Nb, ¹⁰²Nb and ¹⁰³Nb were obtained at the IGISOL (Ion Guide Isotope Separator On-Line) facility at the accelerator laboratory of the University of Jyväskylä. The data were taken using collinear laser spectroscopy of bunched beams. Optical pumping from the ground state to populate metastable atomic states in the ion beam cooler allowed efficient spectroscopy of the ionic system that would otherwise be inaccessible due to a lack of suitable ground state resonance lines. The measurements of the hyperfine structure and the isotope shifts contribute valuable nuclear information to the understanding of the \(A\) ~ 100 region which displays a sudden onset of deformation that cannot be explained by the single particle shell model. It was possible to confirm the spin assignments for ⁹⁹Nb, ¹⁰¹Nb and ¹⁰³Nb as \(I\) = 9/2, \(I\) = 5/2 and \(I\) = 5/2 respectively. The extracted information on the mean square charge radii, δ\big<r²\big>, the magnetic dipole moments, μ, and the electric quadrupole moments, \(Q\), confirm a shape change of nuclei at \(N\) = 60 from soft and oblate (for \(N\)< 60) to more rigid and strongly prolate shapes (for \(N\geq\)60).

Name dc:type.qualificationname

d_ph

Level dc:type.qualificationlevel

d_ph

Grantor dc:publisher.institution

University of Birmingham

Year dc:date.issued

2010

Author dc:creator

• Rueffer, Mareike

• QC Physics