R.E. Rossel

Use of a Continuous Wave Laser and Pockels Cell for Sensitive High-Resolution Collinear Resonance Ionization Spectroscopy.

New technical developments have led to a 2 orders of magnitude improvement of the resolution of the collinear resonance ionization spectroscopy (CRIS) experiment at ISOLDE, CERN, without sacrificing the high efficiency of the CRIS technique. Experimental linewidths of 20(1) MHz were obtained on radioactive beams of francium, allowing us for the first time to determine the electric quadrupole moment of the short lived [t_{1/2}=22.0(5) ms] ^{219}Fr Q_{s}=-1.21(2) eb, which would not have been possible without the advantages offered by the new method. This method relies on a continuous-wave laser and an external Pockels cell to produce narrow-band light pulses, required to reach the high resolution in two-step resonance ionization. Exotic nuclei produced at rates of a few hundred ions/s can now be studied with high resolution, allowing detailed studies of the anchor points for nuclear theories.

Laser spectroscopy of francium isotopes at the borders of the region of reflection asymmetry

The magnetic dipole moments and changes in mean-square charge radii of the neutron-rich 218m,219,229,231Fr isotopes were measured with the newly installed Collinear Resonance Ionization Spectroscopy (CRIS) beam line at the On-Line Isotope Mass Separator (ISOLDE), CERN, probing the 7s2S1/2 to 8p2P3/2 atomic transition. The ??r2?A,221 values for 218m,219Fr and 229,231Fr follow the observed increasing slope of the charge radii beyond N = 126. The charge radii odd-even staggering in this neutron-rich region is discussed, showing that 220Fr has a weakly inverted odd-even staggering while 228Fr has normal staggering. This suggests that both isotopes reside at the borders of a region of inverted staggering, which has been associated with reflection-asymmetric shapes. The g(219Fr) = +0.69 (1) value supports a ?1h9/2 shell-model configuration for the ground state. The g(229,231Fr) valuessupportthetentativeI?(229,231Fr)=(1/2+) spin and point to a ?s?1 intruder ground-state configuration.

Decay-Assisted Laser Spectroscopy of Neutron-Deficient Francium

This paper reports on the hyperfine-structure and radioactive-decay studies of the neutron-deficient francium isotopes

Changes in nuclear structure along the Mn isotopic chain studied via charge radii

^{202-206}

arXiv : Study of the long-lived excited state in the neutron deficient nuclides

Fr performed with the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at the ISOLDE facility, CERN. The high resolution innate to collinear laser spectroscopy is combined with the high efficiency of ion detection to provide a highly-sensitive technique to probe the hyperfine structure of exotic isotopes. The technique of decay-assisted laser spectroscopy is presented, whereby the isomeric ion beam is deflected to a decay spectroscopy station for alpha-decay tagging of the hyperfine components. Here, we present the first hyperfine-structure measurements of the neutron-deficient francium isotopes

^{195,197,199}

^{202-206}

Po by precision mass measurement

Fr, in addition to the identification of the low-lying states of

Network Distributed Data Acquisition, Storage, and Graphical Live Display Software for a Laser Ion Source at CERN

^{202,204}

The CERN/ISOLDE laser ion source

Fr performed at the CRIS experiment.This paper reports on the hyperfine-structure and radioactive-decay studies of the neutron-deficient francium isotopes 202–206 Fr performed with the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at the ISOLDE facility, CERN. The high resolution innate to collinear laser spectroscopy is combined with the high efficiency of ion detection to provide a highly sensitive technique to probe the hyperfine structure of exotic isotopes. The technique of decay-assisted laser spectroscopy is presented, whereby the isomeric ion beam is deflected to a decay-spectroscopy station for alpha-decay tagging of the hyperfine components. Here, we present the first hyperfine-structure measurements of the neutron-deficient francium isotopes 202–206 Fr, in addition to the identification of the low-lying states of 202;204 Fr performed at the CRIS experiment.

Collinear Resonance Ionization Spectroscopy of Neutron-Deficient Francium Isotopes

The hyperfine spectra of