Decay-Assisted Laser Spectroscopy of Neutron-Deficient Francium

K M Lynch ,H Heylen,G Neyens,I Strashnov,I Budinčević,S Franchoo,S Rothe,J Billowes,R F García Ruíz ,Kieran Flanagan ,V N Fedosseev ,T E Cocolios ,B A Marsh ,T.j Procter ,M L Bissell ,R E Rossel ,Sofie De Schepper ,H H Stroke ,R P De Groote ,Κ Wendt

doi:10.1103/physrevx.4.011055

Abstract

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.

Highlights

Recent advances in high-resolution laser spectroscopy have resulted in the ability to measure short-lived isotopes with yields of less than 100 atoms/s [1,2]
This paper reports on the hyperfine-structure and radioactive-decay studies of the neutron-deficient francium isotopes 202–206Fr performed with the Collinear Resonance Ionization Spectroscopy (CRIS)
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

Summary

Introduction

Recent advances in high-resolution laser spectroscopy have resulted in the ability to measure short-lived isotopes with yields of less than 100 atoms/s [1,2]. The Collinear Resonance Ionization Spectroscopy (CRIS) experiment [3], located at the ISOLDE facility, CERN, aims to push the limits of laser spectroscopy further, performing hyperfine-structure measurements on isotopes at the edges of the nuclear landscape. It provides a combination of highdetection efficiency, high resolution, and ultralow background, allowing measurements to be performed on isotopes with yields below, in principle, 1 atom/s. Liberman et al identified the 7s 2S1=2 → 7p 2P3=2 atomic transition, performing hyperfine-structure and isotope-shift measurements first with low-resolution [4] and later with high-resolution laser spectroscopy [5]. The wavelength of this transition λðD2Þ 1⁄4 717.97ð1Þ nm was in excellent agreement with the prediction of Yagoda

Results

Discussion

Conclusion