Progress in laser spectroscopy at radioactive ion beam facilities

In the last decade there has been a renaissance in laser spectroscopy at online facilities. This has included the introduction of ion traps and the use of laser ion sources to study the hyperfine structure of exotic nuclei far from stability and produce selective enhancement of isomeric beams. In-source spectroscopy has allowed the study of rare isotopes with yields as low as 0.1 atoms per second. In the case of high-resolution spectroscopy, cooling and trapping the ions has dramatically improved the sensitivity. Some elements that were previously inaccessible to laser spectroscopy are now available for study through the technique of in-trap optical pumping. This paper reviews the field of laser spectroscopy at on-line facilities, with an emphasis on new techniques. A summary of experimental data is presented.