An alternative approach to populate and study the ${}^{229}$Th nuclear clock isomer

Abstract

A new approach to observe the radiative decay of the ${}^{229}$Th nuclear isomer, and to determine its energy and radiative lifetime, is presented. Situated at a uniquely low excitation energy, this nuclear state might be a key ingredient for the development of a nuclear clock, a nuclear laser and the search for time variations of the fundamental constants. The isomer's ${\hat{I}}^3$ decay towards the ground state will be studied with a high-resolution VUV spectrometer after its production by the ${\hat{I}}^2$ decay of ${}^{229}$Ac. The novel production method presents a number of advantages asserting its competitive nature with respect to the commonly used ${}^{233}$U $\hat{I}\pm$-decay recoil source. In this paper, a feasibility analysis of this new concept, and an experimental investigation of its key ingredients, using a pure ${}^{229}$Ac ion beam produced at the ISOLDE radioactive beam facility, is reported.

11 pages, 5 figures, 2 tables