Ion storage and laser-induced fluorescence measurements in an RFQ trap

Abstract

A radio-frequency quadrupole (RFQ) ion trap has been constructed for laser spectroscopic measurements of isotope shifts (IS) and hyperfine structures (HPS) with a small number of ions produced from a very dilute hafnium sample placed inside the RFQ trap. The target atoms are evaporated by a Nd:YAG heating laser pulse, and then selectively ionized by resonance ionization. Through repetitive application of this procedure, hafnium ions are accumulated in the trap, and a storage time of hours has been achieved with H 2 as a buffer gas. Laser-induced fluorescence (LIF) with the 5d 6s 2 ( a 2D) ( J = 3/2) — 5d6s ( a 3D)6p ( z 4F o) ( J = 5/2) transition is observed. Through an RF phase timing coincident technique, a resolution of about 1 GHz car. Le obtained, sufficient to resolve most of the hyperfine components of the odd A isotopes Also, by continuously monitoring the LIF signal, the ion cooling time in the RFQ trap is measured as a function of buffer gas pressure, and the ion-molecule collision cross section deduced is consistent with theoretical expectations. The sensitivity of this method was tested with the IS measurement of a mass separated 173Hf source.