Coprecipitation Behaviors of Zr, Hf, and Th with Sm Hydroxide for Chemical Study of Element 104, Rf

cle measurement is required to be performed. Herein, we propose a new protocol for rapid preparation of coprecipitates of superheavy elements with Sm hydroxide. The coprecipitation behaviors of Zr, Hf, and Th (homologues of element 104, Rf) with Sm hydroxide in aqueous ammonia (NH3) and sodium hydroxide (NaOH) solutions were investigated by the conventional suction filtration method using 88 Zr, 175 Hf, and 228 Th radiotracers. The precipitation yields obtained by employing an aging time of only 10 s were consistent with those obtained after aging for 10 min, suggesting the rapid chemical reactions in the present coprecipitation. Approximately 100% coprecipitation yields of Zr and Hf were achieved in the solutions with dilute hydroxide concentrations, and the yields decreased with higher hydroxide concentrations. In comparison, the Th yield remained constant at almost 100% under all of the conditions. In addition, a semiautomatic suction filtration apparatus for rapid preparation of precipitated samples was developed and evaluated using the short-lived isotopes 89m,g Zr and 173 Hf, which were transported online from the nuclear reaction chamber by a He/KCl gas-jet system. Using this apparatus, sample preparation was completed within 80–120 s, and precipitation yields consistent with those determined on the basis of the manual method were obtained, suggesting the applicability of the present method to Rf experiment.