A rapid sample changer system for studying fission shape isomers through the electron-capture-delayed fission process

A new sample changer system has been designed to rapidly transport activity from a heavy element production target chamber at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron to a fission, α-particle, X-ray, and γ-ray detection site. This changer was specifically designed to help study the nuclear structure of isotopes involved in electron-capture-delayed fission decay with half-lives greater than 30 s. The system integrates a rotating wheel and a cycling piston to transport samples from the end of a gas transport capillary line to the detection site. The overall efficiency of the sample changer system was determined by running off-line experiments to determine the activity collection site efficiency and the detector efficiencies. Under the most favorable conditions, we calculated a relative He–KCl gas transport and collection efficiency of around 70%. Efficiencies were calculated by comparing the yield of 221Fr (half-life=4.8 min) at the sample changer collection site to the activity collected directly on a piece of glass filter paper.