A fast-valve system for characterizing effusive-flow properties of vapor-transport systems: RIB applications

Decay losses, associated with the times required for particles to diffuse from ISOL production targets and to effusively-flow to an ion source, must be reduced to as low as practically achievable levels in order to deliver useful beam intensities of short-lived isotopes for research at ISOL based Radioactive Ion Beam (RIB) facilities. We have developed a fast-valve system and complementary 3-D Monte-Carlo code which can be used separately or in combination to assess the effusive-flow properties of vapor-transport systems, independent of size, geometry and chemical properties of the transport species. In this report, we describe the fast valve and present time spectra and characteristic time data for noble gases flowing through serial- and parallel-coupled vapor-transport systems similar in geometry but longer than those used for RIB generation at the HRIBF with and without target coating matrices.