The Cryo-Thermochromatographic Separator (CTS):: A new rapid separation and α-detection system for on-line chemical studies of highly volatile osmium and hassium (Z=108) tetroxides

The Cryo-Thermochromatographic Separator (CTS) was designed and constructed for rapid, continuous on-line separation and simultaneous detection of highly volatile compounds of short-lived α-decaying isotopes of osmium and hassium (Hs, Z=108). A flowing carrier gas containing the volatile species is passed through a channel formed by two facing rows of 32 α-particle detectors, cooled to form a temperature gradient extending from 247 K at the channel entrance down to 176 K at the exit. The volatile species adsorb onto the SiO2-coated detector surfaces at a characteristic deposition temperature and are identified by their observed α-decay energies. The CTS was tested on-line with OsO4 prepared from 169–173Os isotopes produced in 118,120Sn(56Fe, 3,4,5n) reactions. An adsorption enthalpy for OsO4 of −40.2±1.5 kJ/mol on SiO2 was deduced by comparing the measured deposition distribution with Monte Carlo simulations. This successful result demonstrates that such a system provides a viable means for the first chemical study of hassium—which is expected to be a homologue of osmium—by determining whether it forms a similarly volatile oxide.