INTERACTION OF BETA-RADIOACTIVE ATOMS IN LIQUID HELIUM

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Radioactive he, Li andB isotopes produced by heavy-ion reactions were ofrmed into fast radioactive nuclear beans and were introduced into liquid helium. Most of the introduced ions are nutralized but still some remain as singly-charged ions. Their spatial distribution changes with time. Solid-state alpha-and teta-ray detectors and pasition sensitive beta-ray detectors enabled us to indentify and trace the spatial distributions. With use of detectors interactions of impurity ions and Bose condensation waer studied. Ion planted solid state detectors working at liquid He temperature were mounted in a cryostat and the study of interaction of impurity ions with superfluid helium became passible only after the ontroduction of the two detection methods stated above. The detection efficiency largely exceeded that of the conventional electric aharge measurements. A cryostat incorporating of 1.2 K.Heavy-ion beams obtained from the ring cyclotron of RCNP, Osaka Unversity were led to the secondary beam (EN) course and radioactive nuclear beans were formed. The behavior of ions and neutralized atoms was studied with use of Li and B.Nuclear spin polarization was proved for the first time to ve maintained in a micro-cluster of He atoms in superfluid helium. A huge first stop has been trodden for the study of nuclear, low-temperature and condensed-matter (say cluster) Physices.