Recoil-α-fission and recoil-α-α-fission events observed in the reaction 48Ca + 243Am

Products of the fusion-evaporation reaction 48Ca + 243Am were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. Amongst the detected thirty correlated α-decay chains associated with the production of element Z=115, two recoil-α-fission and five recoil-α-α-fission events were observed. The latter five chains are similar to four such events reported from experiments performed at the Dubna gas-filled separator, and three such events reported from an experiment at the Berkeley gas-filled separator. The four chains observed at the Dubna gas-filled separator were assigned to start from the 2n-evaporation channel 289115 due to the fact that these recoil-α-α-fission events were observed only at low excitation energies. Contrary to this interpretation, we suggest that some of these recoil-α-α-fission decay chains, as well as some of the recoil-α-α-fission and recoil-α-fission decay chains reported from Berkeley and in this article, start from the 3n-evaporation channel 288115

Alpha-Photon Coincidence Spectroscopy Along Element 115 Decay Chains

Produced in the reaction 48Ca+243Am, thirty correlated α-decay chains were observed in an experiment conducted at the GSI Helmholzzentrum für Schwerionenforschung, Darmstadt, Germany. The decay chains are basically consistent with previous findings and are considered to originate from isotopes of element 115 with mass numbers 287, 288, and 289. A set-up aiming specifically for high-resolution charged particle and photon coincidence spectroscopy was placed behind the gas-filled separator TASCA. For the first time, γ rays as well as X-ray candidates were observed in prompt coincidence with the α-decay chains of element 115

Isomers in superheavy nuclei

International audienceAbstractIsomeric states in atomic nuclei are a well-known phenomenon all over the complete chart of nuclei. Their properties deliver valuable information on the structure of the nuclei. A region of specific interest are the very heavy and superheavy nuclei, where the occurrence and properties of isomeric states will have an impact on the prediction of localization and strength of the spherical superheavy proton and neutron shells. In this review, an overview of the present situation is given. Some specific features are discussed for selected examples.</jats:p

Fine structure in the \mth{\alpha}-decay of radium isotopes with mass numbers 209–212

Radium isotopes with mass numbers from 209 to 212 have been produced by heavy-ion fusion reactions \chem{^{204}Pb}(\chem{^{12}C}, $x$n)\chem{^{216\mbox{-}{\it x}}Ra}. Radioactive decay properties were investigated by means of $\alpha$- and $\alpha$-$\gamma$-spectroscopy after in-flight separation of the evaporation residues from the projectile beam by the velocity filter SHIP and implantation into a 16-strip position-sensitive Si detector. For the even-even nuclei $^{210,212}$Ra we identified $\alpha$ transitions into the first-excited 2$^{+}$-state of the daughter nuclei $^{206,208}$Rn. Weak $\alpha$ transitions into excited levels of the odd-$A$ daughter nuclei $^{205,207}$Rn were also observed