Observation of the Superheavy Nuclide ^(271)Ds

With the recent commissioning of a gas-filled recoil separator at Institute of Modern Physics (IMP) in Lanzhou,the decay properties of 271Ds (Z =110) were studied via the 20sPb(64Ni,n) reaction at a beam energy of 313.3 MeV.Based on the separator coupled with a position sensitive silicon strip detector,we carried out the energy-position-time correlation measurements for the implanted nucleus and its subsequent decay α's.One α-decay chain for 271Ds was established.The α energy and decay time of the 27iDs nucleus were measured to be 10.644 MeV and 96.8ms,which are consistent with the values reported in the literature.

Systematic Study on Alpha Decay Half-Lives of Superheavy Nuclei

The α-decay half-lives of a set of superheavy nuclear isotope chain from Z = 105 to 120 have been analyzed systematically within the WKB method, and some nuclear structure features are found. The decay barriers have been determined in the quasi-molecular shape path within the Generalized Liquid Drop Model （GLDM） including the proximity effects between nucleons in a neck and the mass and charge asymmetry. The results are in reasonable agreement with the published experimental data for the alpha decay half-llves of isotopes of charge 112, 114, and 116, of the element 294118 and of some decay products. A comparison of present calculations with the results by the DDM3Y effective interaction and by the Viola-Seaborg-Sobiczewski （VSS） formulae is also made. The experimental a decay half lives all stand in between the GLDM calculations and VSS formula results. This demonstrates the possibility of these models to provide reasonable estimates for the half-lives of nuclear decays by a emissions for the domain of SHN. The half-lives of these new nuclei are thus well tested from the reasonable consistence of the macroscopic, the microscopic, the empirical formulae and the experimental data. This also shows that the present data of SHN themselves are consistent. It could suggest that the present experimental claims on the existence of new elements Z =110 - 118 are reliable. It is expected that greater deviations of a few SHN between the data and the model may be eliminated by further improvements on the precision of the measurements.

Evidence for Heavy Ion Emission of^(230)U

Radioisotope of^(230)Pa was synthesized by proton irradiation of ThO_(2) powder targets with thickness of about 2g/cm^(2).Pure^(230)Pa was extracted and deep purified from thorium and fission products by the radiochemical method.Thin^(230)Pa→^(230)U sources were prepared for measuring the cluster decay of^(230)U.Two cases of decay via heavy ion emission,which were most probably for the neon decays of^(230)U,were detected by using solid-state track registration detectors.The preliminary branching ratio relative to a-decay comes out to be(1.3±0.8)10^(-14).

Production and Assignment of a New Transuranium Neutron-Deficient Isotope ^(235)Am

A new transuranium neutron-deficient isotope ^(235)Am was produced via the reaction of ^(238)Pu(p,4n)^(235)Am by using a 35 MeV proton beam.The recoiled products were collected by a helium-jet and long-capillary system.Americium isotopes were separated out by a rapid radiochemical method.X-ray,γ-ray,and x-γ coincidence measurements were taken in the study.According to ^(235)Pu decay γ-ray and Np K x-ray growth-decay property,^(235)Am was definitely identified and its half life is determined as 15±5 min.