No abstract available

[en] New isotope ²⁶⁵Bh (Z=107) was produced in bombardment of an ²⁴³Am target with 135 MeV ²⁶Mg ions at HIRFL. Identification was made by observation of correlated α particle decays between the new isotope ²⁶⁵Bh and its ²⁶¹Db and ²⁵⁷Lr daughters with four pairs of detectors. A total of 8 correlated decay events of ²⁶⁵Bh and 4 decay events of ²⁶⁴Bh were identified. ²⁶⁵Bh decays with a 0.94 [(+0.70)-(-0.31)]s half-life by emission of α particle with an average energy of (9.24±0.05) MeV

No abstract available

[en] New isotope ²⁶⁵Bh (Z=107) was produced in bombardment of a ²⁴³Am target with 135 MeV ²⁶Mg ions at HIRFL. Identification was made by observation of correlated α-particle decays between the new isotope ²⁶⁵Bh and its ²⁶¹Db and ²⁵⁷Lr daughters with four pairs of detectors. The experimental results show that the half-life of ²⁶⁵Bh is 0.94_-0.31^+0.70 s and its α energy is (9.24 ± 0.05) MeV. (authors)

[en] The isotope of ²⁶⁶Bh was produced and identified definitely in bombardments of ²⁴³Am target with 162 MeV ²⁶Mg ions at HIRFL. Identification was made by observation of correlated α-particle decays between the Bh isotopes and their Db and Lr daughters using a rotating wheel system. The measured α energy for ²⁶⁶Bh is (9.03 ± 0.08) MeV, and this value close to the 9.07 MeV for ²⁶⁶Bh observed in the first chain of element 113 at RIKEN. The half-life of ²⁶⁶Bh is (0.66)_-0.26^+0.59s. The Q_α value derived from this experiment fits well into the general trend in a 'Q_α-N systematics' for the isotopes with Z=107. (authors)

[en] The present status of heavy elements research at IMP (Institute of Modern Physics, Chinese Academy of Science, Lanzhou) is reviewed. Many efforts have been devoted into the stuclies of actinides and of transactinides. Some progresses have been made in synthesis and identification of new nuclides and studies of their exotic decay properties in these regions. The rapid chemical separation procedures have been widely applied when the half-lives of the expected nuclides are long enough. Three new neutron-rich isotopes of ^237,238Th, ²³⁹Pa were produced by heavy-ion induced multinucleon transfer reaction and fast neutron-induced (n, 2p) reaction. A new neutron-deficient transuranium nuclide ²³⁵Am was also produced via proton-induced reaction and identified for the first time by using He-jet transportation, liquid-liquid extraction and x-γ coincidence measurements. The half-life of ²³⁵Am was determined to be 15±5 min. The β-delayed fission of ²³⁰Ac was observed for the first time and the BDF probability of ²³⁰Ac was determined to be (1.19±0.40)x10^-8. Two new transactinide nuclides of ²⁵⁹Db and ²⁶⁵Bh were produced successfully via the reactions of ²⁴¹Am(²²Ne, 4n) ²⁵⁹Db and ²⁴³Am(²⁶Mg, 4n) ²⁶⁵Bh, respectively at HIRFL (Heavy Ion Research Facility at Lanzhou). The high-radioactive americium targets with thickness of ∼1 mg/cm² were prepared on 7μm aluminum or 15μm beryllium by molecular platting method at one single cycle. The reaction products were transported and collected using the helium-jet coupling with the rotating wheel apparatus. The identification of ²⁵⁹Db was based on the genetic relationship between the new activity and the known nuclide established by α-recoiled milking measurement. The half-life of ²⁵⁹Db were determined to be 0.5 s and the alpha energy was Ea = 9.47 MeV. Another new isotope ²⁶⁵Bh was identified based on observation of the α-α correlation between the ²⁶⁵Bh and its daughter ²⁶¹Db and ²⁵⁷Lr nuclei using an improved rotating-wheel system. A total of 8 correlated events of ²⁶⁵Bh and 4 events of ²⁶⁴Bh were observed in our experiment. The half-life of ²⁶⁵Bh were determined to be 0.9 s and the alpha energy was E_α = 9.24 MeV. In the next stage of heavy element research at IMP, we plan to do Rf and Db gas-chemistry experiments, An apparatus based on the isothermal gas chromatography is now under construction.

[en] The isotope ²⁶¹Sg and its decay product ²⁵⁷Rf were produced in the nuclear reaction ²⁰⁸Pb(⁵⁴Cr, n)²⁶¹Sg. The radioactive decay of these isotopes was investigated by means of α, α - γ and/or α -X-ray spectroscopy. Improved spectroscopic data concerning α energies, γ transitions, tentative spin and parity assignments of low-lying Nilsson single-neutron orbitals are presented for these nuclei. (orig.)